Function shiftReplicationId

src/replication.cpp:2287–2299

Use the current replication ID / offset as secondary replication * ID, and change the current one in order to start a new history. * This should be used when an instance is switched from replica to master * so that it can serve PSYNC requests performed using the master * replication ID. */

 * so that it can serve PSYNC requests performed using the master
 * replication ID. */
void shiftReplicationId(void) {
    memcpy(g_pserver->replid2,g_pserver->replid,sizeof(g_pserver->replid));
    /* We set the second replid offset to the master offset + 1, since
     * the replica will ask for the first byte it has not yet received, so
     * we need to add one to the offset: for example if, as a replica, we are
     * sure we have the same history as the master for 50 bytes, after we
     * are turned into a master, we can accept a PSYNC request with offset
     * 51, since the replica asking has the same history up to the 50th
     * byte, and is asking for the new bytes starting at offset 51. */
    g_pserver->second_replid_offset = g_pserver->master_repl_offset+1;
    changeReplicationId();
    serverLog(LL_WARNING,"Setting secondary replication ID to %s, valid up to offset: %lld. New replication ID is %s", g_pserver->replid2, g_pserver->second_replid_offset, g_pserver->replid);
}

/* ----------------------------------- SLAVE -------------------------------- */