fix: keep lazy dispatch state on VarHandle#3116
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Motivation: PR apache#3035 used a VarHandle-backed volatile Int for LazyDispatch election state. Review raised concern about the field and the VarHandle access semantics. Modification: Keep the VarHandle-backed Int state, but use explicit getVolatile/setVolatile accessors with compareAndSet. This keeps the state in the LazyDispatch object without per-instance AtomicInteger allocation while preserving conservative volatile access semantics. Result: LazyDispatch keeps the same IDLE/SCHEDULED scheduling protocol with explicit volatile state access. Tests: - scalafmt --mode diff-ref=origin/main --non-interactive - scalafmt --list --mode diff-ref=origin/main --non-interactive - sbt "+stream / compile" - sbt "stream-tests / Test / testOnly org.apache.pekko.stream.scaladsl.StageActorRefSpec" (11/11) - git diff --check References: Refs apache#3035
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Motivation
PR #3035 introduced a VarHandle-backed
@volatile var statefor LazyDispatch scheduling state. The review discussion raised concern around the field and the access mode used through the VarHandle.Modification
Keep the static VarHandle and instance
Intstate, but use explicitgetVolatile/setVolatileaccessors withcompareAndSetinstead of plain VarHandleget/set.This avoids per-instance
AtomicIntegerallocation while making the state access mode explicit and conservative.Result
LazyDispatch keeps the same IDLE/SCHEDULED scheduling protocol and uses volatile state access for the scheduling election and IDLE publish/recheck path.
Tests
scalafmt --mode diff-ref=origin/main --non-interactivescalafmt --list --mode diff-ref=origin/main --non-interactivesbt "+stream / compile"sbt "stream-tests / Test / testOnly org.apache.pekko.stream.scaladsl.StageActorRefSpec"(11/11)git diff --checkReferences
Refs #3035