Add async try-with-resources for java api #6357
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| public static <T extends AutoCloseable, U> CompletionStage<U> asyncTryWithResource( | ||
| T resource, Function<T, CompletionStage<U>> body | ||
| ) { | ||
| CompletionStage<U> completionStage = body.apply(resource); |
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If the function body fails to prepare the CompletionStage, the close() is never called.
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I fixed it now and added the test case
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| CompletionStage<U> completionStage = body.apply(resource); | ||
| completionStage.whenCompleteAsync((u, throwable) -> tryCloseResource(resource)); | ||
| return completionStage; | ||
| } catch (Exception e) { |
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It would be nice if we didn't have to catch and re-throw the exception here. Why not use a try-finally?
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I agree that it is cleaner to use try-finally, however, in this case that would mean that we close the resource while the async task is potentially still running and using the resource.
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Well, we would need to avoid closing it twice. If the async task is running, we don't want to close it. But maybe we can just avoid wrapping if we don't need to:
} catch (RuntimeException e) {
tryCloseResource(resource);
throw e;
} catch (Throwable t) {
tryCloseResource(resource);
throw new RuntimeException(t);
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Oh yeah, closing twice would be an issue as well. Anyway, I've changed it now to only wrap it if necessary as you suggested. I did the same for the close expcetion handler just to make sure.
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Should we backport this to 2.5.x? |
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2.5.x: e7d1ccd |
Pull Request Checklist
Helpful things
Fixes
Fixes #5547
Purpose
Introduces function for async try-with-resource
Background Context
References