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Remove rtree support for 0 (NULL) keys.

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NULL can never actually be inserted in practice, and removing support
allows a branch to be removed from the fast path.
This commit is contained in:
Jason Evans 2017-02-05 02:50:59 -08:00
parent f5cf9b19c8
commit 650c070e10
3 changed files with 43 additions and 45 deletions
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58
include/jemalloc/internal/rtree_inlines.h
View File

@ -79,43 +79,41 @@ rtree_elm_write(rtree_elm_t *elm, const extent_t *extent) {
JEMALLOC_ALWAYS_INLINE rtree_elm_t *
rtree_elm_lookup(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
uintptr_t key, bool dependent, bool init_missing) {
assert(key != 0);
assert(!dependent || !init_missing);
if (likely(key != 0)) {
uintptr_t leafkey = rtree_leafkey(key);
uintptr_t leafkey = rtree_leafkey(key);
#define RTREE_CACHE_CHECK(i) do { \
if (likely(rtree_ctx->cache[i].leafkey == leafkey)) { \
rtree_elm_t *leaf = rtree_ctx->cache[i].leaf; \
if (likely(leaf != NULL)) { \
/* Reorder. */ \
memmove(&rtree_ctx->cache[1], \
&rtree_ctx->cache[0], \
sizeof(rtree_ctx_cache_elm_t) * i); \
rtree_ctx->cache[0].leafkey = leafkey; \
rtree_ctx->cache[0].leaf = leaf; \
if (likely(rtree_ctx->cache[i].leafkey == leafkey)) { \
rtree_elm_t *leaf = rtree_ctx->cache[i].leaf; \
if (likely(leaf != NULL)) { \
/* Reorder. */ \
memmove(&rtree_ctx->cache[1], \
&rtree_ctx->cache[0], \
sizeof(rtree_ctx_cache_elm_t) * i); \
rtree_ctx->cache[0].leafkey = leafkey; \
rtree_ctx->cache[0].leaf = leaf; \
\
uintptr_t subkey = rtree_subkey(key, \
RTREE_HEIGHT-1); \
return &leaf[subkey]; \
} \
uintptr_t subkey = rtree_subkey(key, \
RTREE_HEIGHT-1); \
return &leaf[subkey]; \
} \
} \
} while (0)
/* Check the MRU cache entry. */
RTREE_CACHE_CHECK(0);
/*
* Search the remaining cache elements, and on success move the
* matching element to the front. Unroll the first iteration to
* avoid calling memmove() (the compiler typically optimizes it
* into raw moves).
*/
if (RTREE_CTX_NCACHE > 1) {
RTREE_CACHE_CHECK(1);
}
for (unsigned i = 2; i < RTREE_CTX_NCACHE; i++) {
RTREE_CACHE_CHECK(i);
}
#undef RTREE_CACHE_CHECK
/* Check the MRU cache entry. */
RTREE_CACHE_CHECK(0);
/*
* Search the remaining cache elements, and on success move the matching
* element to the front. Unroll the first iteration to avoid calling
* memmove() (the compiler typically optimizes it into raw moves).
*/
if (RTREE_CTX_NCACHE > 1) {
RTREE_CACHE_CHECK(1);
}
for (unsigned i = 2; i < RTREE_CTX_NCACHE; i++) {
RTREE_CACHE_CHECK(i);
}
#undef RTREE_CACHE_CHECK
return rtree_elm_lookup_hard(tsdn, rtree, rtree_ctx, key, dependent,
init_missing);

18
src/rtree.c
View File

@ -170,17 +170,15 @@ rtree_elm_lookup_hard(tsdn_t *tsdn, rtree_t *rtree, rtree_ctx_t *rtree_ctx,
* node is a leaf, so it contains values rather than \
* child pointers. \
*/ \
if (likely(key != 0)) { \
if (RTREE_CTX_NCACHE > 1) { \
memmove(&rtree_ctx->cache[1], \
&rtree_ctx->cache[0], \
sizeof(rtree_ctx_cache_elm_t) * \
(RTREE_CTX_NCACHE-1)); \
} \
uintptr_t leafkey = rtree_leafkey(key); \
rtree_ctx->cache[0].leafkey = leafkey; \
rtree_ctx->cache[0].leaf = node; \
if (RTREE_CTX_NCACHE > 1) { \
memmove(&rtree_ctx->cache[1], \
&rtree_ctx->cache[0], \
sizeof(rtree_ctx_cache_elm_t) * \
(RTREE_CTX_NCACHE-1)); \
} \
uintptr_t leafkey = rtree_leafkey(key); \
rtree_ctx->cache[0].leafkey = leafkey; \
rtree_ctx->cache[0].leaf = node; \
uintptr_t subkey = rtree_subkey(key, level); \
return &node[subkey]; \
}

12
test/unit/rtree.c
View File

@ -40,7 +40,7 @@ TEST_BEGIN(test_rtree_read_empty) {
rtree_ctx_t rtree_ctx = RTREE_CTX_INITIALIZER;
test_rtree = &rtree;
assert_false(rtree_new(&rtree), "Unexpected rtree_new() failure");
assert_ptr_null(rtree_read(tsdn, &rtree, &rtree_ctx, 0, false),
assert_ptr_null(rtree_read(tsdn, &rtree, &rtree_ctx, PAGE, false),
"rtree_read() should return NULL for empty tree");
rtree_delete(tsdn, &rtree);
test_rtree = NULL;
@ -139,9 +139,10 @@ TEST_BEGIN(test_rtree_extrema) {
test_rtree = &rtree;
assert_false(rtree_new(&rtree), "Unexpected rtree_new() failure");
assert_false(rtree_write(tsdn, &rtree, &rtree_ctx, 0, &extent_a),
assert_false(rtree_write(tsdn, &rtree, &rtree_ctx, PAGE, &extent_a),
"Unexpected rtree_write() failure");
assert_ptr_eq(rtree_read(tsdn, &rtree, &rtree_ctx, 0, true), &extent_a,
assert_ptr_eq(rtree_read(tsdn, &rtree, &rtree_ctx, PAGE, true),
&extent_a,
"rtree_read() should return previously set value");
assert_false(rtree_write(tsdn, &rtree, &rtree_ctx, ~((uintptr_t)0),
@ -158,7 +159,8 @@ TEST_END
TEST_BEGIN(test_rtree_bits) {
tsdn_t *tsdn = tsdn_fetch();
uintptr_t keys[] = {0, 1, (((uintptr_t)1) << LG_PAGE) - 1};
uintptr_t keys[] = {PAGE, PAGE + 1,
PAGE + (((uintptr_t)1) << LG_PAGE) - 1};
extent_t extent;
rtree_t rtree;
@ -180,7 +182,7 @@ TEST_BEGIN(test_rtree_bits) {
"key=%#"FMTxPTR, i, j, keys[i], keys[j]);
}
assert_ptr_null(rtree_read(tsdn, &rtree, &rtree_ctx,
(((uintptr_t)1) << LG_PAGE), false),
(((uintptr_t)2) << LG_PAGE), false),
"Only leftmost rtree leaf should be set; i=%u", i);
rtree_clear(tsdn, &rtree, &rtree_ctx, keys[i]);
}