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Add async/await examples (#553)
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‎Examples/GetHTML/GetHTML.swift

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//===----------------------------------------------------------------------===//
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//
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// This source file is part of the AsyncHTTPClient open source project
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//
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// Copyright (c) 2022 Apple Inc. and the AsyncHTTPClient project authors
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// Licensed under Apache License v2.0
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//
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// See LICENSE.txt for license information
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// See CONTRIBUTORS.txt for the list of AsyncHTTPClient project authors
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//
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// SPDX-License-Identifier: Apache-2.0
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//
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//===----------------------------------------------------------------------===//
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import AsyncHTTPClient
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import NIOCore
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@main
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struct GetHTML {
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static func main() async throws {
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let httpClient = HTTPClient(eventLoopGroupProvider: .createNew)
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do {
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let request = HTTPClientRequest(url: "https://apple.com")
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let response = try await httpClient.execute(request, timeout: .seconds(30))
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print("HTTP head", response)
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let body = try await response.body.collect(upTo: 1024 * 1024) // 1 MB
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print(String(buffer: body))
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} catch {
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print("request failed:", error)
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}
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// it is important to shutdown the httpClient after all requests are done, even if one failed
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try await httpClient.shutdown()
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}
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}

‎Examples/GetJSON/GetJSON.swift

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//===----------------------------------------------------------------------===//
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//
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// This source file is part of the AsyncHTTPClient open source project
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//
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// Copyright (c) 2022 Apple Inc. and the AsyncHTTPClient project authors
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// Licensed under Apache License v2.0
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//
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// See LICENSE.txt for license information
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// See CONTRIBUTORS.txt for the list of AsyncHTTPClient project authors
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//
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// SPDX-License-Identifier: Apache-2.0
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//
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//===----------------------------------------------------------------------===//
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import AsyncHTTPClient
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import Foundation
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import NIOCore
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import NIOFoundationCompat
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struct Comic: Codable {
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var num: Int
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var title: String
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var day: String
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var month: String
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var year: String
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var img: String
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var alt: String
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var news: String
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var link: String
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var transcript: String
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}
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@main
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struct GetJSON {
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static func main() async throws {
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let httpClient = HTTPClient(eventLoopGroupProvider: .createNew)
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do {
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let request = HTTPClientRequest(url: "https://xkcd.com/info.0.json")
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let response = try await httpClient.execute(request, timeout: .seconds(30))
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print("HTTP head", response)
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let body = try await response.body.collect(upTo: 1024 * 1024) // 1 MB
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// we use an overload defined in `NIOFoundationCompat` for `decode(_:from:)` to
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// efficiently decode from a `ByteBuffer`
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let comic = try JSONDecoder().decode(Comic.self, from: body)
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dump(comic)
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} catch {
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print("request failed:", error)
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}
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// it is important to shutdown the httpClient after all requests are done, even if one failed
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try await httpClient.shutdown()
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}
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}

‎Examples/Package.swift

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// swift-tools-version:5.5
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//===----------------------------------------------------------------------===//
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//
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// This source file is part of the AsyncHTTPClient open source project
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//
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// Copyright (c) 2018-2022 Apple Inc. and the AsyncHTTPClient project authors
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// Licensed under Apache License v2.0
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//
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// See LICENSE.txt for license information
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// See CONTRIBUTORS.txt for the list of AsyncHTTPClient project authors
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//
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// SPDX-License-Identifier: Apache-2.0
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//
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//===----------------------------------------------------------------------===//
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import PackageDescription
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let package = Package(
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name: "async-http-client-examples",
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platforms: [
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.macOS(.v10_15),
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.iOS(.v13),
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.tvOS(.v13),
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.watchOS(.v6),
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],
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products: [
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.executable(name: "GetHTML", targets: ["GetHTML"]),
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.executable(name: "GetJSON", targets: ["GetJSON"]),
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.executable(name: "StreamingByteCounter", targets: ["StreamingByteCounter"]),
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],
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dependencies: [
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.package(url: "https://github.com/apple/swift-nio.git", .branch("main")),
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// in real-world projects this would be
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// .package(url: "https://github.com/swift-server/async-http-client.git", from: "1.9.0")
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.package(name: "async-http-client", path: "../"),
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],
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targets: [
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// MARK: - Examples
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.executableTarget(
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name: "GetHTML",
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dependencies: [
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.product(name: "AsyncHTTPClient", package: "async-http-client"),
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.product(name: "NIOCore", package: "swift-nio"),
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], path: "GetHTML"
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),
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.executableTarget(
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name: "GetJSON",
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dependencies: [
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.product(name: "AsyncHTTPClient", package: "async-http-client"),
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.product(name: "NIOCore", package: "swift-nio"),
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.product(name: "NIOFoundationCompat", package: "swift-nio"),
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], path: "GetJSON"
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),
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.executableTarget(
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name: "StreamingByteCounter",
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dependencies: [
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.product(name: "AsyncHTTPClient", package: "async-http-client"),
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.product(name: "NIOCore", package: "swift-nio"),
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], path: "StreamingByteCounter"
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),
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]
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)

