Add has_symlink_leading_path() function.
When we are applying a patch that creates a blob at a path, or
when we are switching from a branch that does not have a blob at
the path to another branch that has one, we need to make sure
that there is nothing at the path in the working tree, as such a
file is a local modification made by the user that would be lost
by the operation.
Normally, lstat() on the path and making sure ENOENT is returned
is good enough for that purpose. However there is a twist. We
may be creating a regular file arch/x86_64/boot/Makefile, while
removing an existing symbolic link at arch/x86_64/boot that
points at existing ../i386/boot directory that has Makefile in
it. We always first check without touching filesystem and then
perform the actual operation, so when we verify the new file,
arch/x86_64/boot/Makefile, does not exist, we haven't removed
the symbolic link arc/x86_64/boot symbolic link yet. lstat() on
the file sees through the symbolic link and reports the file is
there, which is not what we want.
The function has_symlink_leading_path() function takes a path,
and sees if any of the leading directory component is a symbolic
link.
When files in a new directory are created, we tend to process
them together because both index and tree are sorted. The
function takes advantage of this and allows the caller to cache
and reuse which symbolic link on the filesystem caused the
function to return true.
The calling sequence would be:
char last_symlink[PATH_MAX];
*last_symlink = '\0';
for each index entry {
if (!lose)
continue;
if (lstat(it))
if (errno == ENOENT)
; /* happy */
else
error;
else if (has_symlink_leading_path(it, last_symlink))
; /* happy */
else
error; /* would lose local changes */
unlink_entry(it, last_symlink);
}
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 13:11:07 +08:00
|
|
|
#include "cache.h"
|
|
|
|
|
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
/*
|
|
|
|
|
* Returns the length (on a path component basis) of the longest
|
2009-02-10 04:54:05 +08:00
|
|
|
* common prefix match of 'name_a' and 'name_b'.
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
*/
|
2009-02-10 04:54:05 +08:00
|
|
|
static int longest_path_match(const char *name_a, int len_a,
|
|
|
|
|
const char *name_b, int len_b,
|
|
|
|
|
int *previous_slash)
|
Optimize symlink/directory detection
This is the base for making symlink detection in the middle fo a pathname
saner and (much) more efficient.
Under various loads, we want to verify that the full path leading up to a
filename is a real directory tree, and that when we successfully do an
'lstat()' on a filename, we don't get a false positive due to a symlink in
the middle of the path that git should have seen as a symlink, not as a
normal path component.
The 'has_symlink_leading_path()' function already did this, and cached
a single level of symlink information, but didn't cache the _lack_ of a
symlink, so the normal behaviour was actually the wrong way around, and we
ended up doing an 'lstat()' on each path component to check that it was a
real directory.
This caches the last detected full directory and symlink entries, and
speeds up especially deep directory structures a lot by avoiding to
lstat() all the directories leading up to each entry in the index.
[ This can - and should - probably be extended upon so that we eventually
never do a bare 'lstat()' on any path entries at *all* when checking the
index, but always check the full path carefully. Right now we do not
generally check the whole path for all our normal quick index
revalidation.
We should also make sure that we're careful about all the invalidation,
ie when we remove a link and replace it by a directory we should
invalidate the symlink cache if it matches (and vice versa for the
directory cache).
But regardless, the basic function needs to be sane to do that. The old
'has_symlink_leading_path()' was not capable enough - or indeed the code
readable enough - to really do that sanely. So I'm pushing this as not
just an optimization, but as a base for further work. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-10 00:21:07 +08:00
|
|
|
{
|
2009-01-18 23:14:53 +08:00
|
|
|
int max_len, match_len = 0, match_len_prev = 0, i = 0;
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
|
2009-02-10 04:54:05 +08:00
|
|
|
max_len = len_a < len_b ? len_a : len_b;
|
|
|
|
|
while (i < max_len && name_a[i] == name_b[i]) {
|
|
|
|
|
if (name_a[i] == '/') {
|
2009-01-18 23:14:53 +08:00
|
|
|
match_len_prev = match_len;
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
match_len = i;
|
2009-01-18 23:14:53 +08:00
|
|
|
}
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
i++;
|
|
|
|
|
}
|
2009-02-10 04:54:04 +08:00
|
|
|
/*
|
2009-02-10 04:54:05 +08:00
|
|
|
* Is 'name_b' a substring of 'name_a', the other way around,
|
|
|
|
|
* or is 'name_a' and 'name_b' the exact same string?
|
2009-02-10 04:54:04 +08:00
|
|
|
*/
|
2009-02-10 04:54:05 +08:00
|
|
|
if (i >= max_len && ((len_a > len_b && name_a[len_b] == '/') ||
|
|
|
|
|
(len_a < len_b && name_b[len_a] == '/') ||
|
|
|
|
|
(len_a == len_b))) {
|
2009-01-18 23:14:53 +08:00
|
|
|
match_len_prev = match_len;
|
2009-02-10 04:54:04 +08:00
|
|
|
match_len = i;
|
2009-01-18 23:14:53 +08:00
|
|
|
}
|
|
|
|
|
*previous_slash = match_len_prev;
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
return match_len;
|
Optimize symlink/directory detection
This is the base for making symlink detection in the middle fo a pathname
saner and (much) more efficient.
