feat: add interceptor client config

Allows configuration of interceptors on a client level by adding interceptor
providers to client config, allowing Plugins to add interceptors.

The primary addition is `InterceptorProvider`, an interface that creates
generic interceptors which can operate on any transport - http or otherwise.
When an operation is executed, interceptor providers are called to create
new instances of service-level interceptors. Creating new instances also
means we don't need to synchronize on the shared interceptors. Transport
specific config, have their own methods for adding interceptor providers, so
you can add `HttpInterceptorProvider`s to http config. Operations know which
transport they operate on, and can choose which transport-specific interceptor
providers to use.

If/when we have operation-level configuration, it might make more sense to
allow plugins to configure more generic 'operation customizations' or
something, rather than just the interceptors. Operations would then call
the customizations before executing.

A few other minor changes were made to the client libraries:
- Removed HasAttributes protocol and corresponding AttributesType from
interceptor interfaces, as we now just use `Context`.
- Changed InterceptorContext `getResult` to `getOutput`. We still store a
`Result<OutputType, Error>` in DefaultInterceptorContext, but `getOutput`
now throws that error if it is present, otherwise just returns `OutputType`
- Added actual builder methods to RequestMessageBuilder, which we would need
eventually, so I could use them in testing
- Made SdkHttpRequestBuilder final

Codegen was also updated to generate the new config methods, and to call
interceptor providers in operations to add configured interceptors.

Sources/ClientRuntime/Config/DefaultClientConfiguration.swift

@@ -31,5 +31,10 @@ public protocol DefaultClientConfiguration: ClientConfiguration {
     /// If none is provided, only a default logger provider will be used.
     var telemetryProvider: TelemetryProvider { get set }
 
+    /// Add an `InterceptorProvider` that will be used to provide interceptors for all operations.
+    ///
+    /// - Parameter provider: The `InterceptorProvider` to add.
+    func addInterceptorProvider(_ provider: InterceptorProvider)
+
     /// TODO(plugins): Add Checksum, etc.
 }

Sources/ClientRuntime/Config/DefaultHttpClientConfiguration.swift

@@ -29,4 +29,9 @@ public protocol DefaultHttpClientConfiguration: ClientConfiguration {
     ///
     /// Defaults to a auth scheme resolver generated based on Smithy service model.
     var authSchemeResolver: AuthSchemeResolver { get set }
+
+    /// Add an `HttpInterceptorProvider` that will be used to provide interceptors for all HTTP operations.
+    ///
+    /// - Parameter provider: The `HttpInterceptorProvider` to add.
+    func addInterceptorProvider(_ provider: HttpInterceptorProvider)
 }

Sources/ClientRuntime/Idempotency/IdempotencyTokenMiddleware.swift

@@ -5,7 +5,6 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
-import protocol Smithy.HasAttributes
 import class Smithy.Context
 
 public struct IdempotencyTokenMiddleware<OperationStackInput, OperationStackOutput>: Middleware {
@@ -42,7 +41,7 @@ extension IdempotencyTokenMiddleware: HttpInterceptor {
     public typealias InputType = OperationStackInput
     public typealias OutputType = OperationStackOutput
 
-    public func modifyBeforeSerialization(context: some MutableInput<InputType, AttributesType>) async throws {
+    public func modifyBeforeSerialization(context: some MutableInput<InputType>) async throws {
         let withToken = addToken(input: context.getInput(), attributes: context.getAttributes())
         context.updateInput(updated: withToken)
     }

Sources/ClientRuntime/Interceptor/AnyInterceptor.swift

@@ -5,9 +5,9 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
+import class Smithy.Context
 import protocol Smithy.RequestMessage
 import protocol Smithy.ResponseMessage
-import protocol Smithy.HasAttributes
 
 /// Type-erased, concrete interceptor.
 ///
@@ -22,11 +22,10 @@ internal struct AnyInterceptor<
     InputType,
     OutputType,
     RequestType: RequestMessage,
-    ResponseType: ResponseMessage,
-    AttributesType: HasAttributes
+    ResponseType: ResponseMessage
 > {
     internal typealias InterceptorContextType = DefaultInterceptorContext<
-        InputType, OutputType, RequestType, ResponseType, AttributesType
+        InputType, OutputType, RequestType, ResponseType
     >
     internal typealias InterceptorFn = (InterceptorContextType) async throws -> Void
 
