From 7e7e68018805b6566060d063d81f7ae5e5bb03e4 Mon Sep 17 00:00:00 2001 From: Christian Grothoff Date: Tue, 20 Oct 2009 07:21:23 +0000 Subject: [PATCH] fix bugs and add comments --- src/util/container_multihashmap.c | 206 ++++++++++++++++++++++++------ 1 file changed, 169 insertions(+), 37 deletions(-) diff --git a/src/util/container_multihashmap.c b/src/util/container_multihashmap.c index 41c11bf1b..ac1905201 100644 --- a/src/util/container_multihashmap.c +++ b/src/util/container_multihashmap.c @@ -29,43 +29,75 @@ #include "gnunet_crypto_lib.h" /** - * + * An entry in the hash map. */ struct MapEntry { + + /** + * Key for the entry. + */ GNUNET_HashCode key; + + /** + * Value of the entry. + */ void *value; + + /** + * If there is a hash collision, we create a linked list. + */ struct MapEntry *next; + }; /** - * + * Internal representation of the hash map. */ struct GNUNET_CONTAINER_MultiHashMap { + /** + * All of our buckets. + */ struct MapEntry **map; + /** + * Number of entries in the map. + */ unsigned int size; + /** + * Length of the "map" array. + */ unsigned int map_length; }; +/** + * Create a multi hash map. + * + * @param len initial size (map will grow as needed) + * @return NULL on error + */ struct GNUNET_CONTAINER_MultiHashMap * GNUNET_CONTAINER_multihashmap_create (unsigned int len) { struct GNUNET_CONTAINER_MultiHashMap *ret; ret = GNUNET_malloc (sizeof (struct GNUNET_CONTAINER_MultiHashMap)); - ret->size = 0; ret->map = GNUNET_malloc (len * sizeof (struct MapEntry *)); - memset (ret->map, 0, len * sizeof (struct MapEntry *)); ret->map_length = len; return ret; } +/** + * Destroy a hash map. Will not free any values + * stored in the hash map! + * + * @param map the map + */ void GNUNET_CONTAINER_multihashmap_destroy (struct GNUNET_CONTAINER_MultiHashMap *map) @@ -85,6 +117,14 @@ GNUNET_CONTAINER_multihashmap_destroy (struct GNUNET_CONTAINER_MultiHashMap GNUNET_free (map); } + +/** + * Compute the index of the bucket for the given key. + * + * @param m hash map for which to compute the index + * @param key what key should the index be computed for + * @return offset into the "map" array of "m" + */ static unsigned int idx_of (const struct GNUNET_CONTAINER_MultiHashMap *m, const GNUNET_HashCode * key) @@ -93,6 +133,12 @@ idx_of (const struct GNUNET_CONTAINER_MultiHashMap *m, } +/** + * Get the number of key-value pairs in the map. + * + * @param map the map + * @return the number of key value pairs + */ unsigned int GNUNET_CONTAINER_multihashmap_size (const struct GNUNET_CONTAINER_MultiHashMap *map) @@ -101,6 +147,16 @@ GNUNET_CONTAINER_multihashmap_size (const struct GNUNET_CONTAINER_MultiHashMap } +/** + * Given a key find a value in the map matching the key. + * + * @param map the map + * @param key what to look for + * @return NULL if no value was found; note that + * this is indistinguishable from values that just + * happen to be NULL; use "contains" to test for + * key-value pairs with value NULL + */ void * GNUNET_CONTAINER_multihashmap_get (const struct GNUNET_CONTAINER_MultiHashMap *map, const GNUNET_HashCode * key) @@ -118,11 +174,20 @@ GNUNET_CONTAINER_multihashmap_get (const struct GNUNET_CONTAINER_MultiHashMap } +/** + * Iterate over all entries in the map. + * + * @param map the map + * @param it function to call on each entry + * @param it_cls extra argument to it + * @return the number of key value pairs processed, + * GNUNET_SYSERR if it aborted iteration + */ int GNUNET_CONTAINER_multihashmap_iterate (const struct GNUNET_CONTAINER_MultiHashMap *map, GNUNET_CONTAINER_HashMapIterator it, - void *cls) + void *it_cls) { int count; unsigned int i; @@ -134,7 +199,8 @@ GNUNET_CONTAINER_multihashmap_iterate (const struct e = map->map[i]; while (e != NULL) { - if ((NULL != it) && (GNUNET_OK != it (cls, &e->key, e->value))) + if ( (NULL != it) && + (GNUNET_OK != it (it_cls, &e->key, e->value)) ) return GNUNET_SYSERR; count++; e = e->next; @@ -144,6 +210,17 @@ GNUNET_CONTAINER_multihashmap_iterate (const struct } +/** + * Remove the given key-value pair from the map. Note that if the + * key-value pair is in the map multiple times, only one of the pairs + * will be removed. + * + * @param map the map + * @param key key of the key-value pair + * @param value value of the key-value pair + * @return GNUNET_YES on success, GNUNET_NO if the key-value pair + * is not in the map + */ int GNUNET_CONTAINER_multihashmap_remove (struct GNUNET_CONTAINER_MultiHashMap *map, const GNUNET_HashCode * key, @@ -158,8 +235,8 @@ GNUNET_CONTAINER_multihashmap_remove (struct GNUNET_CONTAINER_MultiHashMap e = map->map[i]; while (e != NULL) { - if ((0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode))) && - (value == e->value)) + if ( (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode))) && + (value == e->value)) { if (p == NULL) map->map[i] = e->next; @@ -176,6 +253,14 @@ GNUNET_CONTAINER_multihashmap_remove (struct GNUNET_CONTAINER_MultiHashMap } +/** + * Remove all entries for the given key from the map. + * Note that the values would not be "freed". + * + * @param map the map + * @param key identifies values to be removed + * @return number of values removed + */ int GNUNET_CONTAINER_multihashmap_remove_all (struct GNUNET_CONTAINER_MultiHashMap *map, const GNUNET_HashCode * key) @@ -215,16 +300,23 @@ GNUNET_CONTAINER_multihashmap_remove_all (struct GNUNET_CONTAINER_MultiHashMap } +/** + * Check if the map contains any value under the given + * key (including values that are NULL). + * + * @param map the map + * @param key the key to test if a value exists for it + * @return GNUNET_YES if such a value exists, + * GNUNET_NO if not + */ int GNUNET_CONTAINER_multihashmap_contains (const struct GNUNET_CONTAINER_MultiHashMap *map, const GNUNET_HashCode * key) { struct MapEntry *e; - unsigned int i; - i = idx_of (map, key); - e = map->map[i]; + e = map->map[idx_of (map, key)]; while (e != NULL) { if (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode))) @@ -235,32 +327,54 @@ GNUNET_CONTAINER_multihashmap_contains (const struct } +/** + * Grow the given map to a more appropriate size. + * + * @param map the hash map to grow + */ static void grow (struct GNUNET_CONTAINER_MultiHashMap *map) { - struct MapEntry **old; + struct MapEntry **old_map; + struct MapEntry **new_map; struct MapEntry *e; + unsigned int old_len; + unsigned int new_len; + unsigned int idx; unsigned int i; - unsigned int l; - - old = map->map; - l = map->map_length; - map->map_length *= 2; - map->map = GNUNET_malloc (sizeof (struct MapEntry *) * map->map_length); - memset (map->map, 0, sizeof (struct MapEntry *) * map->map_length); - for (i = 0; i < l; i++) + + old_map = map->map; + old_len = map->map_length; + new_len = old_len * 2; + new_map = GNUNET_malloc (sizeof (struct MapEntry *) * new_len); + map->map_length = new_len; + map->map = new_map; + for (i = 0; i < old_len; i++) { - while (NULL != (e = old[i])) + while (NULL != (e = old_map[i])) { - old[i] = e->next; - e->next = map->map[idx_of (map, &e->key)]; - map->map[idx_of (map, &e->key)] = e; + old_map[i] = e->next; + idx = idx_of (map, &e->key); + e->next = new_map[idx]; + new_map[idx] = e; } } - GNUNET_free (old); + GNUNET_free (old_map); } +/** + * Store a key-value pair in the map. + * + * @param map the map + * @param key key to use + * @param value value to use + * @param opt options for put + * @return GNUNET_OK on success, + * GNUNET_NO if a value was replaced (with REPLACE) + * GNUNET_SYSERR if UNIQUE_ONLY was the option and the + * value already exists + */ int GNUNET_CONTAINER_multihashmap_put (struct GNUNET_CONTAINER_MultiHashMap *map, const GNUNET_HashCode * key, @@ -272,14 +386,13 @@ GNUNET_CONTAINER_multihashmap_put (struct GNUNET_CONTAINER_MultiHashMap *map, unsigned int i; i = idx_of (map, key); - if ((opt != GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE) && - (opt != GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST)) + if ( (opt != GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE) && + (opt != GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST) ) { e = map->map[i]; while (e != NULL) { - if ((0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode))) && - (value == e->value)) + if (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode))) { if (opt == GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY) return GNUNET_SYSERR; @@ -289,7 +402,7 @@ GNUNET_CONTAINER_multihashmap_put (struct GNUNET_CONTAINER_MultiHashMap *map, e = e->next; } } - if (map->size / 3 > map->map_length / 4) + if (map->size / 3 >= map->map_length / 4) grow (map); e = GNUNET_malloc (sizeof (struct MapEntry)); e->key = *key; @@ -301,12 +414,22 @@ GNUNET_CONTAINER_multihashmap_put (struct GNUNET_CONTAINER_MultiHashMap *map, } +/** + * Iterate over all entries in the map that match a particular key. + * + * @param map the map + * @param key key that the entries must correspond to + * @param it function to call on each entry + * @param it_cls extra argument to it + * @return the number of key value pairs processed, + * GNUNET_SYSERR if it aborted iteration + */ int GNUNET_CONTAINER_multihashmap_get_multiple (const struct GNUNET_CONTAINER_MultiHashMap *map, const GNUNET_HashCode * key, GNUNET_CONTAINER_HashMapIterator - it, void *cls) + it, void *it_cls) { int count; struct MapEntry *e; @@ -317,7 +440,8 @@ GNUNET_CONTAINER_multihashmap_get_multiple (const struct { if (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode))) { - if ((it != NULL) && (GNUNET_OK != it (&e->key, e->value, cls))) + if ( (it != NULL) && + (GNUNET_OK != it (it_cls, &e->key, e->value)) ) return GNUNET_SYSERR; count++; } @@ -327,26 +451,34 @@ GNUNET_CONTAINER_multihashmap_get_multiple (const struct } +/** + * Returns the stored value of a random non-null entry in the hash + * table. Returns only the first value, does not go inside bucket + * linked list (yet). Runs with a worst case time of N, so it's not + * efficient in any way shape or form!!!!. + * + * @param map the map + * @return value associated with a random key + */ void * GNUNET_CONTAINER_multihashmap_get_random (const struct GNUNET_CONTAINER_MultiHashMap *map) { unsigned int rand; struct MapEntry *e; - e = NULL; if (map->size == 0) return NULL; - - while (e == NULL) + while (1) { rand = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, map->map_length); - e = map->map[rand]; + if (NULL != (e = map->map[rand])) + return e->value; } - return e->value; } + /* end of container_multihashmap.c */ -- 2.25.1