git/read-cache.c

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/*
* GIT - The information manager from hell
*
* Copyright (C) Linus Torvalds, 2005
*/
#define NO_THE_INDEX_COMPATIBILITY_MACROS
#include "cache.h"
#include "cache-tree.h"
#include "refs.h"
#include "dir.h"
#include "tree.h"
#include "commit.h"
#include "blob.h"
#include "resolve-undo.h"
#include "strbuf.h"
#include "varint.h"
static struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really);
/* Mask for the name length in ce_flags in the on-disk index */
#define CE_NAMEMASK (0x0fff)
/* Index extensions.
*
* The first letter should be 'A'..'Z' for extensions that are not
* necessary for a correct operation (i.e. optimization data).
* When new extensions are added that _needs_ to be understood in
* order to correctly interpret the index file, pick character that
* is outside the range, to cause the reader to abort.
*/
#define CACHE_EXT(s) ( (s[0]<<24)|(s[1]<<16)|(s[2]<<8)|(s[3]) )
#define CACHE_EXT_TREE 0x54524545 /* "TREE" */
#define CACHE_EXT_RESOLVE_UNDO 0x52455543 /* "REUC" */
struct index_state the_index;
static void set_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
{
istate->cache[nr] = ce;
add_name_hash(istate, ce);
}
Create pathname-based hash-table lookup into index This creates a hash index of every single file added to the index. Right now that hash index isn't actually used for much: I implemented a "cache_name_exists()" function that uses it to efficiently look up a filename in the index without having to do the O(logn) binary search, but quite frankly, that's not why this patch is interesting. No, the whole and only reason to create the hash of the filenames in the index is that by modifying the hash function, you can fairly easily do things like making it always hash equivalent names into the same bucket. That, in turn, means that suddenly questions like "does this name exist in the index under an _equivalent_ name?" becomes much much cheaper. Guiding principles behind this patch: - it shouldn't be too costly. In fact, my primary goal here was to actually speed up "git commit" with a fully populated kernel tree, by being faster at checking whether a file already existed in the index. I did succeed, but only barely: Best before: [torvalds@woody linux]$ time git commit > /dev/null real 0m0.255s user 0m0.168s sys 0m0.088s Best after: [torvalds@woody linux]$ time ~/git/git commit > /dev/null real 0m0.233s user 0m0.144s sys 0m0.088s so some things are actually faster (~8%). Caveat: that's really the best case. Other things are invariably going to be slightly slower, since we populate that index cache, and quite frankly, few things really use it to look things up. That said, the cost is really quite small. The worst case is probably doing a "git ls-files", which will do very little except puopulate the index, and never actually looks anything up in it, just lists it. Before: [torvalds@woody linux]$ time git ls-files > /dev/null real 0m0.016s user 0m0.016s sys 0m0.000s After: [torvalds@woody linux]$ time ~/git/git ls-files > /dev/null real 0m0.021s user 0m0.012s sys 0m0.008s and while the thing has really gotten relatively much slower, we're still talking about something almost unmeasurable (eg 5ms). And that really should be pretty much the worst case. So we lose 5ms on one "benchmark", but win 22ms on another. Pick your poison - this patch has the advantage that it will _likely_ speed up the cases that are complex and expensive more than it slows down the cases that are already so fast that nobody cares. But if you look at relative speedups/slowdowns, it doesn't look so good. - It should be simple and clean The code may be a bit subtle (the reasons I do hash removal the way I do etc), but it re-uses the existing hash.c files, so it really is fairly small and straightforward apart from a few odd details. Now, this patch on its own doesn't really do much, but I think it's worth looking at, if only because if done correctly, the name hashing really can make an improvement to the whole issue of "do we have a filename that looks like this in the index already". And at least it gets real testing by being used even by default (ie there is a real use-case for it even without any insane filesystems). NOTE NOTE NOTE! The current hash is a joke. I'm ashamed of it, I'm just not ashamed of it enough to really care. I took all the numbers out of my nether regions - I'm sure it's good enough that it works in practice, but the whole point was that you can make a really much fancier hash that hashes characters not directly, but by their upper-case value or something like that, and thus you get a case-insensitive hash, while still keeping the name and the index itself totally case sensitive. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-23 10:41:14 +08:00
static void replace_index_entry(struct index_state *istate, int nr, struct cache_entry *ce)
{
struct cache_entry *old = istate->cache[nr];
remove_name_hash(old);
Fix name re-hashing semantics We handled the case of removing and re-inserting cache entries badly, which is something that merging commonly needs to do (removing the different stages, and then re-inserting one of them as the merged state). We even had a rather ugly special case for this failure case, where replace_index_entry() basically turned itself into a no-op if the new and the old entries were the same, exactly because the hash routines didn't handle it on their own. So what this patch does is to not just have the UNHASHED bit, but a HASHED bit too, and when you insert an entry into the name hash, that involves: - clear the UNHASHED bit, because now it's valid again for lookup (which is really all that UNHASHED meant) - if we're being lazy, we're done here (but we still want to clear the UNHASHED bit regardless of lazy mode, since we can become unlazy later, and so we need the UNHASHED bit to always be set correctly, even if we never actually insert the entry into the hash list) - if it was already hashed, we just leave it on the list - otherwise mark it HASHED and insert it into the list this all means that unhashing and rehashing a name all just works automatically. Obviously, you cannot change the name of an entry (that would be a serious bug), but nothing can validly do that anyway (you'd have to allocate a new struct cache_entry anyway since the name length could change), so that's not a new limitation. The code actually gets simpler in many ways, although the lazy hashing does mean that there are a few odd cases (ie something can be marked unhashed even though it was never on the hash in the first place, and isn't actually marked hashed!). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-02-23 12:37:40 +08:00
set_index_entry(istate, nr, ce);
Create pathname-based hash-table lookup into index This creates a hash index of every single file added to the index. Right now that hash index isn't actually used for much: I implemented a "cache_name_exists()" function that uses it to efficiently look up a filename in the index without having to do the O(logn) binary search, but quite frankly, that's not why this patch is interesting. No, the whole and only reason to create the hash of the filenames in the index is that by modifying the hash function, you can fairly easily do things like making it always hash equivalent names into the same bucket. That, in turn, means that suddenly questions like "does this name exist in the index under an _equivalent_ name?" becomes much much cheaper. Guiding principles behind this patch: - it shouldn't be too costly. In fact, my primary goal here was to actually speed up "git commit" with a fully populated kernel tree, by being faster at checking whether a file already existed in the index. I did succeed, but only barely: Best before: [torvalds@woody linux]$ time git commit > /dev/null real 0m0.255s user 0m0.168s sys 0m0.088s Best after: [torvalds@woody linux]$ time ~/git/git commit > /dev/null real 0m0.233s user 0m0.144s sys 0m0.088s so some things are actually faster (~8%). Caveat: that's really the best case. Other things are invariably going to be slightly slower, since we populate that index cache, and quite frankly, few things really use it to look things up. That said, the cost is really quite small. The worst case is probably doing a "git ls-files", which will do very little except puopulate the index, and never actually looks anything up in it, just lists it. Before: [torvalds@woody linux]$ time git ls-files > /dev/null real 0m0.016s user 0m0.016s sys 0m0.000s After: [torvalds@woody linux]$ time ~/git/git ls-files > /dev/null real 0m0.021s user 0m0.012s sys 0m0.008s and while the thing has really gotten relatively much slower, we're still talking about something almost unmeasurable (eg 5ms). And that really should be pretty much the worst case. So we lose 5ms on one "benchmark", but win 22ms on another. Pick your poison - this patch has the advantage that it will _likely_ speed up the cases that are complex and expensive more than it slows down the cases that are already so fast that nobody cares. But if you look at relative speedups/slowdowns, it doesn't look so good. - It should be simple and clean The code may be a bit subtle (the reasons I do hash removal the way I do etc), but it re-uses the existing hash.c files, so it really is fairly small and straightforward apart from a few odd details. Now, this patch on its own doesn't really do much, but I think it's worth looking at, if only because if done correctly, the name hashing really can make an improvement to the whole issue of "do we have a filename that looks like this in the index already". And at least it gets real testing by being used even by default (ie there is a real use-case for it even without any insane filesystems). NOTE NOTE NOTE! The current hash is a joke. I'm ashamed of it, I'm just not ashamed of it enough to really care. I took all the numbers out of my nether regions - I'm sure it's good enough that it works in practice, but the whole point was that you can make a really much fancier hash that hashes characters not directly, but by their upper-case value or something like that, and thus you get a case-insensitive hash, while still keeping the name and the index itself totally case sensitive. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-23 10:41:14 +08:00
istate->cache_changed = 1;
}
void rename_index_entry_at(struct index_state *istate, int nr, const char *new_name)
{
struct cache_entry *old = istate->cache[nr], *new;
int namelen = strlen(new_name);
new = xmalloc(cache_entry_size(namelen));
copy_cache_entry(new, old);
new->ce_flags &= ~CE_STATE_MASK;
new->ce_namelen = namelen;
memcpy(new->name, new_name, namelen + 1);
cache_tree_invalidate_path(istate->cache_tree, old->name);
remove_index_entry_at(istate, nr);
add_index_entry(istate, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
}
/*
* This only updates the "non-critical" parts of the directory
* cache, ie the parts that aren't tracked by GIT, and only used
* to validate the cache.
*/
void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
{
ce->ce_ctime.sec = (unsigned int)st->st_ctime;
ce->ce_mtime.sec = (unsigned int)st->st_mtime;
ce->ce_ctime.nsec = ST_CTIME_NSEC(*st);
ce->ce_mtime.nsec = ST_MTIME_NSEC(*st);
ce->ce_dev = st->st_dev;
ce->ce_ino = st->st_ino;
ce->ce_uid = st->st_uid;
ce->ce_gid = st->st_gid;
ce->ce_size = st->st_size;
"Assume unchanged" git This adds "assume unchanged" logic, started by this message in the list discussion recently: <Pine.LNX.4.64.0601311807470.7301@g5.osdl.org> This is a workaround for filesystems that do not have lstat() that is quick enough for the index mechanism to take advantage of. On the paths marked as "assumed to be unchanged", the user needs to explicitly use update-index to register the object name to be in the next commit. You can use two new options to update-index to set and reset the CE_VALID bit: git-update-index --assume-unchanged path... git-update-index --no-assume-unchanged path... These forms manipulate only the CE_VALID bit; it does not change the object name recorded in the index file. Nor they add a new entry to the index. When the configuration variable "core.ignorestat = true" is set, the index entries are marked with CE_VALID bit automatically after: - update-index to explicitly register the current object name to the index file. - when update-index --refresh finds the path to be up-to-date. - when tools like read-tree -u and apply --index update the working tree file and register the current object name to the index file. The flag is dropped upon read-tree that does not check out the index entry. This happens regardless of the core.ignorestat settings. Index entries marked with CE_VALID bit are assumed to be unchanged most of the time. However, there are cases that CE_VALID bit is ignored for the sake of safety and usability: - while "git-read-tree -m" or git-apply need to make sure that the paths involved in the merge do not have local modifications. This sacrifices performance for safety. - when git-checkout-index -f -q -u -a tries to see if it needs to checkout the paths. Otherwise you can never check anything out ;-). - when git-update-index --really-refresh (a new flag) tries to see if the index entry is up to date. You can start with everything marked as CE_VALID and run this once to drop CE_VALID bit for paths that are modified. Most notably, "update-index --refresh" honours CE_VALID and does not actively stat, so after you modified a file in the working tree, update-index --refresh would not notice until you tell the index about it with "git-update-index path" or "git-update-index --no-assume-unchanged path". This version is not expected to be perfect. I think diff between index and/or tree and working files may need some adjustment, and there probably needs other cases we should automatically unmark paths that are marked to be CE_VALID. But the basics seem to work, and ready to be tested by people who asked for this feature. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-09 13:15:24 +08:00
if (assume_unchanged)
ce->ce_flags |= CE_VALID;
if (S_ISREG(st->st_mode))
ce_mark_uptodate(ce);
}
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
static int ce_compare_data(struct cache_entry *ce, struct stat *st)
{
int match = -1;
int fd = open(ce->name, O_RDONLY);
if (fd >= 0) {
unsigned char sha1[20];
if (!index_fd(sha1, fd, st, OBJ_BLOB, ce->name, 0))
match = hashcmp(sha1, ce->sha1);
/* index_fd() closed the file descriptor already */
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
}
return match;
}
static int ce_compare_link(struct cache_entry *ce, size_t expected_size)
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
{
int match = -1;
void *buffer;
unsigned long size;
enum object_type type;
struct strbuf sb = STRBUF_INIT;
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
if (strbuf_readlink(&sb, ce->name, expected_size))
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
return -1;
buffer = read_sha1_file(ce->sha1, &type, &size);
if (buffer) {
if (size == sb.len)
match = memcmp(buffer, sb.buf, size);
free(buffer);
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
}
strbuf_release(&sb);
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
return match;
}
static int ce_compare_gitlink(struct cache_entry *ce)
{
unsigned char sha1[20];
/*
* We don't actually require that the .git directory
* under GITLINK directory be a valid git directory. It
* might even be missing (in case nobody populated that
* sub-project).
*
* If so, we consider it always to match.
