2 * Copyright (c) 2008, 2009, 2010 Nicira Networks.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
28 /* A hash map node, to be embedded inside the data structure being mapped. */
30 size_t hash; /* Hash value. */
31 struct hmap_node *next; /* Next in linked list. */
34 /* Returns the hash value embedded in 'node'. */
35 static inline size_t hmap_node_hash(const struct hmap_node *node)
40 #define HMAP_NODE_NULL ((struct hmap_node *) 1)
42 /* Returns true if 'node' has been set to null by hmap_node_nullify() and has
43 * not been un-nullified by being inserted into an hmap. */
45 hmap_node_is_null(const struct hmap_node *node)
47 return node->next == HMAP_NODE_NULL;
50 /* Marks 'node' with a distinctive value that can be tested with
51 * hmap_node_is_null(). */
53 hmap_node_nullify(struct hmap_node *node)
55 node->next = HMAP_NODE_NULL;
60 struct hmap_node **buckets; /* Must point to 'one' iff 'mask' == 0. */
61 struct hmap_node *one;
66 /* Initializer for an empty hash map. */
67 #define HMAP_INITIALIZER(HMAP) { &(HMAP)->one, NULL, 0, 0 }
70 void hmap_init(struct hmap *);
71 void hmap_destroy(struct hmap *);
72 void hmap_swap(struct hmap *a, struct hmap *b);
73 void hmap_moved(struct hmap *hmap);
74 static inline size_t hmap_count(const struct hmap *);
75 static inline bool hmap_is_empty(const struct hmap *);
77 /* Adjusting capacity. */
78 void hmap_expand(struct hmap *);
79 void hmap_shrink(struct hmap *);
80 void hmap_reserve(struct hmap *, size_t capacity);
82 /* Insertion and deletion. */
83 static inline void hmap_insert_fast(struct hmap *,
84 struct hmap_node *, size_t hash);
85 static inline void hmap_insert(struct hmap *, struct hmap_node *, size_t hash);
86 static inline void hmap_remove(struct hmap *, struct hmap_node *);
88 void hmap_node_moved(struct hmap *, struct hmap_node *, struct hmap_node *);
89 static inline void hmap_replace(struct hmap *, const struct hmap_node *old,
90 struct hmap_node *new);
92 struct hmap_node *hmap_random_node(const struct hmap *);
96 * HMAP_FOR_EACH_WITH_HASH iterates NODE over all of the nodes in HMAP that
97 * have hash value equal to HASH. HMAP_FOR_EACH_IN_BUCKET iterates NODE over
98 * all of the nodes in HMAP that would fall in the same bucket as HASH. STRUCT
99 * and MEMBER must be the name of the struct that contains the 'struct
100 * hmap_node' and the name of the 'struct hmap_node' member, respectively.
102 * These macros may be used interchangeably to search for a particular value in
103 * an hmap, see, e.g. shash_find() for an example. Usually, using
104 * HMAP_FOR_EACH_WITH_HASH provides an optimization, because comparing a hash
105 * value is usually cheaper than comparing an entire hash map key. But for
106 * simple hash map keys, it makes sense to use HMAP_FOR_EACH_IN_BUCKET because
107 * it avoids doing two comparisons when a single simple comparison suffices.
109 * The loop should not change NODE to point to a different node or insert or
110 * delete nodes in HMAP (unless it "break"s out of the loop to terminate
113 * HASH is only evaluated once.
115 #define HMAP_FOR_EACH_WITH_HASH(NODE, STRUCT, MEMBER, HASH, HMAP) \
116 for ((NODE) = CONTAINER_OF(hmap_first_with_hash(HMAP, HASH), \
118 &(NODE)->MEMBER != NULL; \
119 (NODE) = CONTAINER_OF(hmap_next_with_hash(&(NODE)->MEMBER), \
121 #define HMAP_FOR_EACH_IN_BUCKET(NODE, STRUCT, MEMBER, HASH, HMAP) \
122 for ((NODE) = CONTAINER_OF(hmap_first_in_bucket(HMAP, HASH), \
124 &(NODE)->MEMBER != NULL; \
125 (NODE) = CONTAINER_OF(hmap_next_in_bucket(&(NODE)->MEMBER), \
128 static inline struct hmap_node *hmap_first_with_hash(const struct hmap *,
130 static inline struct hmap_node *hmap_next_with_hash(const struct hmap_node *);
131 static inline struct hmap_node *hmap_first_in_bucket(const struct hmap *,
133 static inline struct hmap_node *hmap_next_in_bucket(const struct hmap_node *);
137 * The _SAFE version is needed when NODE may be freed. It is not needed when
138 * NODE may be removed from the hash map but its members remain accessible and
140 #define HMAP_FOR_EACH(NODE, STRUCT, MEMBER, HMAP) \
141 for ((NODE) = CONTAINER_OF(hmap_first(HMAP), STRUCT, MEMBER); \
142 &(NODE)->MEMBER != NULL; \
143 (NODE) = CONTAINER_OF(hmap_next(HMAP, &(NODE)->MEMBER), \
146 #define HMAP_FOR_EACH_SAFE(NODE, NEXT, STRUCT, MEMBER, HMAP) \
147 for ((NODE) = CONTAINER_OF(hmap_first(HMAP), STRUCT, MEMBER); \
148 (&(NODE)->MEMBER != NULL \
149 ? (NEXT) = CONTAINER_OF(hmap_next(HMAP, &(NODE)->MEMBER), \
154 static inline struct hmap_node *hmap_first(const struct hmap *);
155 static inline struct hmap_node *hmap_next(const struct hmap *,
156 const struct hmap_node *);
158 /* Returns the number of nodes currently in 'hmap'. */
160 hmap_count(const struct hmap *hmap)
165 /* Returns the maximum number of nodes that 'hmap' may hold before it should be
