main.swift

//===----------------------------------------------------------------------===//
//
// 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 AWSLambdaRuntime

#if canImport(FoundationEssentials)
import FoundationEssentials
#else
import Foundation
#endif

struct BackgroundProcessingHandler: LambdaWithBackgroundProcessingHandler {
    struct Input: Decodable {
        let message: String
    }

    struct Greeting: Encodable {
        let echoedMessage: String
    }

    typealias Event = Input
    typealias Output = Greeting

    func handle(
        _ event: Event,
        outputWriter: some LambdaResponseWriter<Output>,
        context: LambdaContext
    ) async throws {
        // Return result to the Lambda control plane
        context.logger.debug("BackgroundProcessingHandler - message received")
        try await outputWriter.write(Greeting(echoedMessage: event.message))

        // Perform some background work, e.g:
        context.logger.debug("BackgroundProcessingHandler - response sent. Performing background tasks.")
        try await Task.sleep(for: .seconds(10))

        // Exit the function. All asynchronous work has been executed before exiting the scope of this function.
        // Follows structured concurrency principles.
        context.logger.debug("BackgroundProcessingHandler - Background tasks completed. Returning")
        return
    }
}

let adapter = LambdaCodableAdapter(handler: BackgroundProcessingHandler())
let runtime = try LambdaRuntime.init(handler: adapter)
try await runtime.run()