2 * Copyright (c) 2008, 2009, 2010, 2012, 2013 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.
22 #include "ovs-atomic.h"
29 /* A hash map node, to be embedded inside the data structure being mapped. */
31 size_t hash; /* Hash value. */
32 struct hmap_node *next; /* Next in linked list. */
35 /* Returns the hash value embedded in 'node'. */
36 static inline size_t hmap_node_hash(const struct hmap_node *node)
41 #define HMAP_NODE_NULL ((struct hmap_node *) 1)
42 #define HMAP_NODE_NULL_INITIALIZER { 0, HMAP_NODE_NULL }
44 /* Returns true if 'node' has been set to null by hmap_node_nullify() and has
45 * not been un-nullified by being inserted into an hmap. */
47 hmap_node_is_null(const struct hmap_node *node)
49 return node->next == HMAP_NODE_NULL;
52 /* Marks 'node' with a distinctive value that can be tested with
53 * hmap_node_is_null(). */
55 hmap_node_nullify(struct hmap_node *node)
57 node->next = HMAP_NODE_NULL;
62 struct hmap_node **buckets; /* Must point to 'one' iff 'mask' == 0. */
63 struct hmap_node *one;
68 /* Initializer for an empty hash map. */
69 #define HMAP_INITIALIZER(HMAP) \
70 { (struct hmap_node **const) &(HMAP)->one, NULL, 0, 0 }
73 void hmap_init(struct hmap *);
74 void hmap_destroy(struct hmap *);
75 void hmap_clear(struct hmap *);
76 void hmap_swap(struct hmap *a, struct hmap *b);
77 void hmap_moved(struct hmap *hmap);
78 static inline size_t hmap_count(const struct hmap *);
79 static inline bool hmap_is_empty(const struct hmap *);
81 /* Adjusting capacity. */
82 void hmap_expand_at(struct hmap *, const char *where);
83 #define hmap_expand(HMAP) hmap_expand_at(HMAP, SOURCE_LOCATOR)
85 void hmap_shrink_at(struct hmap *, const char *where);
86 #define hmap_shrink(HMAP) hmap_shrink_at(HMAP, SOURCE_LOCATOR)
88 void hmap_reserve_at(struct hmap *, size_t capacity, const char *where);
89 #define hmap_reserve(HMAP, CAPACITY) \
90 hmap_reserve_at(HMAP, CAPACITY, SOURCE_LOCATOR)
92 /* Insertion and deletion. */
93 static inline void hmap_insert_at(struct hmap *, struct hmap_node *,
94 size_t hash, const char *where);
95 #define hmap_insert(HMAP, NODE, HASH) \
96 hmap_insert_at(HMAP, NODE, HASH, SOURCE_LOCATOR)
98 static inline void hmap_insert_fast(struct hmap *,
99 struct hmap_node *, size_t hash);
100 static inline void hmap_remove(struct hmap *, struct hmap_node *);
102 void hmap_node_moved(struct hmap *, struct hmap_node *, struct hmap_node *);
103 static inline void hmap_replace(struct hmap *, const struct hmap_node *old,
104 struct hmap_node *new_node);
106 struct hmap_node *hmap_random_node(const struct hmap *);
110 * HMAP_FOR_EACH_WITH_HASH iterates NODE over all of the nodes in HMAP that
111 * have hash value equal to HASH. HMAP_FOR_EACH_IN_BUCKET iterates NODE over
112 * all of the nodes in HMAP that would fall in the same bucket as HASH. MEMBER
113 * must be the name of the 'struct hmap_node' member within NODE.
115 * These macros may be used interchangeably to search for a particular value in
116 * an hmap, see, e.g. shash_find() for an example. Usually, using
117 * HMAP_FOR_EACH_WITH_HASH provides an optimization, because comparing a hash
118 * value is usually cheaper than comparing an entire hash map key. But for
119 * simple hash map keys, it makes sense to use HMAP_FOR_EACH_IN_BUCKET because
120 * it avoids doing two comparisons when a single simple comparison suffices.
122 * The loop should not change NODE to point to a different node or insert or
123 * delete nodes in HMAP (unless it "break"s out of the loop to terminate
126 * HASH is only evaluated once.
