Add new handler protocols + Codable support (#351)

Sources/AWSLambdaRuntime/Lambda+Codable.swift

@@ -16,9 +16,13 @@
 import NIOCore
 import NIOFoundationCompat
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
 import struct Foundation.Data
 import class Foundation.JSONDecoder
 import class Foundation.JSONEncoder
+#endif
 
 // MARK: - SimpleLambdaHandler Codable support
 
@@ -138,3 +142,45 @@ extension Lambda {
 extension JSONDecoder: LambdaCodableDecoder {}
 
 extension JSONEncoder: LambdaCodableEncoder {}
+
+extension JSONDecoder: AWSLambdaRuntimeCore.LambdaEventDecoder {}
+
+@usableFromInline
+package struct LambdaJSONOutputEncoder<Output: Encodable>: LambdaOutputEncoder {
+    @usableFromInline let jsonEncoder: JSONEncoder
+
+    @inlinable
+    package init(_ jsonEncoder: JSONEncoder) {
+        self.jsonEncoder = jsonEncoder
+    }
+
+    @inlinable
+    package func encode(_ value: Output, into buffer: inout ByteBuffer) throws {
+        try self.jsonEncoder.encode(value, into: &buffer)
+    }
+}
+
+extension LambdaCodableAdapter {
+    /// Initializes an instance given an encoder, decoder, and a handler with a non-`Void` output.
+    ///   - Parameters:
+    ///   - encoder: The encoder object that will be used to encode the generic ``Output`` obtained from the `handler`'s `outputWriter` into a ``ByteBuffer``.
+    ///   - decoder: The decoder object that will be used to decode the received ``ByteBuffer`` event into the generic ``Event`` type served to the `handler`.
+    ///   - handler: The handler object.
+    package init(
+        encoder: JSONEncoder,
+        decoder: JSONDecoder,
+        handler: Handler
+    )
+    where
+        Output: Encodable,
+        Output == Handler.Output,
+        Encoder == LambdaJSONOutputEncoder<Output>,
+        Decoder == JSONDecoder
+    {
+        self.init(
+            encoder: LambdaJSONOutputEncoder(encoder),
+            decoder: decoder,
+            handler: handler
+        )
+    }
+}

Sources/AWSLambdaRuntimeCore/LambdaRuntimeClientProtocol.swift

@@ -14,15 +14,15 @@
 
 import NIOCore
 
-package protocol LambdaResponseStreamWriter {
-    mutating func write(_ buffer: ByteBuffer) async throws
+package protocol LambdaRuntimeClientResponseStreamWriter: LambdaResponseStreamWriter {
+    func write(_ buffer: ByteBuffer) async throws
     func finish() async throws
     func writeAndFinish(_ buffer: ByteBuffer) async throws
     func reportError(_ error: any Error) async throws
 }
 
 package protocol LambdaRuntimeClientProtocol {
-    associatedtype Writer: LambdaResponseStreamWriter
+    associatedtype Writer: LambdaRuntimeClientResponseStreamWriter
 
