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hashmap: document memihash_cont, hashmap_disallow_rehash api

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Document memihash_cont() and hashmap_disallow_rehash()
in Documentation/technical/api-hashmap.txt.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff Hostetler 2017-03-23 13:47:02 +00:00 committed by Junio C Hamano
parent 0607e10009
commit 4f4458aafa
1 changed files with 22 additions and 0 deletions
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Documentation/technical/api-hashmap.txt
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@ -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 `cmpfn` stores the comparison function specified in `hashmap_init()`. In
advanced scenarios, it may be useful to change this, e.g. to switch between advanced scenarios, it may be useful to change this, e.g. to switch between
case-sensitive and case-insensitive lookup. case-sensitive and case-insensitive lookup.
+
When `disallow_rehash` is set, automatic rehashes are prevented during inserts
and deletes.
`struct hashmap_entry`:: `struct hashmap_entry`::
@ -57,6 +60,7 @@ Functions
`unsigned int strihash(const char *buf)`:: `unsigned int strihash(const char *buf)`::
`unsigned int memhash(const void *buf, size_t len)`:: `unsigned int memhash(const void *buf, size_t len)`::
`unsigned int memihash(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 Ready-to-use hash functions for strings, using the FNV-1 algorithm (see
http://www.isthe.com/chongo/tech/comp/fnv). http://www.isthe.com/chongo/tech/comp/fnv).
@ -65,6 +69,9 @@ Functions
`memihash` operate on arbitrary-length memory. `memihash` operate on arbitrary-length memory.
+ +
`strihash` and `memihash` are case insensitive versions. `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)`:: `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. 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_init(struct hashmap *map, struct hashmap_iter *iter)`::
`void *hashmap_iter_next(struct hashmap_iter *iter)`:: `void *hashmap_iter_next(struct hashmap_iter *iter)`::
`void *hashmap_iter_first(struct hashmap *map, struct hashmap_iter *iter)`:: `void *hashmap_iter_first(struct hashmap *map, struct hashmap_iter *iter)`::