2 * Copyright (c) 2008, 2009, 2010, 2012 Nicira, Inc.
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)
41 #define HMAP_NODE_NULL_INITIALIZER { 0, HMAP_NODE_NULL }
43 /* Returns true if 'node' has been set to null by hmap_node_nullify() and has
44 * not been un-nullified by being inserted into an hmap. */
46 hmap_node_is_null(const struct hmap_node *node)
48 return node->next == HMAP_NODE_NULL;
51 /* Marks 'node' with a distinctive value that can be tested with
52 * hmap_node_is_null(). */
54 hmap_node_nullify(struct hmap_node *node)
56 node->next = HMAP_NODE_NULL;
61 struct hmap_node **buckets; /* Must point to 'one' iff 'mask' == 0. */
62 struct hmap_node *one;
67 /* Initializer for an empty hash map. */
68 #define HMAP_INITIALIZER(HMAP) { &(HMAP)->one, NULL, 0, 0 }
71 void hmap_init(struct hmap *);
72 void hmap_destroy(struct hmap *);
73 void hmap_clear(struct hmap *);
74 void hmap_swap(struct hmap *a, struct hmap *b);
75 void hmap_moved(struct hmap *hmap);
76 static inline size_t hmap_count(const struct hmap *);
77 static inline bool hmap_is_empty(const struct hmap *);
79 /* Adjusting capacity. */
80 void hmap_expand(struct hmap *);
81 void hmap_shrink(struct hmap *);
82 void hmap_reserve(struct hmap *, size_t capacity);
84 /* Insertion and deletion. */
85 static inline void hmap_insert_fast(struct hmap *,
86 struct hmap_node *, size_t hash);
87 static inline void hmap_insert(struct hmap *, struct hmap_node *, size_t hash);
88 static inline void hmap_remove(struct hmap *, struct hmap_node *);
90 void hmap_node_moved(struct hmap *, struct hmap_node *, struct hmap_node *);
91 static inline void hmap_replace(struct hmap *, const struct hmap_node *old,
92 struct hmap_node *new_node);
94 struct hmap_node *hmap_random_node(const struct hmap *);
98 * HMAP_FOR_EACH_WITH_HASH iterates NODE over all of the nodes in HMAP that
99 * have hash value equal to HASH. HMAP_FOR_EACH_IN_BUCKET iterates NODE over
100 * all of the nodes in HMAP that would fall in the same bucket as HASH. MEMBER
101 * must be the name of the 'struct hmap_node' member within NODE.
103 * These macros may be used interchangeably to search for a particular value in
104 * an hmap, see, e.g. shash_find() for an example. Usually, using
105 * HMAP_FOR_EACH_WITH_HASH provides an optimization, because comparing a hash
106 * value is usually cheaper than comparing an entire hash map key. But for
107 * simple hash map keys, it makes sense to use HMAP_FOR_EACH_IN_BUCKET because
108 * it avoids doing two comparisons when a single simple comparison suffices.
110 * The loop should not change NODE to point to a different node or insert or
111 * delete nodes in HMAP (unless it "break"s out of the loop to terminate
114 * HASH is only evaluated once.
116 #define HMAP_FOR_EACH_WITH_HASH(NODE, MEMBER, HASH, HMAP) \
117 for (ASSIGN_CONTAINER(NODE, hmap_first_with_hash(HMAP, HASH), MEMBER); \
118 &(NODE)->MEMBER != NULL; \
119 ASSIGN_CONTAINER(NODE, hmap_next_with_hash(&(NODE)->MEMBER), \
121 #define HMAP_FOR_EACH_IN_BUCKET(NODE, MEMBER, HASH, HMAP) \
122 for (ASSIGN_CONTAINER(NODE, hmap_first_in_bucket(HMAP, HASH), MEMBER); \
123 &(NODE)->MEMBER != NULL; \
124 ASSIGN_CONTAINER(NODE, hmap_next_in_bucket(&(NODE)->MEMBER), MEMBER))
126 static inline struct hmap_node *hmap_first_with_hash(const struct hmap *,
128 static inline struct hmap_node *hmap_next_with_hash(const struct hmap_node *);
129 static inline struct hmap_node *hmap_first_in_bucket(const struct hmap *,
131 static inline struct hmap_node *hmap_next_in_bucket(const struct hmap_node *);
133 bool hmap_contains(const struct hmap *, const struct hmap_node *);
137 /* Iterates through every node in HMAP. */
138 #define HMAP_FOR_EACH(NODE, MEMBER, HMAP) \
139 for (ASSIGN_CONTAINER(NODE, hmap_first(HMAP), MEMBER); \
140 &(NODE)->MEMBER != NULL; \
141 ASSIGN_CONTAINER(NODE, hmap_next(HMAP, &(NODE)->MEMBER), MEMBER))
143 /* Safe when NODE may be freed (not needed when NODE may be removed from the
144 * hash map but its members remain accessible and intact). */
145 #define HMAP_FOR_EACH_SAFE(NODE, NEXT, MEMBER, HMAP) \
146 for (ASSIGN_CONTAINER(NODE, hmap_first(HMAP), MEMBER); \
147 (&(NODE)->MEMBER != NULL \
148 ? ASSIGN_CONTAINER(NEXT, hmap_next(HMAP, &(NODE)->MEMBER), MEMBER) \
152 /* Continues an iteration from just after NODE. */
153 #define HMAP_FOR_EACH_CONTINUE(NODE, MEMBER, HMAP) \
154 for (ASSIGN_CONTAINER(NODE, hmap_next(HMAP, &(NODE)->MEMBER), MEMBER); \
155 &(NODE)->MEMBER != NULL; \
156 ASSIGN_CONTAINER(NODE, hmap_next(HMAP, &(NODE)->MEMBER), MEMBER))
158 static inline struct hmap_node *hmap_first(const struct hmap *);
159 static inline struct hmap_node *hmap_next(const struct hmap *,
160 const struct hmap_node *);
162 struct hmap_node *hmap_at_position(const struct hmap *,
163 uint32_t *bucket, uint32_t *offset);
165 /* Returns the number of nodes currently in 'hmap'. */
167 hmap_count(const struct hmap *hmap)
