[RFC] Drop event label from handle methods in LambdaHandlers (#225)

* Drop event label from handle method in LambdaHandlers
* Rename `In` to `Event` and `Out` to `Output` in `EventLoopLambdaHandler`

Author: fabianfett

Examples/LambdaFunctions/Sources/Benchmark/main.swift

@@ -22,10 +22,10 @@ import NIO
 Lambda.run { $0.eventLoop.makeSucceededFuture(BenchmarkHandler()) }
 
 struct BenchmarkHandler: EventLoopLambdaHandler {
-    typealias In = String
-    typealias Out = String
+    typealias Event = String
+    typealias Output = String
 
-    func handle(event: String, context: Lambda.Context) -> EventLoopFuture<String> {
+    func handle(_ event: String, context: Lambda.Context) -> EventLoopFuture<String> {
         context.eventLoop.makeSucceededFuture("hello, world!")
     }
 }

Examples/LambdaFunctions/Sources/CurrencyExchange/CurrencyExchangeHandler.swift

@@ -25,8 +25,8 @@ import Logging
 
 @main
 struct CurrencyExchangeHandler: LambdaHandler {
-    typealias In = Request
-    typealias Out = [Exchange]
+    typealias Event = Request
+    typealias Output = [Exchange]
 
     let calculator: ExchangeRatesCalculator
 
@@ -35,7 +35,7 @@ struct CurrencyExchangeHandler: LambdaHandler {
         self.calculator = ExchangeRatesCalculator()
     }
 
-    func handle(event: Request, context: Lambda.Context) async throws -> [Exchange] {
+    func handle(_ event: Request, context: Lambda.Context) async throws -> [Exchange] {
         try await withCheckedThrowingContinuation { continuation in
             self.calculator.run(logger: context.logger) { result in
                 switch result {

Examples/LambdaFunctions/Sources/ErrorHandling/ErrorsHappenHandler.swift

@@ -18,12 +18,12 @@ import AWSLambdaRuntime
 
 @main
 struct ErrorsHappenHandler: LambdaHandler {
-    typealias In = Request
-    typealias Out = Response
+    typealias Event = Request
+    typealias Output = Response
 
     init(context: Lambda.InitializationContext) async throws {}
 
-    func handle(event request: Request, context: Lambda.Context) async throws -> Response {
+    func handle(_ request: Request, context: Lambda.Context) async throws -> Response {
         // switch over the error type "requested" by the request, and trigger such error accordingly
         switch request.error {
         // no error here!

Examples/LambdaFunctions/Sources/HelloWorld/HelloWorldHandler.swift

@@ -17,14 +17,14 @@ import AWSLambdaRuntime
 // introductory example, the obligatory "hello, world!"
 @main
 struct HelloWorldHandler: LambdaHandler {
-    typealias In = String
-    typealias Out = String
+    typealias Event = String
+    typealias Output = String
 
     init(context: Lambda.InitializationContext) async throws {
         // setup your resources that you want to reuse here.
     }
 
-    func handle(event: String, context: Lambda.Context) async throws -> String {
+    func handle(_ event: String, context: Lambda.Context) async throws -> String {
         "hello, world"
     }
 }

Examples/LocalDebugging/MyLambda/Sources/MyLambda/MyLambdaHandler.swift

@@ -19,14 +19,14 @@ import Shared
 // a local server simulator which will allow local debugging
 @main
 struct MyLambdaHandler: LambdaHandler {
-    typealias In = Request
-    typealias Out = Response
+    typealias Event = Request
+    typealias Output = Response
 
     init(context: Lambda.InitializationContext) async throws {
         // setup your resources that you want to reuse for every invocation here.
     }
 
-    func handle(event request: Request, context: Lambda.Context) async throws -> Response {
+    func handle(_ request: Request, context: Lambda.Context) async throws -> Response {
         // TODO: something useful
         Response(message: "Hello, \(request.name)!")
     }

Sources/AWSLambdaRuntime/Lambda+Codable.swift

@@ -21,33 +21,33 @@ import NIOFoundationCompat
 
 // MARK: - Codable support
 
-/// Implementation of  a`ByteBuffer` to `In` decoding
-extension EventLoopLambdaHandler where In: Decodable {
+/// Implementation of  a`ByteBuffer` to `Event` decoding
+extension EventLoopLambdaHandler where Event: Decodable {
     @inlinable
-    public func decode(buffer: ByteBuffer) throws -> In {
-        try self.decoder.decode(In.self, from: buffer)
+    public func decode(buffer: ByteBuffer) throws -> Event {
+        try self.decoder.decode(Event.self, from: buffer)
     }
 }
 
