When a node role changes, we should brocast the change to notify other nodes.
For example, one primary and one replica, after a failover, the replica became
a new primary, the primary became a new replica.
And then we trigger a second cluster failover for the new replica, the
new replica will send a MFSTART to its primary, ie, the new primary.
But the new primary may reject the MFSTART due to this logic:
```
} else if (type == CLUSTERMSG_TYPE_MFSTART) {
if (!sender || sender->replicaof != myself) return 1;
```
In the new primary views, sender is still a primary, and sender->replicaof
is NULL, so we will return. Then the manual failover timedout.
Another possibility is that other primaries refuse to vote after receiving
the FAILOVER_AUTH_REQUEST, since in their's views, sender is still a primary,
so it refuse to vote, and then manual failover timedout.
```
void clusterSendFailoverAuthIfNeeded(clusterNode *node, clusterMsg *request) {
...
if (clusterNodeIsPrimary(node)) {
serverLog(LL_WARNING, "Failover auth denied to...
```
The reason is that, currently, we only update the node->replicaof information
when we receive a PING/PONG from the sender. For details, see clusterProcessPacket.
Therefore, in some scenarios, such as clusters with many nodes and a large
cluster-ping-interval (that is, cluster-node-timeout), the role change of the node
will be very delayed.
Added a DEBUG DISABLE-CLUSTER-RANDOM-PING command, send cluster ping
to a random node every second (see clusterCron).
Signed-off-by: Binbin <binloveplay1314@qq.com>
b9d224097a