how to Detect leader changed？

[xiatianqiuyu]

How to check whether the leader has changed? How to register an observer and perform certain operations when the leader sends a change

[kevburnsjr]

config.NodeHostConfig.RaftEventListener
https://pkg.go.dev/github.com/lni/dragonboat/v4@v4.0.0-20230202152124-023bafb8e648/config#NodeHostConfig

// RaftEventListener is the listener for Raft events, such as Raft leadership
// change, exposed to user space. NodeHost uses a single dedicated goroutine
// to invoke all RaftEventListener methods one by one, CPU intensive or IO
// related procedures that can cause long delays should be offloaded to worker
// goroutines managed by users. See the raftio.IRaftEventListener definition
// for more details.
RaftEventListener raftio.IRaftEventListener

type IRaftEventListener interface {
	LeaderUpdated(info LeaderInfo)
}

type LeaderInfo struct {
	ShardID   uint64
	ReplicaID uint64
	Term      uint64
	LeaderID  uint64
}

[xiatianqiuyu]

this method is very good。How to check whether the raft node Breakdowns? How to register an observer and perform certain operations when the node Breakdowns

[lni]

your new question is being addressed in #301.

[paulm17]

I've got a use case where I have a scheduler. It only needs to be run on one node. However I'm using dragonboat to provide HA.

What would be the best mechanism to only ensure the scheduler runs in 1 node only?

Thanks