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7e794d0a3f
The unpack_trees() API used in checking out a branch and merging walks one or more trees along with the index. When the cache-tree in the index tells us that we are walking a tree whose flattened contents is known (i.e. matches a span in the index), as linearly scanning a span in the index is much more efficient than having to open tree objects recursively and listing their entries, the walk can be optimized, which is done in this topic. * nd/unpack-trees-with-cache-tree: Document update for nd/unpack-trees-with-cache-tree cache-tree: verify valid cache-tree in the test suite unpack-trees: add missing cache invalidation unpack-trees: reuse (still valid) cache-tree from src_index unpack-trees: reduce malloc in cache-tree walk unpack-trees: optimize walking same trees with cache-tree unpack-trees: add performance tracing trace.h: support nested performance tracing
124 lines
2.8 KiB
C
124 lines
2.8 KiB
C
/*
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* Copyright (C) 2008 Linus Torvalds
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*/
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#include "cache.h"
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#include "pathspec.h"
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#include "dir.h"
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#include "fsmonitor.h"
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#ifdef NO_PTHREADS
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static void preload_index(struct index_state *index,
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const struct pathspec *pathspec)
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{
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; /* nothing */
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}
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#else
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#include <pthread.h>
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/*
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* Mostly randomly chosen maximum thread counts: we
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* cap the parallelism to 20 threads, and we want
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* to have at least 500 lstat's per thread for it to
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* be worth starting a thread.
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*/
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#define MAX_PARALLEL (20)
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#define THREAD_COST (500)
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struct thread_data {
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pthread_t pthread;
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struct index_state *index;
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struct pathspec pathspec;
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int offset, nr;
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};
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static void *preload_thread(void *_data)
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{
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int nr;
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struct thread_data *p = _data;
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struct index_state *index = p->index;
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struct cache_entry **cep = index->cache + p->offset;
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struct cache_def cache = CACHE_DEF_INIT;
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nr = p->nr;
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if (nr + p->offset > index->cache_nr)
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nr = index->cache_nr - p->offset;
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do {
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struct cache_entry *ce = *cep++;
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struct stat st;
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if (ce_stage(ce))
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continue;
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if (S_ISGITLINK(ce->ce_mode))
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continue;
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if (ce_uptodate(ce))
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continue;
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if (ce_skip_worktree(ce))
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continue;
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if (ce->ce_flags & CE_FSMONITOR_VALID)
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continue;
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if (!ce_path_match(index, ce, &p->pathspec, NULL))
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continue;
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if (threaded_has_symlink_leading_path(&cache, ce->name, ce_namelen(ce)))
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continue;
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if (lstat(ce->name, &st))
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continue;
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if (ie_match_stat(index, ce, &st, CE_MATCH_RACY_IS_DIRTY|CE_MATCH_IGNORE_FSMONITOR))
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continue;
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ce_mark_uptodate(ce);
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mark_fsmonitor_valid(ce);
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} while (--nr > 0);
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cache_def_clear(&cache);
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return NULL;
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}
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static void preload_index(struct index_state *index,
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const struct pathspec *pathspec)
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{
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int threads, i, work, offset;
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struct thread_data data[MAX_PARALLEL];
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if (!core_preload_index)
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return;
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threads = index->cache_nr / THREAD_COST;
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if ((index->cache_nr > 1) && (threads < 2) && getenv("GIT_FORCE_PRELOAD_TEST"))
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threads = 2;
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if (threads < 2)
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return;
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trace_performance_enter();
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if (threads > MAX_PARALLEL)
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threads = MAX_PARALLEL;
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offset = 0;
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work = DIV_ROUND_UP(index->cache_nr, threads);
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memset(&data, 0, sizeof(data));
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for (i = 0; i < threads; i++) {
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struct thread_data *p = data+i;
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p->index = index;
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if (pathspec)
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copy_pathspec(&p->pathspec, pathspec);
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p->offset = offset;
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p->nr = work;
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offset += work;
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if (pthread_create(&p->pthread, NULL, preload_thread, p))
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die("unable to create threaded lstat");
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}
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for (i = 0; i < threads; i++) {
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struct thread_data *p = data+i;
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if (pthread_join(p->pthread, NULL))
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die("unable to join threaded lstat");
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}
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trace_performance_leave("preload index");
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}
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#endif
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int read_index_preload(struct index_state *index,
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const struct pathspec *pathspec)
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{
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int retval = read_index(index);
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preload_index(index, pathspec);
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return retval;
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}
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