summaryrefslogtreecommitdiff
path: root/src/util/sortedcache.c
blob: 7ff900efe33335101f928b0b192174b3bef838ed (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
/*
 * Copyright (C) the libgit2 contributors. All rights reserved.
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */

#include "sortedcache.h"

int git_sortedcache_new(
	git_sortedcache **out,
	size_t item_path_offset,
	git_sortedcache_free_item_fn free_item,
	void *free_item_payload,
	git_vector_cmp item_cmp,
	const char *path)
{
	git_sortedcache *sc;
	size_t pathlen, alloclen;

	pathlen = path ? strlen(path) : 0;

	GIT_ERROR_CHECK_ALLOC_ADD(&alloclen, sizeof(git_sortedcache), pathlen);
	GIT_ERROR_CHECK_ALLOC_ADD(&alloclen, alloclen, 1);
	sc = git__calloc(1, alloclen);
	GIT_ERROR_CHECK_ALLOC(sc);

	if (git_pool_init(&sc->pool, 1) < 0 ||
	    git_vector_init(&sc->items, 4, item_cmp) < 0 ||
	    git_strmap_new(&sc->map) < 0)
		goto fail;

	if (git_rwlock_init(&sc->lock)) {
		git_error_set(GIT_ERROR_OS, "failed to initialize lock");
		goto fail;
	}

	sc->item_path_offset  = item_path_offset;
	sc->free_item         = free_item;
	sc->free_item_payload = free_item_payload;
	GIT_REFCOUNT_INC(sc);
	if (pathlen)
		memcpy(sc->path, path, pathlen);

	*out = sc;
	return 0;

fail:
	git_strmap_free(sc->map);
	git_vector_free(&sc->items);
	git_pool_clear(&sc->pool);
	git__free(sc);
	return -1;
}

void git_sortedcache_incref(git_sortedcache *sc)
{
	GIT_REFCOUNT_INC(sc);
}

const char *git_sortedcache_path(git_sortedcache *sc)
{
	return sc->path;
}

static void sortedcache_clear(git_sortedcache *sc)
{
	git_strmap_clear(sc->map);

	if (sc->free_item) {
		size_t i;
		void *item;

		git_vector_foreach(&sc->items, i, item) {
			sc->free_item(sc->free_item_payload, item);
		}
	}

	git_vector_clear(&sc->items);

	git_pool_clear(&sc->pool);
}

static void sortedcache_free(git_sortedcache *sc)
{
	/* acquire write lock to make sure everyone else is done */
	if (git_sortedcache_wlock(sc) < 0)
		return;

	sortedcache_clear(sc);
	git_vector_free(&sc->items);
	git_strmap_free(sc->map);

	git_sortedcache_wunlock(sc);

	git_rwlock_free(&sc->lock);
	git__free(sc);
}

void git_sortedcache_free(git_sortedcache *sc)
{
	if (!sc)
		return;
	GIT_REFCOUNT_DEC(sc, sortedcache_free);
}

static int sortedcache_copy_item(void *payload, void *tgt_item, void *src_item)
{
	git_sortedcache *sc = payload;
	/* path will already have been copied by upsert */
	memcpy(tgt_item, src_item, sc->item_path_offset);
	return 0;
}

/* copy a sorted cache */
int git_sortedcache_copy(
	git_sortedcache **out,
	git_sortedcache *src,
	bool lock,
	int (*copy_item)(void *payload, void *tgt_item, void *src_item),
	void *payload)
{
	int error = 0;
	git_sortedcache *tgt;
	size_t i;
	void *src_item, *tgt_item;

	/* just use memcpy if no special copy fn is passed in */
	if (!copy_item) {
		copy_item = sortedcache_copy_item;
		payload   = src;
	}

	if ((error = git_sortedcache_new(
			&tgt, src->item_path_offset,
			src->free_item, src->free_item_payload,
			src->items._cmp, src->path)) < 0)
		return error;

	if (lock && git_sortedcache_rlock(src) < 0) {
		git_sortedcache_free(tgt);
		return -1;
	}

	git_vector_foreach(&src->items, i, src_item) {
		char *path = ((char *)src_item) + src->item_path_offset;

		if ((error = git_sortedcache_upsert(&tgt_item, tgt, path)) < 0 ||
			(error = copy_item(payload, tgt_item, src_item)) < 0)
			break;
	}

	if (lock)
		git_sortedcache_runlock(src);
	if (error)
		git_sortedcache_free(tgt);

	*out = !error ? tgt : NULL;

	return error;
}

/* lock sortedcache while making modifications */
int git_sortedcache_wlock(git_sortedcache *sc)
{
	GIT_UNUSED(sc); /* prevent warning when compiled w/o threads */

	if (git_rwlock_wrlock(&sc->lock) < 0) {
		git_error_set(GIT_ERROR_OS, "unable to acquire write lock on cache");
		return -1;
	}
	return 0;
}

/* unlock sorted cache when done with modifications */
void git_sortedcache_wunlock(git_sortedcache *sc)
{
	git_vector_sort(&sc->items);
	git_rwlock_wrunlock(&sc->lock);
}

/* lock sortedcache for read */
int git_sortedcache_rlock(git_sortedcache *sc)
{
	GIT_UNUSED(sc); /* prevent warning when compiled w/o threads */

	if (git_rwlock_rdlock(&sc->lock) < 0) {
		git_error_set(GIT_ERROR_OS, "unable to acquire read lock on cache");
		return -1;
	}
	return 0;
}

