Fix AsyncIterableProducer.tee() to properly synchronize producers#298542
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kbhujbal wants to merge 1 commit intomicrosoft:mainfrom
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Fix AsyncIterableProducer.tee() to properly synchronize producers#298542kbhujbal wants to merge 1 commit intomicrosoft:mainfrom
kbhujbal wants to merge 1 commit intomicrosoft:mainfrom
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The previous implementation called `start()` without awaiting it inside
each executor, relying on implicit microtask ordering for correctness.
This was fragile and caused the empty source and error propagation test
cases to be skipped.
Restructure tee() to use an explicit `bothReady` deferred promise that
signals when both emitters are available, and a `done` deferred promise
that keeps the executors alive until source iteration completes. This
eliminates the fire-and-forget `start()` call and makes the data flow
explicit.
Also unskip the two previously skipped test cases ('tee - empty source'
and 'tee - handles errors in source') and remove the related TODO
comments from all four tee tests.
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Fixes a known implementation issue in
AsyncIterableProducer.tee()(added in #276037) wherestart()was called without being awaited inside executors, relying on implicit microtask ordering for correctness.Problem
The previous implementation used a fire-and-forget
start()call from each executor, with an early-return guard (if (!emitter1 || !emitter2) return). This was fragile — two test cases ('tee - empty source' and 'tee - handles errors in source') were skipped with a TODO noting the bug.Solution
Restructure
tee()to use explicit synchronization:bothReadydeferred promise that signals when both emitters are availabledonedeferred promise that keeps executors alive until source iteration completesbothReady.p.then(...)instead of a fire-and-forgetstart()callThis makes the data flow explicit and eliminates reliance on microtask ordering.
Test plan