-/// Implementation of  `Out` to `ByteBuffer` encoding
-extension EventLoopLambdaHandler where Out: Encodable {
+/// Implementation of  `Output` to `ByteBuffer` encoding
+extension EventLoopLambdaHandler where Output: Encodable {
     @inlinable
-    public func encode(allocator: ByteBufferAllocator, value: Out) throws -> ByteBuffer? {
+    public func encode(allocator: ByteBufferAllocator, value: Output) throws -> ByteBuffer? {
         try self.encoder.encode(value, using: allocator)
     }
 }
 
-/// Default `ByteBuffer` to `In` decoder using Foundation's JSONDecoder
+/// Default `ByteBuffer` to `Event` decoder using Foundation's JSONDecoder
 /// Advanced users that want to inject their own codec can do it by overriding these functions.
-extension EventLoopLambdaHandler where In: Decodable {
+extension EventLoopLambdaHandler where Event: Decodable {
     public var decoder: LambdaCodableDecoder {
         Lambda.defaultJSONDecoder
     }
 }
 
-/// Default `Out` to `ByteBuffer` encoder using Foundation's JSONEncoder
+/// Default `Output` to `ByteBuffer` encoder using Foundation's JSONEncoder
 /// Advanced users that want to inject their own codec can do it by overriding these functions.
-extension EventLoopLambdaHandler where Out: Encodable {
+extension EventLoopLambdaHandler where Output: Encodable {
     public var encoder: LambdaCodableEncoder {
         Lambda.defaultJSONEncoder
     }

Sources/AWSLambdaRuntimeCore/Lambda+String.swift

@@ -13,7 +13,7 @@
 //===----------------------------------------------------------------------===//
 import NIOCore
 
-extension EventLoopLambdaHandler where In == String {
+extension EventLoopLambdaHandler where Event == String {
     /// Implementation of a `ByteBuffer` to `String` decoding
     @inlinable
     public func decode(buffer: ByteBuffer) throws -> String {
@@ -25,7 +25,7 @@ extension EventLoopLambdaHandler where In == String {
     }
 }
 
-extension EventLoopLambdaHandler where Out == String {
+extension EventLoopLambdaHandler where Output == String {
     /// Implementation of `String` to `ByteBuffer` encoding
     @inlinable
     public func encode(allocator: ByteBufferAllocator, value: String) throws -> ByteBuffer? {

Sources/AWSLambdaRuntimeCore/LambdaHandler.swift

@@ -19,7 +19,7 @@ import NIOCore
 // MARK: - LambdaHandler
 
 #if compiler(>=5.5)
-/// Strongly typed, processing protocol for a Lambda that takes a user defined `In` and returns a user defined `Out` async.
+/// Strongly typed, processing protocol for a Lambda that takes a user defined `Event` and returns a user defined `Output` async.
 @available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
 public protocol LambdaHandler: EventLoopLambdaHandler {
     /// The Lambda initialization method
@@ -34,19 +34,19 @@ public protocol LambdaHandler: EventLoopLambdaHandler {
     /// Concrete Lambda handlers implement this method to provide the Lambda functionality.
     ///
     /// - parameters:
-    ///     - event: Event of type `In` representing the event or request.
+    ///     - event: Event of type `Event` 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
+    /// - Returns: A Lambda result ot type `Output`.
+    func handle(_ event: Event, context: Lambda.Context) async throws -> Output
 }
 
 @available(macOS 12, iOS 15, tvOS 15, watchOS 8, *)
 extension LambdaHandler {
-    public func handle(event: In, context: Lambda.Context) -> EventLoopFuture<Out> {
-        let promise = context.eventLoop.makePromise(of: Out.self)
+    public func handle(_ event: Event, context: Lambda.Context) -> EventLoopFuture<Output> {
+        let promise = context.eventLoop.makePromise(of: Output.self)
         promise.completeWithTask {
-            try await self.handle(event: event, context: context)
+            try await self.handle(event, context: context)
         }
         return promise.futureResult
     }
@@ -62,59 +62,59 @@ extension LambdaHandler {
 