*/
if (resolve_gitlink_ref(ce->name, "HEAD", sha1) < 0)
return 0;
return hashcmp(sha1, ce->sha1);
}
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
static int ce_modified_check_fs(struct cache_entry *ce, struct stat *st)
{
switch (st->st_mode & S_IFMT) {
case S_IFREG:
if (ce_compare_data(ce, st))
return DATA_CHANGED;
break;
case S_IFLNK:
if (ce_compare_link(ce, xsize_t(st->st_size)))
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
return DATA_CHANGED;
break;
case S_IFDIR:
if (S_ISGITLINK(ce->ce_mode))
2008-07-29 16:13:44 +08:00
return ce_compare_gitlink(ce) ? DATA_CHANGED : 0;
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
default:
return TYPE_CHANGED;
}
return 0;
}
static int ce_match_stat_basic(struct cache_entry *ce, struct stat *st)
{
unsigned int changed = 0;
if (ce->ce_flags & CE_REMOVE)
return MODE_CHANGED | DATA_CHANGED | TYPE_CHANGED;
switch (ce->ce_mode & S_IFMT) {
case S_IFREG:
changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
/* We consider only the owner x bit to be relevant for
* "mode changes"
*/
if (trust_executable_bit &&
(0100 & (ce->ce_mode ^ st->st_mode)))
changed |= MODE_CHANGED;
break;
case S_IFLNK:
if (!S_ISLNK(st->st_mode) &&
(has_symlinks || !S_ISREG(st->st_mode)))
changed |= TYPE_CHANGED;
break;
case S_IFGITLINK:
2008-07-29 16:13:44 +08:00
/* We ignore most of the st_xxx fields for gitlinks */
if (!S_ISDIR(st->st_mode))
changed |= TYPE_CHANGED;
else if (ce_compare_gitlink(ce))
changed |= DATA_CHANGED;
return changed;
default:
die("internal error: ce_mode is %o", ce->ce_mode);
}
if (ce->ce_mtime.sec != (unsigned int)st->st_mtime)
changed |= MTIME_CHANGED;
if (trust_ctime && ce->ce_ctime.sec != (unsigned int)st->st_ctime)
changed |= CTIME_CHANGED;
#ifdef USE_NSEC
if (ce->ce_mtime.nsec != ST_MTIME_NSEC(*st))
changed |= MTIME_CHANGED;
if (trust_ctime && ce->ce_ctime.nsec != ST_CTIME_NSEC(*st))
changed |= CTIME_CHANGED;
#endif
if (ce->ce_uid != (unsigned int) st->st_uid ||
ce->ce_gid != (unsigned int) st->st_gid)
changed |= OWNER_CHANGED;
if (ce->ce_ino != (unsigned int) st->st_ino)
changed |= INODE_CHANGED;
#ifdef USE_STDEV
/*
* st_dev breaks on network filesystems where different
* clients will have different views of what "device"
* the filesystem is on
*/
if (ce->ce_dev != (unsigned int) st->st_dev)
changed |= INODE_CHANGED;
#endif
if (ce->ce_size != (unsigned int) st->st_size)
changed |= DATA_CHANGED;
/* Racily smudged entry? */
if (!ce->ce_size) {
if (!is_empty_blob_sha1(ce->sha1))
changed |= DATA_CHANGED;
}
return changed;
}
static int is_racy_timestamp(const struct index_state *istate, struct cache_entry *ce)
{
return (!S_ISGITLINK(ce->ce_mode) &&
istate->timestamp.sec &&
#ifdef USE_NSEC
/* nanosecond timestamped files can also be racy! */
(istate->timestamp.sec < ce->ce_mtime.sec ||
(istate->timestamp.sec == ce->ce_mtime.sec &&
istate->timestamp.nsec <= ce->ce_mtime.nsec))
#else
istate->timestamp.sec <= ce->ce_mtime.sec
#endif
);
}
int ie_match_stat(const struct index_state *istate,
struct cache_entry *ce, struct stat *st,
unsigned int options)
{
"Assume unchanged" git This adds "assume unchanged" logic, started by this message in the list discussion recently: <Pine.LNX.4.64.0601311807470.7301@g5.osdl.org> This is a workaround for filesystems that do not have lstat() that is quick enough for the index mechanism to take advantage of. On the paths marked as "assumed to be unchanged", the user needs to explicitly use update-index to register the object name to be in the next commit. You can use two new options to update-index to set and reset the CE_VALID bit: git-update-index --assume-unchanged path... git-update-index --no-assume-unchanged path... These forms manipulate only the CE_VALID bit; it does not change the object name recorded in the index file. Nor they add a new entry to the index. When the configuration variable "core.ignorestat = true" is set, the index entries are marked with CE_VALID bit automatically after: - update-index to explicitly register the current object name to the index file. - when update-index --refresh finds the path to be up-to-date. - when tools like read-tree -u and apply --index update the working tree file and register the current object name to the index file. The flag is dropped upon read-tree that does not check out the index entry. This happens regardless of the core.ignorestat settings. Index entries marked with CE_VALID bit are assumed to be unchanged most of the time. However, there are cases that CE_VALID bit is ignored for the sake of safety and usability: - while "git-read-tree -m" or git-apply need to make sure that the paths involved in the merge do not have local modifications. This sacrifices performance for safety. - when git-checkout-index -f -q -u -a tries to see if it needs to checkout the paths. Otherwise you can never check anything out ;-). - when git-update-index --really-refresh (a new flag) tries to see if the index entry is up to date. You can start with everything marked as CE_VALID and run this once to drop CE_VALID bit for paths that are modified. Most notably, "update-index --refresh" honours CE_VALID and does not actively stat, so after you modified a file in the working tree, update-index --refresh would not notice until you tell the index about it with "git-update-index path" or "git-update-index --no-assume-unchanged path". This version is not expected to be perfect. I think diff between index and/or tree and working files may need some adjustment, and there probably needs other cases we should automatically unmark paths that are marked to be CE_VALID. But the basics seem to work, and ready to be tested by people who asked for this feature. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-09 13:15:24 +08:00
unsigned int changed;
int ignore_valid = options & CE_MATCH_IGNORE_VALID;
int ignore_skip_worktree = options & CE_MATCH_IGNORE_SKIP_WORKTREE;
int assume_racy_is_modified = options & CE_MATCH_RACY_IS_DIRTY;
"Assume unchanged" git This adds "assume unchanged" logic, started by this message in the list discussion recently: <Pine.LNX.4.64.0601311807470.7301@g5.osdl.org> This is a workaround for filesystems that do not have lstat() that is quick enough for the index mechanism to take advantage of. On the paths marked as "assumed to be unchanged", the user needs to explicitly use update-index to register the object name to be in the next commit. You can use two new options to update-index to set and reset the CE_VALID bit: git-update-index --assume-unchanged path... git-update-index --no-assume-unchanged path... These forms manipulate only the CE_VALID bit; it does not change the object name recorded in the index file. Nor they add a new entry to the index. When the configuration variable "core.ignorestat = true" is set, the index entries are marked with CE_VALID bit automatically after: - update-index to explicitly register the current object name to the index file. - when update-index --refresh finds the path to be up-to-date. - when tools like read-tree -u and apply --index update the working tree file and register the current object name to the index file. The flag is dropped upon read-tree that does not check out the index entry. This happens regardless of the core.ignorestat settings. Index entries marked with CE_VALID bit are assumed to be unchanged most of the time. However, there are cases that CE_VALID bit is ignored for the sake of safety and usability: - while "git-read-tree -m" or git-apply need to make sure that the paths involved in the merge do not have local modifications. This sacrifices performance for safety. - when git-checkout-index -f -q -u -a tries to see if it needs to checkout the paths. Otherwise you can never check anything out ;-). - when git-update-index --really-refresh (a new flag) tries to see if the index entry is up to date. You can start with everything marked as CE_VALID and run this once to drop CE_VALID bit for paths that are modified. Most notably, "update-index --refresh" honours CE_VALID and does not actively stat, so after you modified a file in the working tree, update-index --refresh would not notice until you tell the index about it with "git-update-index path" or "git-update-index --no-assume-unchanged path". This version is not expected to be perfect. I think diff between index and/or tree and working files may need some adjustment, and there probably needs other cases we should automatically unmark paths that are marked to be CE_VALID. But the basics seem to work, and ready to be tested by people who asked for this feature. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-09 13:15:24 +08:00
/*
* If it's marked as always valid in the index, it's
* valid whatever the checked-out copy says.
*
* skip-worktree has the same effect with higher precedence
"Assume unchanged" git This adds "assume unchanged" logic, started by this message in the list discussion recently: <Pine.LNX.4.64.0601311807470.7301@g5.osdl.org> This is a workaround for filesystems that do not have lstat() that is quick enough for the index mechanism to take advantage of. On the paths marked as "assumed to be unchanged", the user needs to explicitly use update-index to register the object name to be in the next commit. You can use two new options to update-index to set and reset the CE_VALID bit: git-update-index --assume-unchanged path... git-update-index --no-assume-unchanged path... These forms manipulate only the CE_VALID bit; it does not change the object name recorded in the index file. Nor they add a new entry to the index. When the configuration variable "core.ignorestat = true" is set, the index entries are marked with CE_VALID bit automatically after: - update-index to explicitly register the current object name to the index file. - when update-index --refresh finds the path to be up-to-date. - when tools like read-tree -u and apply --index update the working tree file and register the current object name to the index file. The flag is dropped upon read-tree that does not check out the index entry. This happens regardless of the core.ignorestat settings. Index entries marked with CE_VALID bit are assumed to be unchanged most of the time. However, there are cases that CE_VALID bit is ignored for the sake of safety and usability: - while "git-read-tree -m" or git-apply need to make sure that the paths involved in the merge do not have local modifications. This sacrifices performance for safety. - when git-checkout-index -f -q -u -a tries to see if it needs to checkout the paths. Otherwise you can never check anything out ;-). - when git-update-index --really-refresh (a new flag) tries to see if the index entry is up to date. You can start with everything marked as CE_VALID and run this once to drop CE_VALID bit for paths that are modified. Most notably, "update-index --refresh" honours CE_VALID and does not actively stat, so after you modified a file in the working tree, update-index --refresh would not notice until you tell the index about it with "git-update-index path" or "git-update-index --no-assume-unchanged path". This version is not expected to be perfect. I think diff between index and/or tree and working files may need some adjustment, and there probably needs other cases we should automatically unmark paths that are marked to be CE_VALID. But the basics seem to work, and ready to be tested by people who asked for this feature. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-09 13:15:24 +08:00
*/
if (!ignore_skip_worktree && ce_skip_worktree(ce))
return 0;
if (!ignore_valid && (ce->ce_flags & CE_VALID))
"Assume unchanged" git This adds "assume unchanged" logic, started by this message in the list discussion recently: <Pine.LNX.4.64.0601311807470.7301@g5.osdl.org> This is a workaround for filesystems that do not have lstat() that is quick enough for the index mechanism to take advantage of. On the paths marked as "assumed to be unchanged", the user needs to explicitly use update-index to register the object name to be in the next commit. You can use two new options to update-index to set and reset the CE_VALID bit: git-update-index --assume-unchanged path... git-update-index --no-assume-unchanged path... These forms manipulate only the CE_VALID bit; it does not change the object name recorded in the index file. Nor they add a new entry to the index. When the configuration variable "core.ignorestat = true" is set, the index entries are marked with CE_VALID bit automatically after: - update-index to explicitly register the current object name to the index file. - when update-index --refresh finds the path to be up-to-date. - when tools like read-tree -u and apply --index update the working tree file and register the current object name to the index file. The flag is dropped upon read-tree that does not check out the index entry. This happens regardless of the core.ignorestat settings. Index entries marked with CE_VALID bit are assumed to be unchanged most of the time. However, there are cases that CE_VALID bit is ignored for the sake of safety and usability: - while "git-read-tree -m" or git-apply need to make sure that the paths involved in the merge do not have local modifications. This sacrifices performance for safety. - when git-checkout-index -f -q -u -a tries to see if it needs to checkout the paths. Otherwise you can never check anything out ;-). - when git-update-index --really-refresh (a new flag) tries to see if the index entry is up to date. You can start with everything marked as CE_VALID and run this once to drop CE_VALID bit for paths that are modified. Most notably, "update-index --refresh" honours CE_VALID and does not actively stat, so after you modified a file in the working tree, update-index --refresh would not notice until you tell the index about it with "git-update-index path" or "git-update-index --no-assume-unchanged path". This version is not expected to be perfect. I think diff between index and/or tree and working files may need some adjustment, and there probably needs other cases we should automatically unmark paths that are marked to be CE_VALID. But the basics seem to work, and ready to be tested by people who asked for this feature. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-09 13:15:24 +08:00
return 0;
/*
* Intent-to-add entries have not been added, so the index entry
* by definition never matches what is in the work tree until it
* actually gets added.
*/
if (ce->ce_flags & CE_INTENT_TO_ADD)
return DATA_CHANGED | TYPE_CHANGED | MODE_CHANGED;
"Assume unchanged" git This adds "assume unchanged" logic, started by this message in the list discussion recently: <Pine.LNX.4.64.0601311807470.7301@g5.osdl.org> This is a workaround for filesystems that do not have lstat() that is quick enough for the index mechanism to take advantage of. On the paths marked as "assumed to be unchanged", the user needs to explicitly use update-index to register the object name to be in the next commit. You can use two new options to update-index to set and reset the CE_VALID bit: git-update-index --assume-unchanged path... git-update-index --no-assume-unchanged path... These forms manipulate only the CE_VALID bit; it does not change the object name recorded in the index file. Nor they add a new entry to the index. When the configuration variable "core.ignorestat = true" is set, the index entries are marked with CE_VALID bit automatically after: - update-index to explicitly register the current object name to the index file. - when update-index --refresh finds the path to be up-to-date. - when tools like read-tree -u and apply --index update the working tree file and register the current object name to the index file. The flag is dropped upon read-tree that does not check out the index entry. This happens regardless of the core.ignorestat settings. Index entries marked with CE_VALID bit are assumed to be unchanged most of the time. However, there are cases that CE_VALID bit is ignored for the sake of safety and usability: - while "git-read-tree -m" or git-apply need to make sure that the paths involved in the merge do not have local modifications. This sacrifices performance for safety. - when git-checkout-index -f -q -u -a tries to see if it needs to checkout the paths. Otherwise you can never check anything out ;-). - when git-update-index --really-refresh (a new flag) tries to see if the index entry is up to date. You can start with everything marked as CE_VALID and run this once to drop CE_VALID bit for paths that are modified. Most notably, "update-index --refresh" honours CE_VALID and does not actively stat, so after you modified a file in the working tree, update-index --refresh would not notice until you tell the index about it with "git-update-index path" or "git-update-index --no-assume-unchanged path". This version is not expected to be perfect. I think diff between index and/or tree and working files may need some adjustment, and there probably needs other cases we should automatically unmark paths that are marked to be CE_VALID. But the basics seem to work, and ready to be tested by people who asked for this feature. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-09 13:15:24 +08:00
changed = ce_match_stat_basic(ce, st);
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
/*
* Within 1 second of this sequence:
* echo xyzzy >file && git-update-index --add file
* running this command:
* echo frotz >file
* would give a falsely clean cache entry. The mtime and
* length match the cache, and other stat fields do not change.
