Andrew's git - gitweb.git/blob

   1/*
   2 * Copyright (C) 2008 Linus Torvalds
   3 */
   4#include "cache.h"
   5#include "pathspec.h"
   6#include "dir.h"
   7#include "fsmonitor.h"
   8
   9#ifdef NO_PTHREADS
  10static void preload_index(struct index_state *index,
  11                          const struct pathspec *pathspec)
  12{
  13        ; /* nothing */
  14}
  15#else
  16
  17#include <pthread.h>
  18
  19/*
  20 * Mostly randomly chosen maximum thread counts: we
  21 * cap the parallelism to 20 threads, and we want
  22 * to have at least 500 lstat's per thread for it to
  23 * be worth starting a thread.
  24 */
  25#define MAX_PARALLEL (20)
  26#define THREAD_COST (500)
  27
  28struct thread_data {
  29        pthread_t pthread;
  30        struct index_state *index;
  31        struct pathspec pathspec;
  32        int offset, nr;
  33};
  34
  35static void *preload_thread(void *_data)
  36{
  37        int nr;
  38        struct thread_data *p = _data;
  39        struct index_state *index = p->index;
  40        struct cache_entry **cep = index->cache + p->offset;
  41        struct cache_def cache = CACHE_DEF_INIT;
  42
  43        nr = p->nr;
  44        if (nr + p->offset > index->cache_nr)
  45                nr = index->cache_nr - p->offset;
  46
  47        do {
  48                struct cache_entry *ce = *cep++;
  49                struct stat st;
  50
  51                if (ce_stage(ce))
  52                        continue;
  53                if (S_ISGITLINK(ce->ce_mode))
  54                        continue;
  55                if (ce_uptodate(ce))
  56                        continue;
  57                if (ce_skip_worktree(ce))
  58                        continue;
  59                if (ce->ce_flags & CE_FSMONITOR_VALID)
  60                        continue;
  61                if (!ce_path_match(index, ce, &p->pathspec, NULL))
  62                        continue;
  63                if (threaded_has_symlink_leading_path(&cache, ce->name, ce_namelen(ce)))
  64                        continue;
  65                if (lstat(ce->name, &st))
  66                        continue;
  67                if (ie_match_stat(index, ce, &st, CE_MATCH_RACY_IS_DIRTY|CE_MATCH_IGNORE_FSMONITOR))
  68                        continue;
  69                ce_mark_uptodate(ce);
  70                mark_fsmonitor_valid(ce);
  71        } while (--nr > 0);
  72        cache_def_clear(&cache);
  73        return NULL;
  74}
  75
  76static void preload_index(struct index_state *index,
  77                          const struct pathspec *pathspec)
  78{
  79        int threads, i, work, offset;
  80        struct thread_data data[MAX_PARALLEL];
  81
  82        if (!core_preload_index)
  83                return;
  84
  85        threads = index->cache_nr / THREAD_COST;
  86        if ((index->cache_nr > 1) && (threads < 2) && getenv("GIT_FORCE_PRELOAD_TEST"))
  87                threads = 2;
  88        if (threads < 2)
  89                return;
  90        trace_performance_enter();
  91        if (threads > MAX_PARALLEL)
  92                threads = MAX_PARALLEL;
  93        offset = 0;
  94        work = DIV_ROUND_UP(index->cache_nr, threads);
  95        memset(&data, 0, sizeof(data));
  96        for (i = 0; i < threads; i++) {
  97                struct thread_data *p = data+i;
  98                p->index = index;
  99                if (pathspec)
 100                        copy_pathspec(&p->pathspec, pathspec);
 101                p->offset = offset;
 102                p->nr = work;
 103                offset += work;
 104                if (pthread_create(&p->pthread, NULL, preload_thread, p))
 105                        die("unable to create threaded lstat");
 106        }
 107        for (i = 0; i < threads; i++) {
 108                struct thread_data *p = data+i;
 109                if (pthread_join(p->pthread, NULL))
 110                        die("unable to join threaded lstat");
 111        }
 112        trace_performance_leave("preload index");
 113}
 114#endif
 115
 116int read_index_preload(struct index_state *index,
 117                       const struct pathspec *pathspec)
 118{
 119        int retval = read_index(index);
 120
 121        preload_index(index, pathspec);
 122        return retval;
 123}