cache.c 2.43 KB
Newer Older
Vicent Marti committed
1
/*
Edward Thomson committed
2
 * Copyright (C) the libgit2 contributors. All rights reserved.
Vicent Marti committed
3
 *
Vicent Marti committed
4 5
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
Vicent Marti committed
6 7 8 9 10 11
 */

#include "common.h"
#include "repository.h"
#include "commit.h"
#include "thread-utils.h"
12
#include "util.h"
Vicent Marti committed
13
#include "cache.h"
14
#include "git2/oid.h"
Vicent Marti committed
15

16
int git_cache_init(git_cache *cache, size_t size, git_cached_obj_freeptr free_ptr)
Vicent Marti committed
17 18 19
{
	if (size < 8)
		size = 8;
20
	size = git__size_t_powerof2(size);
Vicent Marti committed
21

22
	cache->size_mask = size - 1;
Vicent Marti committed
23 24 25
	cache->lru_count = 0;
	cache->free_obj = free_ptr;

26 27 28
	git_mutex_init(&cache->lock);

	cache->nodes = git__malloc(size * sizeof(git_cached_obj *));
29
	GITERR_CHECK_ALLOC(cache->nodes);
Vicent Marti committed
30

31
	memset(cache->nodes, 0x0, size * sizeof(git_cached_obj *));
32
	return 0;
Vicent Marti committed
33 34 35 36 37 38 39
}

void git_cache_free(git_cache *cache)
{
	size_t i;

	for (i = 0; i < (cache->size_mask + 1); ++i) {
40 41
		if (cache->nodes[i] != NULL)
			git_cached_obj_decref(cache->nodes[i], cache->free_obj);
Vicent Marti committed
42 43
	}

44
	git_mutex_free(&cache->lock);
45
	git__free(cache->nodes);
Vicent Marti committed
46 47 48 49
}

void *git_cache_get(git_cache *cache, const git_oid *oid)
{
50
	uint32_t hash;
51
	git_cached_obj *node = NULL, *result = NULL;
Vicent Marti committed
52

53
	memcpy(&hash, oid->id, sizeof(hash));
Vicent Marti committed
54

55 56 57 58 59
	if (git_mutex_lock(&cache->lock)) {
		giterr_set(GITERR_THREAD, "unable to lock cache mutex");
		return NULL;
	}

60
	{
61 62 63 64 65
		node = cache->nodes[hash & cache->size_mask];

		if (node != NULL && git_oid_cmp(&node->oid, oid) == 0) {
			git_cached_obj_incref(node);
			result = node;
Vicent Marti committed
66 67
		}
	}
68
	git_mutex_unlock(&cache->lock);
Vicent Marti committed
69

70
	return result;
Vicent Marti committed
71 72
}

73
void *git_cache_try_store(git_cache *cache, void *_entry)
Vicent Marti committed
74
{
75
	git_cached_obj *entry = _entry;
76
	uint32_t hash;
Vicent Marti committed
77

78
	memcpy(&hash, &entry->oid, sizeof(uint32_t));
Vicent Marti committed
79

80 81 82 83
	if (git_mutex_lock(&cache->lock)) {
		giterr_set(GITERR_THREAD, "unable to lock cache mutex");
		return NULL;
	}
84 85

	{
Justin Spahr-Summers committed
86 87
		git_cached_obj *node = cache->nodes[hash & cache->size_mask];

88 89 90 91
		/* increase the refcount on this object, because
		 * the cache now owns it */
		git_cached_obj_incref(entry);

92 93 94 95 96 97 98 99 100
		if (node == NULL) {
			cache->nodes[hash & cache->size_mask] = entry;
		} else if (git_oid_cmp(&node->oid, &entry->oid) == 0) {
			git_cached_obj_decref(entry, cache->free_obj);
			entry = node;
		} else {
			git_cached_obj_decref(node, cache->free_obj);
			cache->nodes[hash & cache->size_mask] = entry;
		}
101 102 103 104 105

		/* increase the refcount again, because we are
		 * returning it to the user */
		git_cached_obj_incref(entry);

Vicent Marti committed
106
	}
107
	git_mutex_unlock(&cache->lock);
Vicent Marti committed
108 109 110

	return entry;
}