     func nextInvocation() async throws -> (Invocation, Writer)
 }

Sources/AWSLambdaRuntimeCore/NewLambda+JSON.swift

@@ -0,0 +1,161 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftAWSLambdaRuntime open source project
+//
+// Copyright (c) 2024 Apple Inc. and the SwiftAWSLambdaRuntime project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftAWSLambdaRuntime project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import NIOCore
+
+/// The protocol a decoder must conform to so that it can be used with ``LambdaCodableAdapter`` to decode incoming
+/// ``ByteBuffer`` events.
+package protocol LambdaEventDecoder {
+    /// Decode the ``ByteBuffer`` representing the received event into the generic ``Event`` type
+    /// the handler will receive.
+    /// - Parameters:
+    ///   - type: The type of the object to decode the buffer into.
+    ///   - buffer: The buffer to be decoded.
+    /// - Returns: An object containing the decoded data.
+    func decode<Event: Decodable>(_ type: Event.Type, from buffer: ByteBuffer) throws -> Event
+}
+
+/// The protocol an encoder must conform to so that it can be used with ``LambdaCodableAdapter`` to encode the generic
+/// ``Output`` object into a ``ByteBuffer``.
+package protocol LambdaOutputEncoder {
+    associatedtype Output
+
+    /// Encode the generic type `Output` the handler has returned into a ``ByteBuffer``.
+    /// - Parameters:
+    ///   - value: The object to encode into a ``ByteBuffer``.
+    ///   - buffer: The ``ByteBuffer`` where the encoded value will be written to.
+    func encode(_ value: Output, into buffer: inout ByteBuffer) throws
+}
+
+package struct VoidEncoder: LambdaOutputEncoder {
+    package typealias Output = Void
+
+    @inlinable
+    package func encode(_ value: Void, into buffer: inout NIOCore.ByteBuffer) throws {}
+}
+
+/// Adapts a ``NewLambdaHandler`` conforming handler to conform to ``LambdaWithBackgroundProcessingHandler``.
+package struct LambdaHandlerAdapter<
+    Event: Decodable,
+    Output,
+    Handler: NewLambdaHandler
+>: LambdaWithBackgroundProcessingHandler where Handler.Event == Event, Handler.Output == Output {
+    @usableFromInline let handler: Handler
+
+    /// Initializes an instance given a concrete handler.
+    /// - Parameter handler: The ``NewLambdaHandler`` conforming handler that is to be adapted to ``LambdaWithBackgroundProcessingHandler``.
+    @inlinable
+    package init(handler: Handler) {
+        self.handler = handler
+    }
+
+    /// Passes the generic ``Event`` object to the ``NewLambdaHandler/handle(_:context:)`` function, and
+    /// the resulting output is then written to ``LambdaWithBackgroundProcessingHandler``'s `outputWriter`.
+    /// - Parameters:
+    ///   - event: The received event.
+    ///   - outputWriter: The writer to write the computed response to.
+    ///   - context: The ``NewLambdaContext`` containing the invocation's metadata.
+    @inlinable
+    package func handle(
+        _ event: Event,
+        outputWriter: some LambdaResponseWriter<Output>,
+        context: NewLambdaContext
+    ) async throws {
+        let output = try await self.handler.handle(event, context: context)
+        try await outputWriter.write(output)
+    }
+}
+
+/// Adapts a ``LambdaWithBackgroundProcessingHandler`` conforming handler to conform to ``StreamingLambdaHandler``.
+package struct LambdaCodableAdapter<
+    Handler: LambdaWithBackgroundProcessingHandler,
+    Event: Decodable,
+    Output,
+    Decoder: LambdaEventDecoder,
+    Encoder: LambdaOutputEncoder
+>: StreamingLambdaHandler where Handler.Event == Event, Handler.Output == Output, Encoder.Output == Output {
+    @usableFromInline let handler: Handler
+    @usableFromInline let encoder: Encoder
+    @usableFromInline let decoder: Decoder
+    //
+    @usableFromInline var byteBuffer: ByteBuffer = .init()
+
+    /// Initializes an instance given an encoder, decoder, and a handler with a non-`Void` output.
+    ///   - Parameters:
+    ///   - encoder: The encoder object that will be used to encode the generic ``Output`` obtained from the `handler`'s `outputWriter` into a ``ByteBuffer``.
+    ///   - decoder: The decoder object that will be used to decode the received ``ByteBuffer`` event into the generic ``Event`` type served to the `handler`.
+    ///   - handler: The handler object.
+    @inlinable
+    package init(encoder: Encoder, decoder: Decoder, handler: Handler) where Output: Encodable {
+        self.encoder = encoder
+        self.decoder = decoder
+        self.handler = handler
+    }
+
+    /// Initializes an instance given a decoder, and a handler with a `Void` output.
+    ///   - Parameters:
+    ///   - decoder: The decoder object that will be used to decode the received ``ByteBuffer`` event into the generic ``Event`` type served to the `handler`.
+    ///   - handler: The handler object.
+    @inlinable
+    package init(decoder: Decoder, handler: Handler) where Output == Void, Encoder == VoidEncoder {
+        self.encoder = VoidEncoder()
+        self.decoder = decoder
+        self.handler = handler
+    }
+
+    /// A ``StreamingLambdaHandler/handle(_:responseWriter:context:)`` wrapper.
+    ///   - Parameters:
+    ///   - event: The received event.
+    ///   - outputWriter: The writer to write the computed response to.
+    ///   - context: The ``NewLambdaContext`` containing the invocation's metadata.
+    @inlinable
+    package mutating func handle<Writer: LambdaResponseStreamWriter>(
+        _ request: ByteBuffer,
+        responseWriter: Writer,
+        context: NewLambdaContext
+    ) async throws {
+        let event = try self.decoder.decode(Event.self, from: request)
+
+        let writer = LambdaCodableResponseWriter<Output, Encoder, Writer>(
+            encoder: self.encoder,
+            streamWriter: responseWriter
+        )
+        try await self.handler.handle(event, outputWriter: writer, context: context)
+    }
+}
+
+/// A ``LambdaResponseStreamWriter`` wrapper that conforms to ``LambdaResponseWriter``.
+package struct LambdaCodableResponseWriter<Output, Encoder: LambdaOutputEncoder, Base: LambdaResponseStreamWriter>:
+    LambdaResponseWriter
+where Output == Encoder.Output {
+    @usableFromInline let underlyingStreamWriter: Base
+    @usableFromInline let encoder: Encoder
+
+    /// Initializes an instance given an encoder and an underlying ``LambdaResponseStreamWriter``.
+    /// - Parameters:
+    ///   - encoder: The encoder object that will be used to encode the generic ``Output`` into a ``ByteBuffer``, which will then be passed to `streamWriter`.
+    ///   - streamWriter: The underlying ``LambdaResponseStreamWriter`` that will be wrapped.
+    @inlinable
+    package init(encoder: Encoder, streamWriter: Base) {
+        self.encoder = encoder
+        self.underlyingStreamWriter = streamWriter
+    }
+
+    @inlinable
+    package func write(_ output: Output) async throws {
+        var outputBuffer = ByteBuffer()
+        try self.encoder.encode(output, into: &outputBuffer)
+        try await self.underlyingStreamWriter.writeAndFinish(outputBuffer)
+    }
+}

Sources/AWSLambdaRuntimeCore/NewLambda.swift

@@ -14,15 +14,6 @@
 
 import Dispatch
 import Logging
-import NIOCore
-
-package protocol StreamingLambdaHandler {
-    mutating func handle(
-        _ event: ByteBuffer,
-        responseWriter: some LambdaResponseStreamWriter,
-        context: NewLambdaContext
-    ) async throws
-}
 
 extension Lambda {
     package static func runLoop<RuntimeClient: LambdaRuntimeClientProtocol, Handler>(

Sources/AWSLambdaRuntimeCore/NewLambdaContext.swift

@@ -126,8 +126,7 @@ package struct NewLambdaContext: CustomDebugStringConvertible, Sendable {
         traceID: String,
         invokedFunctionARN: String,
         timeout: DispatchTimeInterval,
-        logger: Logger,
-        eventLoop: EventLoop
+        logger: Logger
     ) -> NewLambdaContext {
         NewLambdaContext(
             requestID: requestID,