Publisher#flatMapMergeSingle catch an propagate unexpected errors downstream #1614
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…nstream Motivation: Publisher#flatMapMergeSingle relies upon the upstream source to catch unexpected exceptions, cleanup necessary state, and propagate an error back downstream. However in the event the upstream source is a Single it will not be able to propagate an error downstream because it has already sent a terminal signal (multiple terminal signals not allowed by the RS spec). This means the upstream can at best log/swallow the error and downstream may not be notified of the failure. Modifications: - Publisher#flatMapMergeSingle exception handling is modified to instead of propagating the exception upstream, exceptions are caught, upstream is cancelled, and the exception is propagated downstream. Result: Publisher#flatMapMergeSingle usages where downstream operators may throw will cancel upstream and propagate and error downstream.
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| return; // Poison emittingUpdater. We prematurely terminated, other signals should be ignored. | ||
| } | ||
| // Release lock after we handle errors, because error handling needs to poison the lock. | ||
| if (!releaseLock(emittingUpdater, this)) { |
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Here is a risk that smth inside onErrorHoldingLock may throw and then lock won't be released
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that is intentional. when onErrorHoldingLock is called the lock is "poisoned" (aka not unlocked) to prevent future signal delivery.
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I see, thanks for clarifying!
...lk-concurrent-api/src/test/java/io/servicetalk/concurrent/api/PublisherFlatMapMergeTest.java
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...k-concurrent-api/src/test/java/io/servicetalk/concurrent/api/PublisherFlatMapSingleTest.java
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...etalk-concurrent-api/src/main/java/io/servicetalk/concurrent/api/PublisherFlatMapSingle.java
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build failure attributed to #1579 |
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another build failure attributed to #1579 |
Motivation:
Publisher#flatMapMergeSingle relies upon the upstream source to catch
unexpected exceptions, cleanup necessary state, and propagate an error
back downstream. However in the event the upstream source is a Single it
will not be able to propagate an error downstream because it has already
sent a terminal signal (multiple terminal signals not allowed by the
RS spec). This means the upstream can at best log/swallow the error and
downstream may not be notified of the failure.
Modifications:
of propagating the exception upstream, exceptions are caught, upstream
is cancelled, and the exception is propagated downstream.
Result:
Publisher#flatMapMergeSingle usages where downstream operators may throw
will cancel upstream and propagate and error downstream.