*
* We could detect this at update-index time (the cache entry
* being registered/updated records the same time as "now")
* and delay the return from git-update-index, but that would
* effectively mean we can make at most one commit per second,
* which is not acceptable. Instead, we check cache entries
* whose mtime are the same as the index file timestamp more
"Assume unchanged" git This adds "assume unchanged" logic, started by this message in the list discussion recently: <Pine.LNX.4.64.0601311807470.7301@g5.osdl.org> This is a workaround for filesystems that do not have lstat() that is quick enough for the index mechanism to take advantage of. On the paths marked as "assumed to be unchanged", the user needs to explicitly use update-index to register the object name to be in the next commit. You can use two new options to update-index to set and reset the CE_VALID bit: git-update-index --assume-unchanged path... git-update-index --no-assume-unchanged path... These forms manipulate only the CE_VALID bit; it does not change the object name recorded in the index file. Nor they add a new entry to the index. When the configuration variable "core.ignorestat = true" is set, the index entries are marked with CE_VALID bit automatically after: - update-index to explicitly register the current object name to the index file. - when update-index --refresh finds the path to be up-to-date. - when tools like read-tree -u and apply --index update the working tree file and register the current object name to the index file. The flag is dropped upon read-tree that does not check out the index entry. This happens regardless of the core.ignorestat settings. Index entries marked with CE_VALID bit are assumed to be unchanged most of the time. However, there are cases that CE_VALID bit is ignored for the sake of safety and usability: - while "git-read-tree -m" or git-apply need to make sure that the paths involved in the merge do not have local modifications. This sacrifices performance for safety. - when git-checkout-index -f -q -u -a tries to see if it needs to checkout the paths. Otherwise you can never check anything out ;-). - when git-update-index --really-refresh (a new flag) tries to see if the index entry is up to date. You can start with everything marked as CE_VALID and run this once to drop CE_VALID bit for paths that are modified. Most notably, "update-index --refresh" honours CE_VALID and does not actively stat, so after you modified a file in the working tree, update-index --refresh would not notice until you tell the index about it with "git-update-index path" or "git-update-index --no-assume-unchanged path". This version is not expected to be perfect. I think diff between index and/or tree and working files may need some adjustment, and there probably needs other cases we should automatically unmark paths that are marked to be CE_VALID. But the basics seem to work, and ready to be tested by people who asked for this feature. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-09 13:15:24 +08:00
* carefully than others.
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
*/
if (!changed && is_racy_timestamp(istate, ce)) {
if (assume_racy_is_modified)
changed |= DATA_CHANGED;
else
changed |= ce_modified_check_fs(ce, st);
}
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
return changed;
}
int ie_modified(const struct index_state *istate,
struct cache_entry *ce, struct stat *st, unsigned int options)
{
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
int changed, changed_fs;
changed = ie_match_stat(istate, ce, st, options);
if (!changed)
return 0;
/*
* If the mode or type has changed, there's no point in trying
* to refresh the entry - it's not going to match
*/
if (changed & (MODE_CHANGED | TYPE_CHANGED))
return changed;
2008-07-29 16:13:44 +08:00
/*
* Immediately after read-tree or update-index --cacheinfo,
* the length field is zero, as we have never even read the
* lstat(2) information once, and we cannot trust DATA_CHANGED
* returned by ie_match_stat() which in turn was returned by
* ce_match_stat_basic() to signal that the filesize of the
* blob changed. We have to actually go to the filesystem to
* see if the contents match, and if so, should answer "unchanged".
*
* The logic does not apply to gitlinks, as ce_match_stat_basic()
* already has checked the actual HEAD from the filesystem in the
* subproject. If ie_match_stat() already said it is different,
* then we know it is.
*/
2008-07-29 16:13:44 +08:00
if ((changed & DATA_CHANGED) &&
(S_ISGITLINK(ce->ce_mode) || ce->ce_size != 0))
return changed;
Racy GIT This fixes the longstanding "Racy GIT" problem, which was pretty much there from the beginning of time, but was first demonstrated by Pasky in this message on October 24, 2005: http://marc.theaimsgroup.com/?l=git&m=113014629716878 If you run the following sequence of commands: echo frotz >infocom git update-index --add infocom echo xyzzy >infocom so that the second update to file "infocom" does not change st_mtime, what is recorded as the stat information for the cache entry "infocom" exactly matches what is on the filesystem (owner, group, inum, mtime, ctime, mode, length). After this sequence, we incorrectly think "infocom" file still has string "frotz" in it, and get really confused. E.g. git-diff-files would say there is no change, git-update-index --refresh would not even look at the filesystem to correct the situation. Some ways of working around this issue were already suggested by Linus in the same thread on the same day, including waiting until the next second before returning from update-index if a cache entry written out has the current timestamp, but that means we can make at most one commit per second, and given that the e-mail patch workflow used by Linus needs to process at least 5 commits per second, it is not an acceptable solution. Linus notes that git-apply is primarily used to update the index while processing e-mailed patches, which is true, and git-apply's up-to-date check is fooled by the same problem but luckily in the other direction, so it is not really a big issue, but still it is disturbing. The function ce_match_stat() is called to bypass the comparison against filesystem data when the stat data recorded in the cache entry matches what stat() returns from the filesystem. This patch tackles the problem by changing it to actually go to the filesystem data for cache entries that have the same mtime as the index file itself. This works as long as the index file and working tree files are on the filesystems that share the same monotonic clock. Files on network mounted filesystems sometimes get skewed timestamps compared to "date" output, but as long as working tree files' timestamps are skewed the same way as the index file's, this approach still works. The only problematic files are the ones that have the same timestamp as the index file's, because two file updates that sandwitch the index file update must happen within the same second to trigger the problem. Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-20 16:02:15 +08:00
changed_fs = ce_modified_check_fs(ce, st);
if (changed_fs)
return changed | changed_fs;
return 0;
}
int base_name_compare(const char *name1, int len1, int mode1,
const char *name2, int len2, int mode2)
{
unsigned char c1, c2;
int len = len1 < len2 ? len1 : len2;
int cmp;
cmp = memcmp(name1, name2, len);
if (cmp)
return cmp;
c1 = name1[len];
c2 = name2[len];
if (!c1 && S_ISDIR(mode1))
c1 = '/';
if (!c2 && S_ISDIR(mode2))
c2 = '/';
return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
}
/*
* df_name_compare() is identical to base_name_compare(), except it
* compares conflicting directory/file entries as equal. Note that
* while a directory name compares as equal to a regular file, they
* then individually compare _differently_ to a filename that has
* a dot after the basename (because '\0' < '.' < '/').
*
* This is used by routines that want to traverse the git namespace
* but then handle conflicting entries together when possible.
*/
int df_name_compare(const char *name1, int len1, int mode1,
const char *name2, int len2, int mode2)
{
int len = len1 < len2 ? len1 : len2, cmp;
unsigned char c1, c2;
cmp = memcmp(name1, name2, len);
if (cmp)
return cmp;
/* Directories and files compare equal (same length, same name) */
if (len1 == len2)
return 0;
c1 = name1[len];
if (!c1 && S_ISDIR(mode1))
c1 = '/';
c2 = name2[len];
if (!c2 && S_ISDIR(mode2))
c2 = '/';
if (c1 == '/' && !c2)
return 0;
if (c2 == '/' && !c1)
return 0;
return c1 - c2;
}
int cache_name_stage_compare(const char *name1, int len1, int stage1, const char *name2, int len2, int stage2)
{
int len = len1 < len2 ? len1 : len2;
int cmp;
cmp = memcmp(name1, name2, len);
if (cmp)
return cmp;
if (len1 < len2)
return -1;
if (len1 > len2)
return 1;
"Assume unchanged" git This adds "assume unchanged" logic, started by this message in the list discussion recently: <Pine.LNX.4.64.0601311807470.7301@g5.osdl.org> This is a workaround for filesystems that do not have lstat() that is quick enough for the index mechanism to take advantage of. On the paths marked as "assumed to be unchanged", the user needs to explicitly use update-index to register the object name to be in the next commit. You can use two new options to update-index to set and reset the CE_VALID bit: git-update-index --assume-unchanged path... git-update-index --no-assume-unchanged path... These forms manipulate only the CE_VALID bit; it does not change the object name recorded in the index file. Nor they add a new entry to the index. When the configuration variable "core.ignorestat = true" is set, the index entries are marked with CE_VALID bit automatically after: - update-index to explicitly register the current object name to the index file. - when update-index --refresh finds the path to be up-to-date. - when tools like read-tree -u and apply --index update the working tree file and register the current object name to the index file. The flag is dropped upon read-tree that does not check out the index entry. This happens regardless of the core.ignorestat settings. Index entries marked with CE_VALID bit are assumed to be unchanged most of the time. However, there are cases that CE_VALID bit is ignored for the sake of safety and usability: - while "git-read-tree -m" or git-apply need to make sure that the paths involved in the merge do not have local modifications. This sacrifices performance for safety. - when git-checkout-index -f -q -u -a tries to see if it needs to checkout the paths. Otherwise you can never check anything out ;-). - when git-update-index --really-refresh (a new flag) tries to see if the index entry is up to date. You can start with everything marked as CE_VALID and run this once to drop CE_VALID bit for paths that are modified. Most notably, "update-index --refresh" honours CE_VALID and does not actively stat, so after you modified a file in the working tree, update-index --refresh would not notice until you tell the index about it with "git-update-index path" or "git-update-index --no-assume-unchanged path". This version is not expected to be perfect. I think diff between index and/or tree and working files may need some adjustment, and there probably needs other cases we should automatically unmark paths that are marked to be CE_VALID. But the basics seem to work, and ready to be tested by people who asked for this feature. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-09 13:15:24 +08:00
if (stage1 < stage2)
return -1;
if (stage1 > stage2)
return 1;
return 0;
}
int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
{
return cache_name_stage_compare(name1, len1, 0, name2, len2, 0);
}
static int index_name_stage_pos(const struct index_state *istate, const char *name, int namelen, int stage)
{
int first, last;
first = 0;
last = istate->cache_nr;
while (last > first) {
int next = (last + first) >> 1;
struct cache_entry *ce = istate->cache[next];
int cmp = cache_name_stage_compare(name, namelen, stage, ce->name, ce_namelen(ce), ce_stage(ce));
if (!cmp)
return next;
if (cmp < 0) {
last = next;
continue;
}
first = next+1;
}
return -first-1;
}
int index_name_pos(const struct index_state *istate, const char *name, int namelen)
{
return index_name_stage_pos(istate, name, namelen, 0);
}
/* Remove entry, return true if there are more entries to go.. */
int remove_index_entry_at(struct index_state *istate, int pos)
{
Create pathname-based hash-table lookup into index This creates a hash index of every single file added to the index. Right now that hash index isn't actually used for much: I implemented a "cache_name_exists()" function that uses it to efficiently look up a filename in the index without having to do the O(logn) binary search, but quite frankly, that's not why this patch is interesting. No, the whole and only reason to create the hash of the filenames in the index is that by modifying the hash function, you can fairly easily do things like making it always hash equivalent names into the same bucket. That, in turn, means that suddenly questions like "does this name exist in the index under an _equivalent_ name?" becomes much much cheaper. Guiding principles behind this patch: - it shouldn't be too costly. In fact, my primary goal here was to actually speed up "git commit" with a fully populated kernel tree, by being faster at checking whether a file already existed in the index. I did succeed, but only barely: Best before: [torvalds@woody linux]$ time git commit > /dev/null real 0m0.255s user 0m0.168s sys 0m0.088s Best after: [torvalds@woody linux]$ time ~/git/git commit > /dev/null real 0m0.233s user 0m0.144s sys 0m0.088s so some things are actually faster (~8%). Caveat: that's really the best case. Other things are invariably going to be slightly slower, since we populate that index cache, and quite frankly, few things really use it to look things up. That said, the cost is really quite small. The worst case is probably doing a "git ls-files", which will do very little except puopulate the index, and never actually looks anything up in it, just lists it. Before: [torvalds@woody linux]$ time git ls-files > /dev/null real 0m0.016s user 0m0.016s sys 0m0.000s After: [torvalds@woody linux]$ time ~/git/git ls-files > /dev/null real 0m0.021s user 0m0.012s sys 0m0.008s and while the thing has really gotten relatively much slower, we're still talking about something almost unmeasurable (eg 5ms). And that really should be pretty much the worst case. So we lose 5ms on one "benchmark", but win 22ms on another. Pick your poison - this patch has the advantage that it will _likely_ speed up the cases that are complex and expensive more than it slows down the cases that are already so fast that nobody cares. But if you look at relative speedups/slowdowns, it doesn't look so good. - It should be simple and clean The code may be a bit subtle (the reasons I do hash removal the way I do etc), but it re-uses the existing hash.c files, so it really is fairly small and straightforward apart from a few odd details. Now, this patch on its own doesn't really do much, but I think it's worth looking at, if only because if done correctly, the name hashing really can make an improvement to the whole issue of "do we have a filename that looks like this in the index already". And at least it gets real testing by being used even by default (ie there is a real use-case for it even without any insane filesystems). NOTE NOTE NOTE! The current hash is a joke. I'm ashamed of it, I'm just not ashamed of it enough to really care. I took all the numbers out of my nether regions - I'm sure it's good enough that it works in practice, but the whole point was that you can make a really much fancier hash that hashes characters not directly, but by their upper-case value or something like that, and thus you get a case-insensitive hash, while still keeping the name and the index itself totally case sensitive. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-23 10:41:14 +08:00
struct cache_entry *ce = istate->cache[pos];
record_resolve_undo(istate, ce);
remove_name_hash(ce);
istate->cache_changed = 1;
istate->cache_nr--;
if (pos >= istate->cache_nr)
return 0;
memmove(istate->cache + pos,
istate->cache + pos + 1,
(istate->cache_nr - pos) * sizeof(struct cache_entry *));
return 1;
}
check_updates(): effective removal of cache entries marked CE_REMOVE Below is oprofile output from GIT command 'git chekcout -q my-v2.6.25' (move from tag v2.6.27 to tag v2.6.25 of the Linux kernel): CPU: Core 2, speed 1999.95 MHz (estimated) Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask of 0x00 (Unhalted core cycles) count 20000 Counted INST_RETIRED_ANY_P events (number of instructions retired) with a unit mask of 0x00 (No unit mask) count 20000 CPU_CLK_UNHALT...|INST_RETIRED:2...| samples| %| samples| %| ------------------------------------ 409247 100.000 342878 100.000 git CPU_CLK_UNHALT...|INST_RETIRED:2...| samples| %| samples| %| ------------------------------------ 260476 63.6476 257843 75.1996 libz.so.1.2.3 100876 24.6492 64378 18.7758 kernel-2.6.28.4_2.vmlinux 30850 7.5382 7874 2.2964 libc-2.9.so 14775 3.6103 8390 2.4469 git 2020 0.4936 4325 1.2614 libcrypto.so.0.9.8 191 0.0467 32 0.0093 libpthread-2.9.so 58 0.0142 36 0.0105 ld-2.9.so 1 2.4e-04 0 0 libldap-2.3.so.0.2.31 Detail list of the top 20 function entries (libz counted in one blob): CPU_CLK_UNHALTED INST_RETIRED_ANY_P samples % samples % image name symbol name 260476 63.6862 257843 75.2725 libz.so.1.2.3 /lib/libz.so.1.2.3 16587 4.0555 3636 1.0615 libc-2.9.so memcpy 7710 1.8851 277 0.0809 libc-2.9.so memmove 3679 0.8995 1108 0.3235 kernel-2.6.28.4_2.vmlinux d_validate 3546 0.8670 2607 0.7611 kernel-2.6.28.4_2.vmlinux __getblk 3174 0.7760 1813 0.5293 libc-2.9.so _int_malloc 2396 0.5858 3681 1.0746 kernel-2.6.28.4_2.vmlinux copy_to_user 2270 0.5550 2528 0.7380 kernel-2.6.28.4_2.vmlinux __link_path_walk 2205 0.5391 1797 0.5246 kernel-2.6.28.4_2.vmlinux ext4_mark_iloc_dirty 2103 0.5142 1203 0.3512 kernel-2.6.28.4_2.vmlinux find_first_zero_bit 2077 0.5078 997 0.2911 kernel-2.6.28.4_2.vmlinux do_get_write_access 2070 0.5061 514 0.1501 git cache_name_compare 2043 0.4995 1501 0.4382 kernel-2.6.28.4_2.vmlinux rcu_irq_exit 2022 0.4944 1732 0.5056 kernel-2.6.28.4_2.vmlinux __ext4_get_inode_loc 2020 0.4939 4325 1.2626 libcrypto.so.0.9.8 /usr/lib/libcrypto.so.0.9.8 1965 0.4804 1384 0.4040 git patch_delta 1708 0.4176 984 0.2873 kernel-2.6.28.4_2.vmlinux rcu_sched_grace_period 1682 0.4112 727 0.2122 kernel-2.6.28.4_2.vmlinux sysfs_slab_alias 1659 0.4056 290 0.0847 git find_pack_entry_one 1480 0.3619 1307 0.3816 kernel-2.6.28.4_2.vmlinux ext4_writepage_trans_blocks Notice the memmove line, where the CPU did 7710 / 277 = 27.8 cycles per instruction, and compared to the total cycles spent inside the source code of GIT for this command, all the memmove() calls translates to (7710 * 100) / 14775 = 52.2% of this. Retesting with a GIT program compiled for gcov usage, I found out that the memmove() calls came from remove_index_entry_at() in read-cache.c, where we have: memmove(istate->cache + pos, istate->cache + pos + 1, (istate->cache_nr - pos) * sizeof(struct cache_entry *)); remove_index_entry_at() is called 4902 times from check_updates() in unpack-trees.c, and each time called we move each cache_entry pointers (from the removed one) one step to the left. Since we have 28828 entries in the cache this time, and if we on average move half of them each time, we in total move approximately 4902 * 0.5 * 28828 * 4 = 282 629 712 bytes, or twice this amount if each pointer is 8 bytes (64 bit). OK, is seems that the function check_updates() is called 28 times, so the estimated guess above had been more correct if check_updates() had been called only once, but the point is: we get lots of bytes moved. To fix this, and use an O(N) algorithm instead, where N is the number of cache_entries, we delete/remove all entries in one loop through all entries. From a retest, the new remove_marked_cache_entries() from the patch below, ended up with the following output line from oprofile: 46 0.0105 15 0.0041 git remove_marked_cache_entries If we can trust the numbers from oprofile in this case, we saved approximately ((7710 - 46) * 20000) / (2 * 1000 * 1000 * 1000) = 0.077 seconds CPU time with this fix for this particular test. And notice that now the CPU did only 46 / 15 = 3.1 cycles/instruction. Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-02-19 06:18:03 +08:00
/*
* Remove all cache ententries marked for removal, that is where
* CE_REMOVE is set in ce_flags. This is much more effective than
* calling remove_index_entry_at() for each entry to be removed.
