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Refactor/fix arenas manipulation.

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Abstract arenas access to use arena_get() (or a0get() where appropriate)
rather than directly reading e.g. arenas[ind].  Prior to the addition of
the arenas.extend mallctl, the worst possible outcome of directly
accessing arenas was a stale read, but arenas.extend may allocate and
assign a new array to arenas.

Add a tsd-based arenas_cache, which amortizes arenas reads.  This
introduces some subtle bootstrapping issues, with tsd_boot() now being
split into tsd_boot[01]() to support tsd wrapper allocation
bootstrapping, as well as an arenas_cache_bypass tsd variable which
dynamically terminates allocation of arenas_cache itself.

Promote a0malloc(), a0calloc(), and a0free() to be generally useful for
internal allocation, and use them in several places (more may be
appropriate).

Abstract arena->nthreads management and fix a missing decrement during
thread destruction (recent tsd refactoring left arenas_cleanup()
unused).

Change arena_choose() to propagate OOM, and handle OOM in all callers.
This is important for providing consistent allocation behavior when the
MALLOCX_ARENA() flag is being used.  Prior to this fix, it was possible
for an OOM to result in allocation silently allocating from a different
arena than the one specified.
This commit is contained in:
Jason Evans 2014-10-07 23:14:57 -07:00
parent bf40641c5c
commit 8bb3198f72
13 changed files with 745 additions and 352 deletions
Download patch file Download diff file Expand all files Collapse all files

14
src/tcache.c
View file

@ -245,6 +245,14 @@ tcache_arena_associate(tcache_t *tcache, arena_t *arena)
tcache->arena = arena;
}
void
tcache_arena_reassociate(tcache_t *tcache, arena_t *arena)
{
tcache_arena_dissociate(tcache);
tcache_arena_associate(tcache, arena);
}
void
tcache_arena_dissociate(tcache_t *tcache)
{
@ -261,13 +269,17 @@ tcache_arena_dissociate(tcache_t *tcache)
tcache_t *
tcache_get_hard(tsd_t *tsd)
{
arena_t *arena;
if (!tcache_enabled_get()) {
if (tsd_nominal(tsd))
tcache_enabled_set(false); /* Memoize. */
return (NULL);
}
return (tcache_create(choose_arena(tsd, NULL)));
arena = arena_choose(tsd, NULL);
if (unlikely(arena == NULL))
return (NULL);
return (tcache_create(arena));
}
tcache_t *