mirror of
https://github.com/openvswitch/ovs
synced 2025-10-17 14:28:02 +00:00
63e60b866f
This prepares for adding a new function that deals with a "struct hmap" moving, as opposed to a "struct hmap_node". Since there was only a single call to this in the whole tree, and its caller didn't have any callers of its own at all, also move this function from hmap.h to hmap.c.
319 lines
11 KiB
C
319 lines
11 KiB
C
/*
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* Copyright (c) 2008, 2009, 2010 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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#define HMAP_NODE_NULL ((struct hmap_node *) 1)
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/* Returns true if 'node' has been set to null by hmap_node_nullify() and has
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* not been un-nullified by being inserted into an hmap. */
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static inline bool
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hmap_node_is_null(const struct hmap_node *node)
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{
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return node->next == HMAP_NODE_NULL;
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}
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/* Marks 'node' with a distinctive value that can be tested with
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* hmap_node_is_null(). */
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static inline void
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hmap_node_nullify(struct hmap_node *node)
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{
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node->next = HMAP_NODE_NULL;
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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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void hmap_node_moved(struct hmap *, 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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*
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* HMAP_FOR_EACH_WITH_HASH iterates NODE over all of the nodes in HMAP that
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* have hash value equal to HASH. HMAP_FOR_EACH_IN_BUCKET iterates NODE over
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* all of the nodes in HMAP that would fall in the same bucket as HASH. STRUCT
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* and MEMBER must be the name of the struct that contains the 'struct
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* hmap_node' and the name of the 'struct hmap_node' member, respectively.
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*
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* These macros may be used interchangeably to search for a particular value in
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* an hmap, see, e.g. shash_find() for an example. Usually, using
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* HMAP_FOR_EACH_WITH_HASH provides an optimization, because comparing a hash
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* value is usually cheaper than comparing an entire hash map key. But for
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* simple hash map keys, it makes sense to use HMAP_FOR_EACH_IN_BUCKET because
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* it avoids doing two comparisons when a single simple comparison suffices.
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*
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* The loop should not change NODE to point to a different node or insert or
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* delete nodes in HMAP (unless it "break"s out of the loop to terminate
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* iteration).
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*
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* HASH is only evaluated once.
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*/
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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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#define HMAP_FOR_EACH_IN_BUCKET(NODE, STRUCT, MEMBER, HASH, HMAP) \
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for ((NODE) = CONTAINER_OF(hmap_first_in_bucket(HMAP, HASH), \
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STRUCT, MEMBER); \
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&(NODE)->MEMBER != NULL; \
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(NODE) = CONTAINER_OF(hmap_next_in_bucket(&(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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static inline struct hmap_node *hmap_first_in_bucket(const struct hmap *,
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size_t hash);
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static inline struct hmap_node *hmap_next_in_bucket(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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/* 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 first node in 'hmap' in the bucket in which the given 'hash'
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* would land, or a null pointer if that bucket is empty. */
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static inline struct hmap_node *
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hmap_first_in_bucket(const struct hmap *hmap, size_t hash)
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{
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return hmap->buckets[hash & hmap->mask];
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}
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/* Returns the next node in the same bucket as 'node', or a null pointer if
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* there are no more nodes in that bucket.
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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_in_bucket(const struct hmap_node *node)
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{
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return node->next;
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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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