Function xreadGetKeys

app/redis-6.2.6/src/db.c:1870–1910

XREAD [BLOCK ] [COUNT ] [GROUP ] * STREAMS key_1 key_2 ... key_N ID_1 ID_2 ... ID_N */

/* XREAD [BLOCK <milliseconds>] [COUNT <count>] [GROUP <groupname> <ttl>]
 *       STREAMS key_1 key_2 ... key_N ID_1 ID_2 ... ID_N */
int xreadGetKeys(struct redisCommand *cmd, robj **argv, int argc, getKeysResult *result) {
    int i, num = 0, *keys;
    UNUSED(cmd);

    /* We need to parse the options of the command in order to seek the first
     * "STREAMS" string which is actually the option. This is needed because
     * "STREAMS" could also be the name of the consumer group and even the
     * name of the stream key. */
    int streams_pos = -1;
    for (i = 1; i < argc; i++) {
        char *arg = argv[i]->ptr;
        if (!strcasecmp(arg, "block")) {
            i++; /* Skip option argument. */
        } else if (!strcasecmp(arg, "count")) {
            i++; /* Skip option argument. */
        } else if (!strcasecmp(arg, "group")) {
            i += 2; /* Skip option argument. */
        } else if (!strcasecmp(arg, "noack")) {
            /* Nothing to do. */
        } else if (!strcasecmp(arg, "streams")) {
            streams_pos = i;
            break;
        } else {
            break; /* Syntax error. */
        }
    }
    if (streams_pos != -1) num = argc - streams_pos - 1;

    /* Syntax error. */
    if (streams_pos == -1 || num == 0 || num % 2 != 0) {
        result->numkeys = 0;
        return 0;
    }
    num /= 2; /* We have half the keys as there are arguments because
                 there are also the IDs, one per key. */

    keys = getKeysPrepareResult(result, num);
    for (i = streams_pos+1; i < argc-num; i++) keys[i-streams_pos-1] = i;
    result->numkeys = num;
    return num;
}

/* Slot to Key API. This is used by Redis Cluster in order to obtain in
 * a fast way a key that belongs to a specified hash slot. This is useful