*/
void remove_marked_cache_entries(struct index_state *istate)
{
struct cache_entry **ce_array = istate->cache;
unsigned int i, j;
for (i = j = 0; i < istate->cache_nr; i++) {
if (ce_array[i]->ce_flags & CE_REMOVE)
remove_name_hash(ce_array[i]);
else
ce_array[j++] = ce_array[i];
}
istate->cache_changed = 1;
istate->cache_nr = j;
}
int remove_file_from_index(struct index_state *istate, const char *path)
{
int pos = index_name_pos(istate, path, strlen(path));
if (pos < 0)
pos = -pos-1;
cache_tree_invalidate_path(istate->cache_tree, path);
while (pos < istate->cache_nr && !strcmp(istate->cache[pos]->name, path))
remove_index_entry_at(istate, pos);
return 0;
}
static int compare_name(struct cache_entry *ce, const char *path, int namelen)
{
return namelen != ce_namelen(ce) || memcmp(path, ce->name, namelen);
}
static int index_name_pos_also_unmerged(struct index_state *istate,
const char *path, int namelen)
{
int pos = index_name_pos(istate, path, namelen);
struct cache_entry *ce;
if (pos >= 0)
return pos;
/* maybe unmerged? */
pos = -1 - pos;
if (pos >= istate->cache_nr ||
compare_name((ce = istate->cache[pos]), path, namelen))
return -1;
/* order of preference: stage 2, 1, 3 */
if (ce_stage(ce) == 1 && pos + 1 < istate->cache_nr &&
ce_stage((ce = istate->cache[pos + 1])) == 2 &&
!compare_name(ce, path, namelen))
pos++;
return pos;
}
static int different_name(struct cache_entry *ce, struct cache_entry *alias)
{
int len = ce_namelen(ce);
return ce_namelen(alias) != len || memcmp(ce->name, alias->name, len);
}
/*
* If we add a filename that aliases in the cache, we will use the
* name that we already have - but we don't want to update the same
* alias twice, because that implies that there were actually two
* different files with aliasing names!
*
* So we use the CE_ADDED flag to verify that the alias was an old
* one before we accept it as
*/
static struct cache_entry *create_alias_ce(struct cache_entry *ce, struct cache_entry *alias)
{
int len;
struct cache_entry *new;
if (alias->ce_flags & CE_ADDED)
die("Will not add file alias '%s' ('%s' already exists in index)", ce->name, alias->name);
/* Ok, create the new entry using the name of the existing alias */
len = ce_namelen(alias);
new = xcalloc(1, cache_entry_size(len));
memcpy(new->name, alias->name, len);
copy_cache_entry(new, ce);
free(ce);
return new;
}
static void record_intent_to_add(struct cache_entry *ce)
{
unsigned char sha1[20];
if (write_sha1_file("", 0, blob_type, sha1))
die("cannot create an empty blob in the object database");
hashcpy(ce->sha1, sha1);
}
int add_to_index(struct index_state *istate, const char *path, struct stat *st, int flags)
{
int size, namelen, was_same;
mode_t st_mode = st->st_mode;
struct cache_entry *ce, *alias;
unsigned ce_option = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE|CE_MATCH_RACY_IS_DIRTY;
int verbose = flags & (ADD_CACHE_VERBOSE | ADD_CACHE_PRETEND);
int pretend = flags & ADD_CACHE_PRETEND;
int intent_only = flags & ADD_CACHE_INTENT;
int add_option = (ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|
(intent_only ? ADD_CACHE_NEW_ONLY : 0));
if (!S_ISREG(st_mode) && !S_ISLNK(st_mode) && !S_ISDIR(st_mode))
return error("%s: can only add regular files, symbolic links or git-directories", path);
namelen = strlen(path);
if (S_ISDIR(st_mode)) {
while (namelen && path[namelen-1] == '/')
namelen--;
}
size = cache_entry_size(namelen);
ce = xcalloc(1, size);
memcpy(ce->name, path, namelen);
ce->ce_namelen = namelen;
if (!intent_only)
fill_stat_cache_info(ce, st);
else
ce->ce_flags |= CE_INTENT_TO_ADD;
if (trust_executable_bit && has_symlinks)
ce->ce_mode = create_ce_mode(st_mode);
else {
/* If there is an existing entry, pick the mode bits and type
* from it, otherwise assume unexecutable regular file.
*/
struct cache_entry *ent;
int pos = index_name_pos_also_unmerged(istate, path, namelen);
ent = (0 <= pos) ? istate->cache[pos] : NULL;
ce->ce_mode = ce_mode_from_stat(ent, st_mode);
}
/* When core.ignorecase=true, determine if a directory of the same name but differing
* case already exists within the Git repository. If it does, ensure the directory
* case of the file being added to the repository matches (is folded into) the existing
* entry's directory case.
*/
if (ignore_case) {
const char *startPtr = ce->name;
const char *ptr = startPtr;
while (*ptr) {
while (*ptr && *ptr != '/')
++ptr;
if (*ptr == '/') {
struct cache_entry *foundce;
++ptr;
foundce = index_name_exists(&the_index, ce->name, ptr - ce->name, ignore_case);
if (foundce) {
memcpy((void *)startPtr, foundce->name + (startPtr - ce->name), ptr - startPtr);
startPtr = ptr;
}
}
}
}
alias = index_name_exists(istate, ce->name, ce_namelen(ce), ignore_case);
if (alias && !ce_stage(alias) && !ie_match_stat(istate, alias, st, ce_option)) {
/* Nothing changed, really */
free(ce);
Make ce_uptodate() trustworthy again The rule has always been that a cache entry that is ce_uptodate(ce) means that we already have checked the work tree entity and we know there is no change in the work tree compared to the index, and nobody should have to double check. Note that false ce_uptodate(ce) does not mean it is known to be dirty---it only means we don't know if it is clean. There are a few codepaths (refresh-index and preload-index are among them) that mark a cache entry as up-to-date based solely on the return value from ie_match_stat(); this function uses lstat() to see if the work tree entity has been touched, and for a submodule entry, if its HEAD points at the same commit as the commit recorded in the index of the superproject (a submodule that is not even cloned is considered clean). A submodule is no longer considered unmodified merely because its HEAD matches the index of the superproject these days, in order to prevent people from forgetting to commit in the submodule and updating the superproject index with the new submodule commit, before commiting the state in the superproject. However, the patch to do so didn't update the codepath that marks cache entries up-to-date based on the updated definition and instead worked it around by saying "we don't trust the return value of ce_uptodate() for submodules." This makes ce_uptodate() trustworthy again by not marking submodule entries up-to-date. The next step _could_ be to introduce a few "in-core" flag bits to cache_entry structure to record "this entry is _known_ to be dirty", call is_submodule_modified() from ie_match_stat(), and use these new bits to avoid running this rather expensive check more than once, but that can be a separate patch. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-01-24 16:10:20 +08:00
if (!S_ISGITLINK(alias->ce_mode))
ce_mark_uptodate(alias);
alias->ce_flags |= CE_ADDED;
return 0;
}
if (!intent_only) {
if (index_path(ce->sha1, path, st, HASH_WRITE_OBJECT))
return error("unable to index file %s", path);
} else
record_intent_to_add(ce);
if (ignore_case && alias && different_name(ce, alias))
ce = create_alias_ce(ce, alias);
ce->ce_flags |= CE_ADDED;
/* It was suspected to be racily clean, but it turns out to be Ok */
was_same = (alias &&
!ce_stage(alias) &&
!hashcmp(alias->sha1, ce->sha1) &&
ce->ce_mode == alias->ce_mode);
if (pretend)
;
else if (add_index_entry(istate, ce, add_option))
return error("unable to add %s to index",path);
if (verbose && !was_same)
printf("add '%s'\n", path);
return 0;
}
int add_file_to_index(struct index_state *istate, const char *path, int flags)
{
struct stat st;
if (lstat(path, &st))
die_errno("unable to stat '%s'", path);
return add_to_index(istate, path, &st, flags);
}
struct cache_entry *make_cache_entry(unsigned int mode,
const unsigned char *sha1, const char *path, int stage,
int refresh)
{
int size, len;
struct cache_entry *ce;
if (!verify_path(path)) {
error("Invalid path '%s'", path);
return NULL;
}
len = strlen(path);
size = cache_entry_size(len);
ce = xcalloc(1, size);
hashcpy(ce->sha1, sha1);
memcpy(ce->name, path, len);
ce->ce_flags = create_ce_flags(stage);
ce->ce_namelen = len;
ce->ce_mode = create_ce_mode(mode);
if (refresh)
return refresh_cache_entry(ce, 0);
return ce;
}
int ce_same_name(struct cache_entry *a, struct cache_entry *b)
{
int len = ce_namelen(a);
return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
}
int ce_path_match(const struct cache_entry *ce, const struct pathspec *pathspec)
{
return match_pathspec_depth(pathspec, ce->name, ce_namelen(ce), 0, NULL);
}
/*
* We fundamentally don't like some paths: we don't want
* dot or dot-dot anywhere, and for obvious reasons don't
* want to recurse into ".git" either.
*
* Also, we don't want double slashes or slashes at the
* end that can make pathnames ambiguous.
*/
static int verify_dotfile(const char *rest)
{
/*
* The first character was '.', but that
* has already been discarded, we now test
* the rest.
*/
/* "." is not allowed */
if (*rest == '\0' || is_dir_sep(*rest))
return 0;
switch (*rest) {
/*
* ".git" followed by NUL or slash is bad. This
* shares the path end test with the ".." case.
*/
case 'g':
if (rest[1] != 'i')
break;
if (rest[2] != 't')
break;
rest += 2;
/* fallthrough */
case '.':
if (rest[1] == '\0' || is_dir_sep(rest[1]))
return 0;
}
return 1;
}
int verify_path(const char *path)
{
char c;
if (has_dos_drive_prefix(path))
return 0;
goto inside;
for (;;) {
if (!c)
return 1;
if (is_dir_sep(c)) {
inside:
c = *path++;
if ((c == '.' && !verify_dotfile(path)) ||
is_dir_sep(c) || c == '\0')
return 0;
}
c = *path++;
}
}
/*
* Do we have another file that has the beginning components being a
* proper superset of the name we're trying to add?