Under various loads, we want to verify that the full path leading up to a
filename is a real directory tree, and that when we successfully do an
'lstat()' on a filename, we don't get a false positive due to a symlink in
the middle of the path that git should have seen as a symlink, not as a
normal path component.
The 'has_symlink_leading_path()' function already did this, and cached
a single level of symlink information, but didn't cache the _lack_ of a
symlink, so the normal behaviour was actually the wrong way around, and we
ended up doing an 'lstat()' on each path component to check that it was a
real directory.
This caches the last detected full directory and symlink entries, and
speeds up especially deep directory structures a lot by avoiding to
lstat() all the directories leading up to each entry in the index.
[ This can - and should - probably be extended upon so that we eventually
never do a bare 'lstat()' on any path entries at *all* when checking the
index, but always check the full path carefully. Right now we do not
generally check the whole path for all our normal quick index
revalidation.
We should also make sure that we're careful about all the invalidation,
ie when we remove a link and replace it by a directory we should
invalidate the symlink cache if it matches (and vice versa for the
directory cache).
But regardless, the basic function needs to be sane to do that. The old
'has_symlink_leading_path()' was not capable enough - or indeed the code
readable enough - to really do that sanely. So I'm pushing this as not
just an optimization, but as a base for further work. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-10 00:21:07 +08:00
|
|
|
}
|
|
|
|
|
|
2009-02-10 04:54:05 +08:00
|
|
|
static struct cache_def {
|
|
|
|
|
char path[PATH_MAX + 1];
|
|
|
|
|
int len;
|
|
|
|
|
int flags;
|
|
|
|
|
int track_flags;
|
|
|
|
|
int prefix_len_stat_func;
|
|
|
|
|
} cache;
|
|
|
|
|
|
2009-02-10 04:54:04 +08:00
|
|
|
static inline void reset_lstat_cache(void)
|
Optimize symlink/directory detection
This is the base for making symlink detection in the middle fo a pathname
saner and (much) more efficient.
Under various loads, we want to verify that the full path leading up to a
filename is a real directory tree, and that when we successfully do an
'lstat()' on a filename, we don't get a false positive due to a symlink in
the middle of the path that git should have seen as a symlink, not as a
normal path component.
The 'has_symlink_leading_path()' function already did this, and cached
a single level of symlink information, but didn't cache the _lack_ of a
symlink, so the normal behaviour was actually the wrong way around, and we
ended up doing an 'lstat()' on each path component to check that it was a
real directory.
This caches the last detected full directory and symlink entries, and
speeds up especially deep directory structures a lot by avoiding to
lstat() all the directories leading up to each entry in the index.
[ This can - and should - probably be extended upon so that we eventually
never do a bare 'lstat()' on any path entries at *all* when checking the
index, but always check the full path carefully. Right now we do not
generally check the whole path for all our normal quick index
revalidation.
We should also make sure that we're careful about all the invalidation,
ie when we remove a link and replace it by a directory we should
invalidate the symlink cache if it matches (and vice versa for the
directory cache).
But regardless, the basic function needs to be sane to do that. The old
'has_symlink_leading_path()' was not capable enough - or indeed the code
readable enough - to really do that sanely. So I'm pushing this as not
just an optimization, but as a base for further work. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-10 00:21:07 +08:00
|
|
|
{
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
cache.path[0] = '\0';
|
|
|
|
|
cache.len = 0;
|
|
|
|
|
cache.flags = 0;
|
2009-02-10 04:54:04 +08:00
|
|
|
/*
|
|
|
|
|
* The track_flags and prefix_len_stat_func members is only
|
|
|
|
|
* set by the safeguard rule inside lstat_cache()
|
|
|
|
|
*/
|
Optimize symlink/directory detection
This is the base for making symlink detection in the middle fo a pathname
saner and (much) more efficient.
Under various loads, we want to verify that the full path leading up to a
filename is a real directory tree, and that when we successfully do an
'lstat()' on a filename, we don't get a false positive due to a symlink in
the middle of the path that git should have seen as a symlink, not as a
normal path component.
The 'has_symlink_leading_path()' function already did this, and cached
a single level of symlink information, but didn't cache the _lack_ of a
symlink, so the normal behaviour was actually the wrong way around, and we
ended up doing an 'lstat()' on each path component to check that it was a
real directory.
