Function replicationResurrectCachedMaster

app/redis-6.2.6/src/replication.c:2991–3022

Turn the cached master into the current master, using the file descriptor * passed as argument as the socket for the new master. * * This function is called when successfully setup a partial resynchronization * so the stream of data that we'll receive will start from were this * master left. */

 * so the stream of data that we'll receive will start from were this
 * master left. */
void replicationResurrectCachedMaster(connection *conn) {
    server.master = server.cached_master;
    server.cached_master = NULL;
    server.master->conn = conn;
    connSetPrivateData(server.master->conn, server.master);
    server.master->flags &= ~(CLIENT_CLOSE_AFTER_REPLY|CLIENT_CLOSE_ASAP);
    server.master->authenticated = 1;
    server.master->lastinteraction = server.unixtime;
    server.repl_state = REPL_STATE_CONNECTED;
    server.repl_down_since = 0;

    /* Fire the master link modules event. */
    moduleFireServerEvent(REDISMODULE_EVENT_MASTER_LINK_CHANGE,
                          REDISMODULE_SUBEVENT_MASTER_LINK_UP,
                          NULL);

    /* Re-add to the list of clients. */
    linkClient(server.master);
    if (connSetReadHandler(server.master->conn, readQueryFromClient)) {
        serverLog(LL_WARNING,"Error resurrecting the cached master, impossible to add the readable handler: %s", strerror(errno));
        freeClientAsync(server.master); /* Close ASAP. */
    }

    /* We may also need to install the write handler as well if there is
     * pending data in the write buffers. */
    if (clientHasPendingReplies(server.master)) {
        if (connSetWriteHandler(server.master->conn, sendReplyToClient)) {
            serverLog(LL_WARNING,"Error resurrecting the cached master, impossible to add the writable handler: %s", strerror(errno));
            freeClientAsync(server.master); /* Close ASAP. */
        }
    }
}

/* ------------------------- MIN-SLAVES-TO-WRITE  --------------------------- */