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Add branch prediction hints to quicklist

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Actually makes a noticeable difference.

Branch hints were selected based on profiler hotspots.
This commit is contained in:
Matt Stancliff 2014-12-16 00:11:21 -05:00
parent 5f506b6d2b
commit bbbbfb1442
1 changed files with 21 additions and 10 deletions
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31
src/quicklist.c
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@ -77,6 +77,14 @@ static const size_t optimization_level[] = {4096, 8192, 16384, 32768, 65536};
(e)->sz = 0; \
} while (0)
#if __GNUC__ >= 3
#define likely(x) __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect(!!(x), 0)
#else
#define likely(x) (x)
#define unlikely(x) (x)
#endif
/* Create a new quicklist.
* Free with quicklistRelease(). */
quicklist *quicklistCreate(void) {
@ -405,7 +413,7 @@ static int _quicklistNodeSizeMeetsOptimizationRequirement(const size_t sz,
static int _quicklistNodeAllowInsert(const quicklistNode *node, const int fill,
const size_t sz) {
if (!node)
if (unlikely(!node))
return 0;
int ziplist_overhead;
@ -418,14 +426,14 @@ static int _quicklistNodeAllowInsert(const quicklistNode *node, const int fill,
/* size of forward offset */
if (sz < 64)
ziplist_overhead += 1;
else if (sz < 16384)
else if (likely(sz < 16384))
ziplist_overhead += 2;
else
ziplist_overhead += 5;
/* new_sz overestimates if 'sz' encodes to an integer type */
unsigned int new_sz = node->sz + sz + ziplist_overhead;
if (_quicklistNodeSizeMeetsOptimizationRequirement(new_sz, fill))
if (likely(_quicklistNodeSizeMeetsOptimizationRequirement(new_sz, fill)))
return 1;
else if (!sizeMeetsSafetyLimit(new_sz))
return 0;
@ -443,7 +451,7 @@ static int _quicklistNodeAllowMerge(const quicklistNode *a,
/* approximate merged ziplist size (- 11 to remove one ziplist
* header/trailer) */
unsigned int merge_sz = a->sz + b->sz - 11;
if (_quicklistNodeSizeMeetsOptimizationRequirement(merge_sz, fill))
if (likely(_quicklistNodeSizeMeetsOptimizationRequirement(merge_sz, fill)))
return 1;
else if (!sizeMeetsSafetyLimit(merge_sz))
return 0;
@ -464,7 +472,8 @@ static int _quicklistNodeAllowMerge(const quicklistNode *a,
* Returns 1 if new head created. */
int quicklistPushHead(quicklist *quicklist, void *value, size_t sz) {
quicklistNode *orig_head = quicklist->head;
if (_quicklistNodeAllowInsert(quicklist->head, quicklist->fill, sz)) {
if (likely(
_quicklistNodeAllowInsert(quicklist->head, quicklist->fill, sz))) {
quicklist->head->zl =
ziplistPush(quicklist->head->zl, value, sz, ZIPLIST_HEAD);
quicklistNodeUpdateSz(quicklist->head);
@ -486,7 +495,8 @@ int quicklistPushHead(quicklist *quicklist, void *value, size_t sz) {
* Returns 1 if new tail created. */
int quicklistPushTail(quicklist *quicklist, void *value, size_t sz) {
quicklistNode *orig_tail = quicklist->tail;
if (_quicklistNodeAllowInsert(quicklist->tail, quicklist->fill, sz)) {
if (likely(
_quicklistNodeAllowInsert(quicklist->tail, quicklist->fill, sz))) {
quicklist->tail->zl =
ziplistPush(quicklist->tail->zl, value, sz, ZIPLIST_TAIL);
quicklistNodeUpdateSz(quicklist->tail);
@ -649,8 +659,8 @@ void quicklistDelEntry(quicklistIter *iter, quicklistEntry *entry) {
int quicklistReplaceAtIndex(quicklist *quicklist, long index, void *data,
int sz) {
quicklistEntry entry;
if (quicklistIndex(quicklist, index, &entry)) {
// quicklistDecompressNode(entry.node);
if (likely(quicklistIndex(quicklist, index, &entry))) {
/* quicklistIndex provides an uncompressed node */
entry.node->zl = ziplistDelete(entry.node->zl, &entry.zi);
entry.node->zl = ziplistInsert(entry.node->zl, entry.zi, data, sz);
quicklistCompress(quicklist, entry.node);
@ -1223,7 +1233,7 @@ int quicklistIndex(const quicklist *quicklist, const long long idx,
if (index >= quicklist->count)
return 0;
while (n) {
while (likely(n)) {
if ((accum + n->count) > index) {
break;
} else {
@ -1253,7 +1263,8 @@ int quicklistIndex(const quicklist *quicklist, const long long idx,
quicklistDecompressNodeForUse(entry->node);
entry->zi = ziplistIndex(entry->node->zl, entry->offset);
ziplistGet(entry->zi, &entry->value, &entry->sz, &entry->longval);
// quicklistCompress(quicklist, entry->node);
/* The caller will use our result, so we don't re-compress here.
* The caller can recompress or delete the node as needed. */
return 1;
}