Andrew's git - gitweb.git/blob

   1/*
   2 * Copyright (C) 2008 Linus Torvalds
   3 */
   4#include "cache.h"
   5#include "pathspec.h"
   6
   7#ifdef NO_PTHREADS
   8static void preload_index(struct index_state *index,
   9                          const struct pathspec *pathspec)
  10{
  11        ; /* nothing */
  12}
  13#else
  14
  15#include <pthread.h>
  16
  17/*
  18 * Mostly randomly chosen maximum thread counts: we
  19 * cap the parallelism to 20 threads, and we want
  20 * to have at least 500 lstat's per thread for it to
  21 * be worth starting a thread.
  22 */
  23#define MAX_PARALLEL (20)
  24#define THREAD_COST (500)
  25
  26struct thread_data {
  27        pthread_t pthread;
  28        struct index_state *index;
  29        struct pathspec pathspec;
  30        int offset, nr;
  31};
  32
  33static void *preload_thread(void *_data)
  34{
  35        int nr;
  36        struct thread_data *p = _data;
  37        struct index_state *index = p->index;
  38        struct cache_entry **cep = index->cache + p->offset;
  39        struct cache_def cache;
  40
  41        memset(&cache, 0, sizeof(cache));
  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))
  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        return NULL;
  67}
  68
  69static void preload_index(struct index_state *index,
  70                          const struct pathspec *pathspec)
  71{
  72        int threads, i, work, offset;
  73        struct thread_data data[MAX_PARALLEL];
  74
  75        if (!core_preload_index)
  76                return;
  77
  78        threads = index->cache_nr / THREAD_COST;
  79        if (threads < 2)
  80                return;
  81        if (threads > MAX_PARALLEL)
  82                threads = MAX_PARALLEL;
  83        offset = 0;
  84        work = DIV_ROUND_UP(index->cache_nr, threads);
  85        memset(&data, 0, sizeof(data));
  86        for (i = 0; i < threads; i++) {
  87                struct thread_data *p = data+i;
  88                p->index = index;
  89                if (pathspec)
  90                        copy_pathspec(&p->pathspec, pathspec);
  91                p->offset = offset;
  92                p->nr = work;
  93                offset += work;
  94                if (pthread_create(&p->pthread, NULL, preload_thread, p))
  95                        die("unable to create threaded lstat");
  96        }
  97        for (i = 0; i < threads; i++) {
  98                struct thread_data *p = data+i;
  99                if (pthread_join(p->pthread, NULL))
 100                        die("unable to join threaded lstat");
 101        }
 102}
 103#endif
 104
 105int read_index_preload(struct index_state *index,
 106                       const struct pathspec *pathspec)
 107{
 108        int retval = read_index(index);
 109
 110        preload_index(index, pathspec);
 111        return retval;
 112}