This caches the last detected full directory and symlink entries, and
speeds up especially deep directory structures a lot by avoiding to
lstat() all the directories leading up to each entry in the index.
[ This can - and should - probably be extended upon so that we eventually
never do a bare 'lstat()' on any path entries at *all* when checking the
index, but always check the full path carefully. Right now we do not
generally check the whole path for all our normal quick index
revalidation.
We should also make sure that we're careful about all the invalidation,
ie when we remove a link and replace it by a directory we should
invalidate the symlink cache if it matches (and vice versa for the
directory cache).
But regardless, the basic function needs to be sane to do that. The old
'has_symlink_leading_path()' was not capable enough - or indeed the code
readable enough - to really do that sanely. So I'm pushing this as not
just an optimization, but as a base for further work. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-10 00:21:07 +08:00
|
|
|
}
|
|
|
|
|
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
#define FL_DIR (1 << 0)
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
#define FL_NOENT (1 << 1)
|
|
|
|
|
#define FL_SYMLINK (1 << 2)
|
|
|
|
|
#define FL_LSTATERR (1 << 3)
|
|
|
|
|
#define FL_ERR (1 << 4)
|
2009-01-18 23:14:52 +08:00
|
|
|
#define FL_FULLPATH (1 << 5)
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Check if name 'name' of length 'len' has a symlink leading
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
* component, or if the directory exists and is real, or not.
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
*
|
|
|
|
|
* To speed up the check, some information is allowed to be cached.
|
2009-01-18 23:14:52 +08:00
|
|
|
* This can be indicated by the 'track_flags' argument, which also can
|
|
|
|
|
* be used to indicate that we should check the full path.
|
|
|
|
|
*
|
|
|
|
|
* The 'prefix_len_stat_func' parameter can be used to set the length
|
|
|
|
|
* of the prefix, where the cache should use the stat() function
|
|
|
|
|
* instead of the lstat() function to test each path component.
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
*/
|
2009-02-10 04:54:06 +08:00
|
|
|
static int lstat_cache(const char *name, int len,
|
2009-01-18 23:14:52 +08:00
|
|
|
int track_flags, int prefix_len_stat_func)
|
Optimize symlink/directory detection
This is the base for making symlink detection in the middle fo a pathname
saner and (much) more efficient.
Under various loads, we want to verify that the full path leading up to a
filename is a real directory tree, and that when we successfully do an
'lstat()' on a filename, we don't get a false positive due to a symlink in
the middle of the path that git should have seen as a symlink, not as a
normal path component.
The 'has_symlink_leading_path()' function already did this, and cached
a single level of symlink information, but didn't cache the _lack_ of a
symlink, so the normal behaviour was actually the wrong way around, and we
ended up doing an 'lstat()' on each path component to check that it was a
real directory.
This caches the last detected full directory and symlink entries, and
speeds up especially deep directory structures a lot by avoiding to
lstat() all the directories leading up to each entry in the index.
[ This can - and should - probably be extended upon so that we eventually
never do a bare 'lstat()' on any path entries at *all* when checking the
index, but always check the full path carefully. Right now we do not
generally check the whole path for all our normal quick index
revalidation.
We should also make sure that we're careful about all the invalidation,
ie when we remove a link and replace it by a directory we should
invalidate the symlink cache if it matches (and vice versa for the
directory cache).
But regardless, the basic function needs to be sane to do that. The old
'has_symlink_leading_path()' was not capable enough - or indeed the code
readable enough - to really do that sanely. So I'm pushing this as not
just an optimization, but as a base for further work. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-10 00:21:07 +08:00
|
|
|
{
|
2009-01-18 23:14:53 +08:00
|
|
|
int match_len, last_slash, last_slash_dir, previous_slash;
|
2009-01-18 23:14:52 +08:00
|
|
|
int match_flags, ret_flags, save_flags, max_len, ret;
|
Optimize symlink/directory detection
This is the base for making symlink detection in the middle fo a pathname
saner and (much) more efficient.
Under various loads, we want to verify that the full path leading up to a
filename is a real directory tree, and that when we successfully do an
'lstat()' on a filename, we don't get a false positive due to a symlink in
the middle of the path that git should have seen as a symlink, not as a
normal path component.
The 'has_symlink_leading_path()' function already did this, and cached
a single level of symlink information, but didn't cache the _lack_ of a
symlink, so the normal behaviour was actually the wrong way around, and we
ended up doing an 'lstat()' on each path component to check that it was a
real directory.
This caches the last detected full directory and symlink entries, and
speeds up especially deep directory structures a lot by avoiding to
lstat() all the directories leading up to each entry in the index.
[ This can - and should - probably be extended upon so that we eventually
never do a bare 'lstat()' on any path entries at *all* when checking the
index, but always check the full path carefully. Right now we do not
generally check the whole path for all our normal quick index
revalidation.
