core: PoC - MirroringInterceptor for traffic shadowing (#12448)#12721
core: PoC - MirroringInterceptor for traffic shadowing (#12448)#12721themechbro wants to merge 7 commits intogrpc:masterfrom
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Add a reachability fence in shutdown() and shutdownNow() to ensure the wrapper is not garbage collected while shutdown logic is executing. This prevents a race condition when using directExecutor() where a warning could be logged despite a proper shutdown. Fixes grpc#12641
This adds a fire-and-forget interceptor that mirrors Unary and Streaming traffic to a secondary channel without blocking the primary call. Headers are copied and propagated safely, and the secondary call respects the lifecycle (halfClose, cancel) of the primary stream. Addresses the Java ClientInterceptor proposal discussed in grpc#12448
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@themechbro - no worries. I was waiting for owners & reviewers to comment before proceeding. Since you have started, please go ahead. Let me know if need to review anything. |
Thanks so much, @sibasispadhi! I really appreciate it. I just pushed a quick fix for some Checkstyle and import errors that the CI caught. As soon as these GitHub Actions turn green, I would absolutely love to get your thoughts and review on the implementation—especially to see if the way I handled the streaming lifecycle and halfClose aligns with your original design thoughts. Thanks again for the great proposal that kicked this off! |
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Description
This Draft PR is a Proof-of-Concept implementation of the
MirroringInterceptordesigned to shadow traffic to a secondaryChannel.Motivation & Credit
This implementation is directly inspired by the excellent architectural proposal outlined by @sibasispadhi in Issue #12448.
@sibasispadhi - I saw your comment about wanting to tackle this and draft a
ClientInterceptorapproach. I didn't want to step on your toes, but I was so interested in the concept that I decided to build a local prototype to see if I could make the fire-and-forget and lifecycle requirements work. I'm submitting this PoC to help validate your proposed architecture. I am more than happy to collaborate on this, hand the branch over to you, or close this if you already have a working branch going!Implementation Details (Based on the proposed design)
Executor.start(), initializes a singlemirrorCallper stream, and reuses it for all subsequentsendMessage()invocations to ensure correct ordering.halfClose()andcancel()signals.Testing Done