async/await support

Author: fabianfett

Package.swift

@@ -24,12 +24,12 @@ let package = Package(
             .byName(name: "AWSLambdaRuntimeCore"),
             .product(name: "NIO", package: "swift-nio"),
             .product(name: "NIOFoundationCompat", package: "swift-nio"),
-        ]),
+        ], swiftSettings: [.unsafeFlags(["-Xfrontend", "-enable-experimental-concurrency"])]),
         .target(name: "AWSLambdaRuntimeCore", dependencies: [
             .product(name: "Logging", package: "swift-log"),
             .product(name: "Backtrace", package: "swift-backtrace"),
             .product(name: "NIOHTTP1", package: "swift-nio"),
-        ]),
+        ], swiftSettings: [.unsafeFlags(["-Xfrontend", "-enable-experimental-concurrency"])]),
         .testTarget(name: "AWSLambdaRuntimeCoreTests", dependencies: [
             .byName(name: "AWSLambdaRuntimeCore"),
             .product(name: "NIOTestUtils", package: "swift-nio"),

Sources/AWSLambdaRuntime/Lambda+Codable.swift

@@ -78,6 +78,69 @@ internal struct CodableVoidClosureWrapper<In: Decodable>: LambdaHandler {
     }
 }
 
+// MARK: - Async
+
+extension Lambda {
+    
+    /// An async Lambda Closure that takes a `In: Decodable` and returns an `Out: Encodable`
+    public typealias CodableAsyncClosure<In: Decodable, Out: Encodable> = (Lambda.Context, In) async throws -> Out
+    
+    /// Run a Lambda defined by implementing the `CodableAsyncClosure` function.
+    ///
+    /// - parameters:
+    ///     - closure: `CodableAsyncClosure` based Lambda.
+    ///
+    /// - note: This is a blocking operation that will run forever, as its lifecycle is managed by the AWS Lambda Runtime Engine.
+    public static func run<In: Decodable, Out: Encodable>(_ closure: @escaping CodableAsyncClosure<In, Out>) {
+        self.run(CodableAsyncWrapper(closure))
+    }
+
+    /// An asynchronous Lambda Closure that takes a `In: Decodable` and returns nothing.
+    public typealias CodableVoidAsyncClosure<In: Decodable> = (Lambda.Context, In) async throws -> ()
+
+    /// Run a Lambda defined by implementing the `CodableVoidAsyncClosure` function.
+    ///
+    /// - parameters:
+    ///     - closure: `CodableVoidAsyncClosure` based Lambda.
+    ///
+    /// - note: This is a blocking operation that will run forever, as its lifecycle is managed by the AWS Lambda Runtime Engine.
+    public static func run<In: Decodable>(_ closure: @escaping CodableVoidAsyncClosure<In>) {
+        self.run(CodableVoidAsyncWrapper(closure))
+    }
+}
+
+internal struct CodableAsyncWrapper<In: Decodable, Out: Encodable>: AsyncLambdaHandler {
+    typealias In = In
+    typealias Out = Out
+
+    private let closure: Lambda.CodableAsyncClosure<In, Out>
+
+    init(_ closure: @escaping Lambda.CodableAsyncClosure<In, Out>) {
+        self.closure = closure
+    }
+
+    func handle(context: Lambda.Context, event: In) async throws -> Out {
+        try await self.closure(context, event)
+    }
+}
+
+internal struct CodableVoidAsyncWrapper<In: Decodable>: AsyncLambdaHandler {
+    typealias In = In
+    typealias Out = Void
+
+    private let closure: Lambda.CodableVoidAsyncClosure<In>
+
+    init(_ closure: @escaping Lambda.CodableVoidAsyncClosure<In>) {
+        self.closure = closure
+    }
+
+    func handle(context: Lambda.Context, event: In) async throws -> Void {
+        try await self.closure(context, event)
+    }
+}
+
+// MARK: - Codable support
+
 /// Implementation of  a`ByteBuffer` to `In` decoding
 extension EventLoopLambdaHandler where In: Decodable {
     public func decode(buffer: ByteBuffer) throws -> In {

Sources/AWSLambdaRuntimeCore/LambdaHandler.swift

@@ -83,6 +83,39 @@ extension LambdaHandler {
     }
 }
 
+// MARK: - AsyncLambdaHandler
+
+/// Strongly typed, processing protocol for a Lambda that takes a user defined `In` and returns a user defined `Out` async.
+public protocol AsyncLambdaHandler: EventLoopLambdaHandler {
+    
+    /// The Lambda handling method
+    /// Concrete Lambda handlers implement this method to provide the Lambda functionality.
+    ///
+    /// - parameters:
+    ///     - context: Runtime `Context`.
+    ///     - event: Event of type `In` representing the event or request.
+    ///
+    /// - Returns: A Lambda result ot type `Out`.
+    func handle(context: Lambda.Context, event: In) async throws -> Out
+}
+
+extension AsyncLambdaHandler {
+    public func handle(context: Lambda.Context, event: In) -> EventLoopFuture<Out> {
+        @asyncHandler func _run(context: Lambda.Context, event: In, promise: EventLoopPromise<Out>) {
+            do {
+                let result = try await handle(context: context, event: event)
+                promise.succeed(result)
+            } catch {
+                promise.fail(error)
+            }
+        }
+        
+        let promise = context.eventLoop.makePromise(of: Out.self)
+        _run(context: context, event: event, promise: promise)
+        return promise.futureResult
+    }
+}
+
 // MARK: - EventLoopLambdaHandler
 
 /// Strongly typed, `EventLoopFuture` based processing protocol for a Lambda that takes a user defined `In` and returns a user defined `Out` asynchronously.