Function clusterHandleConfigEpochCollision

app/redis-6.2.6/src/cluster.c:1167–1182

This function is called when this node is a master, and we receive from * another master a configuration epoch that is equal to our configuration * epoch. * * BACKGROUND * * It is not possible that different slaves get the same config * epoch during a failover election, because the slaves need to get voted * by a majority. However when we perform a manual resharding of the cluster * the n

 * end with a different configuration epoch.
 */
void clusterHandleConfigEpochCollision(clusterNode *sender) {
    /* Prerequisites: nodes have the same configEpoch and are both masters. */
    if (sender->configEpoch != myself->configEpoch ||
        !nodeIsMaster(sender) || !nodeIsMaster(myself)) return;
    /* Don't act if the colliding node has a smaller Node ID. */
    if (memcmp(sender->name,myself->name,CLUSTER_NAMELEN) <= 0) return;
    /* Get the next ID available at the best of this node knowledge. */
    server.cluster->currentEpoch++;
    myself->configEpoch = server.cluster->currentEpoch;
    clusterSaveConfigOrDie(1);
    serverLog(LL_VERBOSE,
        "WARNING: configEpoch collision with node %.40s."
        " configEpoch set to %llu",
        sender->name,
        (unsigned long long) myself->configEpoch);
}

/* -----------------------------------------------------------------------------
 * CLUSTER nodes blacklist