2 * Copyright (c) 2008, 2009 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.
24 /* A hash map node, to be embedded inside the data structure being mapped. */
26 size_t hash; /* Hash value. */
27 struct hmap_node *next; /* Next in linked list. */
30 /* Returns the hash value embedded in 'node'. */
31 static inline size_t hmap_node_hash(const struct hmap_node *node)
38 struct hmap_node **buckets;
39 struct hmap_node *one;
44 /* Initializer for an empty hash map. */
45 #define HMAP_INITIALIZER(HMAP) { &(HMAP)->one, NULL, 0, 0 }
48 void hmap_init(struct hmap *);
49 void hmap_destroy(struct hmap *);
50 void hmap_swap(struct hmap *a, struct hmap *b);
51 static inline size_t hmap_count(const struct hmap *);
52 static inline bool hmap_is_empty(const struct hmap *);
54 /* Adjusting capacity. */
55 void hmap_expand(struct hmap *);
56 void hmap_shrink(struct hmap *);
57 void hmap_reserve(struct hmap *, size_t capacity);
59 /* Insertion and deletion. */
60 static inline void hmap_insert_fast(struct hmap *,
61 struct hmap_node *, size_t hash);
62 static inline void hmap_insert(struct hmap *, struct hmap_node *, size_t hash);
63 static inline void hmap_remove(struct hmap *, struct hmap_node *);
64 static inline void hmap_moved(struct hmap *,
65 struct hmap_node *, struct hmap_node *);
66 static inline void hmap_replace(struct hmap *, const struct hmap_node *old,
67 struct hmap_node *new);
71 * HMAP_FOR_EACH_WITH_HASH iterates NODE over all of the nodes in HMAP that
72 * have hash value equal to HASH. HMAP_FOR_EACH_IN_BUCKET iterates NODE over
73 * all of the nodes in HMAP that would fall in the same bucket as HASH. STRUCT
74 * and MEMBER must be the name of the struct that contains the 'struct
75 * hmap_node' and the name of the 'struct hmap_node' member, respectively.
77 * These macros may be used interchangeably to search for a particular value in
78 * an hmap, see, e.g. shash_find() for an example. Usually, using
79 * HMAP_FOR_EACH_WITH_HASH provides an optimization, because comparing a hash
80 * value is usually cheaper than comparing an entire hash map key. But for
81 * simple hash map keys, it makes sense to use HMAP_FOR_EACH_IN_BUCKET because
82 * it avoids doing two comparisons when a single simple comparison suffices.
84 * The loop should not change NODE to point to a different node or insert or
85 * delete nodes in HMAP (unless it "break"s out of the loop to terminate
88 * HASH is only evaluated once.
90 #define HMAP_FOR_EACH_WITH_HASH(NODE, STRUCT, MEMBER, HASH, HMAP) \
91 for ((NODE) = CONTAINER_OF(hmap_first_with_hash(HMAP, HASH), \
93 &(NODE)->MEMBER != NULL; \
94 (NODE) = CONTAINER_OF(hmap_next_with_hash(&(NODE)->MEMBER), \
96 #define HMAP_FOR_EACH_IN_BUCKET(NODE, STRUCT, MEMBER, HASH, HMAP) \
97 for ((NODE) = CONTAINER_OF(hmap_first_in_bucket(HMAP, HASH), \
99 &(NODE)->MEMBER != NULL; \
100 (NODE) = CONTAINER_OF(hmap_next_in_bucket(&(NODE)->MEMBER), \
103 static inline struct hmap_node *hmap_first_with_hash(const struct hmap *,
105 static inline struct hmap_node *hmap_next_with_hash(const struct hmap_node *);
106 static inline struct hmap_node *hmap_first_in_bucket(const struct hmap *,
108 static inline struct hmap_node *hmap_next_in_bucket(const struct hmap_node *);
112 * The _SAFE version is needed when NODE may be freed. It is not needed when
113 * NODE may be removed from the hash map but its members remain accessible and
115 #define HMAP_FOR_EACH(NODE, STRUCT, MEMBER, HMAP) \
116 for ((NODE) = CONTAINER_OF(hmap_first(HMAP), STRUCT, MEMBER); \
117 &(NODE)->MEMBER != NULL; \
118 (NODE) = CONTAINER_OF(hmap_next(HMAP, &(NODE)->MEMBER), \
121 #define HMAP_FOR_EACH_SAFE(NODE, NEXT, STRUCT, MEMBER, HMAP) \
122 for ((NODE) = CONTAINER_OF(hmap_first(HMAP), STRUCT, MEMBER); \
123 (&(NODE)->MEMBER != NULL \
124 ? (NEXT) = CONTAINER_OF(hmap_next(HMAP, &(NODE)->MEMBER), \
129 static inline struct hmap_node *hmap_first(const struct hmap *);
130 static inline struct hmap_node *hmap_next(const struct hmap *,
131 const struct hmap_node *);
133 /* Returns the number of nodes currently in 'hmap'. */
135 hmap_count(const struct hmap *hmap)
140 /* Returns the maximum number of nodes that 'hmap' may hold before it should be
143 hmap_capacity(const struct hmap *hmap)
145 return hmap->mask * 2 + 1;
148 /* Returns true if 'hmap' currently contains no nodes,
149 * false otherwise. */
151 hmap_is_empty(const struct hmap *hmap)
156 /* Inserts 'node', with the given 'hash', into 'hmap'. 'hmap' is never
157 * expanded automatically. */
159 hmap_insert_fast(struct hmap *hmap, struct hmap_node *node, size_t hash)
161 struct hmap_node **bucket = &hmap->buckets[hash & hmap->mask];
