ReadCancellationException does not play well with `onErrorContinue`

[chringwer]

The way that ReadCancellationException is used in BodyExtractors is apparently meant to be an implementation detail:

spring-framework/spring-webflux/src/main/java/org/springframework/web/reactive/function/BodyExtractors.java

Lines 269 to 273 in 1bff7ce

	.map(buffer -> {
	DataBufferUtils.release(buffer);
	throw new ReadCancellationException();
	})
	.onErrorResume(ReadCancellationException.class, ex -> Mono.empty())

However, if somewhere downstream in the pipeline an onErrorContinue operator is appended, the exception does surface which caused me some confusion. Could this be implemented differently without throwing an exception?

[rstoyanchev]

Good point that a downstream onErrorContinue can quietly overtake onErrorResume handling and preclude buffer handling. Out of curiosity how did you even come across the issue?

We'll explore some alternative. We need to review similar handling elsewhere (e.g. DefaultWebClient).

[chringwer]

I ran into it when using WebClient as a reactive source in spring cloud stream. Under the hood it was FluxMessageChannel from spring integration that registered the onErrorContinue operator here:
https://github.com/spring-projects/spring-integration/blob/v5.2.1.RELEASE/spring-integration-core/src/main/java/org/springframework/integration/channel/FluxMessageChannel.java#L85

But apparently, that has already been fixed by a commit a few minutes ago. :-)

However, thanks for looking into this!