async/await support (#186)

- Add an `AsyncLambdaHandler`. Will be renamed to `LambdaHandler` as soon as we drop the current callback based `LambdaHandler`.
- The default way to use an `AsyncLambdaHandler` is to use `@main` to execute it. Don't use `Lambda.run` for it. We wan't to remove `Lambda.run` for 1.0.

Co-authored-by: tomer doron <tomerd@apple.com>

Package.swift

@@ -15,7 +15,7 @@ let package = Package(
         .library(name: "AWSLambdaTesting", targets: ["AWSLambdaTesting"]),
     ],
     dependencies: [
-        .package(url: "https://github.com/apple/swift-nio.git", .upToNextMajor(from: "2.26.0")),
+        .package(url: "https://github.com/apple/swift-nio.git", .upToNextMajor(from: "2.28.0")),
         .package(url: "https://github.com/apple/swift-log.git", .upToNextMajor(from: "1.0.0")),
         .package(url: "https://github.com/swift-server/swift-backtrace.git", .upToNextMajor(from: "1.1.0")),
     ],
@@ -29,6 +29,7 @@ let package = Package(
             .product(name: "Logging", package: "swift-log"),
             .product(name: "Backtrace", package: "swift-backtrace"),
             .product(name: "NIOHTTP1", package: "swift-nio"),
+            .product(name: "_NIOConcurrency", package: "swift-nio"),
         ]),
         .testTarget(name: "AWSLambdaRuntimeCoreTests", dependencies: [
             .byName(name: "AWSLambdaRuntimeCore"),

Sources/AWSLambdaRuntime/Lambda+Codable.swift

@@ -78,6 +78,8 @@ internal struct CodableVoidClosureWrapper<In: Decodable>: LambdaHandler {
     }
 }
 
+// MARK: - Codable support
+
 /// Implementation of  a`ByteBuffer` to `In` decoding
 extension EventLoopLambdaHandler where In: Decodable {
     @inlinable

Sources/AWSLambdaRuntimeCore/Lambda.swift

@@ -18,6 +18,7 @@ import Glibc
 import Darwin.C
 #endif
 
+import _NIOConcurrency
 import Backtrace
 import Logging
 import NIO

Sources/AWSLambdaRuntimeCore/LambdaHandler.swift

@@ -85,6 +85,56 @@ extension LambdaHandler {
     }
 }
 
+// MARK: - AsyncLambdaHandler
+
+#if compiler(>=5.5)
+/// Strongly typed, processing protocol for a Lambda that takes a user defined `In` and returns a user defined `Out` async.
+@available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
+public protocol AsyncLambdaHandler: EventLoopLambdaHandler {
+    /// The Lambda initialization method
+    /// Use this method to initialize resources that will be used in every request.
+    ///
+    /// Examples for this can be HTTP or database clients.
+    /// - parameters:
+    ///     - context: Runtime `InitializationContext`.
+    init(context: Lambda.InitializationContext) async throws
+
+    /// The Lambda handling method
+    /// Concrete Lambda handlers implement this method to provide the Lambda functionality.
+    ///
+    /// - parameters:
+    ///     - event: Event of type `In` representing the event or request.
+    ///     - context: Runtime `Context`.
+    ///
+    /// - Returns: A Lambda result ot type `Out`.
+    func handle(event: In, context: Lambda.Context) async throws -> Out
+}
+
+@available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
+extension AsyncLambdaHandler {
+    public func handle(context: Lambda.Context, event: In) -> EventLoopFuture<Out> {
+        let promise = context.eventLoop.makePromise(of: Out.self)
+        promise.completeWithAsync {
+            try await self.handle(event: event, context: context)
+        }
+        return promise.futureResult
+    }
+}
+
+@available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
+extension AsyncLambdaHandler {
+    public static func main() {
+        Lambda.run { context -> EventLoopFuture<ByteBufferLambdaHandler> in
+            let promise = context.eventLoop.makePromise(of: ByteBufferLambdaHandler.self)
+            promise.completeWithAsync {
+                try await Self(context: context)
+            }
+            return promise.futureResult
+        }
+    }
+}
+#endif
+
 // MARK: - EventLoopLambdaHandler
 
 /// Strongly typed, `EventLoopFuture` based processing protocol for a Lambda that takes a user defined `In` and returns a user defined `Out` asynchronously.