128 #define HMAP_FOR_EACH_WITH_HASH(NODE, MEMBER, HASH, HMAP) \
129 for (ASSIGN_CONTAINER(NODE, hmap_first_with_hash(HMAP, HASH), MEMBER); \
130 NODE != OBJECT_CONTAINING(NULL, NODE, MEMBER); \
131 ASSIGN_CONTAINER(NODE, hmap_next_with_hash(&(NODE)->MEMBER), \
133 #define HMAP_FOR_EACH_IN_BUCKET(NODE, MEMBER, HASH, HMAP) \
134 for (ASSIGN_CONTAINER(NODE, hmap_first_in_bucket(HMAP, HASH), MEMBER); \
135 NODE != OBJECT_CONTAINING(NULL, NODE, MEMBER); \
136 ASSIGN_CONTAINER(NODE, hmap_next_in_bucket(&(NODE)->MEMBER), MEMBER))
138 static inline struct hmap_node *hmap_first_with_hash(const struct hmap *,
140 static inline struct hmap_node *hmap_next_with_hash(const struct hmap_node *);
141 static inline struct hmap_node *hmap_first_in_bucket(const struct hmap *,
143 static inline struct hmap_node *hmap_next_in_bucket(const struct hmap_node *);
145 bool hmap_contains(const struct hmap *, const struct hmap_node *);
149 /* Iterates through every node in HMAP. */
150 #define HMAP_FOR_EACH(NODE, MEMBER, HMAP) \
151 for (ASSIGN_CONTAINER(NODE, hmap_first(HMAP), MEMBER); \
152 NODE != OBJECT_CONTAINING(NULL, NODE, MEMBER); \
153 ASSIGN_CONTAINER(NODE, hmap_next(HMAP, &(NODE)->MEMBER), MEMBER))
155 /* Safe when NODE may be freed (not needed when NODE may be removed from the
156 * hash map but its members remain accessible and intact). */
157 #define HMAP_FOR_EACH_SAFE(NODE, NEXT, MEMBER, HMAP) \
158 for (ASSIGN_CONTAINER(NODE, hmap_first(HMAP), MEMBER); \
159 (NODE != OBJECT_CONTAINING(NULL, NODE, MEMBER) \
160 ? ASSIGN_CONTAINER(NEXT, hmap_next(HMAP, &(NODE)->MEMBER), MEMBER), 1 \
164 /* Continues an iteration from just after NODE. */
165 #define HMAP_FOR_EACH_CONTINUE(NODE, MEMBER, HMAP) \
166 for (ASSIGN_CONTAINER(NODE, hmap_next(HMAP, &(NODE)->MEMBER), MEMBER); \
167 NODE != OBJECT_CONTAINING(NULL, NODE, MEMBER); \
168 ASSIGN_CONTAINER(NODE, hmap_next(HMAP, &(NODE)->MEMBER), MEMBER))
170 static inline struct hmap_node *hmap_first(const struct hmap *);
171 static inline struct hmap_node *hmap_next(const struct hmap *,
172 const struct hmap_node *);
174 struct hmap_node *hmap_at_position(const struct hmap *,
175 uint32_t *bucket, uint32_t *offset);
177 /* Returns the number of nodes currently in 'hmap'. */
179 hmap_count(const struct hmap *hmap)
184 /* Returns the maximum number of nodes that 'hmap' may hold before it should be
187 hmap_capacity(const struct hmap *hmap)
189 return hmap->mask * 2 + 1;
192 /* Returns true if 'hmap' currently contains no nodes,
194 * Note: While hmap in general is not thread-safe without additional locking,
195 * hmap_is_empty() is. */
197 hmap_is_empty(const struct hmap *hmap)
202 /* Inserts 'node', with the given 'hash', into 'hmap'. 'hmap' is never
203 * expanded automatically. */
205 hmap_insert_fast(struct hmap *hmap, struct hmap_node *node, size_t hash)
207 struct hmap_node **bucket = &hmap->buckets[hash & hmap->mask];
209 node->next = *bucket;
214 /* Inserts 'node', with the given 'hash', into 'hmap', and expands 'hmap' if
215 * necessary to optimize search performance.