‎Examples/README.md

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# Examples
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This folder includes a couple of Examples for `AsyncHTTPClient`.
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You can run them by opening the `Package.swift` in this folder through Xcode.
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In Xcode you can then select the scheme for the example you want run e.g. `GetHTML`.
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You can also run the examples from the command line by executing the follow command in this folder:
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```
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swift run GetHTML
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```
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To run other examples you can just replace `GetHTML` with the name of the example you want to run.
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## [GetHTML](./GetHTML/GetHTML.swift)
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This examples sends a HTTP GET request to `https://apple.com/` and first `await`s and `print`s the HTTP Response Head.
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Afterwards it buffers the full response body in memory and prints the response as a `String`.
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## [GetJSON](./GetJSON/GetJSON.swift)
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This examples sends a HTTP GET request to `https://xkcd.com/info.0.json` and first `await`s and `print`s the HTTP Response Head.
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Afterwards it buffers the full response body in memory, decodes the buffer using a `JSONDecoder` and `dump`s the decoded response.
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## [StreamingByteCounter](./StreamingByteCounter/StreamingByteCounter.swift)
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This examples sends a HTTP GET request to `https://apple.com/` and first `await`s and `print`s the HTTP Response Head.
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Afterwards it asynchronously iterates over all body fragments, counts the received bytes and prints a progress indicator (if the server send a content-length header).
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At the end the total received bytes are printed.
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Note that we drop all received fragment and therefore do **not** buffer the whole response body in-memory.

‎Examples/StreamingByteCounter/StreamingByteCounter.swift

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//===----------------------------------------------------------------------===//
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//
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// This source file is part of the AsyncHTTPClient open source project
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//
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// Copyright (c) 2022 Apple Inc. and the AsyncHTTPClient project authors
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// Licensed under Apache License v2.0
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//
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// See LICENSE.txt for license information
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// See CONTRIBUTORS.txt for the list of AsyncHTTPClient project authors
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//
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// SPDX-License-Identifier: Apache-2.0
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//
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//===----------------------------------------------------------------------===//
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import AsyncHTTPClient
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import NIOCore
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@main
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struct StreamingByteCounter {
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static func main() async throws {
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let httpClient = HTTPClient(eventLoopGroupProvider: .createNew)
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do {
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let request = HTTPClientRequest(url: "https://apple.com")
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let response = try await httpClient.execute(request, timeout: .seconds(30))
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print("HTTP head", response)
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// if defined, the content-length headers announces the size of the body
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let expectedBytes = response.headers.first(name: "content-length").flatMap(Int.init)
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var receivedBytes = 0
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// asynchronously iterates over all body fragments
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// this loop will automatically propagate backpressure correctly
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for try await buffer in response.body {
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// For this example, we are just interested in the size of the fragment
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receivedBytes += buffer.readableBytes
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if let expectedBytes = expectedBytes {
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// if the body size is known, we calculate a progress indicator
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let progress = Double(receivedBytes) / Double(expectedBytes)
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print("progress: \(Int(progress * 100))%")
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}
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}
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print("did receive \(receivedBytes) bytes")
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} catch {
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print("request failed:", error)
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}
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// it is important to shutdown the httpClient after all requests are done, even if one failed
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try await httpClient.shutdown()
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}
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}

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