/* unlock sorted cache when done reading */
void git_sortedcache_runlock(git_sortedcache *sc)
{
	GIT_UNUSED(sc); /* prevent warning when compiled w/o threads */
	git_rwlock_rdunlock(&sc->lock);
}

/* if the file has changed, lock cache and load file contents into buf;
 * returns <0 on error, >0 if file has not changed
 */
int git_sortedcache_lockandload(git_sortedcache *sc, git_str *buf)
{
	int error, fd;
	struct stat st;

	if ((error = git_sortedcache_wlock(sc)) < 0)
		return error;

	if ((error = git_futils_filestamp_check(&sc->stamp, sc->path)) <= 0)
		goto unlock;

	if ((fd = git_futils_open_ro(sc->path)) < 0) {
		error = fd;
		goto unlock;
	}

	if (p_fstat(fd, &st) < 0) {
		git_error_set(GIT_ERROR_OS, "failed to stat file");
		error = -1;
		(void)p_close(fd);
		goto unlock;
	}

	if (!git__is_sizet(st.st_size)) {
		git_error_set(GIT_ERROR_INVALID, "unable to load file larger than size_t");
		error = -1;
		(void)p_close(fd);
		goto unlock;
	}

	if (buf)
		error = git_futils_readbuffer_fd(buf, fd, (size_t)st.st_size);

	(void)p_close(fd);

	if (error < 0)
		goto unlock;

	return 1; /* return 1 -> file needs reload and was successfully loaded */

unlock:
	git_sortedcache_wunlock(sc);
	return error;
}

void git_sortedcache_updated(git_sortedcache *sc)
{
	/* update filestamp to latest value */
	git_futils_filestamp_check(&sc->stamp, sc->path);
}

/* release all items in sorted cache */
int git_sortedcache_clear(git_sortedcache *sc, bool wlock)
{
	if (wlock && git_sortedcache_wlock(sc) < 0)
		return -1;

	sortedcache_clear(sc);

	if (wlock)
		git_sortedcache_wunlock(sc);

	return 0;
}

/* find and/or insert item, returning pointer to item data */
int git_sortedcache_upsert(void **out, git_sortedcache *sc, const char *key)
{
	size_t keylen, itemlen;
	int error = 0;
	char *item_key;
	void *item;

	if ((item = git_strmap_get(sc->map, key)) != NULL)
		goto done;

	keylen  = strlen(key);
	itemlen = sc->item_path_offset + keylen + 1;
	itemlen = (itemlen + 7) & ~7;

	if ((item = git_pool_mallocz(&sc->pool, itemlen)) == NULL) {
		/* don't use GIT_ERROR_CHECK_ALLOC b/c of lock */
		error = -1;
		goto done;
	}

	/* one strange thing is that even if the vector or hash table insert
	 * fail, there is no way to free the pool item so we just abandon it
	 */

	item_key = ((char *)item) + sc->item_path_offset;
	memcpy(item_key, key, keylen);

	if ((error = git_strmap_set(sc->map, item_key, item)) < 0)
		goto done;

	if ((error = git_vector_insert(&sc->items, item)) < 0)
		git_strmap_delete(sc->map, item_key);

done:
	if (out)
		*out = !error ? item : NULL;
	return error;
}

/* lookup item by key */
void *git_sortedcache_lookup(const git_sortedcache *sc, const char *key)
{
	return git_strmap_get(sc->map, key);
}

/* find out how many items are in the cache */
size_t git_sortedcache_entrycount(const git_sortedcache *sc)
{
	return git_vector_length(&sc->items);
}

/* lookup item by index */
void *git_sortedcache_entry(git_sortedcache *sc, size_t pos)
{
	/* make sure the items are sorted so this gets the correct item */
	if (!git_vector_is_sorted(&sc->items))
		git_vector_sort(&sc->items);

	return git_vector_get(&sc->items, pos);
}

/* helper struct so bsearch callback can know offset + key value for cmp */
struct sortedcache_magic_key {
	size_t offset;
	const char *key;
};

static int sortedcache_magic_cmp(const void *key, const void *value)
{
	const struct sortedcache_magic_key *magic = key;
	const char *value_key = ((const char *)value) + magic->offset;
	return strcmp(magic->key, value_key);
}

/* lookup index of item by key */
int git_sortedcache_lookup_index(
	size_t *out, git_sortedcache *sc, const char *key)
{
	struct sortedcache_magic_key magic;

	magic.offset = sc->item_path_offset;
	magic.key    = key;

	return git_vector_bsearch2(out, &sc->items, sortedcache_magic_cmp, &magic);
}

/* remove entry from cache */
int git_sortedcache_remove(git_sortedcache *sc, size_t pos)
{
	char *item;

	/*
	 * Because of pool allocation, this can't actually remove the item,
	 * but we can remove it from the items vector and the hash table.
	 */

	if ((item = git_vector_get(&sc->items, pos)) == NULL) {
		git_error_set(GIT_ERROR_INVALID, "removing item out of range");
		return GIT_ENOTFOUND;
	}

	(void)git_vector_remove(&sc->items, pos);

	git_strmap_delete(sc->map, item + sc->item_path_offset);

	if (sc->free_item)
		sc->free_item(sc->free_item_payload, item);

	return 0;
}