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examples: Adds client/server retrying example via service config
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148 changes: 148 additions & 0 deletions
148
examples/src/main/java/io/grpc/examples/retrying/RetryingHelloWorldClient.java
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/* | ||
* Copyright 2020 The gRPC Authors | ||
* | ||
* Licensed under the Apache License, Version 2.0 (the "License"); | ||
* you may not use this file except in compliance with the License. | ||
* You may obtain a copy of the License at | ||
* | ||
* http://www.apache.org/licenses/LICENSE-2.0 | ||
* | ||
* Unless required by applicable law or agreed to in writing, software | ||
* distributed under the License is distributed on an "AS IS" BASIS, | ||
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
* See the License for the specific language governing permissions and | ||
* limitations under the License. | ||
*/ | ||
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package io.grpc.examples.retrying; | ||
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import static java.nio.charset.StandardCharsets.UTF_8; | ||
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import com.google.gson.Gson; | ||
import com.google.gson.stream.JsonReader; | ||
import io.grpc.ManagedChannel; | ||
import io.grpc.ManagedChannelBuilder; | ||
import io.grpc.StatusRuntimeException; | ||
import io.grpc.examples.helloworld.GreeterGrpc; | ||
import io.grpc.examples.helloworld.HelloReply; | ||
import io.grpc.examples.helloworld.HelloRequest; | ||
import java.io.InputStreamReader; | ||
import java.util.Map; | ||
import java.util.concurrent.ForkJoinPool; | ||
import java.util.concurrent.TimeUnit; | ||
import java.util.concurrent.atomic.AtomicInteger; | ||
import java.util.logging.Level; | ||
import java.util.logging.Logger; | ||
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/** | ||
* A client that requests a greeting from the {@link RetryingHelloWorldServer} with a retrying policy. | ||
*/ | ||
public class RetryingHelloWorldClient { | ||
static final String ENV_DISABLE_RETRYING = "DISABLE_RETRYING_IN_RETRYING_EXAMPLE"; | ||
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private static final Logger logger = Logger.getLogger(RetryingHelloWorldClient.class.getName()); | ||
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private final boolean enableRetries; | ||
private final ManagedChannel channel; | ||
private final GreeterGrpc.GreeterBlockingStub blockingStub; | ||
private final AtomicInteger totalRpcs = new AtomicInteger(); | ||
private final AtomicInteger failedRpcs = new AtomicInteger(); | ||
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protected Map<String, ?> getRetryingServiceConfig() { | ||
return new Gson() | ||
.fromJson( | ||
new JsonReader( | ||
new InputStreamReader( | ||
RetryingHelloWorldClient.class.getResourceAsStream( | ||
"retrying_service_config.json"), | ||
UTF_8)), | ||
Map.class); | ||
} | ||
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/** | ||
* Construct client connecting to HelloWorld server at {@code host:port}. | ||
*/ | ||
public RetryingHelloWorldClient(String host, int port, boolean enableRetries) { | ||
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ManagedChannelBuilder<?> channelBuilder = ManagedChannelBuilder.forAddress(host, port) | ||
// Channels are secure by default (via SSL/TLS). For the example we disable TLS to avoid | ||
// needing certificates. | ||
.usePlaintext(); | ||
if (enableRetries) { | ||
Map<String, ?> serviceConfig = getRetryingServiceConfig(); | ||
logger.info("Client started with retrying configuration: " + serviceConfig.toString()); | ||
channelBuilder.defaultServiceConfig(serviceConfig).enableRetry(); | ||
} | ||
channel = channelBuilder.build(); | ||
blockingStub = GreeterGrpc.newBlockingStub(channel); | ||
this.enableRetries = enableRetries; | ||
} | ||
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public void shutdown() throws InterruptedException { | ||
channel.shutdown().awaitTermination(60, TimeUnit.SECONDS); | ||
} | ||
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/** | ||
* Say hello to server in a blocking unary call. | ||
*/ | ||
public void greet(String name) { | ||
HelloRequest request = HelloRequest.newBuilder().setName(name).build(); | ||
HelloReply response = null; | ||
StatusRuntimeException statusRuntimeException = null; | ||
try { | ||
response = blockingStub.sayHello(request); | ||
} catch (StatusRuntimeException e) { | ||
failedRpcs.incrementAndGet(); | ||
statusRuntimeException = e; | ||
} | ||
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totalRpcs.incrementAndGet(); | ||
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if (statusRuntimeException == null) { | ||
logger.log(Level.INFO,"Greeting: {0}", new Object[]{response.getMessage()}); | ||
} else { | ||
logger.log(Level.INFO,"RPC failed: {0}", new Object[]{statusRuntimeException.getStatus()}); | ||
} | ||
} | ||
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private void printSummary() { | ||
logger.log( | ||
Level.INFO, | ||
"\n\nTotal RPCs sent: {0}. Total RPCs failed: {1}\n", | ||
new Object[]{ | ||
totalRpcs.get(), failedRpcs.get()}); | ||
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if (enableRetries) { | ||
logger.log( | ||
Level.INFO, | ||
"Retrying enabled. To disable retries, run the client with environment variable {0}=true.", | ||
ENV_DISABLE_RETRYING); | ||
} else { | ||
logger.log( | ||
Level.INFO, | ||
"Retrying disabled. To enable retries, unset environment variable {0} and then run the client.", | ||
ENV_DISABLE_RETRYING); | ||
} | ||
} | ||
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public static void main(String[] args) throws Exception { | ||
boolean enableRetries = !Boolean.parseBoolean(System.getenv(ENV_DISABLE_RETRYING)); | ||
