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https://issues.apache.org/jira/browse/GROOVY-12571?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18134529#comment-18134529
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ASF GitHub Bot commented on GROOVY-12571:
-----------------------------------------
codeconsole opened a new pull request, #3105:
URL: https://github.com/apache/groovy/pull/3105
`BroadcastChannel.asPublisher()` now ends a subscriber that arrives after
the broadcast closed the same way as one that was attached before the close.
After `close()` it receives `onComplete`, so `for await (x in
broadcast.asPublisher())` ends without values and `await
broadcast.asPublisher()` returns `null`. Before, both threw
`ChannelClosedException`. After `close(failure)` it receives `failure` itself,
not a `ChannelClosedException` wrapping it. This matches `SubmissionPublisher`,
`Agent.changes()` and `for await` over a closed `AsyncChannel`, and makes the
result independent of whether the consumer subscribed before or after the
producer closed. `BroadcastChannel.subscribe()` still throws
`ChannelClosedException` once the broadcast is closed. The async channels guide
says so.
`BroadcastChannel` shipped in 6.0.0, so this changes behavior there; it is a
candidate for master only.
## Tests
`BroadcastChannelAsPublisherTest` (marked `// GROOVY-12571`): a subscriber
and a `for await` that arrive after `close()` and after `close(failure)`; they
fail without the change.
The `groovy.concurrent` tests pass (271), as do the Checkstyle and CodeNarc
gates.
> BroadcastChannel.asPublisher() fails a subscriber that arrives after the
> broadcast closed
> -----------------------------------------------------------------------------------------
>
> Key: GROOVY-12571
> URL: https://issues.apache.org/jira/browse/GROOVY-12571
> Project: Groovy
> Issue Type: Bug
> Components: async
> Affects Versions: 6.0.0
> Reporter: Scott Murphy Heiberg
> Priority: Major
>
> {code:groovy}
> import groovy.concurrent.BroadcastChannel
> def broadcast = BroadcastChannel.create()
> broadcast.close()
> for await (x in broadcast.asPublisher()) { println x } //
> ChannelClosedException; expected: ends without values
> {code}
> A subscriber that arrives after {{close()}} gets
> {{onError(ChannelClosedException)}}, and after {{close(failure)}} it gets the
> wrapper rather than the failure. A subscriber attached a moment before the
> close completes, or receives the failure itself, so the same program finishes
> or fails depending on timing. Expected: as {{SubmissionPublisher}},
> {{Agent.changes()}} and {{for await}} over a closed {{AsyncChannel}} behave,
> a late subscriber gets {{onComplete}} after {{close()}} and
> {{onError(failure)}} after {{close(failure)}}.
> {{BroadcastChannel.subscribe()}} still throws once closed.
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