@@ -55,8 +54,7 @@ internal struct AnyInterceptor<
         I.InputType == InputType,
         I.OutputType == OutputType,
         I.RequestType == RequestType,
-        I.ResponseType == ResponseType,
-        I.AttributesType == AttributesType {
+        I.ResponseType == ResponseType {
         self.readBeforeExecution = interceptor.readBeforeExecution(context:)
         self.modifyBeforeSerialization = interceptor.modifyBeforeSerialization(context:)
         self.readBeforeSerialization = interceptor.readBeforeSerialization(context:)

Sources/ClientRuntime/Interceptor/DefaultInterceptorContext.swift

@@ -5,9 +5,9 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
+import class Smithy.Context
 import protocol Smithy.RequestMessage
 import protocol Smithy.ResponseMessage
-import protocol Smithy.HasAttributes
 
 /// Default implementation for all interceptor context types.
 ///
@@ -17,16 +17,15 @@ public class DefaultInterceptorContext<
     InputType,
     OutputType,
     RequestType: RequestMessage,
-    ResponseType: ResponseMessage,
-    AttributesType: HasAttributes
+    ResponseType: ResponseMessage
 >: InterceptorContext {
-    private var attributes: AttributesType
+    private var attributes: Context
     private var input: InputType
     private var request: RequestType?
     private var response: ResponseType?
     private var result: Result<OutputType, Error>?
 
-    public init(input: InputType, attributes: AttributesType) {
+    public init(input: InputType, attributes: Context) {
         self.input = input
         self.attributes = attributes
     }
@@ -35,9 +34,13 @@ public class DefaultInterceptorContext<
         self.input
     }
 
-    public func getAttributes() -> AttributesType {
+    public func getAttributes() -> Context {
         return self.attributes
     }
+
+    internal func setResult(result: Result<OutputType, Error>) {
+        self.result = result
+    }
 }
 
 extension DefaultInterceptorContext: BeforeSerialization {}
@@ -73,8 +76,13 @@ extension DefaultInterceptorContext: MutableResponse {
 }
 
 extension DefaultInterceptorContext: AfterDeserialization {
-    public func getResult() -> Result<OutputType, Error> {
-        self.result!
+    public func getOutput() throws -> OutputType {
+        switch self.result! {
+        case .success(let output):
+            return output
+        case .failure(let error):
+            throw error
+        }
     }
 }
 
@@ -85,8 +93,8 @@ extension DefaultInterceptorContext: AfterAttempt {
 }
 
 extension DefaultInterceptorContext: MutableOutputAfterAttempt {
-    public func updateResult(updated: Result<OutputType, Error>) {
-        self.result = updated
+    public func updateOutput(updated: OutputType) {
+        self.result = .success(updated)
     }
 }
 

Sources/ClientRuntime/Interceptor/HttpInterceptor.swift

@@ -10,7 +10,4 @@ import class SmithyHTTPAPI.SdkHttpRequest
 import class SmithyHTTPAPI.HttpResponse
 
 public protocol HttpInterceptor<InputType, OutputType>: Interceptor
-where
-    RequestType == SdkHttpRequest,
-    ResponseType == HttpResponse,
-    AttributesType == Smithy.Context {}
+where RequestType == SdkHttpRequest, ResponseType == HttpResponse {}

Sources/ClientRuntime/Interceptor/HttpInterceptorProvider.swift

@@ -0,0 +1,17 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+/// Provides implementations of `HttpInterceptor`.
+///
+/// For the generic counterpart, see `InterceptorProvider`.
+public protocol HttpInterceptorProvider {
+
+    /// Creates an instance of an `HttpInterceptor` implementation.
+    ///
+    /// - Returns: The `HttpInterceptor` implementation.
+    func create<InputType, OutputType>() -> any HttpInterceptor<InputType, OutputType>
+}