preload-index.c

   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
  10 static 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
  28 struct thread_data {
  29         pthread_t pthread;
  30         struct index_state *index;
  31         struct pathspec pathspec;
  32         int offset, nr;
  33 };
  34
  35 static 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(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
  76 static 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         if (threads > MAX_PARALLEL)
  91                 threads = MAX_PARALLEL;
  92         offset = 0;
  93         work = DIV_ROUND_UP(index->cache_nr, threads);
  94         memset(&data, 0, sizeof(data));
  95         for (i = 0; i < threads; i++) {
  96                 struct thread_data *p = data+i;
  97                 p->index = index;
  98                 if (pathspec)
  99                         copy_pathspec(&p->pathspec, pathspec);
 100                 p->offset = offset;
 101                 p->nr = work;
 102                 offset += work;
 103                 if (pthread_create(&p->pthread, NULL, preload_thread, p))
 104                         die("unable to create threaded lstat");
 105         }
 106         for (i = 0; i < threads; i++) {
 107                 struct thread_data *p = data+i;
 108                 if (pthread_join(p->pthread, NULL))
 109                         die("unable to join threaded lstat");
 110         }
 111 }
 112 #endif
 113
 114 int read_index_preload(struct index_state *index,
 115                        const struct pathspec *pathspec)
 116 {
 117         int retval = read_index(index);
 118
 119         preload_index(index, pathspec);
 120         return retval;
 121 }