final RetryingHelloWorldClient client = new RetryingHelloWorldClient("localhost", 50051, enableRetries); | ||
ForkJoinPool executor = new ForkJoinPool(); | ||
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for (int i = 0; i < 50; i++) { | ||
final String userId = "user" + i; | ||
executor.execute( | ||
new Runnable() { | ||
@Override | ||
public void run() { | ||
client.greet(userId); | ||
} | ||
}); | ||
} | ||
executor.awaitQuiescence(100, TimeUnit.SECONDS); | ||
executor.shutdown(); | ||
client.printSummary(); | ||
client.shutdown(); | ||
} | ||
} |
111 changes: 111 additions & 0 deletions
111
examples/src/main/java/io/grpc/examples/retrying/RetryingHelloWorldServer.java
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/* | ||
* Copyright 2020 The gRPC Authors | ||
* | ||
* Licensed under the Apache License, Version 2.0 (the "License"); | ||
* you may not use this file except in compliance with the License. | ||
* You may obtain a copy of the License at | ||
* | ||
* http://www.apache.org/licenses/LICENSE-2.0 | ||
* | ||
* Unless required by applicable law or agreed to in writing, software | ||
* distributed under the License is distributed on an "AS IS" BASIS, | ||
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
* See the License for the specific language governing permissions and | ||
* limitations under the License. | ||
*/ | ||
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package io.grpc.examples.retrying; | ||
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import java.text.DecimalFormat; | ||
import java.util.Random; | ||
import java.util.concurrent.atomic.AtomicInteger; | ||
import io.grpc.Server; | ||
import io.grpc.ServerBuilder; | ||
import io.grpc.Status; | ||
import io.grpc.examples.helloworld.GreeterGrpc; | ||
import io.grpc.examples.helloworld.HelloReply; | ||
import io.grpc.examples.helloworld.HelloRequest; | ||
import io.grpc.stub.StreamObserver; | ||
import java.io.IOException; | ||
import java.util.concurrent.TimeUnit; | ||
import java.util.logging.Logger; | ||
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/** | ||
* A HelloWorld server that responds to requests with UNAVAILABLE with a given percentage. | ||
*/ | ||
public class RetryingHelloWorldServer { | ||
private static final Logger logger = Logger.getLogger(RetryingHelloWorldServer.class.getName()); | ||
private static final float unavailablePercentage = 0.5F; | ||
private static Random random = new Random(); | ||
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private Server server; | ||
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private void start() throws IOException { | ||
/* The port on which the server should run */ | ||
int port = 50051; | ||
server = ServerBuilder.forPort(port) | ||
.addService(new GreeterImpl()) | ||
.build() | ||
.start(); | ||
logger.info("Server started, listening on " + port); | ||
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DecimalFormat df = new DecimalFormat("#%"); | ||
logger.info("Responding as UNAVAILABLE to " + df.format(unavailablePercentage) + " requests"); | ||
Runtime.getRuntime().addShutdownHook(new Thread() { | ||
@Override | ||
public void run() { | ||
// Use stderr here since the logger may have been reset by its JVM shutdown hook. | ||
System.err.println("*** shutting down gRPC server since JVM is shutting down"); | ||
try { | ||
RetryingHelloWorldServer.this.stop(); | ||
} catch (InterruptedException e) { | ||
e.printStackTrace(System.err); | ||
} | ||
System.err.println("*** server shut down"); | ||
} | ||
}); | ||
} | ||
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private void stop() throws InterruptedException { | ||
if (server != null) { | ||
server.shutdown().awaitTermination(30, TimeUnit.SECONDS); | ||
} | ||
} | ||
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/** | ||
* Await termination on the main thread since the grpc library uses daemon threads. | ||
*/ | ||
private void blockUntilShutdown() throws InterruptedException { | ||
if (server != null) { | ||
server.awaitTermination(); | ||
} | ||
} | ||
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/** | ||
* Main launches the server from the command line. | ||
*/ | ||
public static void main(String[] args) throws IOException, InterruptedException { | ||
final RetryingHelloWorldServer server = new RetryingHelloWorldServer(); | ||
server.start(); | ||
server.blockUntilShutdown(); | ||
} | ||
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static class GreeterImpl extends GreeterGrpc.GreeterImplBase { | ||
AtomicInteger retryCounter = new AtomicInteger(0); | ||
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@Override | ||
public void sayHello(HelloRequest request, StreamObserver<HelloReply> responseObserver) { | ||
int count = retryCounter.incrementAndGet(); | ||
if (random.nextFloat() < unavailablePercentage) { | ||
logger.info("Returning stubbed UNAVAILABLE error. count: " + count); | ||
responseObserver.onError(Status.UNAVAILABLE | ||
.withDescription("Greeter temporarily unavailable...").asRuntimeException()); | ||
} else { | ||
logger.info("Returning successful Hello response, count: " + count); | ||
HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + request.getName()).build(); | ||
responseObserver.onNext(reply); | ||
responseObserver.onCompleted(); | ||
} | ||
} | ||
} | ||
} |
22 changes: 22 additions & 0 deletions
22
examples/src/main/resources/io/grpc/examples/retrying/retrying_service_config.json
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{ | ||
"methodConfig": [ | ||
{ | ||
"name": [ | ||
{ | ||
"service": "helloworld.Greeter", | ||
"method": "SayHello" | ||
} | ||
], | ||
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"retryPolicy": { | ||
"maxAttempts": 5, | ||
"initialBackoff": "0.5s", | ||
"maxBackoff": "30s", | ||
"backoffMultiplier": 2, | ||
"retryableStatusCodes": [ | ||
"UNAVAILABLE" | ||
] | ||
} | ||
} | ||
] | ||
} |