thodg/libgit2/src/cache.c

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• Hash : 71a4c1f1
  Author :
  Date : 2011-09-18T20:07:59
  

  Merge pull request #384 from kiryl/warnings Add more -W flags to CFLAGS

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• src/cache.c

• /*
   * Copyright (C) 2009-2011 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 "cache.h"
  
  int git_cache_init(git_cache *cache, size_t size, git_cached_obj_freeptr free_ptr)
  {
  	size_t i;
  
  	if (size < 8)
  		size = 8;
  
  	/* round up size to closest power of 2 */
  	size--;
  	size |= size >> 1;
  	size |= size >> 2;
  	size |= size >> 4;
  	size |= size >> 8;
  	size |= size >> 16;
  
  	cache->size_mask = size;
  	cache->lru_count = 0;
  	cache->free_obj = free_ptr;
  
  	cache->nodes = git__malloc((size + 1) * sizeof(cache_node));
  	if (cache->nodes == NULL)
  		return GIT_ENOMEM;
  
  	for (i = 0; i < (size + 1); ++i) {
  		git_mutex_init(&cache->nodes[i].lock);
  		cache->nodes[i].ptr = NULL;
  	}
  
  	return GIT_SUCCESS;
  }
  
  void git_cache_free(git_cache *cache)
  {
  	size_t i;
  
  	for (i = 0; i < (cache->size_mask + 1); ++i) {
  		if (cache->nodes[i].ptr)
  			git_cached_obj_decref(cache->nodes[i].ptr, cache->free_obj);
  
  		git_mutex_free(&cache->nodes[i].lock);
  	}
  
  	free(cache->nodes);
  }
  
  void *git_cache_get(git_cache *cache, const git_oid *oid)
  {
  	uint32_t hash;
  	cache_node *node = NULL;
  	void *result = NULL;
  
  	memcpy(&hash, oid->id, sizeof(hash));
  	node = &cache->nodes[hash & cache->size_mask];
  
  	git_mutex_lock(&node->lock);
  	{
  		if (node->ptr && git_cached_obj_compare(node->ptr, oid) == 0) {
  			git_cached_obj_incref(node->ptr);
  			result = node->ptr;
  		}
  	}
  	git_mutex_unlock(&node->lock);
  
  	return result;
  }
  
  void *git_cache_try_store(git_cache *cache, void *entry)
  {
  	uint32_t hash;
  	const git_oid *oid;
  	cache_node *node = NULL;
  
  	oid = &((git_cached_obj*)entry)->oid;
  	memcpy(&hash, oid->id, sizeof(hash));
  	node = &cache->nodes[hash & cache->size_mask];
  
  	/* increase the refcount on this object, because
  	 * the cache now owns it */
  	git_cached_obj_incref(entry);
  	git_mutex_lock(&node->lock);
  
  	if (node->ptr == NULL) {
  		node->ptr = entry;
  	} else if (git_cached_obj_compare(node->ptr, oid) == 0) {
  		git_cached_obj_decref(entry, cache->free_obj);
  		entry = node->ptr;
  	} else {
  		git_cached_obj_decref(node->ptr, cache->free_obj);
  		node->ptr = entry;
  	}
  
  	/* increase the refcount again, because we are
  	 * returning it to the user */
  	git_cached_obj_incref(entry);
  	git_mutex_unlock(&node->lock);
  
  	return entry;
  }
  

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