We should also make sure that we're careful about all the invalidation,
ie when we remove a link and replace it by a directory we should
invalidate the symlink cache if it matches (and vice versa for the
directory cache).
But regardless, the basic function needs to be sane to do that. The old
'has_symlink_leading_path()' was not capable enough - or indeed the code
readable enough - to really do that sanely. So I'm pushing this as not
just an optimization, but as a base for further work. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-10 00:21:07 +08:00
|
|
|
struct stat st;
|
Add has_symlink_leading_path() function.
When we are applying a patch that creates a blob at a path, or
when we are switching from a branch that does not have a blob at
the path to another branch that has one, we need to make sure
that there is nothing at the path in the working tree, as such a
file is a local modification made by the user that would be lost
by the operation.
Normally, lstat() on the path and making sure ENOENT is returned
is good enough for that purpose. However there is a twist. We
may be creating a regular file arch/x86_64/boot/Makefile, while
removing an existing symbolic link at arch/x86_64/boot that
points at existing ../i386/boot directory that has Makefile in
it. We always first check without touching filesystem and then
perform the actual operation, so when we verify the new file,
arch/x86_64/boot/Makefile, does not exist, we haven't removed
the symbolic link arc/x86_64/boot symbolic link yet. lstat() on
the file sees through the symbolic link and reports the file is
there, which is not what we want.
The function has_symlink_leading_path() function takes a path,
and sees if any of the leading directory component is a symbolic
link.
When files in a new directory are created, we tend to process
them together because both index and tree are sorted. The
function takes advantage of this and allows the caller to cache
and reuse which symbolic link on the filesystem caused the
function to return true.
The calling sequence would be:
char last_symlink[PATH_MAX];
*last_symlink = '\0';
for each index entry {
if (!lose)
continue;
if (lstat(it))
if (errno == ENOENT)
; /* happy */
else
error;
else if (has_symlink_leading_path(it, last_symlink))
; /* happy */
else
error; /* would lose local changes */
unlink_entry(it, last_symlink);
}
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 13:11:07 +08:00
|
|
|
|
2009-01-18 23:14:52 +08:00
|
|
|
if (cache.track_flags != track_flags ||
|
|
|
|
|
cache.prefix_len_stat_func != prefix_len_stat_func) {
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
/*
|
2009-02-10 04:54:04 +08:00
|
|
|
* As a safeguard rule we clear the cache if the
|
|
|
|
|
* values of track_flags and/or prefix_len_stat_func
|
|
|
|
|
* does not match with the last supplied values.
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
*/
|
2009-02-10 04:54:04 +08:00
|
|
|
reset_lstat_cache();
|
|
|
|
|
cache.track_flags = track_flags;
|
|
|
|
|
cache.prefix_len_stat_func = prefix_len_stat_func;
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
match_len = last_slash = 0;
|
|
|
|
|
} else {
|
|
|
|
|
/*
|
|
|
|
|
* Check to see if we have a match from the cache for
|
|
|
|
|
* the 2 "excluding" path types.
|
|
|
|
|
*/
|
2009-01-18 23:14:53 +08:00
|
|
|
match_len = last_slash =
|
2009-02-10 04:54:05 +08:00
|
|
|
longest_path_match(name, len, cache.path, cache.len,
|
|
|
|
|
&previous_slash);
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
match_flags = cache.flags & track_flags & (FL_NOENT|FL_SYMLINK);
|
|
|
|
|
if (match_flags && match_len == cache.len)
|
|
|
|
|
return match_flags;
|
|
|
|
|
/*
|
|
|
|
|
* If we now have match_len > 0, we would know that
|
|
|
|
|
* the matched part will always be a directory.
|
|
|
|
|
*
|
|
|
|
|
* Also, if we are tracking directories and 'name' is
|
|
|
|
|
* a substring of the cache on a path component basis,
|
|
|
|
|
* we can return immediately.
|
|
|
|
|
*/
|
|
|
|
|
match_flags = track_flags & FL_DIR;
|
|
|
|
|
if (match_flags && len == match_len)
|
|
|
|
|
return match_flags;
|
|
|
|
|
}
|
Optimize symlink/directory detection
This is the base for making symlink detection in the middle fo a pathname
saner and (much) more efficient.
Under various loads, we want to verify that the full path leading up to a
filename is a real directory tree, and that when we successfully do an
'lstat()' on a filename, we don't get a false positive due to a symlink in
the middle of the path that git should have seen as a symlink, not as a
normal path component.
The 'has_symlink_leading_path()' function already did this, and cached
a single level of symlink information, but didn't cache the _lack_ of a
symlink, so the normal behaviour was actually the wrong way around, and we
ended up doing an 'lstat()' on each path component to check that it was a
real directory.
This caches the last detected full directory and symlink entries, and
speeds up especially deep directory structures a lot by avoiding to
lstat() all the directories leading up to each entry in the index.
