Function zslDeleteRangeByRank

src/t_zset.cpp:443–469

Delete all the elements with rank between start and end from the skiplist. * Start and end are inclusive. Note that start and end need to be 1-based */

/* Delete all the elements with rank between start and end from the skiplist.
 * Start and end are inclusive. Note that start and end need to be 1-based */
unsigned long zslDeleteRangeByRank(zskiplist *zsl, unsigned int start, unsigned int end, dict *dict) {
    zskiplistNode *update[ZSKIPLIST_MAXLEVEL], *x;
    unsigned long traversed = 0, removed = 0;
    int i;

    x = zsl->header;
    for (i = zsl->level-1; i >= 0; i--) {
        while (x->level(i)->forward && (traversed + x->level(i)->span) < start) {
            traversed += x->level(i)->span;
            x = x->level(i)->forward;
        }
        update[i] = x;
    }

    traversed++;
    x = x->level(0)->forward;
    while (x && traversed <= end) {
        zskiplistNode *next = x->level(0)->forward;
        zslDeleteNode(zsl,x,update);
        dictDelete(dict,x->ele);
        zslFreeNode(x);
        removed++;
        traversed++;
        x = next;
    }
    return removed;
}

/* Find the rank for an element by both score and key.
 * Returns 0 when the element cannot be found, rank otherwise.