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When hmap_replace() replaces one hash table node by another, it must ensure that any nodes following the old node also follow the new node, by copying the "next" pointer from "old" to "new".
264 lines
8.8 KiB
C
264 lines
8.8 KiB
C
/*
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* Copyright (c) 2008, 2009 Nicira Networks.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef HMAP_H
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#define HMAP_H 1
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#include <stdbool.h>
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#include <stdlib.h>
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#include "util.h"
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/* A hash map node, to be embedded inside the data structure being mapped. */
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struct hmap_node {
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size_t hash; /* Hash value. */
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struct hmap_node *next; /* Next in linked list. */
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};
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/* Returns the hash value embedded in 'node'. */
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static inline size_t hmap_node_hash(const struct hmap_node *node)
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{
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return node->hash;
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}
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/* A hash map. */
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struct hmap {
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struct hmap_node **buckets;
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struct hmap_node *one;
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size_t mask;
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size_t n;
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};
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/* Initializer for an empty hash map. */
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#define HMAP_INITIALIZER(HMAP) { &(HMAP)->one, NULL, 0, 0 }
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/* Initialization. */
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void hmap_init(struct hmap *);
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void hmap_destroy(struct hmap *);
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void hmap_swap(struct hmap *a, struct hmap *b);
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static inline size_t hmap_count(const struct hmap *);
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static inline bool hmap_is_empty(const struct hmap *);
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/* Adjusting capacity. */
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void hmap_expand(struct hmap *);
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void hmap_shrink(struct hmap *);
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void hmap_reserve(struct hmap *, size_t capacity);
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/* Insertion and deletion. */
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static inline void hmap_insert_fast(struct hmap *,
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struct hmap_node *, size_t hash);
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static inline void hmap_insert(struct hmap *, struct hmap_node *, size_t hash);
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static inline void hmap_remove(struct hmap *, struct hmap_node *);
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static inline void hmap_moved(struct hmap *,
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struct hmap_node *, struct hmap_node *);
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static inline void hmap_replace(struct hmap *, const struct hmap_node *old,
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struct hmap_node *new);
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/* Search. */
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#define HMAP_FOR_EACH_WITH_HASH(NODE, STRUCT, MEMBER, HASH, HMAP) \
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for ((NODE) = CONTAINER_OF(hmap_first_with_hash(HMAP, HASH), \
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STRUCT, MEMBER); \
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&(NODE)->MEMBER != NULL; \
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(NODE) = CONTAINER_OF(hmap_next_with_hash(&(NODE)->MEMBER), \
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STRUCT, MEMBER))
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static inline struct hmap_node *hmap_first_with_hash(const struct hmap *,
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size_t hash);
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static inline struct hmap_node *hmap_next_with_hash(const struct hmap_node *);
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/* Iteration.
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*
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* The _SAFE version is needed when NODE may be freed. It is not needed when
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* NODE may be removed from the hash map but its members remain accessible and
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* intact. */
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#define HMAP_FOR_EACH(NODE, STRUCT, MEMBER, HMAP) \
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for ((NODE) = CONTAINER_OF(hmap_first(HMAP), STRUCT, MEMBER); \
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&(NODE)->MEMBER != NULL; \
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(NODE) = CONTAINER_OF(hmap_next(HMAP, &(NODE)->MEMBER), \
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STRUCT, MEMBER))
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#define HMAP_FOR_EACH_SAFE(NODE, NEXT, STRUCT, MEMBER, HMAP) \
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for ((NODE) = CONTAINER_OF(hmap_first(HMAP), STRUCT, MEMBER); \
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(&(NODE)->MEMBER != NULL \
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? (NEXT) = CONTAINER_OF(hmap_next(HMAP, &(NODE)->MEMBER), \
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STRUCT, MEMBER), 1 \
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: 0); \
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(NODE) = (NEXT))
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static inline struct hmap_node *hmap_first(const struct hmap *);
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static inline struct hmap_node *hmap_next(const struct hmap *,
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const struct hmap_node *);
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/* Returns the number of nodes currently in 'hmap'. */
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static inline size_t
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hmap_count(const struct hmap *hmap)
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{
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return hmap->n;
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}
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/* Returns the maximum number of nodes that 'hmap' may hold before it should be
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* rehashed. */
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static inline size_t
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hmap_capacity(const struct hmap *hmap)
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{
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return hmap->mask * 2 + 1;
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}
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/* Returns true if 'hmap' currently contains no nodes,
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* false otherwise. */
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static inline bool
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hmap_is_empty(const struct hmap *hmap)
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{
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return hmap->n == 0;
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}
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/* Inserts 'node', with the given 'hash', into 'hmap'. 'hmap' is never
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* expanded automatically. */
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static inline void
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hmap_insert_fast(struct hmap *hmap, struct hmap_node *node, size_t hash)
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{
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struct hmap_node **bucket = &hmap->buckets[hash & hmap->mask];
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node->hash = hash;
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node->next = *bucket;
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*bucket = node;
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hmap->n++;
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}
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/* Inserts 'node', with the given 'hash', into 'hmap', and expands 'hmap' if
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* necessary to optimize search performance. */
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static inline void