[ This can - and should - probably be extended upon so that we eventually
never do a bare 'lstat()' on any path entries at *all* when checking the
index, but always check the full path carefully. Right now we do not
generally check the whole path for all our normal quick index
revalidation.
We should also make sure that we're careful about all the invalidation,
ie when we remove a link and replace it by a directory we should
invalidate the symlink cache if it matches (and vice versa for the
directory cache).
But regardless, the basic function needs to be sane to do that. The old
'has_symlink_leading_path()' was not capable enough - or indeed the code
readable enough - to really do that sanely. So I'm pushing this as not
just an optimization, but as a base for further work. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-10 00:21:07 +08:00
|
|
|
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
/*
|
|
|
|
|
* Okay, no match from the cache so far, so now we have to
|
|
|
|
|
* check the rest of the path components.
|
|
|
|
|
*/
|
|
|
|
|
ret_flags = FL_DIR;
|
|
|
|
|
last_slash_dir = last_slash;
|
|
|
|
|
max_len = len < PATH_MAX ? len : PATH_MAX;
|
|
|
|
|
while (match_len < max_len) {
|
|
|
|
|
do {
|
|
|
|
|
cache.path[match_len] = name[match_len];
|
|
|
|
|
match_len++;
|
|
|
|
|
} while (match_len < max_len && name[match_len] != '/');
|
2009-01-18 23:14:52 +08:00
|
|
|
if (match_len >= max_len && !(track_flags & FL_FULLPATH))
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
break;
|
|
|
|
|
last_slash = match_len;
|
|
|
|
|
cache.path[last_slash] = '\0';
|
Add has_symlink_leading_path() function.
When we are applying a patch that creates a blob at a path, or
when we are switching from a branch that does not have a blob at
the path to another branch that has one, we need to make sure
that there is nothing at the path in the working tree, as such a
file is a local modification made by the user that would be lost
by the operation.
Normally, lstat() on the path and making sure ENOENT is returned
is good enough for that purpose. However there is a twist. We
may be creating a regular file arch/x86_64/boot/Makefile, while
removing an existing symbolic link at arch/x86_64/boot that
points at existing ../i386/boot directory that has Makefile in
it. We always first check without touching filesystem and then
perform the actual operation, so when we verify the new file,
arch/x86_64/boot/Makefile, does not exist, we haven't removed
the symbolic link arc/x86_64/boot symbolic link yet. lstat() on
the file sees through the symbolic link and reports the file is
there, which is not what we want.
The function has_symlink_leading_path() function takes a path,
and sees if any of the leading directory component is a symbolic
link.
When files in a new directory are created, we tend to process
them together because both index and tree are sorted. The
function takes advantage of this and allows the caller to cache
and reuse which symbolic link on the filesystem caused the
function to return true.
The calling sequence would be:
char last_symlink[PATH_MAX];
*last_symlink = '\0';
for each index entry {
if (!lose)
continue;
if (lstat(it))
if (errno == ENOENT)
; /* happy */
else
error;
else if (has_symlink_leading_path(it, last_symlink))
; /* happy */
else
error; /* would lose local changes */
unlink_entry(it, last_symlink);
}
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 13:11:07 +08:00
|
|
|
|
2009-01-18 23:14:52 +08:00
|
|
|
if (last_slash <= prefix_len_stat_func)
|
|
|
|
|
ret = stat(cache.path, &st);
|
|
|
|
|
else
|
|
|
|
|
ret = lstat(cache.path, &st);
|
|
|
|
|
|
|
|
|
|
if (ret) {
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
ret_flags = FL_LSTATERR;
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
if (errno == ENOENT)
|
|
|
|
|
ret_flags |= FL_NOENT;
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
} else if (S_ISDIR(st.st_mode)) {
|
|
|
|
|
last_slash_dir = last_slash;
|
Optimize symlink/directory detection
This is the base for making symlink detection in the middle fo a pathname
saner and (much) more efficient.
Under various loads, we want to verify that the full path leading up to a
filename is a real directory tree, and that when we successfully do an
'lstat()' on a filename, we don't get a false positive due to a symlink in
the middle of the path that git should have seen as a symlink, not as a
normal path component.
The 'has_symlink_leading_path()' function already did this, and cached
a single level of symlink information, but didn't cache the _lack_ of a
symlink, so the normal behaviour was actually the wrong way around, and we
ended up doing an 'lstat()' on each path component to check that it was a
real directory.
This caches the last detected full directory and symlink entries, and
speeds up especially deep directory structures a lot by avoiding to
lstat() all the directories leading up to each entry in the index.
[ This can - and should - probably be extended upon so that we eventually
never do a bare 'lstat()' on any path entries at *all* when checking the
index, but always check the full path carefully. Right now we do not
generally check the whole path for all our normal quick index
revalidation.