168 hmap_capacity(const struct hmap *hmap)
170 return hmap->mask * 2 + 1;
173 /* Returns true if 'hmap' currently contains no nodes,
174 * false otherwise. */
176 hmap_is_empty(const struct hmap *hmap)
181 /* Inserts 'node', with the given 'hash', into 'hmap'. 'hmap' is never
182 * expanded automatically. */
184 hmap_insert_fast(struct hmap *hmap, struct hmap_node *node, size_t hash)
186 struct hmap_node **bucket = &hmap->buckets[hash & hmap->mask];
188 node->next = *bucket;
193 /* Inserts 'node', with the given 'hash', into 'hmap', and expands 'hmap' if
194 * necessary to optimize search performance. */
196 hmap_insert(struct hmap *hmap, struct hmap_node *node, size_t hash)
198 hmap_insert_fast(hmap, node, hash);
199 if (hmap->n / 2 > hmap->mask) {
204 /* Removes 'node' from 'hmap'. Does not shrink the hash table; call
205 * hmap_shrink() directly if desired. */
207 hmap_remove(struct hmap *hmap, struct hmap_node *node)
209 struct hmap_node **bucket = &hmap->buckets[node->hash & hmap->mask];
210 while (*bucket != node) {
211 bucket = &(*bucket)->next;
213 *bucket = node->next;
217 /* Puts 'new_node' in the position in 'hmap' currently occupied by 'old_node'.
218 * The 'new_node' must hash to the same value as 'old_node'. The client is
219 * responsible for ensuring that the replacement does not violate any
220 * client-imposed invariants (e.g. uniqueness of keys within a map).
222 * Afterward, 'old_node' is not part of 'hmap', and the client is responsible
223 * for freeing it (if this is desirable). */
225 hmap_replace(struct hmap *hmap,
226 const struct hmap_node *old_node, struct hmap_node *new_node)
228 struct hmap_node **bucket = &hmap->buckets[old_node->hash & hmap->mask];
229 while (*bucket != old_node) {
230 bucket = &(*bucket)->next;
233 new_node->hash = old_node->hash;
234 new_node->next = old_node->next;
237 static inline struct hmap_node *
238 hmap_next_with_hash__(const struct hmap_node *node, size_t hash)
240 while (node != NULL && node->hash != hash) {
243 return (struct hmap_node *) node;
246 /* Returns the first node in 'hmap' with the given 'hash', or a null pointer if
247 * no nodes have that hash value. */
248 static inline struct hmap_node *
249 hmap_first_with_hash(const struct hmap *hmap, size_t hash)
251 return hmap_next_with_hash__(hmap->buckets[hash & hmap->mask], hash);
254 /* Returns the first node in 'hmap' in the bucket in which the given 'hash'
255 * would land, or a null pointer if that bucket is empty. */
256 static inline struct hmap_node *
257 hmap_first_in_bucket(const struct hmap *hmap, size_t hash)
259 return hmap->buckets[hash & hmap->mask];
262 /* Returns the next node in the same bucket as 'node', or a null pointer if
263 * there are no more nodes in that bucket.
265 * If the hash map has been reallocated since 'node' was visited, some nodes
266 * may be skipped; if new nodes with the same hash value have been added, they
267 * will be skipped. (Removing 'node' from the hash map does not prevent
268 * calling this function, since node->next is preserved, although freeing
269 * 'node' of course does.) */
270 static inline struct hmap_node *
271 hmap_next_in_bucket(const struct hmap_node *node)
276 /* Returns the next node in the same hash map as 'node' with the same hash
277 * value, or a null pointer if no more nodes have that hash value.
279 * If the hash map has been reallocated since 'node' was visited, some nodes
280 * may be skipped; if new nodes with the same hash value have been added, they
281 * will be skipped. (Removing 'node' from the hash map does not prevent
282 * calling this function, since node->next is preserved, although freeing
283 * 'node' of course does.) */
284 static inline struct hmap_node *
285 hmap_next_with_hash(const struct hmap_node *node)
287 return hmap_next_with_hash__(node->next, node->hash);
290 static inline struct hmap_node *
291 hmap_next__(const struct hmap *hmap, size_t start)
294 for (i = start; i <= hmap->mask; i++) {
295 struct hmap_node *node = hmap->buckets[i];
303 /* Returns the first node in 'hmap', in arbitrary order, or a null pointer if
304 * 'hmap' is empty. */
305 static inline struct hmap_node *
306 hmap_first(const struct hmap *hmap)
308 return hmap_next__(hmap, 0);
311 /* Returns the next node in 'hmap' following 'node', in arbitrary order, or a
312 * null pointer if 'node' is the last node in 'hmap'.
314 * If the hash map has been reallocated since 'node' was visited, some nodes
315 * may be skipped or visited twice. (Removing 'node' from the hash map does
316 * not prevent calling this function, since node->next is preserved, although
317 * freeing 'node' of course does.) */
318 static inline struct hmap_node *
319 hmap_next(const struct hmap *hmap, const struct hmap_node *node)
323 : hmap_next__(hmap, (node->hash & hmap->mask) + 1));