Add ControlPlaneRequest, ControlPlaneResponse (#238)

### Motivation:

In the coming weeks, we want to restructure the LambdaRuntime internals in such a way, that we allocate a lot less resources per invocation. To accomplish this, we want to encode and decode the ControlPlaneAPI requests directly from their semantic value. For this reason, we need a specialized ControlPlaneRequest and ControlPlaneResponse type that we can encode from and decode into.

### Modifications:

- Add `ControlPlaneRequest`, `ControlPlaneResponse`
- Move `Invocation` and `ErrorResponse` into same file as `ControlPlaneRequest`
- Remove `Lambda` namespace around `Invocation`

Sources/AWSLambdaRuntimeCore/ControlPlaneRequest.swift

@@ -0,0 +1,83 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftAWSLambdaRuntime open source project
+//
+// Copyright (c) 2017-2021 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
+import NIOHTTP1
+
+enum ControlPlaneRequest: Hashable {
+    case next
+    case invocationResponse(String, ByteBuffer?)
+    case invocationError(String, ErrorResponse)
+    case initializationError(ErrorResponse)
+}
+
+enum ControlPlaneResponse: Hashable {
+    case next(Invocation, ByteBuffer)
+    case accepted
+    case error(ErrorResponse)
+}
+
+struct Invocation: Hashable {
+    let requestID: String
+    let deadlineInMillisSinceEpoch: Int64
+    let invokedFunctionARN: String
+    let traceID: String
+    let clientContext: String?
+    let cognitoIdentity: String?
+
+    init(headers: HTTPHeaders) throws {
+        guard let requestID = headers.first(name: AmazonHeaders.requestID), !requestID.isEmpty else {
+            throw Lambda.RuntimeError.invocationMissingHeader(AmazonHeaders.requestID)
+        }
+
+        guard let deadline = headers.first(name: AmazonHeaders.deadline),
+              let unixTimeInMilliseconds = Int64(deadline)
+        else {
+            throw Lambda.RuntimeError.invocationMissingHeader(AmazonHeaders.deadline)
+        }
+
+        guard let invokedFunctionARN = headers.first(name: AmazonHeaders.invokedFunctionARN) else {
+            throw Lambda.RuntimeError.invocationMissingHeader(AmazonHeaders.invokedFunctionARN)
+        }
+
+        guard let traceID = headers.first(name: AmazonHeaders.traceID) else {
+            throw Lambda.RuntimeError.invocationMissingHeader(AmazonHeaders.traceID)
+        }
+
+        self.requestID = requestID
+        self.deadlineInMillisSinceEpoch = unixTimeInMilliseconds
+        self.invokedFunctionARN = invokedFunctionARN
+        self.traceID = traceID
+        self.clientContext = headers["Lambda-Runtime-Client-Context"].first
+        self.cognitoIdentity = headers["Lambda-Runtime-Cognito-Identity"].first
+    }
+}
+
+struct ErrorResponse: Hashable, Codable {
+    var errorType: String
+    var errorMessage: String
+}
+
+extension ErrorResponse {
+    internal func toJSONBytes() -> [UInt8] {
+        var bytes = [UInt8]()
+        bytes.append(UInt8(ascii: "{"))
+        bytes.append(contentsOf: #""errorType":"#.utf8)
+        self.errorType.encodeAsJSONString(into: &bytes)
+        bytes.append(contentsOf: #","errorMessage":"#.utf8)
+        self.errorMessage.encodeAsJSONString(into: &bytes)
+        bytes.append(UInt8(ascii: "}"))
+        return bytes
+    }
+}

Sources/AWSLambdaRuntimeCore/LambdaRunner.swift

@@ -103,7 +103,7 @@ extension Lambda {
 }
 
 extension LambdaContext {
-    init(logger: Logger, eventLoop: EventLoop, allocator: ByteBufferAllocator, invocation: Lambda.Invocation) {
+    init(logger: Logger, eventLoop: EventLoop, allocator: ByteBufferAllocator, invocation: Invocation) {
         self.init(requestID: invocation.requestID,
                   traceID: invocation.traceID,
                   invokedFunctionARN: invocation.invokedFunctionARN,