We should also make sure that we're careful about all the invalidation,
ie when we remove a link and replace it by a directory we should
invalidate the symlink cache if it matches (and vice versa for the
directory cache).
But regardless, the basic function needs to be sane to do that. The old
'has_symlink_leading_path()' was not capable enough - or indeed the code
readable enough - to really do that sanely. So I'm pushing this as not
just an optimization, but as a base for further work. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-10 00:21:07 +08:00
|
|
|
continue;
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
} else if (S_ISLNK(st.st_mode)) {
|
|
|
|
|
ret_flags = FL_SYMLINK;
|
|
|
|
|
} else {
|
|
|
|
|
ret_flags = FL_ERR;
|
Add has_symlink_leading_path() function.
When we are applying a patch that creates a blob at a path, or
when we are switching from a branch that does not have a blob at
the path to another branch that has one, we need to make sure
that there is nothing at the path in the working tree, as such a
file is a local modification made by the user that would be lost
by the operation.
Normally, lstat() on the path and making sure ENOENT is returned
is good enough for that purpose. However there is a twist. We
may be creating a regular file arch/x86_64/boot/Makefile, while
removing an existing symbolic link at arch/x86_64/boot that
points at existing ../i386/boot directory that has Makefile in
it. We always first check without touching filesystem and then
perform the actual operation, so when we verify the new file,
arch/x86_64/boot/Makefile, does not exist, we haven't removed
the symbolic link arc/x86_64/boot symbolic link yet. lstat() on
the file sees through the symbolic link and reports the file is
there, which is not what we want.
The function has_symlink_leading_path() function takes a path,
and sees if any of the leading directory component is a symbolic
link.
When files in a new directory are created, we tend to process
them together because both index and tree are sorted. The
function takes advantage of this and allows the caller to cache
and reuse which symbolic link on the filesystem caused the
function to return true.
The calling sequence would be:
char last_symlink[PATH_MAX];
*last_symlink = '\0';
for each index entry {
if (!lose)
continue;
if (lstat(it))
if (errno == ENOENT)
; /* happy */
else
error;
else if (has_symlink_leading_path(it, last_symlink))
; /* happy */
else
error; /* would lose local changes */
unlink_entry(it, last_symlink);
}
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 13:11:07 +08:00
|
|
|
}
|
Optimize symlink/directory detection
This is the base for making symlink detection in the middle fo a pathname
saner and (much) more efficient.
Under various loads, we want to verify that the full path leading up to a
filename is a real directory tree, and that when we successfully do an
'lstat()' on a filename, we don't get a false positive due to a symlink in
the middle of the path that git should have seen as a symlink, not as a
normal path component.
The 'has_symlink_leading_path()' function already did this, and cached
a single level of symlink information, but didn't cache the _lack_ of a
symlink, so the normal behaviour was actually the wrong way around, and we
ended up doing an 'lstat()' on each path component to check that it was a
real directory.
This caches the last detected full directory and symlink entries, and
speeds up especially deep directory structures a lot by avoiding to
lstat() all the directories leading up to each entry in the index.
[ This can - and should - probably be extended upon so that we eventually
never do a bare 'lstat()' on any path entries at *all* when checking the
index, but always check the full path carefully. Right now we do not
generally check the whole path for all our normal quick index
revalidation.
We should also make sure that we're careful about all the invalidation,
ie when we remove a link and replace it by a directory we should
invalidate the symlink cache if it matches (and vice versa for the
directory cache).
But regardless, the basic function needs to be sane to do that. The old
'has_symlink_leading_path()' was not capable enough - or indeed the code
readable enough - to really do that sanely. So I'm pushing this as not
just an optimization, but as a base for further work. ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2008-05-10 00:21:07 +08:00
|
|
|
break;
|
Add has_symlink_leading_path() function.
When we are applying a patch that creates a blob at a path, or
when we are switching from a branch that does not have a blob at
the path to another branch that has one, we need to make sure
that there is nothing at the path in the working tree, as such a
file is a local modification made by the user that would be lost
by the operation.
Normally, lstat() on the path and making sure ENOENT is returned
is good enough for that purpose. However there is a twist. We
may be creating a regular file arch/x86_64/boot/Makefile, while
removing an existing symbolic link at arch/x86_64/boot that
points at existing ../i386/boot directory that has Makefile in
it. We always first check without touching filesystem and then
perform the actual operation, so when we verify the new file,
arch/x86_64/boot/Makefile, does not exist, we haven't removed
the symbolic link arc/x86_64/boot symbolic link yet. lstat() on
the file sees through the symbolic link and reports the file is
there, which is not what we want.
The function has_symlink_leading_path() function takes a path,
and sees if any of the leading directory component is a symbolic
link.
When files in a new directory are created, we tend to process
them together because both index and tree are sorted. The
function takes advantage of this and allows the caller to cache
and reuse which symbolic link on the filesystem caused the
function to return true.
