Function extent_recycle

app/redis-6.2.6/deps/jemalloc/src/extent.c:1060–1129

* Tries to satisfy the given allocation request by reusing one of the extents * in the given extents_t. */

 * in the given extents_t.
 */
static extent_t *
extent_recycle(tsdn_t *tsdn, arena_t *arena, extent_hooks_t **r_extent_hooks,
    extents_t *extents, void *new_addr, size_t size, size_t pad,
    size_t alignment, bool slab, szind_t szind, bool *zero, bool *commit,
    bool growing_retained) {
	witness_assert_depth_to_rank(tsdn_witness_tsdp_get(tsdn),
	    WITNESS_RANK_CORE, growing_retained ? 1 : 0);
	assert(new_addr == NULL || !slab);
	assert(pad == 0 || !slab);
	assert(!*zero || !slab);

	rtree_ctx_t rtree_ctx_fallback;
	rtree_ctx_t *rtree_ctx = tsdn_rtree_ctx(tsdn, &rtree_ctx_fallback);

	extent_t *extent = extent_recycle_extract(tsdn, arena, r_extent_hooks,
	    rtree_ctx, extents, new_addr, size, pad, alignment, slab,
	    growing_retained);
	if (extent == NULL) {
		return NULL;
	}

	extent = extent_recycle_split(tsdn, arena, r_extent_hooks, rtree_ctx,
	    extents, new_addr, size, pad, alignment, slab, szind, extent,
	    growing_retained);
	if (extent == NULL) {
		return NULL;
	}

	if (*commit && !extent_committed_get(extent)) {
		if (extent_commit_impl(tsdn, arena, r_extent_hooks, extent,
		    0, extent_size_get(extent), growing_retained)) {
			extent_record(tsdn, arena, r_extent_hooks, extents,
			    extent, growing_retained);
			return NULL;
		}
		extent_zeroed_set(extent, true);
	}

	if (extent_committed_get(extent)) {
		*commit = true;
	}
	if (extent_zeroed_get(extent)) {
		*zero = true;
	}

	if (pad != 0) {
		extent_addr_randomize(tsdn, extent, alignment);
	}
	assert(extent_state_get(extent) == extent_state_active);
	if (slab) {
		extent_slab_set(extent, slab);
		extent_interior_register(tsdn, rtree_ctx, extent, szind);
	}

	if (*zero) {
		void *addr = extent_base_get(extent);
		size_t size = extent_size_get(extent);
		if (!extent_zeroed_get(extent)) {