Add scaffolding for client interceptors #986
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| /// Forwards the response part to the next inbound interceptor in the pipeline, if there is one. | ||
| /// | ||
| /// - Parameter part: The response part to forward. | ||
| /// - Note: This does *not* have to be called from the `EventLoop`. |
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Is that worthwhile? NIO doesn't bother with this.
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Hmm I figured it'd be better to avoid failure since this could be called from off of the event loop, e.g. after deferring to e.g. UI for authentication or something. Perhaps it'd be better to document that it must be called from the event loop and keep the relevant assertions. WDYT?
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Yeah, I think that that's probably better? It's a pretty significant perf win to avoid the check.
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I gave the pipeline the same treatment: it'll be internal and the inbound side will already be on the event loop. The outbound side will be invoked from the call object, so we can push the check there instead.
| if let outbound = self.nextOutbound { | ||
| outbound.invokeWrite(part, promise: promise) | ||
| } else { | ||
| promise?.fail(GRPCStatus(code: .unavailable, message: "The RPC has already completed")) |
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Is this right? There seems to be some inconsistency between _read and _write that I don't fully understand about when the next interceptor might be nil.
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So _read is more like NIOs fireChannelRead rather than NIOs read.
What's not implemented here is removing the contexts when the RPC completes, that's when we expect them to be nil.
Motivation: To support client interceptors we first need to define a few types to work with. Modifications: - Add client request and response parts. - Add the client interceptor protocol. - Add the client interceptor context, which is passed to functions on the interceptor protocol in order to allow implementations to invoke functions on interceptors either side of it in the pipeline. - Add a stubbed out client interceptor pipeline. Result: We have some base types for client side interceptors.
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Motivation: To support client interceptors we first need to define a few types to work with. Modifications: - Add client request and response parts. - Add the client interceptor protocol. - Add the client interceptor context, which is passed to functions on the interceptor protocol in order to allow implementations to invoke functions on interceptors either side of it in the pipeline. - Add a stubbed out client interceptor pipeline. Result: We have some base types for client side interceptors.
Motivation: To support client interceptors we first need to define a few types to work with. Modifications: - Add client request and response parts. - Add the client interceptor protocol. - Add the client interceptor context, which is passed to functions on the interceptor protocol in order to allow implementations to invoke functions on interceptors either side of it in the pipeline. - Add a stubbed out client interceptor pipeline. Result: We have some base types for client side interceptors.
Motivation: To support client interceptors we first need to define a few types to work with. Modifications: - Add client request and response parts. - Add the client interceptor protocol. - Add the client interceptor context, which is passed to functions on the interceptor protocol in order to allow implementations to invoke functions on interceptors either side of it in the pipeline. - Add a stubbed out client interceptor pipeline. Result: We have some base types for client side interceptors.
Motivation:
To support client interceptors we first need to define a few types to
work with.
Modifications:
the interceptor protocol in order to allow implementations to invoke
functions on interceptors either side of it in the pipeline.
Result:
We have some base types for client side interceptors.