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hashmap: add disallow_rehash setting

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Teach hashmap to allow rehashes to be suppressed.
This is useful when hashmaps are accessed by multiple
threads.  It still requires the caller to properly
manage their locking.  This just prevents unexpected
rehashing during inserts and deletes.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jeff Hostetler
2017-03-22 17:14:22 +00:00
committed by Junio C Hamano
parent f75619bd6d
commit 0607e10009
2 changed files with 35 additions and 1 deletions
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12
hashmap.c
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@ -104,11 +104,19 @@ static inline unsigned int bucket(const struct hashmap *map,
return key->hash & (map->tablesize - 1);
}
int hashmap_bucket(const struct hashmap *map, unsigned int hash)
{
return hash & (map->tablesize - 1);
}
static void rehash(struct hashmap *map, unsigned int newsize)
{
unsigned int i, oldsize = map->tablesize;
struct hashmap_entry **oldtable = map->table;
if (map->disallow_rehash)
return;
alloc_table(map, newsize);
for (i = 0; i < oldsize; i++) {
struct hashmap_entry *e = oldtable[i];
@ -141,7 +149,9 @@ void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function,
size_t initial_size)
{
unsigned int size = HASHMAP_INITIAL_SIZE;
map->size = 0;
memset(map, 0, sizeof(*map));
map->cmpfn = equals_function ? equals_function : always_equal;
/* calculate initial table size and allocate the table */