Speed up index file writing by chunking it nicely.
[git/git.git] / read-cache.c
CommitLineData
8bc9a0c7
LT
1/*
2 * GIT - The information manager from hell
3 *
4 * Copyright (C) Linus Torvalds, 2005
5 */
2de381f9 6#include <stdarg.h>
e83c5163
LT
7#include "cache.h"
8
e83c5163
LT
9struct cache_entry **active_cache = NULL;
10unsigned int active_nr = 0, active_alloc = 0;
11
734aab75
LT
12int cache_match_stat(struct cache_entry *ce, struct stat *st)
13{
14 unsigned int changed = 0;
15
ccc4feb5 16 if (ce->ce_mtime.sec != htonl(st->st_mtime))
734aab75 17 changed |= MTIME_CHANGED;
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LT
18 if (ce->ce_ctime.sec != htonl(st->st_ctime))
19 changed |= CTIME_CHANGED;
20
bdd4da59 21#ifdef NSEC
ccc4feb5
LT
22 /*
23 * nsec seems unreliable - not all filesystems support it, so
24 * as long as it is in the inode cache you get right nsec
25 * but after it gets flushed, you get zero nsec.
26 */
27 if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec)
28 changed |= MTIME_CHANGED;
29 if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec)
734aab75 30 changed |= CTIME_CHANGED;
ccc4feb5
LT
31#endif
32
33 if (ce->ce_uid != htonl(st->st_uid) ||
34 ce->ce_gid != htonl(st->st_gid))
734aab75 35 changed |= OWNER_CHANGED;
e4479470 36 /* We consider only the owner x bit to be relevant for "mode changes" */
e8871e88 37 if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
734aab75 38 changed |= MODE_CHANGED;
ccc4feb5
LT
39 if (ce->ce_dev != htonl(st->st_dev) ||
40 ce->ce_ino != htonl(st->st_ino))
734aab75 41 changed |= INODE_CHANGED;
ccc4feb5 42 if (ce->ce_size != htonl(st->st_size))
734aab75
LT
43 changed |= DATA_CHANGED;
44 return changed;
45}
46
95fd5bf8 47int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
eb38c22f 48{
95fd5bf8
LT
49 int len1 = flags1 & CE_NAMEMASK;
50 int len2 = flags2 & CE_NAMEMASK;
eb38c22f
LT
51 int len = len1 < len2 ? len1 : len2;
52 int cmp;
53
54 cmp = memcmp(name1, name2, len);
55 if (cmp)
56 return cmp;
57 if (len1 < len2)
58 return -1;
59 if (len1 > len2)
60 return 1;
95fd5bf8
LT
61 if (flags1 < flags2)
62 return -1;
63 if (flags1 > flags2)
64 return 1;
eb38c22f
LT
65 return 0;
66}
67
68int cache_name_pos(const char *name, int namelen)
69{
70 int first, last;
71
72 first = 0;
73 last = active_nr;
74 while (last > first) {
75 int next = (last + first) >> 1;
76 struct cache_entry *ce = active_cache[next];
95fd5bf8 77 int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
eb38c22f 78 if (!cmp)
76e7f4ec 79 return next;
eb38c22f
LT
80 if (cmp < 0) {
81 last = next;
82 continue;
83 }
84 first = next+1;
85 }
76e7f4ec 86 return -first-1;
eb38c22f
LT
87}
88
7b937ca3
LT
89/* Remove entry, return true if there are more entries to go.. */
90static int remove_entry_at(int pos)
91{
92 active_nr--;
93 if (pos >= active_nr)
94 return 0;
95 memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos) * sizeof(struct cache_entry *));
96 return 1;
97}
98
197ee8c9
LT
99int remove_file_from_cache(char *path)
100{
101 int pos = cache_name_pos(path, strlen(path));
c4e3cca1
JH
102 if (pos < 0)
103 pos = -pos-1;
104 while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
7b937ca3 105 remove_entry_at(pos);
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LT
106 return 0;
107}
108
7b937ca3
LT
109static int same_name(struct cache_entry *a, struct cache_entry *b)
110{
111 int len = ce_namelen(a);
112 return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
113}
114
121481ab 115int add_cache_entry(struct cache_entry *ce, int ok_to_add)
197ee8c9
LT
116{
117 int pos;
118
95fd5bf8 119 pos = cache_name_pos(ce->name, htons(ce->ce_flags));
197ee8c9
LT
120
121 /* existing match? Just replace it */
76e7f4ec
LT
122 if (pos >= 0) {
123 active_cache[pos] = ce;
197ee8c9
LT
124 return 0;
125 }
76e7f4ec 126 pos = -pos-1;
197ee8c9 127
7b937ca3
LT
128 /*
129 * Inserting a merged entry ("stage 0") into the index
130 * will always replace all non-merged entries..
