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Add an example using swift-service-lifecycle (#2195)
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Diff for: ‎Examples/service-lifecycle/Package.swift

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// swift-tools-version:6.0
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/*
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* Copyright 2025, gRPC Authors All rights reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import PackageDescription
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let package = Package(
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name: "service-lifecycle",
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platforms: [.macOS(.v15)],
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dependencies: [
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.package(url: "https://github.com/grpc/grpc-swift.git", from: "2.0.0"),
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.package(url: "https://github.com/grpc/grpc-swift-protobuf.git", from: "1.0.0"),
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.package(url: "https://github.com/grpc/grpc-swift-extras", from: "1.0.0"),
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],
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targets: [
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.executableTarget(
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name: "service-lifecycle",
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dependencies: [
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.product(name: "GRPCCore", package: "grpc-swift"),
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.product(name: "GRPCInProcessTransport", package: "grpc-swift"),
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.product(name: "GRPCProtobuf", package: "grpc-swift-protobuf"),
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.product(name: "GRPCServiceLifecycle", package: "grpc-swift-extras"),
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],
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plugins: [
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.plugin(name: "GRPCProtobufGenerator", package: "grpc-swift-protobuf")
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]
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)
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]
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)

Diff for: ‎Examples/service-lifecycle/README.md

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# Service Lifecycle
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This example demonstrates gRPC Swift's integration with Swift Service Lifecycle
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which is provided by the gRPC Swift Extras package.
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## Overview
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A "service-lifecycle" command line tool that uses generated stubs for a
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'greeter' service starts an in-process client and server orchestrated using
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Swift Service Lifecycle. The client makes requests against the server which
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periodically changes its greeting.
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## Prerequisites
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You must have the Protocol Buffers compiler (`protoc`) installed. You can find
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the instructions for doing this in the [gRPC Swift Protobuf documentation][0].
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The `swift` commands below are all prefixed with `PROTOC_PATH=$(which protoc)`,
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this is to let the build system know where `protoc` is located so that it can
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generate stubs for you. You can read more about it in the [gRPC Swift Protobuf
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documentation][1].
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## Usage
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Build and run the server using the CLI:
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```console
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$ PROTOC_PATH=$(which protoc) swift run service-lifecycle
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Здравствуйте, request-1!
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नमस्ते, request-2!
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你好, request-3!
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French, request-4!
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Olá, request-5!
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Hola, request-6!
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Hello, request-7!
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Hello, request-8!
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नमस्ते, request-9!
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Hello, request-10!
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```
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[0]: https://swiftpackageindex.com/grpc/grpc-swift-protobuf/documentation/grpcprotobuf/installing-protoc
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[1]: https://swiftpackageindex.com/grpc/grpc-swift-protobuf/documentation/grpcprotobuf/generating-stubs

Diff for: ‎Examples/service-lifecycle/Sources/GreetingService.swift

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/*
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* Copyright 2025, gRPC Authors All rights reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import GRPCCore
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import ServiceLifecycle
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import Synchronization
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/// Implements the "Hello World" gRPC service but modifies the greeting on a timer.
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///
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/// The service conforms to the 'ServiceLifecycle.Service' and uses its 'run()' method
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/// to execute the run loop which updates the greeting.
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final class GreetingService {
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private let updateInterval: Duration
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private let currentGreetingIndex: Mutex<Int>
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private let greetings: [String] = [
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"Hello",
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"你好",
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"नमस्ते",
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"Hola",
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"French",
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"Olá",
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"Здравствуйте",
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"こんにちは",
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"Ciao",
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]
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private func personalizedGreeting(forName name: String) -> String {
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let index = self.currentGreetingIndex.withLock { $0 }
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return "\(self.greetings[index]), \(name)!"
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}
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private func periodicallyUpdateGreeting() async throws {
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while !Task.isShuttingDownGracefully {
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try await Task.sleep(for: self.updateInterval)
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// Increment the greeting index.
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self.currentGreetingIndex.withLock { index in
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// '!' is fine; greetings is non-empty.
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index = self.greetings.indices.randomElement()!
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}
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}
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}
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init(updateInterval: Duration) {
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// '!' is fine; greetings is non-empty.
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let index = self.greetings.indices.randomElement()!
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self.currentGreetingIndex = Mutex(index)
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self.updateInterval = updateInterval
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}
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}
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extension GreetingService: Helloworld_Greeter.SimpleServiceProtocol {
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func sayHello(
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request: Helloworld_HelloRequest,
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context: ServerContext
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) async throws -> Helloworld_HelloReply {
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return .with {
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$0.message = self.personalizedGreeting(forName: request.name)
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}
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}
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}
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extension GreetingService: Service {
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func run() async throws {
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try await self.periodicallyUpdateGreeting()
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}
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}

Diff for: ‎Examples/service-lifecycle/Sources/LifecycleExample.swift

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/*
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* Copyright 2025, gRPC Authors All rights reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import GRPCCore
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import GRPCInProcessTransport
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import GRPCServiceLifecycle
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import Logging
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import ServiceLifecycle
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@main
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struct LifecycleExample {
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static func main() async throws {
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// Create the gRPC service. It periodically changes the greeting returned to the client.
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// It also conforms to 'ServiceLifecycle.Service' and uses the 'run()' method to perform
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// the updates.
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//
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// A more realistic service may use the run method to maintain a connection to an upstream
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// service or database.
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let greetingService = GreetingService(updateInterval: .microseconds(250))
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// Create the client and server using the in-process transport (which is used here for
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// simplicity.)
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let inProcess = InProcessTransport()
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let server = GRPCServer(transport: inProcess.server, services: [greetingService])
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let client = GRPCClient(transport: inProcess.client)
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// Configure the service group with the services. They're started in the order they're listed
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// and shutdown in reverse order.
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let serviceGroup = ServiceGroup(
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services: [
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greetingService,
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server,
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client,
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],
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logger: Logger(label: "io.grpc.examples.service-lifecycle")
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)
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try await withThrowingDiscardingTaskGroup { group in
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// Run the service group in a task group. This isn't typically required but is here in
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// order to make requests using the client while the service group is running.
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group.addTask {
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try await serviceGroup.run()
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}
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// Make some requests, pausing between each to give the server a chance to update
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// the greeting.
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let greeter = Helloworld_Greeter.Client(wrapping: client)
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for request in 1 ... 10 {
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let reply = try await greeter.sayHello(.with { $0.name = "request-\(request)" })
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print(reply.message)
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// Sleep for a moment.
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let waitTime = Duration.milliseconds((50 ... 400).randomElement()!)
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try await Task.sleep(for: waitTime)
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}
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// Finally, shutdown the service group gracefully.
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await serviceGroup.triggerGracefulShutdown()
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}
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}
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}

Diff for: ‎Examples/service-lifecycle/Sources/Protos/grpc-swift-proto-generator-config.json

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{
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"generate": {
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"clients": true,
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"servers": true,
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"messages": true
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}
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}

Diff for: ‎Examples/service-lifecycle/Sources/Protos/helloworld.proto

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../../../../dev/protos/upstream/grpc/examples/helloworld.proto

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