Function failoverCommand

app/redis-6.2.6/src/replication.c:3614–3719

* FAILOVER [TO [FORCE]] [ABORT] [TIMEOUT ] * * This command will coordinate a failover between the master and one * of its replicas. The happy path contains the following steps: * 1) The master will initiate a client pause write, to stop replication * traffic. * 2) The master will periodically check if any of its replicas has * consumed the entire replication stream

 * will attempt forever and must be manually aborted.
 */
void failoverCommand(client *c) {
    if (server.cluster_enabled) {
        addReplyError(c,"FAILOVER not allowed in cluster mode. "
                        "Use CLUSTER FAILOVER command instead.");
        return;
    }
    
    /* Handle special case for abort */
    if ((c->argc == 2) && !strcasecmp(c->argv[1]->ptr,"abort")) {
        if (server.failover_state == NO_FAILOVER) {
            addReplyError(c, "No failover in progress.");
            return;
        }

        abortFailover("Failover manually aborted");
        addReply(c,shared.ok);
        return;
    }

    long timeout_in_ms = 0;
    int force_flag = 0;
    long port = 0;
    char *host = NULL;

    /* Parse the command for syntax and arguments. */
    for (int j = 1; j < c->argc; j++) {
        if (!strcasecmp(c->argv[j]->ptr,"timeout") && (j + 1 < c->argc) &&
            timeout_in_ms == 0)
        {
            if (getLongFromObjectOrReply(c,c->argv[j + 1],
                        &timeout_in_ms,NULL) != C_OK) return;
            if (timeout_in_ms <= 0) {
                addReplyError(c,"FAILOVER timeout must be greater than 0");
                return;
            }
            j++;
        } else if (!strcasecmp(c->argv[j]->ptr,"to") && (j + 2 < c->argc) &&
            !host) 
        {
            if (getLongFromObjectOrReply(c,c->argv[j + 2],&port,NULL) != C_OK)
                return;
            host = c->argv[j + 1]->ptr;
            j += 2;
        } else if (!strcasecmp(c->argv[j]->ptr,"force") && !force_flag) {
            force_flag = 1;
        } else {
            addReplyErrorObject(c,shared.syntaxerr);
            return;
        }
    }

    if (server.failover_state != NO_FAILOVER) {
        addReplyError(c,"FAILOVER already in progress.");
        return;
    }

    if (server.masterhost) {
        addReplyError(c,"FAILOVER is not valid when server is a replica.");