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hmap_insert(struct hmap *hmap, struct hmap_node *node, size_t hash)
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{
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hmap_insert_fast(hmap, node, hash);
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if (hmap->n / 2 > hmap->mask) {
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hmap_expand(hmap);
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}
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}
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/* Removes 'node' from 'hmap'. Does not shrink the hash table; call
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* hmap_shrink() directly if desired. */
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static inline void
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hmap_remove(struct hmap *hmap, struct hmap_node *node)
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{
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struct hmap_node **bucket = &hmap->buckets[node->hash & hmap->mask];
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while (*bucket != node) {
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bucket = &(*bucket)->next;
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}
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*bucket = node->next;
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hmap->n--;
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}
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/* Adjusts 'hmap' to compensate for 'old_node' having moved position in memory
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* to 'node' (e.g. due to realloc()). */
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static inline void
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hmap_moved(struct hmap *hmap,
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struct hmap_node *old_node, struct hmap_node *node)
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{
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struct hmap_node **bucket = &hmap->buckets[node->hash & hmap->mask];
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while (*bucket != old_node) {
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bucket = &(*bucket)->next;
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}
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*bucket = node;
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}
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/* Puts 'new' in the position in 'hmap' currently occupied by 'old'. The 'new'
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* node must hash to the same value as 'old'. The client is responsible for
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* ensuring that the replacement does not violate any client-imposed
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* invariants (e.g. uniqueness of keys within a map).
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*
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* Afterward, 'old' is not part of 'hmap', and the client is responsible for
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* freeing it (if this is desirable). */
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static inline void
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hmap_replace(struct hmap *hmap,
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const struct hmap_node *old, struct hmap_node *new)
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{
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struct hmap_node **bucket = &hmap->buckets[old->hash & hmap->mask];
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while (*bucket != old) {
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bucket = &(*bucket)->next;
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}
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*bucket = new;
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new->hash = old->hash;
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new->next = old->next;
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}
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static inline struct hmap_node *
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hmap_next_with_hash__(const struct hmap_node *node, size_t hash)
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{
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while (node != NULL && node->hash != hash) {
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node = node->next;
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}
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return (struct hmap_node *) node;
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}
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/* Returns the first node in 'hmap' with the given 'hash', or a null pointer if
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* no nodes have that hash value. */
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static inline struct hmap_node *
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hmap_first_with_hash(const struct hmap *hmap, size_t hash)
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{
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return hmap_next_with_hash__(hmap->buckets[hash & hmap->mask], hash);
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}
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/* Returns the next node in the same hash map as 'node' with the same hash
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* value, or a null pointer if no more nodes have that hash value.
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*
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* If the hash map has been reallocated since 'node' was visited, some nodes
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* may be skipped; if new nodes with the same hash value have been added, they
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* will be skipped. (Removing 'node' from the hash map does not prevent
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* calling this function, since node->next is preserved, although freeing
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* 'node' of course does.) */
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static inline struct hmap_node *
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hmap_next_with_hash(const struct hmap_node *node)
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{
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return hmap_next_with_hash__(node->next, node->hash);
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}
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static inline struct hmap_node *
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hmap_next__(const struct hmap *hmap, size_t start)
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{
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size_t i;
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for (i = start; i <= hmap->mask; i++) {
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struct hmap_node *node = hmap->buckets[i];
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if (node) {
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return node;
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}
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}
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return NULL;
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}
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/* Returns the first node in 'hmap', in arbitrary order, or a null pointer if
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* 'hmap' is empty. */
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static inline struct hmap_node *
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hmap_first(const struct hmap *hmap)
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{
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return hmap_next__(hmap, 0);
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}
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/* Returns the next node in 'hmap' following 'node', in arbitrary order, or a
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* null pointer if 'node' is the last node in 'hmap'.
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*
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* If the hash map has been reallocated since 'node' was visited, some nodes
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* may be skipped or visited twice. (Removing 'node' from the hash map does
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* not prevent calling this function, since node->next is preserved, although
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* freeing 'node' of course does.) */
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static inline struct hmap_node *
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hmap_next(const struct hmap *hmap, const struct hmap_node *node)
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{
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return (node->next
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? node->next
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: hmap_next__(hmap, (node->hash & hmap->mask) + 1));
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}
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#endif /* hmap.h */
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