*/
static int has_file_name(struct index_state *istate,
const struct cache_entry *ce, int pos, int ok_to_replace)
{
int retval = 0;
int len = ce_namelen(ce);
int stage = ce_stage(ce);
const char *name = ce->name;
while (pos < istate->cache_nr) {
struct cache_entry *p = istate->cache[pos++];
if (len >= ce_namelen(p))
break;
if (memcmp(name, p->name, len))
break;
if (ce_stage(p) != stage)
continue;
if (p->name[len] != '/')
continue;
if (p->ce_flags & CE_REMOVE)
continue;
retval = -1;
if (!ok_to_replace)
break;
remove_index_entry_at(istate, --pos);
}
return retval;
}
/*
* Do we have another file with a pathname that is a proper
* subset of the name we're trying to add?
*/
static int has_dir_name(struct index_state *istate,
const struct cache_entry *ce, int pos, int ok_to_replace)
{
int retval = 0;
int stage = ce_stage(ce);
const char *name = ce->name;
const char *slash = name + ce_namelen(ce);
for (;;) {
int len;
for (;;) {
if (*--slash == '/')
break;
if (slash <= ce->name)
return retval;
}
len = slash - name;
pos = index_name_stage_pos(istate, name, len, stage);
if (pos >= 0) {
/*
* Found one, but not so fast. This could
* be a marker that says "I was here, but
* I am being removed". Such an entry is
* not a part of the resulting tree, and
* it is Ok to have a directory at the same
* path.
*/
if (!(istate->cache[pos]->ce_flags & CE_REMOVE)) {
retval = -1;
if (!ok_to_replace)
break;
remove_index_entry_at(istate, pos);
continue;
}
}
else
pos = -pos-1;
/*
* Trivial optimization: if we find an entry that
* already matches the sub-directory, then we know
* we're ok, and we can exit.
*/
while (pos < istate->cache_nr) {
struct cache_entry *p = istate->cache[pos];
if ((ce_namelen(p) <= len) ||
(p->name[len] != '/') ||
memcmp(p->name, name, len))
break; /* not our subdirectory */
if (ce_stage(p) == stage && !(p->ce_flags & CE_REMOVE))
/*
* p is at the same stage as our entry, and
* is a subdirectory of what we are looking
* at, so we cannot have conflicts at our
* level or anything shorter.
*/
return retval;
pos++;
}
}
return retval;
}
/* We may be in a situation where we already have path/file and path
* is being added, or we already have path and path/file is being
* added. Either one would result in a nonsense tree that has path
* twice when git-write-tree tries to write it out. Prevent it.
*
* If ok-to-replace is specified, we remove the conflicting entries
* from the cache so the caller should recompute the insert position.
* When this happens, we return non-zero.
*/
static int check_file_directory_conflict(struct index_state *istate,
const struct cache_entry *ce,
int pos, int ok_to_replace)
{
int retval;
/*
* When ce is an "I am going away" entry, we allow it to be added
*/
if (ce->ce_flags & CE_REMOVE)
return 0;
/*
* We check if the path is a sub-path of a subsequent pathname
* first, since removing those will not change the position
* in the array.
*/
retval = has_file_name(istate, ce, pos, ok_to_replace);
/*
* Then check if the path might have a clashing sub-directory
* before it.
*/
return retval + has_dir_name(istate, ce, pos, ok_to_replace);
}
static int add_index_entry_with_check(struct index_state *istate, struct cache_entry *ce, int option)
{
int pos;
int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
int new_only = option & ADD_CACHE_NEW_ONLY;
"Assume unchanged" git This adds "assume unchanged" logic, started by this message in the list discussion recently: <Pine.LNX.4.64.0601311807470.7301@g5.osdl.org> This is a workaround for filesystems that do not have lstat() that is quick enough for the index mechanism to take advantage of. On the paths marked as "assumed to be unchanged", the user needs to explicitly use update-index to register the object name to be in the next commit. You can use two new options to update-index to set and reset the CE_VALID bit: git-update-index --assume-unchanged path... git-update-index --no-assume-unchanged path... These forms manipulate only the CE_VALID bit; it does not change the object name recorded in the index file. Nor they add a new entry to the index. When the configuration variable "core.ignorestat = true" is set, the index entries are marked with CE_VALID bit automatically after: - update-index to explicitly register the current object name to the index file. - when update-index --refresh finds the path to be up-to-date. - when tools like read-tree -u and apply --index update the working tree file and register the current object name to the index file. The flag is dropped upon read-tree that does not check out the index entry. This happens regardless of the core.ignorestat settings. Index entries marked with CE_VALID bit are assumed to be unchanged most of the time. However, there are cases that CE_VALID bit is ignored for the sake of safety and usability: - while "git-read-tree -m" or git-apply need to make sure that the paths involved in the merge do not have local modifications. This sacrifices performance for safety. - when git-checkout-index -f -q -u -a tries to see if it needs to checkout the paths. Otherwise you can never check anything out ;-). - when git-update-index --really-refresh (a new flag) tries to see if the index entry is up to date. You can start with everything marked as CE_VALID and run this once to drop CE_VALID bit for paths that are modified. Most notably, "update-index --refresh" honours CE_VALID and does not actively stat, so after you modified a file in the working tree, update-index --refresh would not notice until you tell the index about it with "git-update-index path" or "git-update-index --no-assume-unchanged path". This version is not expected to be perfect. I think diff between index and/or tree and working files may need some adjustment, and there probably needs other cases we should automatically unmark paths that are marked to be CE_VALID. But the basics seem to work, and ready to be tested by people who asked for this feature. Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-02-09 13:15:24 +08:00
cache_tree_invalidate_path(istate->cache_tree, ce->name);
pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
/* existing match? Just replace it. */
if (pos >= 0) {
if (!new_only)
replace_index_entry(istate, pos, ce);
return 0;
}
pos = -pos-1;
/*
* Inserting a merged entry ("stage 0") into the index
* will always replace all non-merged entries..
*/
if (pos < istate->cache_nr && ce_stage(ce) == 0) {
while (ce_same_name(istate->cache[pos], ce)) {
ok_to_add = 1;
if (!remove_index_entry_at(istate, pos))
break;
}
}
if (!ok_to_add)
return -1;
if (!verify_path(ce->name))
return error("Invalid path '%s'", ce->name);
if (!skip_df_check &&
check_file_directory_conflict(istate, ce, pos, ok_to_replace)) {
if (!ok_to_replace)
return error("'%s' appears as both a file and as a directory",
ce->name);
pos = index_name_stage_pos(istate, ce->name, ce_namelen(ce), ce_stage(ce));
pos = -pos-1;
}
return pos + 1;
}
int add_index_entry(struct index_state *istate, struct cache_entry *ce, int option)
{
int pos;
if (option & ADD_CACHE_JUST_APPEND)
pos = istate->cache_nr;
else {
int ret;
ret = add_index_entry_with_check(istate, ce, option);
if (ret <= 0)
return ret;
pos = ret - 1;
}
/* Make sure the array is big enough .. */
if (istate->cache_nr == istate->cache_alloc) {
istate->cache_alloc = alloc_nr(istate->cache_alloc);
istate->cache = xrealloc(istate->cache,
istate->cache_alloc * sizeof(struct cache_entry *));
}
/* Add it in.. */
istate->cache_nr++;
if (istate->cache_nr > pos + 1)
memmove(istate->cache + pos + 1,
istate->cache + pos,
(istate->cache_nr - pos - 1) * sizeof(ce));
Create pathname-based hash-table lookup into index This creates a hash index of every single file added to the index. Right now that hash index isn't actually used for much: I implemented a "cache_name_exists()" function that uses it to efficiently look up a filename in the index without having to do the O(logn) binary search, but quite frankly, that's not why this patch is interesting. No, the whole and only reason to create the hash of the filenames in the index is that by modifying the hash function, you can fairly easily do things like making it always hash equivalent names into the same bucket. That, in turn, means that suddenly questions like "does this name exist in the index under an _equivalent_ name?" becomes much much cheaper. Guiding principles behind this patch: - it shouldn't be too costly. In fact, my primary goal here was to actually speed up "git commit" with a fully populated kernel tree, by being faster at checking whether a file already existed in the index. I did succeed, but only barely: Best before: [torvalds@woody linux]$ time git commit > /dev/null real 0m0.255s user 0m0.168s sys 0m0.088s Best after: [torvalds@woody linux]$ time ~/git/git commit > /dev/null real 0m0.233s user 0m0.144s sys 0m0.088s so some things are actually faster (~8%). Caveat: that's really the best case. Other things are invariably going to be slightly slower, since we populate that index cache, and quite frankly, few things really use it to look things up. That said, the cost is really quite small. The worst case is probably doing a "git ls-files", which will do very little except puopulate the index, and never actually looks anything up in it, just lists it. Before: [torvalds@woody linux]$ time git ls-files > /dev/null real 0m0.016s user 0m0.016s sys 0m0.000s After: [torvalds@woody linux]$ time ~/git/git ls-files > /dev/null real 0m0.021s user 0m0.012s sys 0m0.008s and while the thing has really gotten relatively much slower, we're still talking about something almost unmeasurable (eg 5ms). And that really should be pretty much the worst case. So we lose 5ms on one "benchmark", but win 22ms on another. Pick your poison - this patch has the advantage that it will _likely_ speed up the cases that are complex and expensive more than it slows down the cases that are already so fast that nobody cares. But if you look at relative speedups/slowdowns, it doesn't look so good. - It should be simple and clean The code may be a bit subtle (the reasons I do hash removal the way I do etc), but it re-uses the existing hash.c files, so it really is fairly small and straightforward apart from a few odd details. Now, this patch on its own doesn't really do much, but I think it's worth looking at, if only because if done correctly, the name hashing really can make an improvement to the whole issue of "do we have a filename that looks like this in the index already". And at least it gets real testing by being used even by default (ie there is a real use-case for it even without any insane filesystems). NOTE NOTE NOTE! The current hash is a joke. I'm ashamed of it, I'm just not ashamed of it enough to really care. I took all the numbers out of my nether regions - I'm sure it's good enough that it works in practice, but the whole point was that you can make a really much fancier hash that hashes characters not directly, but by their upper-case value or something like that, and thus you get a case-insensitive hash, while still keeping the name and the index itself totally case sensitive. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-23 10:41:14 +08:00
set_index_entry(istate, pos, ce);
istate->cache_changed = 1;
return 0;
}
/*
* "refresh" does not calculate a new sha1 file or bring the
* cache up-to-date for mode/content changes. But what it
* _does_ do is to "re-match" the stat information of a file
* with the cache, so that you can refresh the cache for a
* file that hasn't been changed but where the stat entry is
* out of date.
*
* For example, you'd want to do this after doing a "git-read-tree",
* to link up the stat cache details with the proper files.
*/
static struct cache_entry *refresh_cache_ent(struct index_state *istate,
struct cache_entry *ce,
unsigned int options, int *err,
int *changed_ret)
{
struct stat st;
struct cache_entry *updated;
int changed, size;
int ignore_valid = options & CE_MATCH_IGNORE_VALID;
int ignore_skip_worktree = options & CE_MATCH_IGNORE_SKIP_WORKTREE;
if (ce_uptodate(ce))
return ce;
/*
* CE_VALID or CE_SKIP_WORKTREE means the user promised us
* that the change to the work tree does not matter and told
* us not to worry.
*/
if (!ignore_skip_worktree && ce_skip_worktree(ce)) {
ce_mark_uptodate(ce);
return ce;
}
if (!ignore_valid && (ce->ce_flags & CE_VALID)) {
ce_mark_uptodate(ce);
return ce;
}
if (lstat(ce->name, &st) < 0) {
if (err)
*err = errno;
return NULL;
}
changed = ie_match_stat(istate, ce, &st, options);
if (changed_ret)
*changed_ret = changed;
if (!changed) {
/*
* The path is unchanged. If we were told to ignore
* valid bit, then we did the actual stat check and
* found that the entry is unmodified. If the entry
* is not marked VALID, this is the place to mark it
* valid again, under "assume unchanged" mode.
*/
if (ignore_valid && assume_unchanged &&
!(ce->ce_flags & CE_VALID))
; /* mark this one VALID again */
else {
/*
* We do not mark the index itself "modified"
* because CE_UPTODATE flag is in-core only;
* we are not going to write this change out.
*/
Make ce_uptodate() trustworthy again The rule has always been that a cache entry that is ce_uptodate(ce) means that we already have checked the work tree entity and we know there is no change in the work tree compared to the index, and nobody should have to double check. Note that false ce_uptodate(ce) does not mean it is known to be dirty---it only means we don't know if it is clean. There are a few codepaths (refresh-index and preload-index are among them) that mark a cache entry as up-to-date based solely on the return value from ie_match_stat(); this function uses lstat() to see if the work tree entity has been touched, and for a submodule entry, if its HEAD points at the same commit as the commit recorded in the index of the superproject (a submodule that is not even cloned is considered clean). A submodule is no longer considered unmodified merely because its HEAD matches the index of the superproject these days, in order to prevent people from forgetting to commit in the submodule and updating the superproject index with the new submodule commit, before commiting the state in the superproject. However, the patch to do so didn't update the codepath that marks cache entries up-to-date based on the updated definition and instead worked it around by saying "we don't trust the return value of ce_uptodate() for submodules." This makes ce_uptodate() trustworthy again by not marking submodule entries up-to-date. The next step _could_ be to introduce a few "in-core" flag bits to cache_entry structure to record "this entry is _known_ to be dirty", call is_submodule_modified() from ie_match_stat(), and use these new bits to avoid running this rather expensive check more than once, but that can be a separate patch. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-01-24 16:10:20 +08:00
if (!S_ISGITLINK(ce->ce_mode))
ce_mark_uptodate(ce);
return ce;
}
}
if (ie_modified(istate, ce, &st, options)) {
if (err)
*err = EINVAL;
return NULL;
}
size = ce_size(ce);
updated = xmalloc(size);
memcpy(updated, ce, size);
fill_stat_cache_info(updated, &st);
/*
* If ignore_valid is not set, we should leave CE_VALID bit
* alone. Otherwise, paths marked with --no-assume-unchanged
* (i.e. things to be edited) will reacquire CE_VALID bit
* automatically, which is not really what we want.
