Merge branch 'ak/add-i-empty-candidates' into maint
[git] / preload-index.c
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
9 static 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
27 struct thread_data {
28         pthread_t pthread;
29         struct index_state *index;
30         struct pathspec pathspec;
31         int offset, nr;
32 };
33
34 static 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
70 static 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
106 int 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 }