Add the router and service protocol #1717
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Motivation: The transport layer accepts streams from the client and transforms them into requests which are handled by services. Services, written by users, need a way to tell the server which streams should be handled by which methods. Modifications: - Add the RPC router which routes streams to "handlers" - Add the RegistrableRPCService protocol which services can conform to to register routes with a router. The `RegistrableRPCService` is typically not implemented by users and instead will be implemented in the generated code. However, it builds on public API offered by the router. Result: We have interfaces which allow streams to be routed to a service handler.
| public var methods: [MethodDescriptor] { | ||
| Array(self.handlers.keys) | ||
| } | ||
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| /// Returns the number of methods registered with the router. | ||
| public var count: Int { | ||
| self.handlers.count | ||
| } | ||
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| /// Returns whether a handler exists for a given method. | ||
| /// | ||
| /// - Parameter descriptor: A descriptor of the method. | ||
| /// - Returns: Whether a handler exists for the method. | ||
| public func hasHandler(forMethod descriptor: MethodDescriptor) -> Bool { |
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Do those things have to be public?
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I think there's value in having methods (e.g. logging what methods your server serves). You can obviously just query methods instead of using this function but it's then O(n) rather than O(1) which is a bit sad and the main reason to add this.
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Wouldn't this be solved if methods was a Set instead of an Array?
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No, while the lookup would be O(1) creating the set would still be O(n).
| /// - Parameter descriptor: A descriptor of the method to remove a handler for. | ||
| /// - Returns: Whether a handler was removed. | ||
| @discardableResult | ||
| public mutating func removeHandler(forMethod descriptor: MethodDescriptor) -> Bool { |
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Same here. Does this need to be public?
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If you don't want to offer all methods in a service then this is one way to remove the ones you don't want (the other being to reimplement the service protocol).
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I see. I am wondering if we should expose this publicly right away. Do we have concrete use-cases in mind where want to do this or did we get a feature request for this before?
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One concrete use case is the interoperability tests. One test uses the generated client to call a method which isn't implemented on the server. At the moment we achieve this by patching the generated code.
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I also think having these methods is very low burden: they're unlikely to change and they still make sense if we change the internals of the router.
| public var methods: [MethodDescriptor] { | ||
| Array(self.handlers.keys) | ||
| } | ||
|
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||
| /// Returns the number of methods registered with the router. | ||
| public var count: Int { | ||
| self.handlers.count | ||
| } | ||
|
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||
| /// Returns whether a handler exists for a given method. | ||
| /// | ||
| /// - Parameter descriptor: A descriptor of the method. | ||
| /// - Returns: Whether a handler exists for the method. | ||
| public func hasHandler(forMethod descriptor: MethodDescriptor) -> Bool { |
There was a problem hiding this comment.
Wouldn't this be solved if methods was a Set instead of an Array?
Motivation:
The transport layer accepts streams from the client and transforms them into requests which are handled by services. Services, written by users, need a way to tell the server which streams should be handled by which methods.
Modifications:
The
RegistrableRPCServiceis typically not implemented by users and instead will be implemented in the generated code. However, it builds on public API offered by the router.Result:
We have interfaces which allow streams to be routed to a service handler.