 // MARK: - EventLoopLambdaHandler
 
-/// Strongly typed, `EventLoopFuture` based processing protocol for a Lambda that takes a user defined `In` and returns a user defined `Out` asynchronously.
-/// `EventLoopLambdaHandler` extends `ByteBufferLambdaHandler`, performing `ByteBuffer` -> `In` decoding and `Out` -> `ByteBuffer` encoding.
+/// Strongly typed, `EventLoopFuture` based processing protocol for a Lambda that takes a user defined `Event` and returns a user defined `Output` asynchronously.
+/// `EventLoopLambdaHandler` extends `ByteBufferLambdaHandler`, performing `ByteBuffer` -> `Event` decoding and `Output` -> `ByteBuffer` encoding.
 ///
 /// - note: To implement a Lambda, implement either `LambdaHandler` or the `EventLoopLambdaHandler` protocol.
 ///         The `LambdaHandler` will offload the Lambda execution to a `DispatchQueue` making processing safer but slower
 ///         The `EventLoopLambdaHandler` will execute the Lambda on the same `EventLoop` as the core runtime engine, making the processing faster but requires
 ///         more care from the implementation to never block the `EventLoop`.
 public protocol EventLoopLambdaHandler: ByteBufferLambdaHandler {
-    associatedtype In
-    associatedtype Out
+    associatedtype Event
+    associatedtype Output
 
     /// 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.
+    ///     - event: Event of type `Event` representing the event or request.
     ///
     /// - Returns: An `EventLoopFuture` to report the result of the Lambda back to the runtime engine.
-    ///            The `EventLoopFuture` should be completed with either a response of type `Out` or an `Error`
-    func handle(event: In, context: Lambda.Context) -> EventLoopFuture<Out>
+    ///            The `EventLoopFuture` should be completed with either a response of type `Output` or an `Error`
+    func handle(_ event: Event, context: Lambda.Context) -> EventLoopFuture<Output>
 
-    /// Encode a response of type `Out` to `ByteBuffer`
+    /// Encode a response of type `Output` to `ByteBuffer`
     /// Concrete Lambda handlers implement this method to provide coding functionality.
     /// - parameters:
     ///     - allocator: A `ByteBufferAllocator` to help allocate the `ByteBuffer`.
-    ///     - value: Response of type `Out`.
+    ///     - value: Response of type `Output`.
     ///
     /// - Returns: A `ByteBuffer` with the encoded version of the `value`.
-    func encode(allocator: ByteBufferAllocator, value: Out) throws -> ByteBuffer?
+    func encode(allocator: ByteBufferAllocator, value: Output) throws -> ByteBuffer?
 
-    /// Decode a`ByteBuffer` to a request or event of type `In`
+    /// Decode a`ByteBuffer` to a request or event of type `Event`
     /// Concrete Lambda handlers implement this method to provide coding functionality.
     ///
     /// - parameters:
     ///     - buffer: The `ByteBuffer` to decode.
     ///
-    /// - Returns: A request or event of type `In`.
-    func decode(buffer: ByteBuffer) throws -> In
+    /// - Returns: A request or event of type `Event`.
+    func decode(buffer: ByteBuffer) throws -> Event
 }
 
 extension EventLoopLambdaHandler {
-    /// Driver for `ByteBuffer` -> `In` decoding and `Out` -> `ByteBuffer` encoding
+    /// Driver for `ByteBuffer` -> `Event` decoding and `Output` -> `ByteBuffer` encoding
     @inlinable
-    public func handle(event: ByteBuffer, context: Lambda.Context) -> EventLoopFuture<ByteBuffer?> {
-        let input: In
+    public func handle(_ event: ByteBuffer, context: Lambda.Context) -> EventLoopFuture<ByteBuffer?> {
+        let input: Event
         do {
             input = try self.decode(buffer: event)
         } catch {
             return context.eventLoop.makeFailedFuture(CodecError.requestDecoding(error))
         }
 
-        return self.handle(event: input, context: context).flatMapThrowing { output in
+        return self.handle(input, context: context).flatMapThrowing { output in
             do {
                 return try self.encode(allocator: context.allocator, value: output)
             } catch {
@@ -125,7 +125,7 @@ extension EventLoopLambdaHandler {
 }
 