*/
if (!ignore_valid && assume_unchanged &&
!(ce->ce_flags & CE_VALID))
updated->ce_flags &= ~CE_VALID;
return updated;
}
static void show_file(const char * fmt, const char * name, int in_porcelain,
int * first, const char *header_msg)
{
if (in_porcelain && *first && header_msg) {
printf("%s\n", header_msg);
*first = 0;
}
printf(fmt, name);
}
int refresh_index(struct index_state *istate, unsigned int flags, const char **pathspec,
char *seen, const char *header_msg)
{
int i;
int has_errors = 0;
int really = (flags & REFRESH_REALLY) != 0;
int allow_unmerged = (flags & REFRESH_UNMERGED) != 0;
int quiet = (flags & REFRESH_QUIET) != 0;
int not_new = (flags & REFRESH_IGNORE_MISSING) != 0;
int ignore_submodules = (flags & REFRESH_IGNORE_SUBMODULES) != 0;
int first = 1;
int in_porcelain = (flags & REFRESH_IN_PORCELAIN);
unsigned int options = really ? CE_MATCH_IGNORE_VALID : 0;
const char *modified_fmt;
const char *deleted_fmt;
const char *typechange_fmt;
const char *added_fmt;
const char *unmerged_fmt;
modified_fmt = (in_porcelain ? "M\t%s\n" : "%s: needs update\n");
deleted_fmt = (in_porcelain ? "D\t%s\n" : "%s: needs update\n");
typechange_fmt = (in_porcelain ? "T\t%s\n" : "%s needs update\n");
added_fmt = (in_porcelain ? "A\t%s\n" : "%s needs update\n");
unmerged_fmt = (in_porcelain ? "U\t%s\n" : "%s: needs merge\n");
for (i = 0; i < istate->cache_nr; i++) {
struct cache_entry *ce, *new;
int cache_errno = 0;
int changed = 0;
int filtered = 0;
ce = istate->cache[i];
if (ignore_submodules && S_ISGITLINK(ce->ce_mode))
continue;
if (pathspec &&
!match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, seen))
filtered = 1;
if (ce_stage(ce)) {
while ((i < istate->cache_nr) &&
! strcmp(istate->cache[i]->name, ce->name))
i++;
i--;
if (allow_unmerged)
continue;
if (!filtered)
show_file(unmerged_fmt, ce->name, in_porcelain,
&first, header_msg);
has_errors = 1;
continue;
}
if (filtered)
continue;
new = refresh_cache_ent(istate, ce, options, &cache_errno, &changed);
if (new == ce)
continue;
if (!new) {
const char *fmt;
if (not_new && cache_errno == ENOENT)
continue;
if (really && cache_errno == EINVAL) {
/* If we are doing --really-refresh that
* means the index is not valid anymore.
*/
ce->ce_flags &= ~CE_VALID;
istate->cache_changed = 1;
}
if (quiet)
continue;
if (cache_errno == ENOENT)
fmt = deleted_fmt;
else if (ce->ce_flags & CE_INTENT_TO_ADD)
fmt = added_fmt; /* must be before other checks */
else if (changed & TYPE_CHANGED)
fmt = typechange_fmt;
else
fmt = modified_fmt;
show_file(fmt,
ce->name, in_porcelain, &first, header_msg);
has_errors = 1;
continue;
}
Create pathname-based hash-table lookup into index This creates a hash index of every single file added to the index. Right now that hash index isn't actually used for much: I implemented a "cache_name_exists()" function that uses it to efficiently look up a filename in the index without having to do the O(logn) binary search, but quite frankly, that's not why this patch is interesting. No, the whole and only reason to create the hash of the filenames in the index is that by modifying the hash function, you can fairly easily do things like making it always hash equivalent names into the same bucket. That, in turn, means that suddenly questions like "does this name exist in the index under an _equivalent_ name?" becomes much much cheaper. Guiding principles behind this patch: - it shouldn't be too costly. In fact, my primary goal here was to actually speed up "git commit" with a fully populated kernel tree, by being faster at checking whether a file already existed in the index. I did succeed, but only barely: Best before: [torvalds@woody linux]$ time git commit > /dev/null real 0m0.255s user 0m0.168s sys 0m0.088s Best after: [torvalds@woody linux]$ time ~/git/git commit > /dev/null real 0m0.233s user 0m0.144s sys 0m0.088s so some things are actually faster (~8%). Caveat: that's really the best case. Other things are invariably going to be slightly slower, since we populate that index cache, and quite frankly, few things really use it to look things up. That said, the cost is really quite small. The worst case is probably doing a "git ls-files", which will do very little except puopulate the index, and never actually looks anything up in it, just lists it. Before: [torvalds@woody linux]$ time git ls-files > /dev/null real 0m0.016s user 0m0.016s sys 0m0.000s After: [torvalds@woody linux]$ time ~/git/git ls-files > /dev/null real 0m0.021s user 0m0.012s sys 0m0.008s and while the thing has really gotten relatively much slower, we're still talking about something almost unmeasurable (eg 5ms). And that really should be pretty much the worst case. So we lose 5ms on one "benchmark", but win 22ms on another. Pick your poison - this patch has the advantage that it will _likely_ speed up the cases that are complex and expensive more than it slows down the cases that are already so fast that nobody cares. But if you look at relative speedups/slowdowns, it doesn't look so good. - It should be simple and clean The code may be a bit subtle (the reasons I do hash removal the way I do etc), but it re-uses the existing hash.c files, so it really is fairly small and straightforward apart from a few odd details. Now, this patch on its own doesn't really do much, but I think it's worth looking at, if only because if done correctly, the name hashing really can make an improvement to the whole issue of "do we have a filename that looks like this in the index already". And at least it gets real testing by being used even by default (ie there is a real use-case for it even without any insane filesystems). NOTE NOTE NOTE! The current hash is a joke. I'm ashamed of it, I'm just not ashamed of it enough to really care. I took all the numbers out of my nether regions - I'm sure it's good enough that it works in practice, but the whole point was that you can make a really much fancier hash that hashes characters not directly, but by their upper-case value or something like that, and thus you get a case-insensitive hash, while still keeping the name and the index itself totally case sensitive. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-23 10:41:14 +08:00
replace_index_entry(istate, i, new);
}
return has_errors;
}
static struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really)
{
return refresh_cache_ent(&the_index, ce, really, NULL, NULL);
}
/*****************************************************************
* Index File I/O
*****************************************************************/
#define INDEX_FORMAT_DEFAULT 3
/*
* dev/ino/uid/gid/size are also just tracked to the low 32 bits
* Again - this is just a (very strong in practice) heuristic that
* the inode hasn't changed.
*
* We save the fields in big-endian order to allow using the
* index file over NFS transparently.
*/
struct ondisk_cache_entry {
struct cache_time ctime;
struct cache_time mtime;
unsigned int dev;
unsigned int ino;
unsigned int mode;
unsigned int uid;
unsigned int gid;
unsigned int size;
unsigned char sha1[20];
unsigned short flags;
char name[FLEX_ARRAY]; /* more */
};
/*
* This struct is used when CE_EXTENDED bit is 1
* The struct must match ondisk_cache_entry exactly from
* ctime till flags
*/
struct ondisk_cache_entry_extended {
struct cache_time ctime;
struct cache_time mtime;
unsigned int dev;
unsigned int ino;
unsigned int mode;
unsigned int uid;
unsigned int gid;
unsigned int size;
unsigned char sha1[20];
unsigned short flags;
unsigned short flags2;
char name[FLEX_ARRAY]; /* more */
};
/* These are only used for v3 or lower */
#define align_flex_name(STRUCT,len) ((offsetof(struct STRUCT,name) + (len) + 8) & ~7)
#define ondisk_cache_entry_size(len) align_flex_name(ondisk_cache_entry,len)
#define ondisk_cache_entry_extended_size(len) align_flex_name(ondisk_cache_entry_extended,len)
#define ondisk_ce_size(ce) (((ce)->ce_flags & CE_EXTENDED) ? \
ondisk_cache_entry_extended_size(ce_namelen(ce)) : \
ondisk_cache_entry_size(ce_namelen(ce)))
static int verify_hdr(struct cache_header *hdr, unsigned long size)
{
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
git_SHA_CTX c;
unsigned char sha1[20];
int hdr_version;
if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
return error("bad signature");
hdr_version = ntohl(hdr->hdr_version);
if (hdr_version < 2 || 4 < hdr_version)
return error("bad index version %d", hdr_version);
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
git_SHA1_Init(&c);
git_SHA1_Update(&c, hdr, size - 20);
git_SHA1_Final(sha1, &c);
if (hashcmp(sha1, (unsigned char *)hdr + size - 20))
return error("bad index file sha1 signature");
return 0;
}
static int read_index_extension(struct index_state *istate,
const char *ext, void *data, unsigned long sz)
{
switch (CACHE_EXT(ext)) {
case CACHE_EXT_TREE:
istate->cache_tree = cache_tree_read(data, sz);
break;
case CACHE_EXT_RESOLVE_UNDO:
istate->resolve_undo = resolve_undo_read(data, sz);
break;
default:
if (*ext < 'A' || 'Z' < *ext)
return error("index uses %.4s extension, which we do not understand",
ext);
fprintf(stderr, "ignoring %.4s extension\n", ext);
break;
}
return 0;
}
int read_index(struct index_state *istate)
{
return read_index_from(istate, get_index_file());
}
#ifndef NEEDS_ALIGNED_ACCESS
#define ntoh_s(var) ntohs(var)
#define ntoh_l(var) ntohl(var)
#else
static inline uint16_t ntoh_s_force_align(void *p)
{
uint16_t x;
memcpy(&x, p, sizeof(x));
return ntohs(x);
}
static inline uint32_t ntoh_l_force_align(void *p)
{
uint32_t x;
memcpy(&x, p, sizeof(x));
return ntohl(x);
}
#define ntoh_s(var) ntoh_s_force_align(&(var))
#define ntoh_l(var) ntoh_l_force_align(&(var))
#endif
static struct cache_entry *cache_entry_from_ondisk(struct ondisk_cache_entry *ondisk,
unsigned int flags,
const char *name,
size_t len)
{
struct cache_entry *ce = xmalloc(cache_entry_size(len));
ce->ce_ctime.sec = ntoh_l(ondisk->ctime.sec);
ce->ce_mtime.sec = ntoh_l(ondisk->mtime.sec);
ce->ce_ctime.nsec = ntoh_l(ondisk->ctime.nsec);
ce->ce_mtime.nsec = ntoh_l(ondisk->mtime.nsec);
ce->ce_dev = ntoh_l(ondisk->dev);
ce->ce_ino = ntoh_l(ondisk->ino);
ce->ce_mode = ntoh_l(ondisk->mode);
ce->ce_uid = ntoh_l(ondisk->uid);
ce->ce_gid = ntoh_l(ondisk->gid);
ce->ce_size = ntoh_l(ondisk->size);
ce->ce_flags = flags & ~CE_NAMEMASK;
ce->ce_namelen = len;
hashcpy(ce->sha1, ondisk->sha1);
memcpy(ce->name, name, len);
ce->name[len] = '\0';
return ce;
}
/*
* Adjacent cache entries tend to share the leading paths, so it makes
* sense to only store the differences in later entries. In the v4
* on-disk format of the index, each on-disk cache entry stores the
* number of bytes to be stripped from the end of the previous name,
* and the bytes to append to the result, to come up with its name.
