Function zslUpdateScore

src/t_zset.cpp:259–301

Update the score of an element inside the sorted set skiplist. * Note that the element must exist and must match 'score'. * This function does not update the score in the hash table side, the * caller should take care of it. * * Note that this function attempts to just update the node, in case after * the score update, the node would be exactly at the same position. * Otherwise the skiplist

 *
 * 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;

    /* We need to seek to element to update to start: this is useful anyway,
     * we'll have to update or remove it. */
    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;
}

int zslValueGteMin(double value, zrangespec *spec) {
    return spec->minex ? (value > spec->min) : (value >= spec->min);