X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Fhmap.h;h=2f4a302fa4180eaf7f214ff88204abf2299cec59;hb=2ad2eb042517b975d761d456cceb5c9325c4aaa7;hp=1809a91b5f85b5b1f4c97fcc5085f4d15bc5c9f9;hpb=00908dc27a4d93bd1c5bda3bcdc84ec351e9a09a;p=sliver-openvswitch.git diff --git a/lib/hmap.h b/lib/hmap.h index 1809a91b5..2f4a302fa 100644 --- a/lib/hmap.h +++ b/lib/hmap.h @@ -1,5 +1,5 @@ /* - * Copyright (c) 2008, 2009 Nicira Networks. + * Copyright (c) 2008, 2009, 2010 Nicira Networks. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -21,6 +21,10 @@ #include #include "util.h" +#ifdef __cplusplus +extern "C" { +#endif + /* A hash map node, to be embedded inside the data structure being mapped. */ struct hmap_node { size_t hash; /* Hash value. */ @@ -33,9 +37,27 @@ static inline size_t hmap_node_hash(const struct hmap_node *node) return node->hash; } +#define HMAP_NODE_NULL ((struct hmap_node *) 1) + +/* Returns true if 'node' has been set to null by hmap_node_nullify() and has + * not been un-nullified by being inserted into an hmap. */ +static inline bool +hmap_node_is_null(const struct hmap_node *node) +{ + return node->next == HMAP_NODE_NULL; +} + +/* Marks 'node' with a distinctive value that can be tested with + * hmap_node_is_null(). */ +static inline void +hmap_node_nullify(struct hmap_node *node) +{ + node->next = HMAP_NODE_NULL; +} + /* A hash map. */ struct hmap { - struct hmap_node **buckets; + struct hmap_node **buckets; /* Must point to 'one' iff 'mask' == 0. */ struct hmap_node *one; size_t mask; size_t n; @@ -48,6 +70,7 @@ struct hmap { void hmap_init(struct hmap *); void hmap_destroy(struct hmap *); void hmap_swap(struct hmap *a, struct hmap *b); +void hmap_moved(struct hmap *hmap); static inline size_t hmap_count(const struct hmap *); static inline bool hmap_is_empty(const struct hmap *); @@ -61,22 +84,51 @@ static inline void hmap_insert_fast(struct hmap *, struct hmap_node *, size_t hash); static inline void hmap_insert(struct hmap *, struct hmap_node *, size_t hash); static inline void hmap_remove(struct hmap *, struct hmap_node *); -static inline void hmap_moved(struct hmap *, - struct hmap_node *, struct hmap_node *); + +void hmap_node_moved(struct hmap *, struct hmap_node *, struct hmap_node *); static inline void hmap_replace(struct hmap *, const struct hmap_node *old, struct hmap_node *new); -/* Search. */ +/* Search. + * + * HMAP_FOR_EACH_WITH_HASH iterates NODE over all of the nodes in HMAP that + * have hash value equal to HASH. HMAP_FOR_EACH_IN_BUCKET iterates NODE over + * all of the nodes in HMAP that would fall in the same bucket as HASH. STRUCT + * and MEMBER must be the name of the struct that contains the 'struct + * hmap_node' and the name of the 'struct hmap_node' member, respectively. + * + * These macros may be used interchangeably to search for a particular value in + * an hmap, see, e.g. shash_find() for an example. Usually, using + * HMAP_FOR_EACH_WITH_HASH provides an optimization, because comparing a hash + * value is usually cheaper than comparing an entire hash map key. But for + * simple hash map keys, it makes sense to use HMAP_FOR_EACH_IN_BUCKET because + * it avoids doing two comparisons when a single simple comparison suffices. + * + * The loop should not change NODE to point to a different node or insert or + * delete nodes in HMAP (unless it "break"s out of the loop to terminate + * iteration). + * + * HASH is only evaluated once. + */ #define HMAP_FOR_EACH_WITH_HASH(NODE, STRUCT, MEMBER, HASH, HMAP) \ for ((NODE) = CONTAINER_OF(hmap_first_with_hash(HMAP, HASH), \ STRUCT, MEMBER); \ &(NODE)->MEMBER != NULL; \ (NODE) = CONTAINER_OF(hmap_next_with_hash(&(NODE)->MEMBER), \ STRUCT, MEMBER)) +#define HMAP_FOR_EACH_IN_BUCKET(NODE, STRUCT, MEMBER, HASH, HMAP) \ + for ((NODE) = CONTAINER_OF(hmap_first_in_bucket(HMAP, HASH), \ + STRUCT, MEMBER); \ + &(NODE)->MEMBER != NULL; \ + (NODE) = CONTAINER_OF(hmap_next_in_bucket(&(NODE)->MEMBER), \ + STRUCT, MEMBER)) static inline struct hmap_node *hmap_first_with_hash(const struct hmap *, size_t hash); static inline struct hmap_node *hmap_next_with_hash(const struct hmap_node *); +static inline struct hmap_node *hmap_first_in_bucket(const struct hmap *, + size_t hash); +static inline struct hmap_node *hmap_next_in_bucket(const struct hmap_node *); /* Iteration. * @@ -160,36 +212,24 @@ hmap_remove(struct hmap *hmap, struct hmap_node *node) hmap->n--; } -/* Adjusts 'hmap' to compensate for 'old_node' having moved position in memory - * to 'node' (e.g. due to realloc()). */ -static inline void -hmap_moved(struct hmap *hmap, - struct hmap_node *old_node, struct hmap_node *node) -{ - struct hmap_node **bucket = &hmap->buckets[node->hash & hmap->mask]; - while (*bucket != old_node) { - bucket = &(*bucket)->next; - } - *bucket = node; -} - -/* Puts 'new' in the position in 'hmap' currently occupied by 'old'. The 'new' - * node must hash to the same value as 'old'. The client is responsible for - * ensuring that the replacement does not violate any client-imposed - * invariants (e.g. uniqueness of keys within a map). +/* Puts 'new_node' in the position in 'hmap' currently occupied by 'old_node'. + * The 'new_node' must hash to the same value as 'old_node'. The client is + * responsible for ensuring that the replacement does not violate any + * client-imposed invariants (e.g. uniqueness of keys within a map). * - * Afterward, 'old' is not part of 'hmap', and the client is responsible for - * freeing it (if this is desirable). */ + * Afterward, 'old_node' is not part of 'hmap', and the client is responsible + * for freeing it (if this is desirable). */ static inline void hmap_replace(struct hmap *hmap, - const struct hmap_node *old, struct hmap_node *new) + const struct hmap_node *old_node, struct hmap_node *new_node) { - struct hmap_node **bucket = &hmap->buckets[old->hash & hmap->mask]; - while (*bucket != old) { + struct hmap_node **bucket = &hmap->buckets[old_node->hash & hmap->mask]; + while (*bucket != old_node) { bucket = &(*bucket)->next; } - *bucket = new; - new->hash = old->hash; + *bucket = new_node; + new_node->hash = old_node->hash; + new_node->next = old_node->next; } static inline struct hmap_node * @@ -209,6 +249,28 @@ hmap_first_with_hash(const struct hmap *hmap, size_t hash) return hmap_next_with_hash__(hmap->buckets[hash & hmap->mask], hash); } +/* Returns the first node in 'hmap' in the bucket in which the given 'hash' + * would land, or a null pointer if that bucket is empty. */ +static inline struct hmap_node * +hmap_first_in_bucket(const struct hmap *hmap, size_t hash) +{ + return hmap->buckets[hash & hmap->mask]; +} + +/* Returns the next node in the same bucket as 'node', or a null pointer if + * there are no more nodes in that bucket. + * + * If the hash map has been reallocated since 'node' was visited, some nodes + * may be skipped; if new nodes with the same hash value have been added, they + * will be skipped. (Removing 'node' from the hash map does not prevent + * calling this function, since node->next is preserved, although freeing + * 'node' of course does.) */ +static inline struct hmap_node * +hmap_next_in_bucket(const struct hmap_node *node) +{ + return node->next; +} + /* Returns the next node in the same hash map as 'node' with the same hash * value, or a null pointer if no more nodes have that hash value. * @@ -259,4 +321,8 @@ hmap_next(const struct hmap *hmap, const struct hmap_node *node) : hmap_next__(hmap, (node->hash & hmap->mask) + 1)); } +#ifdef __cplusplus +} +#endif + #endif /* hmap.h */