Function extent_split_impl

deps/memkind/src/jemalloc/src/extent.c:1724–1797

#endif

static extent_t *
extent_split_impl(tsdn_t *tsdn, arena_t *arena,
    extent_hooks_t **r_extent_hooks, extent_t *extent, size_t size_a,
    szind_t szind_a, bool slab_a, size_t size_b, szind_t szind_b, bool slab_b,
    bool growing_retained) {
	assert(extent_size_get(extent) == size_a + size_b);
	witness_assert_depth_to_rank(tsdn_witness_tsdp_get(tsdn),
	    WITNESS_RANK_CORE, growing_retained ? 1 : 0);

	extent_hooks_assure_initialized(arena, r_extent_hooks);

	if ((*r_extent_hooks)->split == NULL) {
		return NULL;
	}

	extent_t *trail = extent_alloc(tsdn, arena);
	if (trail == NULL) {
		goto label_error_a;
	}

	extent_init(trail, arena, (void *)((uintptr_t)extent_base_get(extent) +
	    size_a), size_b, slab_b, szind_b, extent_sn_get(extent),
	    extent_state_get(extent), extent_zeroed_get(extent),
	    extent_committed_get(extent));

	rtree_ctx_t rtree_ctx_fallback;
	rtree_ctx_t *rtree_ctx = tsdn_rtree_ctx(tsdn, &rtree_ctx_fallback);
	rtree_leaf_elm_t *lead_elm_a, *lead_elm_b;
	{
		extent_t lead;

		extent_init(&lead, arena, extent_addr_get(extent), size_a,
		    slab_a, szind_a, extent_sn_get(extent),
		    extent_state_get(extent), extent_zeroed_get(extent),
		    extent_committed_get(extent));

		extent_rtree_leaf_elms_lookup(tsdn, rtree_ctx, &lead, false,
		    true, &lead_elm_a, &lead_elm_b);
	}
	rtree_leaf_elm_t *trail_elm_a, *trail_elm_b;
	extent_rtree_leaf_elms_lookup(tsdn, rtree_ctx, trail, false, true,
	    &trail_elm_a, &trail_elm_b);

	if (lead_elm_a == NULL || lead_elm_b == NULL || trail_elm_a == NULL
	    || trail_elm_b == NULL) {
		goto label_error_b;
	}

	extent_lock2(tsdn, extent, trail);

	if ((*r_extent_hooks)->split(*r_extent_hooks, extent_base_get(extent),
	    size_a + size_b, size_a, size_b, extent_committed_get(extent),
	    arena_ind_get(arena))) {
		goto label_error_c;
	}

	extent_size_set(extent, size_a);
	extent_szind_set(extent, szind_a);