refactor(app/core): a unit test suite for rescue body #3615
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in #3559 (4b53081), we introduced a backported `Frame<T>` type, and a `ForwardCompatibleBody<B>` type that allows us to interact with a `http_body::Body` circa 0.4.6 in terms of frame-based interfaces that match those of the 1.0 interface. see linkerd/linkerd2#8733 for more information on upgrading hyper. in #3559, we narrowly added this as an internal submodule of the `linkerd-http-retry` library. these facilities however, would have utility in other places such as `linkerd-app-core`. this commit pulls these compatibility shims out into a `linkerd-http-body-compat` library so that they can be imported and reused elsewhere. Signed-off-by: katelyn martin <[email protected]>
Signed-off-by: katelyn martin <[email protected]>
Signed-off-by: katelyn martin <[email protected]>
these are header values. `http::HeaderName` has a const fn constructor, so let's use that. Signed-off-by: katelyn martin <[email protected]>
Signed-off-by: katelyn martin <[email protected]>
Signed-off-by: katelyn martin <[email protected]>
we'll add a few tests for this middleware shortly. this commit moves this middleware out into its own submodule. Signed-off-by: katelyn martin <[email protected]>
for other body middleware, we hide inner enum variants and their constituent members by using the "inner" pattern. this commit tweaks `ResponseBody` to follow suit, such that it now holds an `Inner`, but does not expose its passthrough and rescue variants to callers. Signed-off-by: katelyn martin <[email protected]>
this adds a small documentation comment describing what this type does. Signed-off-by: katelyn martin <[email protected]>
this commit introduces a test suite for our error recovery middleware. this body middleware provides a mechanism to "rescue" errors, gracefully mapping an error encountered when polling a gRPC body into e.g. trailers with a gRPC status code. before we upgrade this middleware in service of linkerd/linkerd2#8733, we add some test coverage to ensure that we preserve this middleware. Signed-off-by: katelyn martin <[email protected]>
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February 13, 2025 13:47
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Feb 13, 2025
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this commit makes some minor alterations to our error recovery body middleware. see linkerd/linkerd2#8733 for more information. this commit removes an `assert!` statement from the implementation of `<Response<R, B> as Body>::poll_data()`. see the documentation of `Body::poll_frame()`: > Once the end of the stream is reached, implementations should > continue to return [`Poll::Ready(None)`]. hyperium/http-body@1090bff#diff-33aabe8c2aaa7614022addf244245e09bbff576a67a9ae3c6938c8a868201d36R60-R61 to do this, this commit introduces a distinct terminal state `Inner::Rescued` to represent when the underlying `B`-typed body has yielded an error and been rescued. once in this state the body will yield no more data frames, instead yielding a collection of trailers describing the mid-stream error that was encountered by the underlying body. the call to `R::rescue` is also moved down into the helper function fka `grpc_trailers()`. this helps the function follow the grain of our "state machine" a little more directly. see #3615, #3614, and #3611 for pretext to this change.
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this commit makes some minor alterations to our error recovery body middleware. see linkerd/linkerd2#8733 for more information. this commit removes an `assert!` statement from the implementation of `<Response<R, B> as Body>::poll_data()`. see the documentation of `Body::poll_frame()`: > Once the end of the stream is reached, implementations should > continue to return [`Poll::Ready(None)`]. hyperium/http-body@1090bff#diff-33aabe8c2aaa7614022addf244245e09bbff576a67a9ae3c6938c8a868201d36R60-R61 to do this, this commit introduces a distinct terminal state `Inner::Rescued` to represent when the underlying `B`-typed body has yielded an error and been rescued. once in this state the body will yield no more data frames, instead yielding a collection of trailers describing the mid-stream error that was encountered by the underlying body. the call to `R::rescue` is also moved down into the helper function fka `grpc_trailers()`. this helps the function follow the grain of our "state machine" a little more directly. see #3615, #3614, and #3611 for pretext to this change. Signed-off-by: katelyn martin <[email protected]>
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linkerd-app-coreincludes an error recovery body middleware. this middleware will gracefully catch and report errors encountered when polling an inner body, and via anR-typed recovery strategy provided by the caller, will attempt to map the error to a gRPC status code denoting an error.before we upgrade to hyper 1.0 in service of linkerd/linkerd2#8733, we add some test coverage to ensure that we preserve the behavior of this middleware.
see:
ForwardCompatibleBody<B>#3614.for historical context on this tower layer, see: