feat: Make lots of types Sendable

Sources/ClientRuntime/Client/Client.swift

@@ -4,7 +4,7 @@
 //
 // SPDX-License-Identifier: Apache-2.0
 //
-public protocol Client {
+public protocol Client: Sendable {
     associatedtype Config: ClientConfiguration
     init(config: Config)
 }

Sources/ClientRuntime/Client/ClientBuilder.swift

@@ -22,11 +22,21 @@ public class ClientBuilder<ClientType: Client> {
         return ClientType(config: configuration)
     }
 
+    enum ClientBuilderError: Error {
+        case incompatibleConfigurationType(expected: String, received: String)
+    }
+
     func resolve(plugins: [any Plugin]) async throws -> ClientType.Config {
-        let clientConfiguration = try await ClientType.Config()
+        var clientConfiguration: any ClientConfiguration = try await ClientType.Config()
         for plugin in plugins {
-            try await plugin.configureClient(clientConfiguration: clientConfiguration)
+            try await plugin.configureClient(clientConfiguration: &clientConfiguration)
+        }
+        guard let typedConfig = clientConfiguration as? ClientType.Config else {
+            throw ClientBuilderError.incompatibleConfigurationType(
+                expected: String(describing: ClientType.Config.self),
+                received: String(describing: type(of: clientConfiguration))
+            )
         }
-        return clientConfiguration
+        return typedConfig
     }
 }

Sources/ClientRuntime/Config/ClientConfiguration.swift

@@ -5,6 +5,10 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
+/// Base protocol for client configuration.
+///
+/// Note: This protocol will inherit `Sendable` after the deprecation period of class-based configurations.
+/// The struct-based configuration already conforms to `Sendable` via `@unchecked Sendable`.
 public protocol ClientConfiguration {
     init() async throws
 }

Sources/ClientRuntime/Config/Context+Config.swift

@@ -30,14 +30,15 @@ private let clientConfigKey = AttributeKey<ClientConfigurationWrapper>(name: "Sm
 
 /// A wrapper used to allow a client configuration object to be placed in Context, since client config is not Sendable.
 ///
-/// Placing the client config into Context is safe because the client config is not modified after being placed into Context.
-/// Client config is unwrapped, then may be used to create a service client and make calls as part of performing an operation.
+/// Placing the client config into Context is safe because the client config is not modified after
+/// being placed into Context. Client config is unwrapped, then may be used to create a service
+/// client and make calls as part of performing an operation.
 ///
-/// This type is public so that it may be accessed in other runtime modules.  It is protected as SPI because it is a cross-module
-/// implementation detail that does not affect customers.
+/// This type is public so that it may be accessed in other runtime modules.  It is protected as
+/// SPI because it is a cross-module implementation detail that does not affect customers.
 ///
-/// `@unchecked Sendable` is used to make the wrapper Sendable even though it is technically not, due to the non-Sendable
-/// client config stored within.
+/// `@unchecked Sendable` is used to make the wrapper Sendable even though it is technically not,
+/// due to the non-Sendable client config stored within.
 @_spi(ClientConfigWrapper)
 public final class ClientConfigurationWrapper: @unchecked Sendable {
     public let clientConfig: DefaultClientConfiguration

Sources/ClientRuntime/Config/DefaultClientConfiguration.swift

@@ -39,7 +39,7 @@ public protocol DefaultClientConfiguration: ClientConfiguration {
     /// Adds an `InterceptorProvider` that will be used to provide interceptors for all operations.
     ///
     /// - Parameter provider: The `InterceptorProvider` to add.
-    func addInterceptorProvider(_ provider: InterceptorProvider)
+    mutating func addInterceptorProvider(_ provider: InterceptorProvider)
 
