Function replicationSetMaster

app/redis-6.2.6/src/replication.c:2613–2658

Set replication to the specified master address and port. */

/* Set replication to the specified master address and port. */
void replicationSetMaster(char *ip, int port) {
    int was_master = server.masterhost == NULL;

    sdsfree(server.masterhost);
    server.masterhost = NULL;
    if (server.master) {
        freeClient(server.master);
    }
    disconnectAllBlockedClients(); /* Clients blocked in master, now slave. */

    /* Setting masterhost only after the call to freeClient since it calls
     * replicationHandleMasterDisconnection which can trigger a re-connect
     * directly from within that call. */
    server.masterhost = sdsnew(ip);
    server.masterport = port;

    /* Update oom_score_adj */
    setOOMScoreAdj(-1);

    /* Force our slaves to resync with us as well. They may hopefully be able
     * to partially resync with us, but we can notify the replid change. */
    disconnectSlaves();
    cancelReplicationHandshake(0);
    /* Before destroying our master state, create a cached master using
     * our own parameters, to later PSYNC with the new master. */
    if (was_master) {
        replicationDiscardCachedMaster();
        replicationCacheMasterUsingMyself();
    }

    /* Fire the role change modules event. */
    moduleFireServerEvent(REDISMODULE_EVENT_REPLICATION_ROLE_CHANGED,
                          REDISMODULE_EVENT_REPLROLECHANGED_NOW_REPLICA,
                          NULL);

    /* Fire the master link modules event. */
    if (server.repl_state == REPL_STATE_CONNECTED)
        moduleFireServerEvent(REDISMODULE_EVENT_MASTER_LINK_CHANGE,
                              REDISMODULE_SUBEVENT_MASTER_LINK_DOWN,
                              NULL);

    server.repl_state = REPL_STATE_CONNECT;
    serverLog(LL_NOTICE,"Connecting to MASTER %s:%d",
        server.masterhost, server.masterport);
    connectWithMaster();
}

/* Cancel replication, setting the instance as a master itself. */
void replicationUnsetMaster(void) {