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 #include "config.h"
   9
  10 #ifdef NO_PTHREADS
  11 static void preload_index(struct index_state *index,
  12                           const struct pathspec *pathspec)
  13 {
  14         ; /* nothing */
  15 }
  16 #else
  17
  18 #include <pthread.h>
  19
  20 /*
  21  * Mostly randomly chosen maximum thread counts: we
  22  * cap the parallelism to 20 threads, and we want
  23  * to have at least 500 lstat's per thread for it to
  24  * be worth starting a thread.
  25  */
  26 #define MAX_PARALLEL (20)
  27 #define THREAD_COST (500)
  28
  29 struct thread_data {
  30         pthread_t pthread;
  31         struct index_state *index;
  32         struct pathspec pathspec;
  33         int offset, nr;
  34 };
  35
  36 static void *preload_thread(void *_data)
  37 {
  38         int nr;
  39         struct thread_data *p = _data;
  40         struct index_state *index = p->index;
  41         struct cache_entry **cep = index->cache + p->offset;
  42         struct cache_def cache = CACHE_DEF_INIT;
  43
  44         nr = p->nr;
  45         if (nr + p->offset > index->cache_nr)
  46                 nr = index->cache_nr - p->offset;
  47
  48         do {
  49                 struct cache_entry *ce = *cep++;
  50                 struct stat st;
  51
  52                 if (ce_stage(ce))
  53                         continue;
  54                 if (S_ISGITLINK(ce->ce_mode))
  55                         continue;
  56                 if (ce_uptodate(ce))
  57                         continue;
  58                 if (ce_skip_worktree(ce))
  59                         continue;
  60                 if (ce->ce_flags & CE_FSMONITOR_VALID)
  61                         continue;
  62                 if (!ce_path_match(index, ce, &p->pathspec, NULL))
  63                         continue;
  64                 if (threaded_has_symlink_leading_path(&cache, ce->name, ce_namelen(ce)))
  65                         continue;
  66                 if (lstat(ce->name, &st))
  67                         continue;
  68                 if (ie_match_stat(index, ce, &st, CE_MATCH_RACY_IS_DIRTY|CE_MATCH_IGNORE_FSMONITOR))
  69                         continue;
  70                 ce_mark_uptodate(ce);
  71                 mark_fsmonitor_valid(ce);
  72         } while (--nr > 0);
  73         cache_def_clear(&cache);
  74         return NULL;
  75 }
  76
  77 static void preload_index(struct index_state *index,
  78                           const struct pathspec *pathspec)
  79 {
  80         int threads, i, work, offset;
  81         struct thread_data data[MAX_PARALLEL];
  82         uint64_t start = getnanotime();
  83
  84         if (!core_preload_index)
  85                 return;
  86
  87         threads = index->cache_nr / THREAD_COST;
  88         if ((index->cache_nr > 1) && (threads < 2) && git_env_bool("GIT_FORCE_PRELOAD_TEST", 0))
  89                 threads = 2;
  90         if (threads < 2)
  91                 return;
  92         if (threads > MAX_PARALLEL)
  93                 threads = MAX_PARALLEL;
  94         offset = 0;
  95         work = DIV_ROUND_UP(index->cache_nr, threads);
  96         memset(&data, 0, sizeof(data));
  97         for (i = 0; i < threads; i++) {
  98                 struct thread_data *p = data+i;
  99                 p->index = index;
 100                 if (pathspec)
 101                         copy_pathspec(&p->pathspec, pathspec);
 102                 p->offset = offset;
 103                 p->nr = work;
 104                 offset += work;
 105                 if (pthread_create(&p->pthread, NULL, preload_thread, p))
 106                         die("unable to create threaded lstat");
 107         }
 108         for (i = 0; i < threads; i++) {
 109                 struct thread_data *p = data+i;
 110                 if (pthread_join(p->pthread, NULL))
 111                         die("unable to join threaded lstat");
 112         }
 113         trace_performance_since(start, "preload index");
 114 }
 115 #endif
 116
 117 int read_index_preload(struct index_state *index,
 118                        const struct pathspec *pathspec)
 119 {
 120         int retval = read_index(index);
 121
 122         preload_index(index, pathspec);
 123         return retval;
 124 }