     /// TODO(plugins): Add Checksum, etc.
 }

Sources/ClientRuntime/Config/DefaultHttpClientConfiguration.swift

@@ -32,7 +32,8 @@ public protocol DefaultHttpClientConfiguration: ClientConfiguration {
     /// An ordered, prioritized list of auth scheme IDs that should be used for this client's requests.
     ///
     /// If no auth scheme preference is given, the first supported auth scheme defined in `authSchemes`
-    /// will be used.  If a value was not provided for `authSchemes`, then the service's first defined, supported auth scheme will be used.
+    /// will be used.  If a value was not provided for `authSchemes`, then the service's first defined,
+    /// supported auth scheme will be used.
     var authSchemePreference: [String]? { get set }
 
     /// The auth scheme resolver to use for resolving the auth scheme.
@@ -51,5 +52,5 @@ public protocol DefaultHttpClientConfiguration: ClientConfiguration {
     /// Adds a `HttpInterceptorProvider` that will be used to provide interceptors for all HTTP operations.
     ///
     /// - Parameter provider: The `HttpInterceptorProvider` to add.
-    func addInterceptorProvider(_ provider: HttpInterceptorProvider)
+    mutating func addInterceptorProvider(_ provider: HttpInterceptorProvider)
 }

Sources/ClientRuntime/Config/DefaultSDKRuntimeConfiguration.swift

@@ -29,7 +29,8 @@ public struct DefaultSDKRuntimeConfiguration<DefaultSDKRuntimeRetryStrategy: Ret
 
     /// The HTTP client to use for HTTP connections.
     ///
-    /// By default, Swift SDK will set this to `CRTClientEngine` client on Linux platforms, and `URLSessionHttpClient` on Apple platforms.
+    /// By default, Swift SDK will set this to `CRTClientEngine` client on Linux platforms, and
+    /// `URLSessionHttpClient` on Apple platforms.
     public var httpClientEngine: HTTPClient
 
     /// The HTTP client configuration.
@@ -114,7 +115,8 @@ public extension DefaultSDKRuntimeConfiguration {
     /// The default idempotency token generator that returns UUIDs.
     static var defaultIdempotencyTokenGenerator: IdempotencyTokenGenerator { DefaultIdempotencyTokenGenerator() }
 
-    /// The default retry strategy options with the exponential backoff strategy & other defaults defined in `RetryStrategyOptions`.
+    /// The default retry strategy options with the exponential backoff strategy & other defaults
+    /// defined in `RetryStrategyOptions`.
     static var defaultRetryStrategyOptions: RetryStrategyOptions {
         RetryStrategyOptions(backoffStrategy: ExponentialBackoffStrategy())
     }

Sources/ClientRuntime/Endpoints/DefaultEndpointResolver.swift

@@ -9,7 +9,7 @@ import struct SmithyHTTPAPI.Endpoint
 import enum SmithyHTTPAPI.EndpointPropertyValue
 import struct SmithyHTTPAPI.Headers
 
-public struct DefaultEndpointResolver<Params: EndpointsRequestContextProviding> {
+public struct DefaultEndpointResolver<Params: EndpointsRequestContextProviding>: Sendable {
 
     private let engine: ClientRuntime.EndpointsRuleEngine
 

Sources/ClientRuntime/Endpoints/EndpointsRuleEngine.swift

@@ -4,7 +4,7 @@
 import AwsCommonRuntimeKit
 
 /// Wrapper for CRTAWSEndpointsRuleEngine
-public class EndpointsRuleEngine {
+public final class EndpointsRuleEngine: @unchecked Sendable {
 
     let crtEngine: AwsCommonRuntimeKit.EndpointsRuleEngine
 

Sources/ClientRuntime/Endpoints/StaticEndpointResolver.swift

@@ -7,7 +7,7 @@
 
 import struct SmithyHTTPAPI.Endpoint
 
-public struct StaticEndpointResolver<Params: EndpointsRequestContextProviding> {
+public struct StaticEndpointResolver<Params: EndpointsRequestContextProviding>: Sendable {
 
