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A trivial change makes the new implementation O(log(N)) instead of O(log(N))+O(M) when there are M repeated scores!

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antirez 2009-10-26 20:47:23 +01:00
parent 2b59cfdfe9
commit 9d60e6e466
1 changed files with 25 additions and 22 deletions
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47
redis.c
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@ -3855,7 +3855,10 @@ static void zslInsert(zskiplist *zsl, double score, robj *obj) {
x = zsl->header;
for (i = zsl->level-1; i >= 0; i--) {
while (x->forward[i] && x->forward[i]->score < score)
while (x->forward[i] &&
(x->forward[i]->score < score ||
(x->forward[i]->score == score &&
compareStringObjects(x->forward[i]->obj,obj) < 0)))
x = x->forward[i];
update[i] = x;
}
@ -3888,34 +3891,34 @@ static int zslDelete(zskiplist *zsl, double score, robj *obj) {
x = zsl->header;
for (i = zsl->level-1; i >= 0; i--) {
while (x->forward[i] && x->forward[i]->score < score)
while (x->forward[i] &&
(x->forward[i]->score < score ||
(x->forward[i]->score == score &&
compareStringObjects(x->forward[i]->obj,obj) < 0)))
x = x->forward[i];
update[i] = x;
}
/* We may have multiple elements with the same score, what we need
* is to find the element with both the right score and object. */
x = x->forward[0];
while(x->score == score) {
if (compareStringObjects(x->obj,obj) == 0) {
for (i = 0; i < zsl->level; i++) {
if (update[i]->forward[i] != x) break;
update[i]->forward[i] = x->forward[i];
}
if (x->forward[0]) {
x->forward[0]->backward = (x->backward == zsl->header) ?
NULL : x->backward;
} else {
zsl->tail = x->backward;
}
zslFreeNode(x);
while(zsl->level > 1 && zsl->header->forward[zsl->level-1] == NULL)
zsl->level--;
zsl->length--;
return 1;
} else {
x = x->forward[0];
if (!x) return 0; /* end of the list reached, not found */
if (compareStringObjects(x->obj,obj) == 0) {
for (i = 0; i < zsl->level; i++) {
if (update[i]->forward[i] != x) break;
update[i]->forward[i] = x->forward[i];
}
if (x->forward[0]) {
x->forward[0]->backward = (x->backward == zsl->header) ?
NULL : x->backward;
} else {
zsl->tail = x->backward;
}
zslFreeNode(x);
while(zsl->level > 1 && zsl->header->forward[zsl->level-1] == NULL)
zsl->level--;
zsl->length--;
return 1;
} else {
return 0; /* not found */
}
return 0; /* not found */
}