*/
static unsigned long expand_name_field(struct strbuf *name, const char *cp_)
{
const unsigned char *ep, *cp = (const unsigned char *)cp_;
size_t len = decode_varint(&cp);
if (name->len < len)
die("malformed name field in the index");
strbuf_remove(name, name->len - len, len);
for (ep = cp; *ep; ep++)
; /* find the end */
strbuf_add(name, cp, ep - cp);
return (const char *)ep + 1 - cp_;
}
static struct cache_entry *create_from_disk(struct ondisk_cache_entry *ondisk,
unsigned long *ent_size,
struct strbuf *previous_name)
{
struct cache_entry *ce;
size_t len;
const char *name;
unsigned int flags;
/* On-disk flags are just 16 bits */
flags = ntoh_s(ondisk->flags);
len = flags & CE_NAMEMASK;
if (flags & CE_EXTENDED) {
struct ondisk_cache_entry_extended *ondisk2;
int extended_flags;
ondisk2 = (struct ondisk_cache_entry_extended *)ondisk;
extended_flags = ntoh_s(ondisk2->flags2) << 16;
/* We do not yet understand any bit out of CE_EXTENDED_FLAGS */
if (extended_flags & ~CE_EXTENDED_FLAGS)
die("Unknown index entry format %08x", extended_flags);
flags |= extended_flags;
name = ondisk2->name;
}
else
name = ondisk->name;
if (!previous_name) {
/* v3 and earlier */
if (len == CE_NAMEMASK)
len = strlen(name);
ce = cache_entry_from_ondisk(ondisk, flags, name, len);
*ent_size = ondisk_ce_size(ce);
} else {
unsigned long consumed;
consumed = expand_name_field(previous_name, name);
ce = cache_entry_from_ondisk(ondisk, flags,
previous_name->buf,
previous_name->len);
*ent_size = (name - ((char *)ondisk)) + consumed;
}
return ce;
Create pathname-based hash-table lookup into index This creates a hash index of every single file added to the index. Right now that hash index isn't actually used for much: I implemented a "cache_name_exists()" function that uses it to efficiently look up a filename in the index without having to do the O(logn) binary search, but quite frankly, that's not why this patch is interesting. No, the whole and only reason to create the hash of the filenames in the index is that by modifying the hash function, you can fairly easily do things like making it always hash equivalent names into the same bucket. That, in turn, means that suddenly questions like "does this name exist in the index under an _equivalent_ name?" becomes much much cheaper. Guiding principles behind this patch: - it shouldn't be too costly. In fact, my primary goal here was to actually speed up "git commit" with a fully populated kernel tree, by being faster at checking whether a file already existed in the index. I did succeed, but only barely: Best before: [torvalds@woody linux]$ time git commit > /dev/null real 0m0.255s user 0m0.168s sys 0m0.088s Best after: [torvalds@woody linux]$ time ~/git/git commit > /dev/null real 0m0.233s user 0m0.144s sys 0m0.088s so some things are actually faster (~8%). Caveat: that's really the best case. Other things are invariably going to be slightly slower, since we populate that index cache, and quite frankly, few things really use it to look things up. That said, the cost is really quite small. The worst case is probably doing a "git ls-files", which will do very little except puopulate the index, and never actually looks anything up in it, just lists it. Before: [torvalds@woody linux]$ time git ls-files > /dev/null real 0m0.016s user 0m0.016s sys 0m0.000s After: [torvalds@woody linux]$ time ~/git/git ls-files > /dev/null real 0m0.021s user 0m0.012s sys 0m0.008s and while the thing has really gotten relatively much slower, we're still talking about something almost unmeasurable (eg 5ms). And that really should be pretty much the worst case. So we lose 5ms on one "benchmark", but win 22ms on another. Pick your poison - this patch has the advantage that it will _likely_ speed up the cases that are complex and expensive more than it slows down the cases that are already so fast that nobody cares. But if you look at relative speedups/slowdowns, it doesn't look so good. - It should be simple and clean The code may be a bit subtle (the reasons I do hash removal the way I do etc), but it re-uses the existing hash.c files, so it really is fairly small and straightforward apart from a few odd details. Now, this patch on its own doesn't really do much, but I think it's worth looking at, if only because if done correctly, the name hashing really can make an improvement to the whole issue of "do we have a filename that looks like this in the index already". And at least it gets real testing by being used even by default (ie there is a real use-case for it even without any insane filesystems). NOTE NOTE NOTE! The current hash is a joke. I'm ashamed of it, I'm just not ashamed of it enough to really care. I took all the numbers out of my nether regions - I'm sure it's good enough that it works in practice, but the whole point was that you can make a really much fancier hash that hashes characters not directly, but by their upper-case value or something like that, and thus you get a case-insensitive hash, while still keeping the name and the index itself totally case sensitive. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-23 10:41:14 +08:00
}
/* remember to discard_cache() before reading a different cache! */
int read_index_from(struct index_state *istate, const char *path)
{
int fd, i;
struct stat st;
unsigned long src_offset;
struct cache_header *hdr;
void *mmap;
size_t mmap_size;
struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
unpack_trees(): protect the handcrafted in-core index from read_cache() unpack_trees() rebuilds the in-core index from scratch by allocating a new structure and finishing it off by copying the built one to the final index. The resulting in-core index is Ok for most use, but read_cache() does not recognize it as such. The function is meant to be no-op if you already have loaded the index, until you call discard_cache(). This change the way read_cache() detects an already initialized in-core index, by introducing an extra bit, and marks the handcrafted in-core index as initialized, to avoid this problem. A better fix in the longer term would be to change the read_cache() API so that it will always discard and re-read from the on-disk index to avoid confusion. But there are higher level API that have relied on the current semantics, and they and their users all need to get converted, which is outside the scope of 'maint' track. An example of such a higher level API is write_cache_as_tree(), which is used by git-write-tree as well as later Porcelains like git-merge, revert and cherry-pick. In the longer term, we should remove read_cache() from there and add one to cmd_write_tree(); other callers expect that the in-core index they prepared is what gets written as a tree so no other change is necessary for this particular codepath. The original version of this patch marked the index by pointing an otherwise wasted malloc'ed memory with o->result.alloc, but this version uses Linus's idea to use a new "initialized" bit, which is conceptually much cleaner. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-08-24 03:57:30 +08:00
if (istate->initialized)
return istate->cache_nr;
istate->timestamp.sec = 0;
istate->timestamp.nsec = 0;
fd = open(path, O_RDONLY);
if (fd < 0) {
if (errno == ENOENT)
return 0;
die_errno("index file open failed");
}
if (fstat(fd, &st))
die_errno("cannot stat the open index");
mmap_size = xsize_t(st.st_size);
if (mmap_size < sizeof(struct cache_header) + 20)
die("index file smaller than expected");
mmap = xmmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
if (mmap == MAP_FAILED)
die_errno("unable to map index file");
close(fd);
hdr = mmap;
if (verify_hdr(hdr, mmap_size) < 0)
goto unmap;
istate->version = ntohl(hdr->hdr_version);
istate->cache_nr = ntohl(hdr->hdr_entries);
istate->cache_alloc = alloc_nr(istate->cache_nr);
istate->cache = xcalloc(istate->cache_alloc, sizeof(struct cache_entry *));
unpack_trees(): protect the handcrafted in-core index from read_cache() unpack_trees() rebuilds the in-core index from scratch by allocating a new structure and finishing it off by copying the built one to the final index. The resulting in-core index is Ok for most use, but read_cache() does not recognize it as such. The function is meant to be no-op if you already have loaded the index, until you call discard_cache(). This change the way read_cache() detects an already initialized in-core index, by introducing an extra bit, and marks the handcrafted in-core index as initialized, to avoid this problem. A better fix in the longer term would be to change the read_cache() API so that it will always discard and re-read from the on-disk index to avoid confusion. But there are higher level API that have relied on the current semantics, and they and their users all need to get converted, which is outside the scope of 'maint' track. An example of such a higher level API is write_cache_as_tree(), which is used by git-write-tree as well as later Porcelains like git-merge, revert and cherry-pick. In the longer term, we should remove read_cache() from there and add one to cmd_write_tree(); other callers expect that the in-core index they prepared is what gets written as a tree so no other change is necessary for this particular codepath. The original version of this patch marked the index by pointing an otherwise wasted malloc'ed memory with o->result.alloc, but this version uses Linus's idea to use a new "initialized" bit, which is conceptually much cleaner. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-08-24 03:57:30 +08:00
istate->initialized = 1;
if (istate->version == 4)
previous_name = &previous_name_buf;
else
previous_name = NULL;
src_offset = sizeof(*hdr);
for (i = 0; i < istate->cache_nr; i++) {
struct ondisk_cache_entry *disk_ce;
struct cache_entry *ce;
unsigned long consumed;
disk_ce = (struct ondisk_cache_entry *)((char *)mmap + src_offset);
ce = create_from_disk(disk_ce, &consumed, previous_name);
Create pathname-based hash-table lookup into index This creates a hash index of every single file added to the index. Right now that hash index isn't actually used for much: I implemented a "cache_name_exists()" function that uses it to efficiently look up a filename in the index without having to do the O(logn) binary search, but quite frankly, that's not why this patch is interesting. No, the whole and only reason to create the hash of the filenames in the index is that by modifying the hash function, you can fairly easily do things like making it always hash equivalent names into the same bucket. That, in turn, means that suddenly questions like "does this name exist in the index under an _equivalent_ name?" becomes much much cheaper. Guiding principles behind this patch: - it shouldn't be too costly. In fact, my primary goal here was to actually speed up "git commit" with a fully populated kernel tree, by being faster at checking whether a file already existed in the index. I did succeed, but only barely: Best before: [torvalds@woody linux]$ time git commit > /dev/null real 0m0.255s user 0m0.168s sys 0m0.088s Best after: [torvalds@woody linux]$ time ~/git/git commit > /dev/null real 0m0.233s user 0m0.144s sys 0m0.088s so some things are actually faster (~8%). Caveat: that's really the best case. Other things are invariably going to be slightly slower, since we populate that index cache, and quite frankly, few things really use it to look things up. That said, the cost is really quite small. The worst case is probably doing a "git ls-files", which will do very little except puopulate the index, and never actually looks anything up in it, just lists it. Before: [torvalds@woody linux]$ time git ls-files > /dev/null real 0m0.016s user 0m0.016s sys 0m0.000s After: [torvalds@woody linux]$ time ~/git/git ls-files > /dev/null real 0m0.021s user 0m0.012s sys 0m0.008s and while the thing has really gotten relatively much slower, we're still talking about something almost unmeasurable (eg 5ms). And that really should be pretty much the worst case. So we lose 5ms on one "benchmark", but win 22ms on another. Pick your poison - this patch has the advantage that it will _likely_ speed up the cases that are complex and expensive more than it slows down the cases that are already so fast that nobody cares. But if you look at relative speedups/slowdowns, it doesn't look so good. - It should be simple and clean The code may be a bit subtle (the reasons I do hash removal the way I do etc), but it re-uses the existing hash.c files, so it really is fairly small and straightforward apart from a few odd details. Now, this patch on its own doesn't really do much, but I think it's worth looking at, if only because if done correctly, the name hashing really can make an improvement to the whole issue of "do we have a filename that looks like this in the index already". And at least it gets real testing by being used even by default (ie there is a real use-case for it even without any insane filesystems). NOTE NOTE NOTE! The current hash is a joke. I'm ashamed of it, I'm just not ashamed of it enough to really care. I took all the numbers out of my nether regions - I'm sure it's good enough that it works in practice, but the whole point was that you can make a really much fancier hash that hashes characters not directly, but by their upper-case value or something like that, and thus you get a case-insensitive hash, while still keeping the name and the index itself totally case sensitive. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-23 10:41:14 +08:00
set_index_entry(istate, i, ce);
src_offset += consumed;
}
strbuf_release(&previous_name_buf);
istate->timestamp.sec = st.st_mtime;
istate->timestamp.nsec = ST_MTIME_NSEC(st);
while (src_offset <= mmap_size - 20 - 8) {
/* After an array of active_nr index entries,
* there can be arbitrary number of extended
* sections, each of which is prefixed with
* extension name (4-byte) and section length
* in 4-byte network byte order.
*/
uint32_t extsize;
memcpy(&extsize, (char *)mmap + src_offset + 4, 4);
extsize = ntohl(extsize);
if (read_index_extension(istate,
(const char *) mmap + src_offset,
(char *) mmap + src_offset + 8,
extsize) < 0)
goto unmap;
src_offset += 8;
src_offset += extsize;
}
munmap(mmap, mmap_size);
return istate->cache_nr;
unmap:
munmap(mmap, mmap_size);
die("index file corrupt");
}
int is_index_unborn(struct index_state *istate)
{
return (!istate->cache_nr && !istate->timestamp.sec);
}
int discard_index(struct index_state *istate)
{
int i;
for (i = 0; i < istate->cache_nr; i++)
free(istate->cache[i]);
resolve_undo_clear_index(istate);
istate->cache_nr = 0;
istate->cache_changed = 0;
istate->timestamp.sec = 0;
istate->timestamp.nsec = 0;
istate->name_hash_initialized = 0;
Create pathname-based hash-table lookup into index This creates a hash index of every single file added to the index. Right now that hash index isn't actually used for much: I implemented a "cache_name_exists()" function that uses it to efficiently look up a filename in the index without having to do the O(logn) binary search, but quite frankly, that's not why this patch is interesting. No, the whole and only reason to create the hash of the filenames in the index is that by modifying the hash function, you can fairly easily do things like making it always hash equivalent names into the same bucket. That, in turn, means that suddenly questions like "does this name exist in the index under an _equivalent_ name?" becomes much much cheaper. Guiding principles behind this patch: - it shouldn't be too costly. In fact, my primary goal here was to actually speed up "git commit" with a fully populated kernel tree, by being faster at checking whether a file already existed in the index. I did succeed, but only barely: Best before: [torvalds@woody linux]$ time git commit > /dev/null real 0m0.255s user 0m0.168s sys 0m0.088s Best after: [torvalds@woody linux]$ time ~/git/git commit > /dev/null real 0m0.233s user 0m0.144s sys 0m0.088s so some things are actually faster (~8%). Caveat: that's really the best case. Other things are invariably going to be slightly slower, since we populate that index cache, and quite frankly, few things really use it to look things up. That said, the cost is really quite small. The worst case is probably doing a "git ls-files", which will do very little except puopulate the index, and never actually looks anything up in it, just lists it. Before: [torvalds@woody linux]$ time git ls-files > /dev/null real 0m0.016s user 0m0.016s sys 0m0.000s After: [torvalds@woody linux]$ time ~/git/git ls-files > /dev/null real 0m0.021s user 0m0.012s sys 0m0.008s and while the thing has really gotten relatively much slower, we're still talking about something almost unmeasurable (eg 5ms). And that really should be pretty much the worst case. So we lose 5ms on one "benchmark", but win 22ms on another. Pick your poison - this patch has the advantage that it will _likely_ speed up the cases that are complex and expensive more than it slows down the cases that are already so fast that nobody cares. But if you look at relative speedups/slowdowns, it doesn't look so good. - It should be simple and clean The code may be a bit subtle (the reasons I do hash removal the way I do etc), but it re-uses the existing hash.c files, so it really is fairly small and straightforward apart from a few odd details. Now, this patch on its own doesn't really do much, but I think it's worth looking at, if only because if done correctly, the name hashing really can make an improvement to the whole issue of "do we have a filename that looks like this in the index already". And at least it gets real testing by being used even by default (ie there is a real use-case for it even without any insane filesystems). NOTE NOTE NOTE! The current hash is a joke. I'm ashamed of it, I'm just not ashamed of it enough to really care. I took all the numbers out of my nether regions - I'm sure it's good enough that it works in practice, but the whole point was that you can make a really much fancier hash that hashes characters not directly, but by their upper-case value or something like that, and thus you get a case-insensitive hash, while still keeping the name and the index itself totally case sensitive. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-01-23 10:41:14 +08:00
free_hash(&istate->name_hash);
cache_tree_free(&(istate->cache_tree));
unpack_trees(): protect the handcrafted in-core index from read_cache() unpack_trees() rebuilds the in-core index from scratch by allocating a new structure and finishing it off by copying the built one to the final index. The resulting in-core index is Ok for most use, but read_cache() does not recognize it as such. The function is meant to be no-op if you already have loaded the index, until you call discard_cache(). This change the way read_cache() detects an already initialized in-core index, by introducing an extra bit, and marks the handcrafted in-core index as initialized, to avoid this problem. A better fix in the longer term would be to change the read_cache() API so that it will always discard and re-read from the on-disk index to avoid confusion. But there are higher level API that have relied on the current semantics, and they and their users all need to get converted, which is outside the scope of 'maint' track. An example of such a higher level API is write_cache_as_tree(), which is used by git-write-tree as well as later Porcelains like git-merge, revert and cherry-pick. In the longer term, we should remove read_cache() from there and add one to cmd_write_tree(); other callers expect that the in-core index they prepared is what gets written as a tree so no other change is necessary for this particular codepath. The original version of this patch marked the index by pointing an otherwise wasted malloc'ed memory with o->result.alloc, but this version uses Linus's idea to use a new "initialized" bit, which is conceptually much cleaner. Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-08-24 03:57:30 +08:00
istate->initialized = 0;
/* no need to throw away allocated active_cache */
return 0;
}
int unmerged_index(const struct index_state *istate)
{
int i;
for (i = 0; i < istate->cache_nr; i++) {
if (ce_stage(istate->cache[i]))
return 1;
}
return 0;
}
#define WRITE_BUFFER_SIZE 8192
static unsigned char write_buffer[WRITE_BUFFER_SIZE];
static unsigned long write_buffer_len;
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
static int ce_write_flush(git_SHA_CTX *context, int fd)
{
unsigned int buffered = write_buffer_len;
if (buffered) {
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
git_SHA1_Update(context, write_buffer, buffered);
if (write_in_full(fd, write_buffer, buffered) != buffered)
return -1;
write_buffer_len = 0;
}
return 0;
}
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
static int ce_write(git_SHA_CTX *context, int fd, void *data, unsigned int len)
{
while (len) {
unsigned int buffered = write_buffer_len;
unsigned int partial = WRITE_BUFFER_SIZE - buffered;
if (partial > len)
partial = len;
memcpy(write_buffer + buffered, data, partial);
buffered += partial;
if (buffered == WRITE_BUFFER_SIZE) {
write_buffer_len = buffered;
if (ce_write_flush(context, fd))
return -1;
buffered = 0;
}
write_buffer_len = buffered;
len -= partial;
data = (char *) data + partial;
}
return 0;
}
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
static int write_index_ext_header(git_SHA_CTX *context, int fd,
unsigned int ext, unsigned int sz)
{
ext = htonl(ext);
sz = htonl(sz);
return ((ce_write(context, fd, &ext, 4) < 0) ||
(ce_write(context, fd, &sz, 4) < 0)) ? -1 : 0;
}
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
static int ce_flush(git_SHA_CTX *context, int fd)
{
unsigned int left = write_buffer_len;
if (left) {
write_buffer_len = 0;
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
git_SHA1_Update(context, write_buffer, left);
}
/* Flush first if not enough space for SHA1 signature */
if (left + 20 > WRITE_BUFFER_SIZE) {
if (write_in_full(fd, write_buffer, left) != left)
return -1;
left = 0;
}
/* Append the SHA1 signature at the end */
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
git_SHA1_Final(write_buffer + left, context);
left += 20;
return (write_in_full(fd, write_buffer, left) != left) ? -1 : 0;
}
static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
{
/*
* The only thing we care about in this function is to smudge the
* falsely clean entry due to touch-update-touch race, so we leave
* everything else as they are. We are called for entries whose
* ce_mtime match the index file mtime.