     private let endpoint: SmithyHTTPAPI.Endpoint
 

Sources/ClientRuntime/Interceptor/SendableHttpInterceptorProviderBox.swift

@@ -0,0 +1,29 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import class SmithyHTTPAPI.HTTPRequest
+import class SmithyHTTPAPI.HTTPResponse
+
+/// A `Sendable` wrapper for `HttpInterceptorProvider` that enables safe concurrent access.
+///
+/// This wrapper allows non-`Sendable` HTTP interceptor providers to be stored in `Sendable` contexts
+/// by boxing them and forwarding method calls.
+///
+/// Note: Uses `@unchecked Sendable` because the wrapper is designed to safely encapsulate
+/// non-Sendable providers for use in concurrent contexts. The safety is ensured by the
+/// immutability of the stored provider reference.
+public struct SendableHttpInterceptorProviderBox: HttpInterceptorProvider, @unchecked Sendable {
+    internal let _provider: any HttpInterceptorProvider
+
+    public init(_ provider: any HttpInterceptorProvider) {
+        self._provider = provider
+    }
+
+    public func create<InputType, OutputType>() -> any Interceptor<InputType, OutputType, HTTPRequest, HTTPResponse> {
+        return _provider.create()
+    }
+}

Sources/ClientRuntime/Interceptor/SendableInterceptorProviderBox.swift

@@ -0,0 +1,34 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import protocol Smithy.RequestMessage
+import protocol Smithy.ResponseMessage
+
+/// A `Sendable` wrapper for `InterceptorProvider` that enables safe concurrent access.
+///
+/// This wrapper allows non-`Sendable` interceptor providers to be stored in `Sendable` contexts
+/// by boxing them and forwarding method calls.
+///
+/// Note: Uses `@unchecked Sendable` because the wrapper is designed to safely encapsulate
+/// non-Sendable providers for use in concurrent contexts. The safety is ensured by the
+/// immutability of the stored provider reference.
+public struct SendableInterceptorProviderBox: InterceptorProvider, @unchecked Sendable {
+    internal let _provider: any InterceptorProvider
+
+    public init(_ provider: any InterceptorProvider) {
+        self._provider = provider
+    }
+
+    public func create<
+        InputType,
+        OutputType,
+        RequestType: RequestMessage,
+        ResponseType: ResponseMessage
+    >() -> any Interceptor<InputType, OutputType, RequestType, ResponseType> {
+        return _provider.create()
+    }
+}

Sources/ClientRuntime/Networking/Http/CRT/CRTClientEngine.swift

@@ -29,7 +29,7 @@ import Glibc
 import Darwin
 #endif
 
-public class CRTClientEngine: HTTPClient {
+public class CRTClientEngine: HTTPClient, @unchecked Sendable {
     public static let noOpCrtClientEngineTelemetry = HttpTelemetry(
         httpScope: "CRTClientEngine",
         telemetryProvider: DefaultTelemetry.provider
@@ -171,7 +171,7 @@ public class CRTClientEngine: HTTPClient {
 
     public typealias StreamContinuation = CheckedContinuation<HTTPResponse, Error>
     private let telemetry: HttpTelemetry
-    private var logger: LogAgent
+    private let logger: LogAgent
     private let serialExecutor: SerialExecutor
     private let CONTENT_LENGTH_HEADER = "Content-Length"
     private let AWS_COMMON_RUNTIME = "AwsCommonRuntime"

Sources/ClientRuntime/Networking/Http/SdkHttpClient.swift

@@ -9,7 +9,7 @@ import class SmithyHTTPAPI.HTTPRequest
 import class SmithyHTTPAPI.HTTPResponse
 
