Allow a segment claim to trigger an ad-hoc replay#4620
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Extend SegmentChangeListener#onSegmentClaimed to return a TrackingToken on segment claim, the segment's reset position. When the returned token is strictly behind the segment's stored token, the Coordinator wraps the stored token in a ReplayToken so the segment streams from the reset position instead of the stored one. Returning null leaves the stored position untouched. On a first-ever claim (stored token null) the returned token is ignored, as a reset is only meaningful relative to a position the processor has already moved past. Reset positions returned by composed listeners are merged via TrackingToken#lowerBound, yielding the lowest position required by any constituent. Add SegmentChangeListener#onClaimWithReset for listeners that supply such a position. Introduce HandlerAwareProcessorCustomization: a customization hook invoked when a PooledStreamingEventProcessor is built, with access to the resolved EventHandlingComponent list, allowing processor configuration to be derived from the handlers themselves. PooledStreamingEventProcessorModule discovers these customizations from the root configuration so registration location is irrelevant.
abuijze
requested review from
MateuszNaKodach,
hjohn and
zambrovski
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Converted back to draft. John had some questions and suggestions that gave me another idea. Working on that one. |
smcvb
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Type: Feature
smcvb
added
the
Status: Obsolete
Contributor
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Marked as obsolete due to #4636. |
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Summary
Adds two building blocks to the pooled streaming event processor so that a component can request an ad-hoc replay of a single segment at the moment it is claimed.
Segment claim can return a reset position
SegmentChangeListener#onSegmentClaimednow returns aTrackingToken— the position the segment should be reset to. When that token is strictly behind the segment's stored token, theCoordinatorwraps the stored token in aReplayToken, so the segment streams from the returned position instead of the stored one. Returningnullleaves the stored position untouched.null) the returned position is ignored — a reset is only meaningful relative to a position the processor has already moved past. The listener is still invoked for any side effects.andThen) listeners are merged viaTrackingToken#lowerBound, so the chain requests the lowest position any constituent requires.SegmentChangeListener#onClaimWithReset(...)is added for listeners that supply such a position.Handler-aware processor customization
HandlerAwareProcessorCustomizationis a new hook invoked when aPooledStreamingEventProcessoris built, with access to the resolvedEventHandlingComponentlist. This lets processor configuration (such as registering aSegmentChangeListener) be derived from the handlers assigned to that processor.PooledStreamingEventProcessorModulediscovers these customizations from the root configuration, so where they are registered does not matter.Testing
./mvnw -pl messaging test -Dtest='SegmentChangeListenerTest,HandlerAwareProcessorCustomizationTest,CoordinatorTest'— 40 tests, all green.