axon-framework-replay-bug-demo

Demonstrates a bug in axon framework 3.4.2

How to run

Run the provided entrypoint script: run.sh

Expectation

When replaying events, no handlers marked with @AllowReplay(false) should be invoked.

Reality

For the last event in the sequence, the handler marked with @AllowReplay(false) is invoked when it shouldn't be.

Example output:

[EventProcessor[projections]-0] INFO org.axonframework.eventhandling.TrackingEventProcessor - Using current Thread for last segment worker: TrackingSegmentWorker{processor=projections, segment=Segment[0/0]}
[EventProcessor[projections]-0] INFO org.axonframework.eventhandling.TrackingEventProcessor - Fetched token: null for segment: Segment[0/0]
[EventProcessor[projections]-0] INFO com.example.ReplayableProjection - REPLAYABLE: id=1, isReplay=false
[EventProcessor[projections]-0] INFO com.example.NonReplayableProjection - NON REPLAYABLE: id=1, isReplay=false
[EventProcessor[projections]-0] INFO com.example.ReplayableProjection - REPLAYABLE: id=2, isReplay=false
[EventProcessor[projections]-0] INFO com.example.NonReplayableProjection - NON REPLAYABLE: id=2, isReplay=false
[EventProcessor[projections]-0] INFO com.example.ReplayableProjection - REPLAYABLE: id=3, isReplay=false
[EventProcessor[projections]-0] INFO com.example.NonReplayableProjection - NON REPLAYABLE: id=3, isReplay=false
[com.example.Main.main()] INFO org.axonframework.eventhandling.TrackingEventProcessor - Shutdown state set for Processor 'projections'. Awaiting termination...
[EventProcessor[projections]-1] INFO org.axonframework.eventhandling.TrackingEventProcessor - Using current Thread for last segment worker: TrackingSegmentWorker{processor=projections, segment=Segment[0/0]}
[EventProcessor[projections]-1] INFO org.axonframework.eventhandling.TrackingEventProcessor - Fetched token: ReplayToken{currentToken=IndexTrackingToken{globalIndex=-1}, tokenAtReset=IndexTrackingToken{globalIndex=2}} for segment: Segment[0/0]
[EventProcessor[projections]-1] INFO com.example.ReplayableProjection - REPLAYABLE: id=1, isReplay=true
[EventProcessor[projections]-1] INFO com.example.ReplayableProjection - REPLAYABLE: id=2, isReplay=true
[EventProcessor[projections]-1] INFO com.example.ReplayableProjection - REPLAYABLE: id=3, isReplay=true
[EventProcessor[projections]-1] INFO com.example.NonReplayableProjection - NON REPLAYABLE: id=3, isReplay=true
[com.example.Main.main()] INFO org.axonframework.eventhandling.TrackingEventProcessor - Shutdown state set for Processor 'projections'. Awaiting termination...

Note the line with NON REPLAYABLE: id=3, isReplay=true where a non replayable event handler is invoked.

Likely cause

This is likely due to a bad implementation of the covers method in GlobalSequenceTrackingToken:

@Override
public boolean covers(TrackingToken other) {
    Assert.isTrue(other instanceof GlobalSequenceTrackingToken, () -> "Incompatible token type provided.");
    GlobalSequenceTrackingToken otherToken = (GlobalSequenceTrackingToken) other;

    return otherToken.globalIndex < this.globalIndex;
}

I expect that it should rather return return otherToken.globalIndex <= this.globalIndex;. i.e. less than or equals