Function moduleDelKeyIfEmpty

app/redis-6.2.6/src/module.c:577–598

This function is called in low-level API implementation functions in order * to check if the value associated with the key remained empty after an * operation that removed elements from an aggregate data type. * * If this happens, the key is deleted from the DB and the key object state * is set to the right one in order to be targeted again by write operations * possibly recreating the key i

 * The function returns 1 if the key value object is found empty and is
 * deleted, otherwise 0 is returned. */
int moduleDelKeyIfEmpty(RedisModuleKey *key) {
    if (!(key->mode & REDISMODULE_WRITE) || key->value == NULL) return 0;
    int isempty;
    robj *o = key->value;

    switch(o->type) {
    case OBJ_LIST: isempty = listTypeLength(o) == 0; break;
    case OBJ_SET: isempty = setTypeSize(o) == 0; break;
    case OBJ_ZSET: isempty = zsetLength(o) == 0; break;
    case OBJ_HASH: isempty = hashTypeLength(o) == 0; break;
    case OBJ_STREAM: isempty = streamLength(o) == 0; break;
    default: isempty = 0;
    }

    if (isempty) {
        dbDelete(key->db,key->key);
        key->value = NULL;
        return 1;
    } else {
        return 0;
    }
}

/* --------------------------------------------------------------------------
 * Service API exported to modules