 /// Implementation of  `ByteBuffer` to `Void` decoding
-extension EventLoopLambdaHandler where Out == Void {
+extension EventLoopLambdaHandler where Output == Void {
     @inlinable
     public func encode(allocator: ByteBufferAllocator, value: Void) throws -> ByteBuffer? {
         nil
@@ -148,7 +148,7 @@ public protocol ByteBufferLambdaHandler {
     ///
     /// - Returns: An `EventLoopFuture` to report the result of the Lambda back to the runtime engine.
     ///            The `EventLoopFuture` should be completed with either a response encoded as `ByteBuffer` or an `Error`
-    func handle(event: ByteBuffer, context: Lambda.Context) -> EventLoopFuture<ByteBuffer?>
+    func handle(_ event: ByteBuffer, context: Lambda.Context) -> EventLoopFuture<ByteBuffer?>
 
     /// Clean up the Lambda resources asynchronously.
     /// Concrete Lambda handlers implement this method to shutdown resources like `HTTPClient`s and database connections.

Sources/AWSLambdaRuntimeCore/LambdaRunner.swift

@@ -62,15 +62,15 @@ extension Lambda {
             self.isGettingNextInvocation = true
             return self.runtimeClient.getNextInvocation(logger: logger).peekError { error in
                 logger.error("could not fetch work from lambda runtime engine: \(error)")
-            }.flatMap { invocation, event in
+            }.flatMap { invocation, bytes in
                 // 2. send invocation to handler
                 self.isGettingNextInvocation = false
                 let context = Context(logger: logger,
                                       eventLoop: self.eventLoop,
                                       allocator: self.allocator,
                                       invocation: invocation)
                 logger.debug("sending invocation to lambda handler \(handler)")
-                return handler.handle(event: event, context: context)
+                return handler.handle(bytes, context: context)
                     // Hopping back to "our" EventLoop is important in case the handler returns a future that
                     // originiated from a foreign EventLoop/EventLoopGroup.
                     // This can happen if the handler uses a library (lets say a DB client) that manages its own threads/loops

Sources/AWSLambdaTesting/Lambda+Testing.swift

@@ -66,9 +66,9 @@ extension Lambda {
 
     public static func test<Handler: LambdaHandler>(
         _ handlerType: Handler.Type,
-        with event: Handler.In,
+        with event: Handler.Event,
         using config: TestConfig = .init()
-    ) throws -> Handler.Out {
+    ) throws -> Handler.Output {
         let logger = Logger(label: "test")
         let eventLoopGroup = MultiThreadedEventLoopGroup(numberOfThreads: 1)
         defer {
@@ -97,7 +97,7 @@ extension Lambda {
         let handler = try promise.futureResult.wait()
 
         return try eventLoop.flatSubmit {
-            handler.handle(event: event, context: context)
+            handler.handle(event, context: context)
         }.wait()
     }
 }

Sources/CodableSample/main.swift

@@ -26,10 +26,10 @@ struct Response: Codable {
 // in this example we are receiving and responding with codables. Request and Response above are examples of how to use
 // codables to model your reqeuest and response objects
 struct Handler: EventLoopLambdaHandler {
-    typealias In = Request
-    typealias Out = Response
+    typealias Event = Request
+    typealias Output = Response
 
-    func handle(event: Request, context: Lambda.Context) -> EventLoopFuture<Response> {
+    func handle(_ event: Request, context: Lambda.Context) -> EventLoopFuture<Response> {
         // as an example, respond with the input event's reversed body
         context.eventLoop.makeSucceededFuture(Response(body: String(event.body.reversed())))
     }

Sources/StringSample/main.swift

@@ -17,10 +17,10 @@ import NIOCore
 
 // in this example we are receiving and responding with strings
 struct Handler: EventLoopLambdaHandler {
-    typealias In = String
-    typealias Out = String
+    typealias Event = String
+    typealias Output = String
 
-    func handle(event: String, context: Lambda.Context) -> EventLoopFuture<String> {
+    func handle(_ event: String, context: Lambda.Context) -> EventLoopFuture<String> {
         // as an example, respond with the event's reversed body
         context.eventLoop.makeSucceededFuture(String(event.reversed()))
     }