172 /* Returns the maximum number of nodes that 'hmap' may hold before it should be
175 hmap_capacity(const struct hmap *hmap)
177 return hmap->mask * 2 + 1;
180 /* Returns true if 'hmap' currently contains no nodes,
181 * false otherwise. */
183 hmap_is_empty(const struct hmap *hmap)
188 /* Inserts 'node', with the given 'hash', into 'hmap'. 'hmap' is never
189 * expanded automatically. */
191 hmap_insert_fast(struct hmap *hmap, struct hmap_node *node, size_t hash)
193 struct hmap_node **bucket = &hmap->buckets[hash & hmap->mask];
195 node->next = *bucket;
200 /* Inserts 'node', with the given 'hash', into 'hmap', and expands 'hmap' if
201 * necessary to optimize search performance. */
203 hmap_insert(struct hmap *hmap, struct hmap_node *node, size_t hash)
205 hmap_insert_fast(hmap, node, hash);
206 if (hmap->n / 2 > hmap->mask) {
211 /* Removes 'node' from 'hmap'. Does not shrink the hash table; call
212 * hmap_shrink() directly if desired. */
214 hmap_remove(struct hmap *hmap, struct hmap_node *node)
216 struct hmap_node **bucket = &hmap->buckets[node->hash & hmap->mask];
217 while (*bucket != node) {
218 bucket = &(*bucket)->next;
220 *bucket = node->next;
224 /* Puts 'new_node' in the position in 'hmap' currently occupied by 'old_node'.
225 * The 'new_node' must hash to the same value as 'old_node'. The client is
226 * responsible for ensuring that the replacement does not violate any
227 * client-imposed invariants (e.g. uniqueness of keys within a map).
229 * Afterward, 'old_node' is not part of 'hmap', and the client is responsible
230 * for freeing it (if this is desirable). */
232 hmap_replace(struct hmap *hmap,
233 const struct hmap_node *old_node, struct hmap_node *new_node)
235 struct hmap_node **bucket = &hmap->buckets[old_node->hash & hmap->mask];
236 while (*bucket != old_node) {
237 bucket = &(*bucket)->next;
240 new_node->hash = old_node->hash;
241 new_node->next = old_node->next;
244 static inline struct hmap_node *
245 hmap_next_with_hash__(const struct hmap_node *node, size_t hash)
247 while (node != NULL && node->hash != hash) {
250 return CONST_CAST(struct hmap_node *, node);
253 /* Returns the first node in 'hmap' with the given 'hash', or a null pointer if
254 * no nodes have that hash value. */
255 static inline struct hmap_node *
256 hmap_first_with_hash(const struct hmap *hmap, size_t hash)
258 return hmap_next_with_hash__(hmap->buckets[hash & hmap->mask], hash);
261 /* Returns the first node in 'hmap' in the bucket in which the given 'hash'
262 * would land, or a null pointer if that bucket is empty. */
263 static inline struct hmap_node *
264 hmap_first_in_bucket(const struct hmap *hmap, size_t hash)
266 return hmap->buckets[hash & hmap->mask];
269 /* Returns the next node in the same bucket as 'node', or a null pointer if
270 * there are no more nodes in that bucket.
272 * If the hash map has been reallocated since 'node' was visited, some nodes
273 * may be skipped; if new nodes with the same hash value have been added, they
274 * will be skipped. (Removing 'node' from the hash map does not prevent
275 * calling this function, since node->next is preserved, although freeing
276 * 'node' of course does.) */
277 static inline struct hmap_node *
278 hmap_next_in_bucket(const struct hmap_node *node)
283 /* Returns the next node in the same hash map as 'node' with the same hash
284 * value, or a null pointer if no more nodes have that hash value.
286 * If the hash map has been reallocated since 'node' was visited, some nodes
287 * may be skipped; if new nodes with the same hash value have been added, they
288 * will be skipped. (Removing 'node' from the hash map does not prevent
289 * calling this function, since node->next is preserved, although freeing
290 * 'node' of course does.) */
291 static inline struct hmap_node *
292 hmap_next_with_hash(const struct hmap_node *node)
294 return hmap_next_with_hash__(node->next, node->hash);
297 static inline struct hmap_node *
298 hmap_next__(const struct hmap *hmap, size_t start)
301 for (i = start; i <= hmap->mask; i++) {
302 struct hmap_node *node = hmap->buckets[i];
310 /* Returns the first node in 'hmap', in arbitrary order, or a null pointer if
311 * 'hmap' is empty. */
312 static inline struct hmap_node *
313 hmap_first(const struct hmap *hmap)
315 return hmap_next__(hmap, 0);
318 /* Returns the next node in 'hmap' following 'node', in arbitrary order, or a
319 * null pointer if 'node' is the last node in 'hmap'.
321 * If the hash map has been reallocated since 'node' was visited, some nodes
322 * may be skipped or visited twice. (Removing 'node' from the hash map does
323 * not prevent calling this function, since node->next is preserved, although
324 * freeing 'node' of course does.) */
325 static inline struct hmap_node *
326 hmap_next(const struct hmap *hmap, const struct hmap_node *node)
330 : hmap_next__(hmap, (node->hash & hmap->mask) + 1));