Function zsetDup

src/t_zset.cpp:1579–1622

This is a helper function for the COPY command. * Duplicate a sorted set object, with the guarantee that the returned object * has the same encoding as the original one. * * The resulting object always has refcount set to 1 */

 *
 * The resulting object always has refcount set to 1 */
robj *zsetDup(robj *o) {
    robj *zobj;
    zset *zs;
    zset *new_zs;

    serverAssert(o->type == OBJ_ZSET);

    /* Create a new sorted set object that have the same encoding as the original object's encoding */
    if (o->encoding == OBJ_ENCODING_ZIPLIST) {
        unsigned char *zl = (unsigned char*)ptrFromObj(o);
        size_t sz = ziplistBlobLen(zl);
        unsigned char *new_zl = (unsigned char*)zmalloc(sz);
        memcpy(new_zl, zl, sz);
        zobj = createObject(OBJ_ZSET, new_zl);
        zobj->encoding = OBJ_ENCODING_ZIPLIST;
    } else if (o->encoding == OBJ_ENCODING_SKIPLIST) {
        zobj = createZsetObject();
        zs = (zset*)ptrFromObj(o);
        new_zs = (zset*)ptrFromObj(zobj);
        dictExpand(new_zs->dict,dictSize(zs->dict));
        zskiplist *zsl = zs->zsl;
        zskiplistNode *ln;
        sds ele;
        long llen = zsetLength(o);

        /* We copy the skiplist elements from the greatest to the
         * smallest (that's trivial since the elements are already ordered in
         * the skiplist): this improves the load process, since the next loaded
         * element will always be the smaller, so adding to the skiplist
         * will always immediately stop at the head, making the insertion
         * O(1) instead of O(log(N)). */
        ln = zsl->tail;
        while (llen--) {
            ele = ln->ele;
            sds new_ele = sdsdup(ele);
            zskiplistNode *znode = zslInsert(new_zs->zsl,ln->score,new_ele);
            dictAdd(new_zs->dict,new_ele,&znode->score);
            ln = ln->backward;
        }
    } else {
        serverPanic("Unknown sorted set encoding");
    }
    return zobj;
}

struct zset_validate_data {
    long count;