The calling sequence would be:
char last_symlink[PATH_MAX];
*last_symlink = '\0';
for each index entry {
if (!lose)
continue;
if (lstat(it))
if (errno == ENOENT)
; /* happy */
else
error;
else if (has_symlink_leading_path(it, last_symlink))
; /* happy */
else
error; /* would lose local changes */
unlink_entry(it, last_symlink);
}
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 13:11:07 +08:00
|
|
|
}
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
|
|
|
|
|
/*
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
* At the end update the cache. Note that max 3 different
|
|
|
|
|
* path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached
|
|
|
|
|
* for the moment!
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
*/
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
save_flags = ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
|
2009-01-18 23:14:52 +08:00
|
|
|
if (save_flags && last_slash > 0 && last_slash <= PATH_MAX) {
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
cache.path[last_slash] = '\0';
|
|
|
|
|
cache.len = last_slash;
|
|
|
|
|
cache.flags = save_flags;
|
2009-02-10 04:54:04 +08:00
|
|
|
} else if ((track_flags & FL_DIR) &&
|
2009-01-18 23:14:52 +08:00
|
|
|
last_slash_dir > 0 && last_slash_dir <= PATH_MAX) {
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
/*
|
|
|
|
|
* We have a separate test for the directory case,
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
* since it could be that we have found a symlink or a
|
|
|
|
|
* non-existing directory and the track_flags says
|
|
|
|
|
* that we cannot cache this fact, so the cache would
|
|
|
|
|
* then have been left empty in this case.
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
*
|
|
|
|
|
* But if we are allowed to track real directories, we
|
|
|
|
|
* can still cache the path components before the last
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
* one (the found symlink or non-existing component).
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
*/
|
|
|
|
|
cache.path[last_slash_dir] = '\0';
|
|
|
|
|
cache.len = last_slash_dir;
|
|
|
|
|
cache.flags = FL_DIR;
|
|
|
|
|
} else {
|
2009-02-10 04:54:04 +08:00
|
|
|
reset_lstat_cache();
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
}
|
|
|
|
|
return ret_flags;
|
|
|
|
|
}
|
|
|
|
|
|
2009-01-18 23:14:53 +08:00
|
|
|
/*
|
|
|
|
|
* Invalidate the given 'name' from the cache, if 'name' matches
|
|
|
|
|
* completely with the cache.
|
|
|
|
|
*/
|
2009-02-10 04:54:06 +08:00
|
|
|
void invalidate_lstat_cache(const char *name, int len)
|
2009-01-18 23:14:53 +08:00
|
|
|
{
|
|
|
|
|
int match_len, previous_slash;
|
|
|
|
|
|
2009-02-10 04:54:05 +08:00
|
|
|
match_len = longest_path_match(name, len, cache.path, cache.len,
|
|
|
|
|
&previous_slash);
|
2009-01-18 23:14:53 +08:00
|
|
|
if (len == match_len) {
|
|
|
|
|
if ((cache.track_flags & FL_DIR) && previous_slash > 0) {
|
|
|
|
|
cache.path[previous_slash] = '\0';
|
|
|
|
|
cache.len = previous_slash;
|
|
|
|
|
cache.flags = FL_DIR;
|
|
|
|
|
} else
|
2009-02-10 04:54:04 +08:00
|
|
|
reset_lstat_cache();
|
2009-01-18 23:14:53 +08:00
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
2009-01-18 23:14:54 +08:00
|
|
|
/*
|
|
|
|
|
* Completely clear the contents of the cache
|
|
|
|
|
*/
|
|
|
|
|
void clear_lstat_cache(void)
|
|
|
|
|
{
|
2009-02-10 04:54:04 +08:00
|
|
|
reset_lstat_cache();
|
2009-01-18 23:14:54 +08:00
|
|
|
}
|
|
|
|
|
|
2009-01-18 23:14:52 +08:00
|
|
|
#define USE_ONLY_LSTAT 0
|
|
|
|
|
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
/*
|
|
|
|
|
* Return non-zero if path 'name' has a leading symlink component
|
|
|
|
|
*/
|
2009-02-10 04:54:06 +08:00
|
|
|
int has_symlink_leading_path(const char *name, int len)
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
{
|
2009-02-10 04:54:06 +08:00
|
|
|
return lstat_cache(name, len,
|
2009-01-18 23:14:52 +08:00
|
|
|
FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) &
|
lstat_cache(): more cache effective symlink/directory detection
Make the cache functionality more effective. Previously when A/B/C/D
was in the cache and A/B/C/E/file.c was called for, there was no match
at all from the cache. Now we use the fact that the paths "A", "A/B"
and "A/B/C" are already tested, and we only need to do an lstat() call
on "A/B/C/E".