Sources/AWSLambdaRuntimeCore/LambdaRuntimeClient.swift

@@ -137,62 +137,6 @@ extension Lambda {
     }
 }
 
-internal struct ErrorResponse: Codable {
-    var errorType: String
-    var errorMessage: String
-}
-
-extension ErrorResponse {
-    internal func toJSONBytes() -> [UInt8] {
-        var bytes = [UInt8]()
-        bytes.append(UInt8(ascii: "{"))
-        bytes.append(contentsOf: #""errorType":"#.utf8)
-        self.errorType.encodeAsJSONString(into: &bytes)
-        bytes.append(contentsOf: #","errorMessage":"#.utf8)
-        self.errorMessage.encodeAsJSONString(into: &bytes)
-        bytes.append(UInt8(ascii: "}"))
-        return bytes
-    }
-}
-
-extension Lambda {
-    internal struct Invocation {
-        let requestID: String
-        let deadlineInMillisSinceEpoch: Int64
-        let invokedFunctionARN: String
-        let traceID: String
-        let clientContext: String?
-        let cognitoIdentity: String?
-
-        init(headers: HTTPHeaders) throws {
-            guard let requestID = headers.first(name: AmazonHeaders.requestID), !requestID.isEmpty else {
-                throw RuntimeError.invocationMissingHeader(AmazonHeaders.requestID)
-            }
-
-            guard let deadline = headers.first(name: AmazonHeaders.deadline),
-                  let unixTimeInMilliseconds = Int64(deadline)
-            else {
-                throw RuntimeError.invocationMissingHeader(AmazonHeaders.deadline)
-            }
-
-            guard let invokedFunctionARN = headers.first(name: AmazonHeaders.invokedFunctionARN) else {
-                throw RuntimeError.invocationMissingHeader(AmazonHeaders.invokedFunctionARN)
-            }
-
-            guard let traceID = headers.first(name: AmazonHeaders.traceID) else {
-                throw RuntimeError.invocationMissingHeader(AmazonHeaders.traceID)
-            }
-
-            self.requestID = requestID
-            self.deadlineInMillisSinceEpoch = unixTimeInMilliseconds
-            self.invokedFunctionARN = invokedFunctionARN
-            self.traceID = traceID
-            self.clientContext = headers["Lambda-Runtime-Client-Context"].first
-            self.cognitoIdentity = headers["Lambda-Runtime-Cognito-Identity"].first
-        }
-    }
-}
-
 extension Lambda.RuntimeClient {
     internal static let defaultHeaders = HTTPHeaders([("user-agent", "Swift-Lambda/Unknown")])
 

Tests/AWSLambdaRuntimeCoreTests/LambdaRuntimeClientTest.swift

@@ -260,8 +260,8 @@ class LambdaRuntimeClientTest: XCTestCase {
             (AmazonHeaders.invokedFunctionARN, "arn:aws:lambda:us-east-1:123456789012:function:custom-runtime"),
             (AmazonHeaders.traceID, "Root=\(AmazonHeaders.generateXRayTraceID());Sampled=1"),
         ])
-        var inv: Lambda.Invocation?
-        XCTAssertNoThrow(inv = try Lambda.Invocation(headers: header))
+        var inv: Invocation?
+        XCTAssertNoThrow(inv = try Invocation(headers: header))
         guard let invocation = inv else { return }
 
         let result = client.reportResults(logger: logger, invocation: invocation, result: Result.failure(TestError("boom")))
@@ -300,8 +300,8 @@ class LambdaRuntimeClientTest: XCTestCase {
             (AmazonHeaders.invokedFunctionARN, "arn:aws:lambda:us-east-1:123456789012:function:custom-runtime"),
             (AmazonHeaders.traceID, "Root=\(AmazonHeaders.generateXRayTraceID());Sampled=1"),
         ])
-        var inv: Lambda.Invocation?
-        XCTAssertNoThrow(inv = try Lambda.Invocation(headers: header))
+        var inv: Invocation?
+        XCTAssertNoThrow(inv = try Invocation(headers: header))
         guard let invocation = inv else { return }
 
         let result = client.reportResults(logger: logger, invocation: invocation, result: Result.success(nil))