/* Set replication to the specified master address and port. */void replicationSetMaster(char *ip, int port) {    sdsfree(server.masterhost);    server.masterhost = sdsnew(ip);    server.masterport = port;    if (server.master) freeClient(server.master);    disconnectAllBlockedClients(); /* Clients blocked in master, now slave. */    disconnectSlaves(); /* Force our slaves to resync with us as well. */    replicationDiscardCachedMaster(); /* Don‘t try a PSYNC. */    freeReplicationBacklog(); /* Don‘t allow our chained slaves to PSYNC. */    cancelReplicationHandshake();    server.repl_state = REPL_STATE_CONNECT;    server.master_repl_offset = 0;    server.repl_down_since = 0;}