 /// this class will implement Handler per new middleware implementation
-public class SdkHttpClient: ExecuteRequest {
+public class SdkHttpClient: ExecuteRequest, @unchecked Sendable {
 
     let engine: HTTPClient
 

Sources/ClientRuntime/Networking/Http/URLSession/URLSessionHTTPClient.swift

@@ -48,15 +48,15 @@ import class SmithyStreams.BufferedStream
 
 /// A client that can be used to make requests to AWS services using `Foundation`'s `URLSession` HTTP client.
 ///
-/// This client is usable on all Swift platforms that support both the `URLSession` library and Objective-C interoperability features
-/// (these are generally the Apple platforms.)
+/// This client is usable on all Swift platforms that support both the `URLSession` library and
+/// Objective-C interoperability features (these are generally the Apple platforms.)
 ///
 /// Use of this client is recommended on all Apple platforms, and is required on Apple Watch ( see
 /// [TN3135: Low-level networking on watchOS](https://developer.apple.com/documentation/technotes/tn3135-low-level-networking-on-watchos)
 /// for details about allowable modes of networking on the Apple Watch platform.)
 ///
 /// On Linux platforms, we recommend using the CRT-based HTTP client for its configurability and performance.
-public final class URLSessionHTTPClient: HTTPClient {
+public final class URLSessionHTTPClient: HTTPClient, @unchecked Sendable {
     public static let noOpURLSessionHTTPClientTelemetry = HttpTelemetry(
         httpScope: "URLSessionHTTPClient",
         telemetryProvider: DefaultTelemetry.provider
@@ -107,7 +107,8 @@ public final class URLSessionHTTPClient: HTTPClient {
         /// `urlSession(_:task:didCompleteWithError)` for this connection.
         var error: Error?
 
-        /// A response stream that streams the response back to the caller.  Data is buffered in-memory until read by the caller.
+        /// A response stream that streams the response back to the caller.  Data is buffered
+        /// in-memory until read by the caller.
         let responseStream = BufferedStream()
 
         /// Creates a new connection object
@@ -406,7 +407,7 @@ public final class URLSessionHTTPClient: HTTPClient {
     private let telemetry: HttpTelemetry
 
     /// The logger for this HTTP client.
-    private var logger: LogAgent
+    private let logger: LogAgent
 
     /// The TLS options for this HTTP client.
     private let tlsConfiguration: URLSessionTLSOptions?

Sources/ClientRuntime/Orchestrator/OrchestratorTelemetry.swift

@@ -13,7 +13,7 @@ import enum SmithyHTTPAPI.SmithyHTTPAPIKeys
 /// Container for Orchestrator telemetry, including configurable attributes and names.
 ///
 /// Note: This is intended to be used within generated code, not directly.
-public class OrchestratorTelemetry {
+public final class OrchestratorTelemetry: Sendable {
     internal let contextManager: any TelemetryContextManager
     internal let tracerProvider: any TracerProvider
 

Sources/ClientRuntime/Pagination/PaginatorSequence.swift

@@ -33,14 +33,22 @@ public struct PaginatorSequence<OperationStackInput: PaginateToken, OperationSta
         var token: OperationStackInput.Token?
         var isFirstPage: Bool = true
 
-        // swiftlint:disable force_cast
         public mutating func next() async throws -> OperationStackOutput? {
             while token != nil || isFirstPage {
 
-                if let token = token,
-                   (token is String && !(token as! String).isEmpty) ||
-                    (token is [String: Any] && !(token as! [String: Any]).isEmpty) {
-                    self.input = input.usingPaginationToken(token)
+                if let token = token {
+                    let shouldUsePaginationToken: Bool
+                    if let stringToken = token as? String {
+                        shouldUsePaginationToken = !stringToken.isEmpty
+                    } else if let dictToken = token as? [String: Any] {
+                        shouldUsePaginationToken = !dictToken.isEmpty
+                    } else {
+                        shouldUsePaginationToken = true
+                    }
+
+                    if shouldUsePaginationToken {
+                        self.input = input.usingPaginationToken(token)
+                    }
                 }
                 let output = try await sequence.paginationFunction(input)
                 isFirstPage = false
@@ -62,7 +70,6 @@ public struct PaginatorSequence<OperationStackInput: PaginateToken, OperationSta
             }
             return nil
         }
-        // swiftlint:enable force_cast
     }
 
     public func makeAsyncIterator() -> PaginationIterator {

Sources/ClientRuntime/Plugins/AuthSchemePlugin.swift

@@ -21,14 +21,14 @@ public class AuthSchemePlugin: Plugin {
         self.authSchemes = authSchemes
     }
 