2008-07-29 16:13:44 +08:00
*
* Note that this actually does not do much for gitlinks, for
* which ce_match_stat_basic() always goes to the actual
* contents. The caller checks with is_racy_timestamp() which
* always says "no" for gitlinks, so we are not called for them ;-)
*/
struct stat st;
if (lstat(ce->name, &st) < 0)
return;
if (ce_match_stat_basic(ce, &st))
return;
if (ce_modified_check_fs(ce, &st)) {
/* This is "racily clean"; smudge it. Note that this
* is a tricky code. At first glance, it may appear
* that it can break with this sequence:
*
* $ echo xyzzy >frotz
* $ git-update-index --add frotz
* $ : >frotz
* $ sleep 3
* $ echo filfre >nitfol
* $ git-update-index --add nitfol
*
* but it does not. When the second update-index runs,
* it notices that the entry "frotz" has the same timestamp
* as index, and if we were to smudge it by resetting its
* size to zero here, then the object name recorded
* in index is the 6-byte file but the cached stat information
* becomes zero --- which would then match what we would
* obtain from the filesystem next time we stat("frotz").
*
* However, the second update-index, before calling
* this function, notices that the cached size is 6
* bytes and what is on the filesystem is an empty
* file, and never calls us, so the cached size information
* for "frotz" stays 6 which does not match the filesystem.
*/
ce->ce_size = 0;
}
}
/* Copy miscellaneous fields but not the name */
static char *copy_cache_entry_to_ondisk(struct ondisk_cache_entry *ondisk,
struct cache_entry *ce)
{
short flags;
ondisk->ctime.sec = htonl(ce->ce_ctime.sec);
ondisk->mtime.sec = htonl(ce->ce_mtime.sec);
ondisk->ctime.nsec = htonl(ce->ce_ctime.nsec);
ondisk->mtime.nsec = htonl(ce->ce_mtime.nsec);
ondisk->dev = htonl(ce->ce_dev);
ondisk->ino = htonl(ce->ce_ino);
ondisk->mode = htonl(ce->ce_mode);
ondisk->uid = htonl(ce->ce_uid);
ondisk->gid = htonl(ce->ce_gid);
ondisk->size = htonl(ce->ce_size);
hashcpy(ondisk->sha1, ce->sha1);
flags = ce->ce_flags;
flags |= (ce_namelen(ce) >= CE_NAMEMASK ? CE_NAMEMASK : ce_namelen(ce));
ondisk->flags = htons(flags);
if (ce->ce_flags & CE_EXTENDED) {
struct ondisk_cache_entry_extended *ondisk2;
ondisk2 = (struct ondisk_cache_entry_extended *)ondisk;
ondisk2->flags2 = htons((ce->ce_flags & CE_EXTENDED_FLAGS) >> 16);
return ondisk2->name;
}
else {
return ondisk->name;
}
}
static int ce_write_entry(git_SHA_CTX *c, int fd, struct cache_entry *ce,
struct strbuf *previous_name)
{
int size;
struct ondisk_cache_entry *ondisk;
char *name;
int result;
if (!previous_name) {
size = ondisk_ce_size(ce);
ondisk = xcalloc(1, size);
name = copy_cache_entry_to_ondisk(ondisk, ce);
memcpy(name, ce->name, ce_namelen(ce));
} else {
int common, to_remove, prefix_size;
unsigned char to_remove_vi[16];
for (common = 0;
(ce->name[common] &&
common < previous_name->len &&
ce->name[common] == previous_name->buf[common]);
common++)
; /* still matching */
to_remove = previous_name->len - common;
prefix_size = encode_varint(to_remove, to_remove_vi);
if (ce->ce_flags & CE_EXTENDED)
size = offsetof(struct ondisk_cache_entry_extended, name);
else
size = offsetof(struct ondisk_cache_entry, name);
size += prefix_size + (ce_namelen(ce) - common + 1);
ondisk = xcalloc(1, size);
name = copy_cache_entry_to_ondisk(ondisk, ce);
memcpy(name, to_remove_vi, prefix_size);
memcpy(name + prefix_size, ce->name + common, ce_namelen(ce) - common);
strbuf_splice(previous_name, common, to_remove,
ce->name + common, ce_namelen(ce) - common);
}
result = ce_write(c, fd, ondisk, size);
free(ondisk);
return result;
}
static int has_racy_timestamp(struct index_state *istate)
{
int entries = istate->cache_nr;
int i;
for (i = 0; i < entries; i++) {
struct cache_entry *ce = istate->cache[i];
if (is_racy_timestamp(istate, ce))
return 1;
}
return 0;
}
/*
* Opportunisticly update the index but do not complain if we can't
*/
void update_index_if_able(struct index_state *istate, struct lock_file *lockfile)
{
if ((istate->cache_changed || has_racy_timestamp(istate)) &&
!write_index(istate, lockfile->fd))
commit_locked_index(lockfile);
else
rollback_lock_file(lockfile);
}
int write_index(struct index_state *istate, int newfd)
{
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
git_SHA_CTX c;
struct cache_header hdr;
int i, err, removed, extended, hdr_version;
struct cache_entry **cache = istate->cache;
int entries = istate->cache_nr;
struct stat st;
struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
for (i = removed = extended = 0; i < entries; i++) {
if (cache[i]->ce_flags & CE_REMOVE)
removed++;
/* reduce extended entries if possible */
cache[i]->ce_flags &= ~CE_EXTENDED;
if (cache[i]->ce_flags & CE_EXTENDED_FLAGS) {
extended++;
cache[i]->ce_flags |= CE_EXTENDED;
}
}
if (!istate->version)
istate->version = INDEX_FORMAT_DEFAULT;
/* demote version 3 to version 2 when the latter suffices */
if (istate->version == 3 || istate->version == 2)
istate->version = extended ? 3 : 2;
hdr_version = istate->version;
hdr.hdr_signature = htonl(CACHE_SIGNATURE);
hdr.hdr_version = htonl(hdr_version);
hdr.hdr_entries = htonl(entries - removed);
fix openssl headers conflicting with custom SHA1 implementations On ARM I have the following compilation errors: CC fast-import.o In file included from cache.h:8, from builtin.h:6, from fast-import.c:142: arm/sha1.h:14: error: conflicting types for 'SHA_CTX' /usr/include/openssl/sha.h:105: error: previous declaration of 'SHA_CTX' was here arm/sha1.h:16: error: conflicting types for 'SHA1_Init' /usr/include/openssl/sha.h:115: error: previous declaration of 'SHA1_Init' was here arm/sha1.h:17: error: conflicting types for 'SHA1_Update' /usr/include/openssl/sha.h:116: error: previous declaration of 'SHA1_Update' was here arm/sha1.h:18: error: conflicting types for 'SHA1_Final' /usr/include/openssl/sha.h:117: error: previous declaration of 'SHA1_Final' was here make: *** [fast-import.o] Error 1 This is because openssl header files are always included in git-compat-util.h since commit 684ec6c63c whenever NO_OPENSSL is not set, which somehow brings in <openssl/sha1.h> clashing with the custom ARM version. Compilation of git is probably broken on PPC too for the same reason. Turns out that the only file requiring openssl/ssl.h and openssl/err.h is imap-send.c. But only moving those problematic includes there doesn't solve the issue as it also includes cache.h which brings in the conflicting local SHA1 header file. As suggested by Jeff King, the best solution is to rename our references to SHA1 functions and structure to something git specific, and define those according to the implementation used. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-10-02 02:05:20 +08:00
git_SHA1_Init(&c);
if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
return -1;
previous_name = (hdr_version == 4) ? &previous_name_buf : NULL;
for (i = 0; i < entries; i++) {
struct cache_entry *ce = cache[i];
if (ce->ce_flags & CE_REMOVE)
continue;
if (!ce_uptodate(ce) && is_racy_timestamp(istate, ce))
ce_smudge_racily_clean_entry(ce);
do not write null sha1s to on-disk index We should never need to write the null sha1 into an index entry (short of the 1 in 2^160 chance that somebody actually has content that hashes to it). If we attempt to do so, it is much more likely that it is a bug, since we use the null sha1 as a sentinel value to mean "not valid". The presence of null sha1s in the index (which can come from, among other things, "update-index --cacheinfo", or by reading a corrupted tree) can cause problems for later readers, because they cannot distinguish the literal null sha1 from its use a sentinel value. For example, "git diff-files" on such an entry would make it appear as if it is stat-dirty, and until recently, the diff code assumed such an entry meant that we should be diffing a working tree file rather than a blob. Ideally, we would stop such entries from entering even our in-core index. However, we do sometimes legitimately add entries with null sha1s in order to represent these sentinel situations; simply forbidding them in add_index_entry breaks a lot of the existing code. However, we can at least make sure that our in-core sentinel representation never makes it to disk. To be thorough, we will test an attempt to add both a blob and a submodule entry. In the former case, we might run into problems anyway because we will be missing the blob object. But in the latter case, we do not enforce connectivity across gitlink entries, making this our only point of enforcement. The current implementation does not care which type of entry we are seeing, but testing both cases helps future-proof the test suite in case that changes. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-07-28 23:05:24 +08:00
if (is_null_sha1(ce->sha1))
return error("cache entry has null sha1: %s", ce->name);
if (ce_write_entry(&c, newfd, ce, previous_name) < 0)
return -1;
}
strbuf_release(&previous_name_buf);
/* Write extension data here */
if (istate->cache_tree) {
struct strbuf sb = STRBUF_INIT;
cache_tree_write(&sb, istate->cache_tree);
err = write_index_ext_header(&c, newfd, CACHE_EXT_TREE, sb.len) < 0
|| ce_write(&c, newfd, sb.buf, sb.len) < 0;
strbuf_release(&sb);
if (err)
return -1;
}
if (istate->resolve_undo) {
struct strbuf sb = STRBUF_INIT;
resolve_undo_write(&sb, istate->resolve_undo);
err = write_index_ext_header(&c, newfd, CACHE_EXT_RESOLVE_UNDO,
sb.len) < 0
|| ce_write(&c, newfd, sb.buf, sb.len) < 0;
strbuf_release(&sb);
if (err)
return -1;
}
if (ce_flush(&c, newfd) || fstat(newfd, &st))
return -1;
istate->timestamp.sec = (unsigned int)st.st_mtime;
istate->timestamp.nsec = ST_MTIME_NSEC(st);
return 0;
}
/*
* Read the index file that is potentially unmerged into given
* index_state, dropping any unmerged entries. Returns true if
* the index is unmerged. Callers who want to refuse to work
* from an unmerged state can call this and check its return value,
* instead of calling read_cache().
*/
int read_index_unmerged(struct index_state *istate)
{
int i;
int unmerged = 0;
read_index(istate);
for (i = 0; i < istate->cache_nr; i++) {
struct cache_entry *ce = istate->cache[i];
struct cache_entry *new_ce;
int size, len;
if (!ce_stage(ce))
continue;
unmerged = 1;
len = ce_namelen(ce);
size = cache_entry_size(len);
new_ce = xcalloc(1, size);
memcpy(new_ce->name, ce->name, len);
new_ce->ce_flags = create_ce_flags(0) | CE_CONFLICTED;
new_ce->ce_namelen = len;
new_ce->ce_mode = ce->ce_mode;
if (add_index_entry(istate, new_ce, 0))
return error("%s: cannot drop to stage #0",
ce->name);
i = index_name_pos(istate, new_ce->name, len);
}
return unmerged;
}
/*
* Returns 1 if the path is an "other" path with respect to
* the index; that is, the path is not mentioned in the index at all,
* either as a file, a directory with some files in the index,
* or as an unmerged entry.
*
* We helpfully remove a trailing "/" from directories so that
* the output of read_directory can be used as-is.
*/
int index_name_is_other(const struct index_state *istate, const char *name,
int namelen)
{
int pos;
if (namelen && name[namelen - 1] == '/')
namelen--;
pos = index_name_pos(istate, name, namelen);
if (0 <= pos)
return 0; /* exact match */
pos = -pos - 1;
if (pos < istate->cache_nr) {
struct cache_entry *ce = istate->cache[pos];
if (ce_namelen(ce) == namelen &&
!memcmp(ce->name, name, namelen))
return 0; /* Yup, this one exists unmerged */
}
return 1;
}