enforces ordering on concurrent subscription to FluxRefCount
#3517
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Signed-off-by: OlegDokuka <odokuka@vmware.com>
Late subscribe may observe zero events when multiple inners subscribes to FluxRefCount simultaneously so the one which does not invoke connect method subscribes to the FluxPublish too late (e.g. the one which call connect subscribe faster and invoke connect method earlier)
```
subscribe 1 subscriber 2
| |
count + 1 (1) |
| count + 1 (2)
| |
| subscribe
| |
| connect
| onComplete
subscribe
(hanging)
```
to solve the problem subscribe should happen before count is incremented so we have strong ordering
Signed-off-by: OlegDokuka <odokuka@vmware.com>
Signed-off-by: OlegDokuka <odokuka@vmware.com>
OlegDokuka
changed the title
FluxRefCount
chemicL
reviewed
Jun 28, 2023
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Perhaps adding corresponding cases for Flux.error(Throwable) in the fusion/hide/delay variants to also validate how error is handled could be worthwhile?
|
|
||
| RefCountInner(CoreSubscriber<? super T> actual, RefCountMonitor<T> connection) { | ||
| volatile int state; //used to guard against doubly terminating subscribers (e.g. double cancel) |
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I suppose the comment is no longer relevant, as the state represents more situations and before it was just about termination/cancellation, while now it also represents the readiness (monitor set). Perhaps we can remove it.
|
@OlegDokuka , if you wish to know whether the tests I wrote pass with your fix, I can confirm they do! :) Thanks! |
Signed-off-by: OlegDokuka <odokuka@vmware.com>
chemicL
approved these changes
Jul 4, 2023
|
@OlegDokuka this PR seems to have been merged on a maintenance branch, please ensure the change is merge-forwarded to intermediate maintenance branches and up to |
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Signed-off-by: OlegDokuka <odokuka@vmware.com>
OlegDokuka
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Signed-off-by: OlegDokuka <odokuka@vmware.com>
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Late subscribe may observe zero events when multiple inners subscribe to
FluxRefCountsimultaneously so the one which does not invoke theconnectmethod subscribes to theFluxPublishtoo late (e.g. the one which calls theconnectsubscribe faster and invoke theconnectmethod earlier than the others):to solve the problem subscribe should happen before the count is incremented so we have strong ordering guaranteed by the
synchronizeblockfixes #3487