131 */
132 if (pos < active_nr && ce_stage(ce) == 0) {
133 while (same_name(active_cache[pos], ce)) {
134 ok_to_add = 1;
7b937ca3
LT
135 if (!remove_entry_at(pos))
136 break;
137 }
138 }
139
121481ab
LT
140 if (!ok_to_add)
141 return -1;
142
197ee8c9
LT
143 /* Make sure the array is big enough .. */
144 if (active_nr == active_alloc) {
145 active_alloc = alloc_nr(active_alloc);
146 active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
147 }
148
149 /* Add it in.. */
150 active_nr++;
151 if (active_nr > pos)
152 memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
153 active_cache[pos] = ce;
154 return 0;
155}
156
e83c5163
LT
157static int verify_hdr(struct cache_header *hdr, unsigned long size)
158{
159 SHA_CTX c;
160 unsigned char sha1[20];
161
ccc4feb5 162 if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
e83c5163 163 return error("bad signature");
ccc4feb5 164 if (hdr->hdr_version != htonl(1))
e83c5163
LT
165 return error("bad version");
166 SHA1_Init(&c);
167 SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
168 SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
169 SHA1_Final(sha1, &c);
170 if (memcmp(sha1, hdr->sha1, 20))
171 return error("bad header sha1");
172 return 0;
173}
174
175int read_cache(void)
176{
177 int fd, i;
178 struct stat st;
179 unsigned long size, offset;
180 void *map;
181 struct cache_header *hdr;
182
183 errno = EBUSY;
184 if (active_cache)
185 return error("more than one cachefile");
186 errno = ENOENT;
187 sha1_file_directory = getenv(DB_ENVIRONMENT);
188 if (!sha1_file_directory)
189 sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
190 if (access(sha1_file_directory, X_OK) < 0)
191 return error("no access to SHA1 file directory");
4bb04f21 192 fd = open(".git/index", O_RDONLY);
e83c5163
LT
193 if (fd < 0)
194 return (errno == ENOENT) ? 0 : error("open failed");
195
19b2860c 196 size = 0; // avoid gcc warning
e83c5163
LT
197 map = (void *)-1;
198 if (!fstat(fd, &st)) {
e83c5163
LT
199 size = st.st_size;
200 errno = EINVAL;
59c1e249 201 if (size >= sizeof(struct cache_header))
e83c5163
LT
202 map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
203 }
204 close(fd);
205 if (-1 == (int)(long)map)
206 return error("mmap failed");
207
208 hdr = map;
209 if (verify_hdr(hdr, size) < 0)
210 goto unmap;
211
ccc4feb5 212 active_nr = ntohl(hdr->hdr_entries);
e83c5163
LT
213 active_alloc = alloc_nr(active_nr);
214 active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
215
216 offset = sizeof(*hdr);
ccc4feb5 217 for (i = 0; i < active_nr; i++) {
e83c5163
LT
218 struct cache_entry *ce = map + offset;
219 offset = offset + ce_size(ce);
220 active_cache[i] = ce;
221 }
222 return active_nr;
223
224unmap:
225 munmap(map, size);
226 errno = EINVAL;
227 return error("verify header failed");
228}
229
4990aadc
LT
230#define WRITE_BUFFER_SIZE 8192
231static char write_buffer[WRITE_BUFFER_SIZE];
232static unsigned long write_buffer_len;
233
234static int ce_write(int fd, void *data, unsigned int len)
235{
236 while (len) {
237 unsigned int buffered = write_buffer_len;
238 unsigned int partial = WRITE_BUFFER_SIZE - buffered;
239 if (partial > len)
240 partial = len;
241 memcpy(write_buffer + buffered, data, partial);
242 buffered += partial;
243 if (buffered == WRITE_BUFFER_SIZE) {
244 if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
245 return -1;
246 buffered = 0;
247 }
248 write_buffer_len = buffered;
249 len -= partial;
250 data += partial;
251 }
252 return 0;
253}
254
255static int ce_flush(int fd)
256{
257 unsigned int left = write_buffer_len;
258 if (left) {
259 write_buffer_len = 0;
260 if (write(fd, write_buffer, left) != left)
261 return -1;
262 }
263 return 0;
264}
265
197ee8c9
LT
266int write_cache(int newfd, struct cache_entry **cache, int entries)
267{
268 SHA_CTX c;
269 struct cache_header hdr;
270 int i;
271
ccc4feb5
LT
272 hdr.hdr_signature = htonl(CACHE_SIGNATURE);
273 hdr.hdr_version = htonl(1);
274 hdr.hdr_entries = htonl(entries);
197ee8c9
LT
275
276 SHA1_Init(&c);
277 SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
278 for (i = 0; i < entries; i++) {
279 struct cache_entry *ce = cache[i];
280 int size = ce_size(ce);
281 SHA1_Update(&c, ce, size);
282 }
283 SHA1_Final(hdr.sha1, &c);
284
4990aadc 285 if (ce_write(newfd, &hdr, sizeof(hdr)) < 0)
197ee8c9
LT
286 return -1;
287
288 for (i = 0; i < entries; i++) {
289 struct cache_entry *ce = cache[i];
4990aadc 290 if (ce_write(newfd, ce, ce_size(ce)) < 0)
197ee8c9
LT
291 return -1;
292 }
4990aadc 293 return ce_flush(newfd);
197ee8c9 294}