We only cache/store the last path regardless of its type. Since the
cache functionality is always used with alphabetically sorted names
(at least it seems so for me), there is no need to store both the last
symlink-leading path and the last real-directory path. Note that if
the cache is not called with (mostly) alphabetically sorted names,
neither the old, nor this new one, would be very effective.
Previously, when symlink A/B/C/S was cached/stored in the symlink-
leading path, and A/B/C/file.c was called for, it was not easy to use
the fact that we already knew that the paths "A", "A/B" and "A/B/C"
are real directories.
Avoid copying the first path components of the name 2 zillion times
when we test new path components. Since we always cache/store the
last path, we can copy each component as we test those directly into
the cache. Previously we ended up doing a memcpy() for the full
path/name right before each lstat() call, and when updating the cache
for each time we have tested a new path component.
We also use less memory, that is, PATH_MAX bytes less memory on the
stack and PATH_MAX bytes less memory on the heap.
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:50 +08:00
|
|
|
FL_SYMLINK;
|
Add has_symlink_leading_path() function.
When we are applying a patch that creates a blob at a path, or
when we are switching from a branch that does not have a blob at
the path to another branch that has one, we need to make sure
that there is nothing at the path in the working tree, as such a
file is a local modification made by the user that would be lost
by the operation.
Normally, lstat() on the path and making sure ENOENT is returned
is good enough for that purpose. However there is a twist. We
may be creating a regular file arch/x86_64/boot/Makefile, while
removing an existing symbolic link at arch/x86_64/boot that
points at existing ../i386/boot directory that has Makefile in
it. We always first check without touching filesystem and then
perform the actual operation, so when we verify the new file,
arch/x86_64/boot/Makefile, does not exist, we haven't removed
the symbolic link arc/x86_64/boot symbolic link yet. lstat() on
the file sees through the symbolic link and reports the file is
there, which is not what we want.
The function has_symlink_leading_path() function takes a path,
and sees if any of the leading directory component is a symbolic
link.
When files in a new directory are created, we tend to process
them together because both index and tree are sorted. The
function takes advantage of this and allows the caller to cache
and reuse which symbolic link on the filesystem caused the
function to return true.
The calling sequence would be:
char last_symlink[PATH_MAX];
*last_symlink = '\0';
for each index entry {
if (!lose)
continue;
if (lstat(it))
if (errno == ENOENT)
; /* happy */
else
error;
else if (has_symlink_leading_path(it, last_symlink))
; /* happy */
else
error; /* would lose local changes */
unlink_entry(it, last_symlink);
}
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-12 13:11:07 +08:00
|
|
|
}
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Return non-zero if path 'name' has a leading symlink component or
|
|
|
|
|
* if some leading path component does not exists.
|
|
|
|
|
*/
|
2009-02-10 04:54:06 +08:00
|
|
|
int has_symlink_or_noent_leading_path(const char *name, int len)
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
{
|
2009-02-10 04:54:06 +08:00
|
|
|
return lstat_cache(name, len,
|
2009-01-18 23:14:52 +08:00
|
|
|
FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT) &
|
lstat_cache(): introduce has_symlink_or_noent_leading_path() function
In some cases, especially inside the unpack-trees.c file, and inside
the verify_absent() function, we can avoid some unnecessary calls to
lstat(), if the lstat_cache() function can also be told to keep track
of non-existing directories.
So we update the lstat_cache() function to handle this new fact,
introduce a new wrapper function, and the result is that we save lots
of lstat() calls for a removed directory which previously contained
lots of files, when we call this new wrapper of lstat_cache() instead
of the old one.
We do similar changes inside the unlink_entry() function, since if we
can already say that the leading directory component of a pathname
does not exist, it is not necessary to try to remove a pathname below
it!
Thanks to Junio C Hamano, Linus Torvalds and Rene Scharfe for valuable
comments to this patch!
Signed-off-by: Kjetil Barvik <barvik@broadpark.no>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-01-18 23:14:51 +08:00
|
|
|
(FL_SYMLINK|FL_NOENT);
|
|
|
|
|
}
|
2009-01-18 23:14:52 +08:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Return non-zero if all path components of 'name' exists as a
|
|
|
|
|
* directory. If prefix_len > 0, we will test with the stat()
|
|
|
|
|
* function instead of the lstat() function for a prefix length of
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* 'prefix_len', thus we then allow for symlinks in the prefix part as
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* long as those points to real existing directories.
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*/
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2009-02-10 04:54:06 +08:00
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int has_dirs_only_path(const char *name, int len, int prefix_len)
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2009-01-18 23:14:52 +08:00
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{
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2009-02-10 04:54:06 +08:00
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return lstat_cache(name, len,
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2009-01-18 23:14:52 +08:00
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FL_DIR|FL_FULLPATH, prefix_len) &
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FL_DIR;
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}
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