Imagine we have a cluster, for example a three-shard cluster,
if shard 1 doing a CLUSTER RESET HARD, it will change the node
name, and then other nodes will mark it as NOADR since the node
name received by PONG has changed.
In the eyes of other nodes, there is one working primary node
left but with no address, and in this case, the address report
in MOVED will be invalid and will confuse the clients. And in
the same time, the replica will not failover since its primary
is not in the FAIL state. And the cluster looks OK to everyone.
This leaves a cluster that appears OK, but with no coverage for
shard 1, obviously we should do something like CLUSTER FORGET
to remove the node and fix the cluster before using it.
But the point in here, we can mark the NOADDR node as FAIL to
advance the cluster state. If a node is NOADDR means it does
not have a valid address, so we won't reconnect it, we won't
send PING, we won't gossip it, it seems reasonable to mark it
as FAIL.
Signed-off-by: Binbin <binloveplay1314@qq.com>
10357ceda5