Pausable channels #2667
Pausable channels #2667
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ozangunalp
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| import io.smallrye.mutiny.subscription.MultiSubscriber; | ||
| import io.smallrye.reactive.messaging.PausableChannel; | ||
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| public class PausableMulti<T> extends MultiOperator<T, T> implements PausableChannel { |
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Would like to have @jponge review on this one.
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Something that could be done is passing that operator through the Reactive Streams (Flow) TCK. I don't think there's anything incorrect in that implementation, but you know... 🤣
...g-provider/src/main/java/io/smallrye/reactive/messaging/providers/helpers/PausableMulti.java
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| @Override | ||
| public void request(long numberOfItems) { |
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What happens when Long.MAX value is requested? (unbounded subscription)
My understanding is that the pausing mechanism delays upstream requests when paused (aka a kind of passive pausing).
Also this should be documented as per reactive streams expectations.
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It is much like demand capping. pause/resume won't work if the subscription is unbounded.
How would you define active pausing? To buffer items until resumed?
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Yes, but TBH in this case what you have totally makes sense. Just make sure you document the case of unbounded requests, or even "large" requests 😉 (e.g., Long.MAX_VALUE - 100)
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Also, we could've contributed this operator to Mutiny itself, but I couldn't find a Mutiny-like API to give the control of pause/resume. Would you've any ideas on that ?
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We'd need an extended subscription to support these additional operations I guess.
| import io.smallrye.mutiny.subscription.MultiSubscriber; | ||
| import io.smallrye.reactive.messaging.PausableChannel; | ||
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| public class PausableMulti<T> extends MultiOperator<T, T> implements PausableChannel { |
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Something that could be done is passing that operator through the Reactive Streams (Flow) TCK. I don't think there's anything incorrect in that implementation, but you know... 🤣
ozangunalp
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Pushed a small change to pass the flow publisher tck. |
ozangunalp
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| ``` | ||
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| !!!warning | ||
| Pausable channels only work with back-pressure aware subscribers, with bounded downstream requests. |
Adds a new decorator for pausing and accumulating downstream requests to connector channels.
A channel needs to set the
pausableflag to true. The pause/resume is controlled by thePausableChannelthat is accessible fromChannelRegistryby channel name.Closes #1649