thodg/libgit2/src/hashtable.h

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• Hash : c16c8b9a
  Author :
  Date : 2012-04-23T09:23:58
  

  Adding stash to hashtable implementation Adding a small stash of nodes with key conflicts has been demonstrated to greatly increase the efficiency of a cuckoo hashtable. See: http://research.microsoft.com/pubs/73856/stash-full.9-30.pdf for more details.

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• src/hashtable.h

• /*
   * 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.
   */
  #ifndef INCLUDE_hashtable_h__
  #define INCLUDE_hashtable_h__
  
  #include "git2/common.h"
  #include "git2/oid.h"
  #include "git2/odb.h"
  #include "common.h"
  
  #define GIT_HASHTABLE_HASHES 3
  
  typedef uint32_t (*git_hash_ptr)(const void *, int hash_id);
  typedef int (*git_hash_keyeq_ptr)(const void *key_a, const void *key_b);
  
  struct git_hashtable_node {
  	const void *key;
  	void *value;
  };
  
  #define GIT_HASHTABLE_STASH_SIZE 3
  
  struct git_hashtable {
  	struct git_hashtable_node *nodes;
  
  	size_t size_mask;
  	size_t size;
  	size_t key_count;
  
  	struct git_hashtable_node stash[GIT_HASHTABLE_STASH_SIZE];
  	int stash_count;
  
  	int is_resizing;
  
  	git_hash_ptr hash;
  	git_hash_keyeq_ptr key_equal;
  };
  
  typedef struct git_hashtable_node git_hashtable_node;
  typedef struct git_hashtable git_hashtable;
  
  git_hashtable *git_hashtable_alloc(
  	size_t min_size,
  	git_hash_ptr hash,
  	git_hash_keyeq_ptr key_eq);
  
  void *git_hashtable_lookup(git_hashtable *h, const void *key);
  int git_hashtable_remove2(git_hashtable *table, const void *key, void **old_value);
  
  GIT_INLINE(int) git_hashtable_remove(git_hashtable *table, const void *key)
  {
  	void *_unused;
  	return git_hashtable_remove2(table, key, &_unused);
  }
  
  
  void git_hashtable_free(git_hashtable *h);
  void git_hashtable_clear(git_hashtable *h);
  int git_hashtable_merge(git_hashtable *self, git_hashtable *other);
  
  int git_hashtable_insert2(git_hashtable *h, const void *key, void *value, void **old_value);
  
  GIT_INLINE(int) git_hashtable_insert(git_hashtable *h, const void *key, void *value)
  {
  	void *_unused;
  	return git_hashtable_insert2(h, key, value, &_unused);
  }
  
  #define git_hashtable_node_at(nodes, pos) ((git_hashtable_node *)(&nodes[pos]))
  
  #define GIT_HASHTABLE__FOREACH(self,block) { \
  	size_t _c; \
  	git_hashtable_node *_n = (self)->nodes; \
  	for (_c = (self)->size; _c > 0; _c--, _n++)	{ \
  		if (!_n->key) continue; block } }
  
  #define GIT_HASHTABLE_FOREACH(self, pkey, pvalue, code)\
  	GIT_HASHTABLE__FOREACH(self,{(pkey)=_n->key;(pvalue)=_n->value;code;})
  
  #define GIT_HASHTABLE_FOREACH_KEY(self, pkey, code)\
  	GIT_HASHTABLE__FOREACH(self,{(pkey)=_n->key;code;})
  
  #define GIT_HASHTABLE_FOREACH_VALUE(self, pvalue, code)\
  	GIT_HASHTABLE__FOREACH(self,{(pvalue)=_n->value;code;})
  
  #define GIT_HASHTABLE_FOREACH_DELETE() {\
  	_node->key = NULL; _node->value = NULL; _self->key_count--;\
  }
  
  /*
   * If you want a hashtable with standard string keys, you can
   * just pass git_hash__strcmp_cb and git_hash__strhash_cb to
   * git_hashtable_alloc.
   */
  #define git_hash__strcmp_cb git__strcmp_cb
  extern uint32_t git_hash__strhash_cb(const void *key, int hash_id);
  
  #endif
  

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