commit-graph: implement git-commit-graph write
[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 #include "fsmonitor.h"
8
9 #ifdef NO_PTHREADS
10 static void preload_index(struct index_state *index,
11                           const struct pathspec *pathspec)
12 {
13         ; /* nothing */
14 }
15 #else
16
17 #include <pthread.h>
18
19 /*
20  * Mostly randomly chosen maximum thread counts: we
21  * cap the parallelism to 20 threads, and we want
22  * to have at least 500 lstat's per thread for it to
23  * be worth starting a thread.
24  */
25 #define MAX_PARALLEL (20)
26 #define THREAD_COST (500)
27
28 struct thread_data {
29         pthread_t pthread;
30         struct index_state *index;
31         struct pathspec pathspec;
32         int offset, nr;
33 };
34
35 static void *preload_thread(void *_data)
36 {
37         int nr;
38         struct thread_data *p = _data;
39         struct index_state *index = p->index;
40         struct cache_entry **cep = index->cache + p->offset;
41         struct cache_def cache = CACHE_DEF_INIT;
42
43         nr = p->nr;
44         if (nr + p->offset > index->cache_nr)
45                 nr = index->cache_nr - p->offset;
46
47         do {
48                 struct cache_entry *ce = *cep++;
49                 struct stat st;
50
51                 if (ce_stage(ce))
52                         continue;
53                 if (S_ISGITLINK(ce->ce_mode))
54                         continue;
55                 if (ce_uptodate(ce))
56                         continue;
57                 if (ce_skip_worktree(ce))
58                         continue;
59                 if (ce->ce_flags & CE_FSMONITOR_VALID)
60                         continue;
61                 if (!ce_path_match(ce, &p->pathspec, NULL))
62                         continue;
63                 if (threaded_has_symlink_leading_path(&cache, ce->name, ce_namelen(ce)))
64                         continue;
65                 if (lstat(ce->name, &st))
66                         continue;
67                 if (ie_match_stat(index, ce, &st, CE_MATCH_RACY_IS_DIRTY|CE_MATCH_IGNORE_FSMONITOR))
68                         continue;
69                 ce_mark_uptodate(ce);
70                 mark_fsmonitor_valid(ce);
71         } while (--nr > 0);
72         cache_def_clear(&cache);
73         return NULL;
74 }
75
76 static void preload_index(struct index_state *index,
77                           const struct pathspec *pathspec)
78 {
79         int threads, i, work, offset;
80         struct thread_data data[MAX_PARALLEL];
81         uint64_t start = getnanotime();
82
83         if (!core_preload_index)
84                 return;
85
86         threads = index->cache_nr / THREAD_COST;
87         if ((index->cache_nr > 1) && (threads < 2) && getenv("GIT_FORCE_PRELOAD_TEST"))
88                 threads = 2;
89         if (threads < 2)
90                 return;
91         if (threads > MAX_PARALLEL)
92                 threads = MAX_PARALLEL;
93         offset = 0;
94         work = DIV_ROUND_UP(index->cache_nr, threads);
95         memset(&data, 0, sizeof(data));
96         for (i = 0; i < threads; i++) {
97                 struct thread_data *p = data+i;
98                 p->index = index;
99                 if (pathspec)
100                         copy_pathspec(&p->pathspec, pathspec);
101                 p->offset = offset;
102                 p->nr = work;
103                 offset += work;
104                 if (pthread_create(&p->pthread, NULL, preload_thread, p))
105                         die("unable to create threaded lstat");
106         }
107         for (i = 0; i < threads; i++) {
108                 struct thread_data *p = data+i;
109                 if (pthread_join(p->pthread, NULL))
110                         die("unable to join threaded lstat");
111         }
112         trace_performance_since(start, "preload index");
113 }
114 #endif
115
116 int read_index_preload(struct index_state *index,
117                        const struct pathspec *pathspec)
118 {
119         int retval = read_index(index);
120
121         preload_index(index, pathspec);
122         return retval;
123 }