An initial, simple approach to this. The PeerMonitor will
check it's metrics, compare to the current set of peers and put
an alert in the alerts channel if the metrics for a peer have expired.
Cluster reads this channel looking for "ping" alerts. The leader
is in charge of triggering repins in all the Cids allocated to
a given peer.
Also, metrics are now broadcasted to the cluster instead of pushed only
to the leader. Since they happen every few seconds it should be okay
regarding how it scales. Main problem was that if the leader is the node
going down, the new leader will not now about it as it doesn't have any
metrics for it, so it won't trigger an alert. If it acted on that then
the component needs to know it is the leader, or cluster needs to
handle alerts in complicated ways when leadership changes. Detecting
leadership changes or letting a component know who is the leader is another
dependency from the consensus algorithm that should be avoided. Therefore
we broadcast, for the moment.
License: MIT
Signed-off-by: Hector Sanjuan <hector@protocol.ai>
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