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Diffstat (limited to 'Documentation/technical/api-hashmap.txt')
| -rw-r--r-- | Documentation/technical/api-hashmap.txt | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/Documentation/technical/api-hashmap.txt b/Documentation/technical/api-hashmap.txt index a3f020cd9e..ccc634bbd7 100644 --- a/Documentation/technical/api-hashmap.txt +++ b/Documentation/technical/api-hashmap.txt @@ -21,6 +21,9 @@ that the hashmap is initialized. It may also be useful for statistical purposes `cmpfn` stores the comparison function specified in `hashmap_init()`. In advanced scenarios, it may be useful to change this, e.g. to switch between case-sensitive and case-insensitive lookup. ++ +When `disallow_rehash` is set, automatic rehashes are prevented during inserts +and deletes. `struct hashmap_entry`:: @@ -57,6 +60,7 @@ Functions `unsigned int strihash(const char *buf)`:: `unsigned int memhash(const void *buf, size_t len)`:: `unsigned int memihash(const void *buf, size_t len)`:: +`unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len)`:: Ready-to-use hash functions for strings, using the FNV-1 algorithm (see http://www.isthe.com/chongo/tech/comp/fnv). @@ -65,6 +69,9 @@ Functions `memihash` operate on arbitrary-length memory. + `strihash` and `memihash` are case insensitive versions. ++ +`memihash_cont` is a variant of `memihash` that allows a computation to be +continued with another chunk of data. `unsigned int sha1hash(const unsigned char *sha1)`:: @@ -184,6 +191,21 @@ passed to `hashmap_cmp_fn` to decide whether the entry matches the key. + Returns the removed entry, or NULL if not found. +`void hashmap_disallow_rehash(struct hashmap *map, unsigned value)`:: + + Disallow/allow automatic rehashing of the hashmap during inserts + and deletes. ++ +This is useful if the caller knows that the hashmap will be accessed +by multiple threads. ++ +The caller is still responsible for any necessary locking; this simply +prevents unexpected rehashing. The caller is also responsible for properly +sizing the initial hashmap to ensure good performance. ++ +A call to allow rehashing does not force a rehash; that might happen +with the next insert or delete. + `void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter)`:: `void *hashmap_iter_next(struct hashmap_iter *iter)`:: `void *hashmap_iter_first(struct hashmap *map, struct hashmap_iter *iter)`:: |