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Spin adaptively in rtree_elm_acquire().

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This commit is contained in:
Jason Evans 2017-02-05 23:58:02 -08:00
parent de8a68e853
commit db7da56359
1 changed files with 11 additions and 10 deletions
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21
include/jemalloc/internal/rtree_inlines.h
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@ -153,21 +153,22 @@ rtree_read(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx, uintptr_t key,
JEMALLOC_INLINE rtree_elm_t *
rtree_elm_acquire(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key, bool dependent, bool init_missing) {
rtree_elm_t *elm;
elm = rtree_elm_lookup(tsdn, rtree, rtree_ctx, key, dependent,
init_missing);
rtree_elm_t *elm = rtree_elm_lookup(tsdn, rtree, rtree_ctx, key,
dependent, init_missing);
if (!dependent && elm == NULL) {
return NULL;
}
extent_t *extent;
void *s;
do {
extent = rtree_elm_read(elm, false);
spin_t spinner = SPIN_INITIALIZER;
while (true) {
extent_t *extent = rtree_elm_read(elm, false);
/* The least significant bit serves as a lock. */
s = (void *)((uintptr_t)extent | (uintptr_t)0x1);
} while (atomic_cas_p(&elm->pun, (void *)extent, s));
void *s = (void *)((uintptr_t)extent | (uintptr_t)0x1);
if (!atomic_cas_p(&elm->pun, (void *)extent, s)) {
break;
}
spin_adaptive(&spinner);
}
if (config_debug) {
rtree_elm_witness_acquire(tsdn, rtree, key, elm);