Andrew's git - gitweb.git/blob

   1/*
   2 * Copyright (C) 2008 Linus Torvalds
   3 */
   4#include "cache.h"
   5#include <pthread.h>
   6
   7/*
   8 * Mostly randomly chosen maximum thread counts: we
   9 * cap the parallelism to 20 threads, and we want
  10 * to have at least 500 lstat's per thread for it to
  11 * be worth starting a thread.
  12 */
  13#define MAX_PARALLEL (20)
  14#define THREAD_COST (500)
  15
  16struct thread_data {
  17        pthread_t pthread;
  18        struct index_state *index;
  19        const char **pathspec;
  20        int offset, nr;
  21};
  22
  23static void *preload_thread(void *_data)
  24{
  25        int nr;
  26        struct thread_data *p = _data;
  27        struct index_state *index = p->index;
  28        struct cache_entry **cep = index->cache + p->offset;
  29
  30        nr = p->nr;
  31        if (nr + p->offset > index->cache_nr)
  32                nr = index->cache_nr - p->offset;
  33
  34        do {
  35                struct cache_entry *ce = *cep++;
  36                struct stat st;
  37
  38                if (ce_stage(ce))
  39                        continue;
  40                if (ce_uptodate(ce))
  41                        continue;
  42                if (!ce_path_match(ce, p->pathspec))
  43                        continue;
  44                if (lstat(ce->name, &st))
  45                        continue;
  46                if (ie_match_stat(index, ce, &st, CE_MATCH_RACY_IS_DIRTY))
  47                        continue;
  48                ce_mark_uptodate(ce);
  49        } while (--nr > 0);
  50        return NULL;
  51}
  52
  53static void preload_index(struct index_state *index, const char **pathspec)
  54{
  55        int threads, i, work, offset;
  56        struct thread_data data[MAX_PARALLEL];
  57
  58        if (!core_preload_index)
  59                return;
  60
  61        threads = index->cache_nr / THREAD_COST;
  62        if (threads < 2)
  63                return;
  64        if (threads > MAX_PARALLEL)
  65                threads = MAX_PARALLEL;
  66        offset = 0;
  67        work = (index->cache_nr + threads - 1) / threads;
  68        for (i = 0; i < threads; i++) {
  69                struct thread_data *p = data+i;
  70                p->index = index;
  71                p->pathspec = pathspec;
  72                p->offset = offset;
  73                p->nr = work;
  74                offset += work;
  75                if (pthread_create(&p->pthread, NULL, preload_thread, p))
  76                        die("unable to create threaded lstat");
  77        }
  78        for (i = 0; i < threads; i++) {
  79                struct thread_data *p = data+i;
  80                if (pthread_join(p->pthread, NULL))
  81                        die("unable to join threaded lstat");
  82        }
  83}
  84
  85int read_index_preload(struct index_state *index, const char **pathspec)
  86{
  87        int retval = read_index(index);
  88
  89        preload_index(index, pathspec);
  90        return retval;
  91}