1 files changed, 99 insertions, 0 deletions
diff --git a/samples/C/cache.c b/samples/C/cache.c
new file mode 100644
index 0000000..f8d8940
--- /dev/null
+++ b/samples/C/cache.c
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2009-2012 the libgit2 contributors
+ *
+ * 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 "common.h"
+#include "repository.h"
+#include "commit.h"
+#include "thread-utils.h"
+#include "util.h"
+#include "cache.h"
+
+int git_cache_init(git_cache *cache, size_t size, git_cached_obj_freeptr free_ptr)
+{
+	if (size < 8)
+		size = 8;
+	size = git__size_t_powerof2(size);
+
+	cache->size_mask = size - 1;
+	cache->lru_count = 0;
+	cache->free_obj = free_ptr;
+
+	git_mutex_init(&cache->lock);
+
+	cache->nodes = git__malloc(size * sizeof(git_cached_obj *));
+	GITERR_CHECK_ALLOC(cache->nodes);
+
+	memset(cache->nodes, 0x0, size * sizeof(git_cached_obj *));
+	return 0;
+}
+
+void git_cache_free(git_cache *cache)
+{
+	size_t i;
+
+	for (i = 0; i < (cache->size_mask + 1); ++i) {
+		if (cache->nodes[i] != NULL)
+			git_cached_obj_decref(cache->nodes[i], cache->free_obj);
+	}
+
+	git__free(cache->nodes);
+}
+
+void *git_cache_get(git_cache *cache, const git_oid *oid)
+{
+	uint32_t hash;
+	git_cached_obj *node = NULL, *result = NULL;
+
+	memcpy(&hash, oid->id, sizeof(hash));
+
+	git_mutex_lock(&cache->lock);
+	{
+		node = cache->nodes[hash & cache->size_mask];
+
+		if (node != NULL && git_oid_cmp(&node->oid, oid) == 0) {
+			git_cached_obj_incref(node);
+			result = node;
+		}
+	}
+	git_mutex_unlock(&cache->lock);
+
+	return result;
+}
+
+void *git_cache_try_store(git_cache *cache, void *_entry)
+{
+	git_cached_obj *entry = _entry;
+	uint32_t hash;
+
+	memcpy(&hash, &entry->oid, sizeof(uint32_t));
+
+	/* increase the refcount on this object, because
+	 * the cache now owns it */
+	git_cached_obj_incref(entry);
+
+	git_mutex_lock(&cache->lock);
+	{
+		git_cached_obj *node = cache->nodes[hash & cache->size_mask];
+
+		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;
+		}
+	}
+	git_mutex_unlock(&cache->lock);
+
+	/* increase the refcount again, because we are
+	 * returning it to the user */
+	git_cached_obj_incref(entry);
+
+	return entry;
+}