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Optimize zslUpdateScore() as asked in #5179.

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This commit is contained in:
antirez 2018-08-01 18:50:31 +02:00
parent 6dd0d6f7dd
commit 0b800c4332
1 changed files with 44 additions and 0 deletions
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44
src/t_zset.c
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@ -250,6 +250,49 @@ int zslDelete(zskiplist *zsl, double score, sds ele, zskiplistNode **node) {
* caller should take care of it.
*
* The function returns the updated element skiplist node pointer. */
zskiplistNode *zslUpdateScore(zskiplist *zsl, double curscore, sds ele, double newscore) {
zskiplistNode *update[ZSKIPLIST_MAXLEVEL], *x;
int i;
x = zsl->header;
for (i = zsl->level-1; i >= 0; i--) {
while (x->level[i].forward &&
(x->level[i].forward->score < curscore ||
(x->level[i].forward->score == curscore &&
sdscmp(x->level[i].forward->ele,ele) < 0)))
{
x = x->level[i].forward;
}
update[i] = x;
}
/* Jump to our element: note that this function assumes that the
* element with the matching score exists. */
x = x->level[0].forward;
serverAssert(x && curscore == x->score && sdscmp(x->ele,ele) == 0);
/* If the node, after the score update, would be still exactly
* at the same position, we can just update the score without
* actually removing and re-inserting the element in the skiplist. */
if ((x->backward == NULL || x->backward->score <= newscore) &&
(x->level[0].forward == NULL || x->level[0].forward->score >= newscore))
{
x->score = newscore;
return x;
}
/* No way to reuse the old node: we need to remove and insert a new
* one at a different place. */
zslDeleteNode(zsl, x, update);
zskiplistNode *newnode = zslInsert(zsl,newscore,x->ele);
/* We reused the old node x->ele SDS string, free the node now
* since zslInsert created a new one. */
x->ele = NULL;
zslFreeNode(x);
return newnode;
}
#if 0
zskiplistNode *zslUpdateScore(zskiplist *zsl, double curscore, sds ele, double newscore) {
zskiplistNode *node, *newnode;
serverAssert(zslDelete(zsl,curscore,ele,&node));
@ -260,6 +303,7 @@ zskiplistNode *zslUpdateScore(zskiplist *zsl, double curscore, sds ele, double n
zslFreeNode(node);
return newnode;
}
#endif
int zslValueGteMin(double value, zrangespec *spec) {
return spec->minex ? (value > spec->min) : (value >= spec->min);