bool
ckh_new(ckh_t *ckh, size_t minitems, ckh_hash_t *hash, ckh_keycomp_t *keycomp)
{
bool ret;
size_t mincells, usize;
unsigned lg_mincells;
assert(minitems > 0);
assert(hash != NULL);
assert(keycomp != NULL);
#ifdef CKH_COUNT
ckh->ngrows = 0;
ckh->nshrinks = 0;
ckh->nshrinkfails = 0;
ckh->ninserts = 0;
ckh->nrelocs = 0;
#endif
ckh->prn_state = 42; /* Value doesn't really matter. */
ckh->count = 0;
/*
* Find the minimum power of 2 that is large enough to fit aBaseCount
* entries. We are using (2+,2) cuckoo hashing, which has an expected
* maximum load factor of at least ~0.86, so 0.75 is a conservative load
* factor that will typically allow 2^aLgMinItems to fit without ever
* growing the table.
*/
assert(LG_CKH_BUCKET_CELLS > 0);
mincells = ((minitems + (3 - (minitems % 3))) / 3) << 2;
for (lg_mincells = LG_CKH_BUCKET_CELLS;
(ZU(1) << lg_mincells) < mincells;
lg_mincells++)
; /* Do nothing. */
ckh->lg_minbuckets = lg_mincells - LG_CKH_BUCKET_CELLS;
ckh->lg_curbuckets = lg_mincells - LG_CKH_BUCKET_CELLS;
ckh->hash = hash;
ckh->keycomp = keycomp;
usize = sa2u(sizeof(ckhc_t) << lg_mincells, CACHELINE, NULL);
if (usize == 0) {
ret = true;
goto RETURN;
}
ckh->tab = (ckhc_t *)ipalloc(usize, CACHELINE, true);
if (ckh->tab == NULL) {
ret = true;
goto RETURN;
}
#ifdef JEMALLOC_DEBUG
ckh->magic = CKH_MAGIC;
#endif
ret = false;
RETURN:
return (ret);
}
static bool
ckh_grow(ckh_t *ckh)
{
bool ret;
ckhc_t *tab, *ttab;
size_t lg_curcells;
unsigned lg_prevbuckets;
#ifdef CKH_COUNT
ckh->ngrows++;
#endif
/*
* It is possible (though unlikely, given well behaved hashes) that the
* table will have to be doubled more than once in order to create a
* usable table.
*/
lg_prevbuckets = ckh->lg_curbuckets;
lg_curcells = ckh->lg_curbuckets + LG_CKH_BUCKET_CELLS;
while (true) {
size_t usize;
lg_curcells++;
usize = sa2u(sizeof(ckhc_t) << lg_curcells, CACHELINE);
if (usize == 0) {
ret = true;
goto label_return;
}
tab = (ckhc_t *)ipalloc(usize, CACHELINE, true);
if (tab == NULL) {
ret = true;
goto label_return;
}
/* Swap in new table. */
ttab = ckh->tab;
ckh->tab = tab;
tab = ttab;
ckh->lg_curbuckets = lg_curcells - LG_CKH_BUCKET_CELLS;
if (ckh_rebuild(ckh, tab) == false) {
idalloc(tab);
break;
}
/* Rebuilding failed, so back out partially rebuilt table. */
idalloc(ckh->tab);
ckh->tab = tab;
ckh->lg_curbuckets = lg_prevbuckets;
}
ret = false;
label_return:
return (ret);
}
static void
ckh_shrink(ckh_t *ckh)
{
ckhc_t *tab, *ttab;
size_t lg_curcells, usize;
unsigned lg_prevbuckets;
/*
* It is possible (though unlikely, given well behaved hashes) that the
* table rebuild will fail.
*/
lg_prevbuckets = ckh->lg_curbuckets;
lg_curcells = ckh->lg_curbuckets + LG_CKH_BUCKET_CELLS - 1;
usize = sa2u(sizeof(ckhc_t) << lg_curcells, CACHELINE);
if (usize == 0)
return;
tab = (ckhc_t *)ipalloc(usize, CACHELINE, true);
if (tab == NULL) {
/*
* An OOM error isn't worth propagating, since it doesn't
* prevent this or future operations from proceeding.
*/
return;
}
/* Swap in new table. */
ttab = ckh->tab;
ckh->tab = tab;
tab = ttab;
ckh->lg_curbuckets = lg_curcells - LG_CKH_BUCKET_CELLS;
if (ckh_rebuild(ckh, tab) == false) {
idalloc(tab);
#ifdef CKH_COUNT
ckh->nshrinks++;
#endif
return;
}
/* Rebuilding failed, so back out partially rebuilt table. */
idalloc(ckh->tab);
ckh->tab = tab;
ckh->lg_curbuckets = lg_prevbuckets;
#ifdef CKH_COUNT
ckh->nshrinkfails++;
#endif
}