Function syncWithMaster

src/replication.cpp:3428–3804

This handler fires when the non blocking connect was able to * establish a connection with the master. */

/* This handler fires when the non blocking connect was able to
 * establish a connection with the master. */
void syncWithMaster(connection *conn) {
    serverAssert(GlobalLocksAcquired());
    char tmpfile[256] = {0}, *err = NULL;
    int dfd = -1, maxtries = 5;
    int psync_result;

    redisMaster *mi = (redisMaster*)connGetPrivateData(conn);
    if (mi == nullptr) {
        // We're about to be closed, bail
        return;
    }

    /* If this event fired after the user turned the instance into a master
     * with SLAVEOF NO ONE we must just return ASAP. */
    if (mi->repl_state == REPL_STATE_NONE) {
        connClose(conn);
        return;
    }

    /* Check for errors in the socket: after a non blocking connect() we
     * may find that the socket is in error state. */
    if (connGetState(conn) != CONN_STATE_CONNECTED) {
        serverLog(LL_WARNING,"Error condition on socket for SYNC: %s",
                connGetLastError(conn));
        goto error;
    }

retry_connect:
    /* Send a PING to check the master is able to reply without errors. */
    if (mi->repl_state == REPL_STATE_CONNECTING || mi->repl_state == REPL_STATE_RETRY_NOREPLPING) {
        serverLog(LL_NOTICE,"Non blocking connect for SYNC fired the event.");
        /* Delete the writable event so that the readable event remains
         * registered and we can wait for the PONG reply. */
        connSetReadHandler(conn, syncWithMaster);
        connSetWriteHandler(conn, NULL);
        /* Send the PING, don't check for errors at all, we have the timeout
         * that will take care about this. */
        err = sendCommand(conn,mi->repl_state == REPL_STATE_RETRY_NOREPLPING ? "PING" : "REPLPING",NULL);
        if (err) goto write_error;
        mi->repl_state = REPL_STATE_RECEIVE_PING_REPLY;
        return;
    }

    /* Receive the PONG command. */
    if (mi->repl_state == REPL_STATE_RECEIVE_PING_REPLY) {
        err = receiveSynchronousResponse(mi, conn);

        /* We accept only two replies as valid, a positive +PONG reply
         * (we just check for "+") or an authentication error.
         * Note that older versions of Redis replied with "operation not
         * permitted" instead of using a proper error code, so we test
         * both. */
        if (strncmp(err,"-ERR unknown command",20) == 0) {
            serverLog(LL_NOTICE,"Master does not support REPLPING, sending PING instead...");
            mi->repl_state = REPL_STATE_RETRY_NOREPLPING;
            sdsfree(err);
            err = NULL;
            goto retry_connect;