217 * ('where' is used in debug logging. Commonly one would use hmap_insert() to
218 * automatically provide the caller's source file and line number for
221 hmap_insert_at(struct hmap *hmap, struct hmap_node *node, size_t hash,
224 hmap_insert_fast(hmap, node, hash);
225 if (hmap->n / 2 > hmap->mask) {
226 hmap_expand_at(hmap, where);
230 /* Removes 'node' from 'hmap'. Does not shrink the hash table; call
231 * hmap_shrink() directly if desired. */
233 hmap_remove(struct hmap *hmap, struct hmap_node *node)
235 struct hmap_node **bucket = &hmap->buckets[node->hash & hmap->mask];
236 while (*bucket != node) {
237 bucket = &(*bucket)->next;
239 *bucket = node->next;
243 /* Puts 'new_node' in the position in 'hmap' currently occupied by 'old_node'.
244 * The 'new_node' must hash to the same value as 'old_node'. The client is
245 * responsible for ensuring that the replacement does not violate any
246 * client-imposed invariants (e.g. uniqueness of keys within a map).
248 * Afterward, 'old_node' is not part of 'hmap', and the client is responsible
249 * for freeing it (if this is desirable). */
251 hmap_replace(struct hmap *hmap,
252 const struct hmap_node *old_node, struct hmap_node *new_node)
254 struct hmap_node **bucket = &hmap->buckets[old_node->hash & hmap->mask];
255 while (*bucket != old_node) {
256 bucket = &(*bucket)->next;
259 new_node->hash = old_node->hash;
260 new_node->next = old_node->next;
263 static inline struct hmap_node *
264 hmap_next_with_hash__(const struct hmap_node *node, size_t hash)
266 while (node != NULL && node->hash != hash) {
269 return CONST_CAST(struct hmap_node *, node);
272 /* Returns the first node in 'hmap' with the given 'hash', or a null pointer if
273 * no nodes have that hash value. */
274 static inline struct hmap_node *
275 hmap_first_with_hash(const struct hmap *hmap, size_t hash)
277 return hmap_next_with_hash__(hmap->buckets[hash & hmap->mask], hash);
280 /* Returns the first node in 'hmap' in the bucket in which the given 'hash'
281 * would land, or a null pointer if that bucket is empty. */
282 static inline struct hmap_node *
283 hmap_first_in_bucket(const struct hmap *hmap, size_t hash)
285 return hmap->buckets[hash & hmap->mask];
288 /* Returns the next node in the same bucket as 'node', or a null pointer if
289 * there are no more nodes in that bucket.
291 * If the hash map has been reallocated since 'node' was visited, some nodes
292 * may be skipped; if new nodes with the same hash value have been added, they
293 * will be skipped. (Removing 'node' from the hash map does not prevent
294 * calling this function, since node->next is preserved, although freeing
295 * 'node' of course does.) */
296 static inline struct hmap_node *
297 hmap_next_in_bucket(const struct hmap_node *node)
302 /* Returns the next node in the same hash map as 'node' with the same hash
303 * value, or a null pointer if no more nodes have that hash value.
305 * If the hash map has been reallocated since 'node' was visited, some nodes
306 * may be skipped; if new nodes with the same hash value have been added, they
307 * will be skipped. (Removing 'node' from the hash map does not prevent
308 * calling this function, since node->next is preserved, although freeing
309 * 'node' of course does.) */
310 static inline struct hmap_node *
311 hmap_next_with_hash(const struct hmap_node *node)
313 return hmap_next_with_hash__(node->next, node->hash);
316 static inline struct hmap_node *
317 hmap_next__(const struct hmap *hmap, size_t start)
320 for (i = start; i <= hmap->mask; i++) {
321 struct hmap_node *node = hmap->buckets[i];
329 /* Returns the first node in 'hmap', in arbitrary order, or a null pointer if
330 * 'hmap' is empty. */
331 static inline struct hmap_node *
332 hmap_first(const struct hmap *hmap)
334 return hmap_next__(hmap, 0);
337 /* Returns the next node in 'hmap' following 'node', in arbitrary order, or a
338 * null pointer if 'node' is the last node in 'hmap'.
340 * If the hash map has been reallocated since 'node' was visited, some nodes
341 * may be skipped or visited twice. (Removing 'node' from the hash map does
342 * not prevent calling this function, since node->next is preserved, although
343 * freeing 'node' of course does.) */
344 static inline struct hmap_node *
345 hmap_next(const struct hmap *hmap, const struct hmap_node *node)
349 : hmap_next__(hmap, (node->hash & hmap->mask) + 1));