163 node->next = *bucket;
168 /* Inserts 'node', with the given 'hash', into 'hmap', and expands 'hmap' if
169 * necessary to optimize search performance. */
171 hmap_insert(struct hmap *hmap, struct hmap_node *node, size_t hash)
173 hmap_insert_fast(hmap, node, hash);
174 if (hmap->n / 2 > hmap->mask) {
179 /* Removes 'node' from 'hmap'. Does not shrink the hash table; call
180 * hmap_shrink() directly if desired. */
182 hmap_remove(struct hmap *hmap, struct hmap_node *node)
184 struct hmap_node **bucket = &hmap->buckets[node->hash & hmap->mask];
185 while (*bucket != node) {
186 bucket = &(*bucket)->next;
188 *bucket = node->next;
192 /* Adjusts 'hmap' to compensate for 'old_node' having moved position in memory
193 * to 'node' (e.g. due to realloc()). */
195 hmap_moved(struct hmap *hmap,
196 struct hmap_node *old_node, struct hmap_node *node)
198 struct hmap_node **bucket = &hmap->buckets[node->hash & hmap->mask];
199 while (*bucket != old_node) {
200 bucket = &(*bucket)->next;
205 /* Puts 'new' in the position in 'hmap' currently occupied by 'old'. The 'new'
206 * node must hash to the same value as 'old'. The client is responsible for
207 * ensuring that the replacement does not violate any client-imposed
208 * invariants (e.g. uniqueness of keys within a map).
210 * Afterward, 'old' is not part of 'hmap', and the client is responsible for
211 * freeing it (if this is desirable). */
213 hmap_replace(struct hmap *hmap,
214 const struct hmap_node *old, struct hmap_node *new)
216 struct hmap_node **bucket = &hmap->buckets[old->hash & hmap->mask];
217 while (*bucket != old) {
218 bucket = &(*bucket)->next;
221 new->hash = old->hash;
222 new->next = old->next;
225 static inline struct hmap_node *
226 hmap_next_with_hash__(const struct hmap_node *node, size_t hash)
228 while (node != NULL && node->hash != hash) {
231 return (struct hmap_node *) node;
234 /* Returns the first node in 'hmap' with the given 'hash', or a null pointer if
235 * no nodes have that hash value. */
236 static inline struct hmap_node *
237 hmap_first_with_hash(const struct hmap *hmap, size_t hash)
239 return hmap_next_with_hash__(hmap->buckets[hash & hmap->mask], hash);
242 /* Returns the first node in 'hmap' in the bucket in which the given 'hash'
243 * would land, or a null pointer if that bucket is empty. */
244 static inline struct hmap_node *
245 hmap_first_in_bucket(const struct hmap *hmap, size_t hash)
247 return hmap->buckets[hash & hmap->mask];
250 /* Returns the next node in the same bucket as 'node', or a null pointer if
251 * there are no more nodes in that bucket.
253 * If the hash map has been reallocated since 'node' was visited, some nodes
254 * may be skipped; if new nodes with the same hash value have been added, they
255 * will be skipped. (Removing 'node' from the hash map does not prevent
256 * calling this function, since node->next is preserved, although freeing
257 * 'node' of course does.) */
258 static inline struct hmap_node *
259 hmap_next_in_bucket(const struct hmap_node *node)
264 /* Returns the next node in the same hash map as 'node' with the same hash
265 * value, or a null pointer if no more nodes have that hash value.
267 * If the hash map has been reallocated since 'node' was visited, some nodes
268 * may be skipped; if new nodes with the same hash value have been added, they
269 * will be skipped. (Removing 'node' from the hash map does not prevent
270 * calling this function, since node->next is preserved, although freeing
271 * 'node' of course does.) */
272 static inline struct hmap_node *
273 hmap_next_with_hash(const struct hmap_node *node)
275 return hmap_next_with_hash__(node->next, node->hash);
278 static inline struct hmap_node *
279 hmap_next__(const struct hmap *hmap, size_t start)
282 for (i = start; i <= hmap->mask; i++) {
283 struct hmap_node *node = hmap->buckets[i];
291 /* Returns the first node in 'hmap', in arbitrary order, or a null pointer if
292 * 'hmap' is empty. */
293 static inline struct hmap_node *
294 hmap_first(const struct hmap *hmap)
296 return hmap_next__(hmap, 0);
299 /* Returns the next node in 'hmap' following 'node', in arbitrary order, or a
300 * null pointer if 'node' is the last node in 'hmap'.
302 * If the hash map has been reallocated since 'node' was visited, some nodes
303 * may be skipped or visited twice. (Removing 'node' from the hash map does
304 * not prevent calling this function, since node->next is preserved, although
305 * freeing 'node' of course does.) */
306 static inline struct hmap_node *
307 hmap_next(const struct hmap *hmap, const struct hmap_node *node)
311 : hmap_next__(hmap, (node->hash & hmap->mask) + 1));