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