-    public func configureClient(clientConfiguration: ClientConfiguration) {
-        if var config = clientConfiguration as? DefaultHttpClientConfiguration {
-            if self.authSchemes != nil {
-                config.authSchemes = self.authSchemes!
-            }
-            if self.authSchemeResolver != nil {
-                config.authSchemeResolver = self.authSchemeResolver!
-            }
+    public func configureClient(clientConfiguration: inout ClientConfiguration) async throws {
+        guard var config = clientConfiguration as? any DefaultHttpClientConfiguration else { return }
+        if self.authSchemes != nil {
+            config.authSchemes = self.authSchemes!
         }
+        if self.authSchemeResolver != nil {
+            config.authSchemeResolver = self.authSchemeResolver!
+        }
+        clientConfiguration = config
     }
 }

Sources/ClientRuntime/Plugins/DefaultClientPlugin.swift

@@ -9,21 +9,23 @@ import struct SmithyRetries.DefaultRetryStrategy
 
 public class DefaultClientPlugin: Plugin {
     public init() {}
-    public func configureClient(clientConfiguration: ClientConfiguration) {
-        if var config = clientConfiguration as? DefaultClientConfiguration {
+    public func configureClient(clientConfiguration: inout ClientConfiguration) async throws {
+        if var config = clientConfiguration as? any DefaultClientConfiguration {
             config.retryStrategyOptions =
                 DefaultSDKRuntimeConfiguration<DefaultRetryStrategy, DefaultRetryErrorInfoProvider>
                     .defaultRetryStrategyOptions
+            clientConfiguration = config
         }
 
-        if var config = clientConfiguration as? DefaultHttpClientConfiguration {
+        if var config = clientConfiguration as? any DefaultHttpClientConfiguration {
             let httpClientConfiguration =
                 DefaultSDKRuntimeConfiguration<DefaultRetryStrategy, DefaultRetryErrorInfoProvider>
                     .defaultHttpClientConfiguration
             config.httpClientConfiguration = httpClientConfiguration
             config.httpClientEngine =
                 DefaultSDKRuntimeConfiguration<DefaultRetryStrategy, DefaultRetryErrorInfoProvider>
                     .makeClient(httpClientConfiguration: httpClientConfiguration)
+            clientConfiguration = config
         }
     }
 }

Sources/ClientRuntime/Plugins/HttpClientPlugin.swift

@@ -27,10 +27,10 @@ public class DefaultHttpClientPlugin: Plugin {
         )
     }
 
-    public func configureClient(clientConfiguration: ClientConfiguration) {
-        if var config = clientConfiguration as? DefaultHttpClientConfiguration {
-            config.httpClientConfiguration = self.httpClientConfiguration
-            config.httpClientEngine = self.httpClient
-        }
+    public func configureClient(clientConfiguration: inout ClientConfiguration) async throws {
+        guard var config = clientConfiguration as? any DefaultHttpClientConfiguration else { return }
+        config.httpClientConfiguration = self.httpClientConfiguration
+        config.httpClientEngine = self.httpClient
+        clientConfiguration = config
     }
 }

Sources/ClientRuntime/Plugins/Plugin.swift

@@ -6,5 +6,5 @@
 //
 
 public protocol Plugin {
-    func configureClient(clientConfiguration: ClientConfiguration) async throws
+    func configureClient(clientConfiguration: inout ClientConfiguration) async throws
 }