Tests/AWSLambdaRuntimeCoreTests/LambdaHandlerTest.swift

@@ -16,7 +16,9 @@
 import NIO
 import XCTest
 
-class StringLambdaTest: XCTestCase {
+class LambdaHandlerTest: XCTestCase {
+    // MARK: - Callback
+
     func testCallbackSuccess() {
         let server = MockLambdaServer(behavior: Behavior())
         XCTAssertNoThrow(try server.start().wait())
@@ -77,6 +79,80 @@ class StringLambdaTest: XCTestCase {
         assertLambdaLifecycleResult(result, shoudHaveRun: maxTimes)
     }
 
+    #if compiler(>=5.5)
+
+    // MARK: - AsyncLambdaHandler
+
+    @available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
+    func testAsyncHandlerSuccess() {
+        let server = MockLambdaServer(behavior: Behavior())
+        XCTAssertNoThrow(try server.start().wait())
+        defer { XCTAssertNoThrow(try server.stop().wait()) }
+
+        struct Handler: AsyncLambdaHandler {
+            typealias In = String
+            typealias Out = String
+
+            init(context: Lambda.InitializationContext) {}
+
+            func handle(event: String, context: Lambda.Context) async throws -> String {
+                event
+            }
+        }
+
+        let maxTimes = Int.random(in: 1 ... 10)
+        let configuration = Lambda.Configuration(lifecycle: .init(maxTimes: maxTimes))
+        let result = Lambda.run(configuration: configuration, factory: Handler.init)
+        assertLambdaLifecycleResult(result, shoudHaveRun: maxTimes)
+    }
+
+    @available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
+    func testVoidAsyncHandlerSuccess() {
+        let server = MockLambdaServer(behavior: Behavior(result: .success(nil)))
+        XCTAssertNoThrow(try server.start().wait())
+        defer { XCTAssertNoThrow(try server.stop().wait()) }
+
+        struct Handler: AsyncLambdaHandler {
+            typealias In = String
+            typealias Out = Void
+
+            init(context: Lambda.InitializationContext) {}
+
+            func handle(event: String, context: Lambda.Context) async throws {}
+        }
+
+        let maxTimes = Int.random(in: 1 ... 10)
+        let configuration = Lambda.Configuration(lifecycle: .init(maxTimes: maxTimes))
+        let result = Lambda.run(configuration: configuration, factory: Handler.init)
+        assertLambdaLifecycleResult(result, shoudHaveRun: maxTimes)
+    }
+
+    @available(macOS 9999, iOS 9999, watchOS 9999, tvOS 9999, *)
+    func testAsyncHandlerFailure() {
+        let server = MockLambdaServer(behavior: Behavior(result: .failure(TestError("boom"))))
+        XCTAssertNoThrow(try server.start().wait())
+        defer { XCTAssertNoThrow(try server.stop().wait()) }
+
+        struct Handler: AsyncLambdaHandler {
+            typealias In = String
+            typealias Out = String
+
+            init(context: Lambda.InitializationContext) {}
+
+            func handle(event: String, context: Lambda.Context) async throws -> String {
+                throw TestError("boom")
+            }
+        }
+
+        let maxTimes = Int.random(in: 1 ... 10)
+        let configuration = Lambda.Configuration(lifecycle: .init(maxTimes: maxTimes))
+        let result = Lambda.run(configuration: configuration, factory: Handler.init)
+        assertLambdaLifecycleResult(result, shoudHaveRun: maxTimes)
+    }
+    #endif
+
+    // MARK: - EventLoop
+
     func testEventLoopSuccess() {
         let server = MockLambdaServer(behavior: Behavior())
         XCTAssertNoThrow(try server.start().wait())
@@ -137,6 +213,8 @@ class StringLambdaTest: XCTestCase {
         assertLambdaLifecycleResult(result, shoudHaveRun: maxTimes)
     }
 
+    // MARK: - Closure
+
     func testClosureSuccess() {
         let server = MockLambdaServer(behavior: Behavior())
         XCTAssertNoThrow(try server.start().wait())

Tests/AWSLambdaRuntimeTests/Lambda+CodeableTest.swift

@@ -53,7 +53,7 @@ class CodableLambdaTest: XCTestCase {
         var response: Response?
 
         let closureWrapper = CodableClosureWrapper { (_, req: Request, completion: (Result<Response, Error>) -> Void) in
-            XCTAssertEqual(request, request)
+            XCTAssertEqual(request, req)
             completion(.success(Response(requestId: req.requestId)))
         }
 

docker/docker-compose.al2.main.yaml

@@ -10,9 +10,14 @@ services:
 
   test:
     image: swift-aws-lambda:al2-main
+    command: /bin/bash -cl "swift test --enable-test-discovery -Xswiftc -warnings-as-errors $${SANITIZER_ARG-} -Xswiftc -Xfrontend -Xswiftc -enable-experimental-concurrency"
 
   test-samples:
     image: swift-aws-lambda:al2-main
+    command: >-
+      /bin/bash -clx "
+      swift build -Xswiftc -Xfrontend -Xswiftc -enable-experimental-concurrency --package-path Examples/LambdaFunctions &&
+      swift build -Xswiftc -Xfrontend -Xswiftc -enable-experimental-concurrency --package-path Examples/LocalDebugging/MyLambda"
 
   shell:
     image: swift-aws-lambda:al2-main