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ErrorHandlingClient.java
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ErrorHandlingClient.java
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/*
* Copyright 2016 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.
*/
package io.grpc.examples.errorhandling;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import com.google.common.base.Verify;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.Uninterruptibles;
import io.grpc.CallOptions;
import io.grpc.ClientCall;
import io.grpc.Grpc;
import io.grpc.InsecureChannelCredentials;
import io.grpc.InsecureServerCredentials;
import io.grpc.ManagedChannel;
import io.grpc.Metadata;
import io.grpc.Server;
import io.grpc.Status;
import io.grpc.examples.helloworld.GreeterGrpc;
import io.grpc.examples.helloworld.GreeterGrpc.GreeterBlockingStub;
import io.grpc.examples.helloworld.GreeterGrpc.GreeterFutureStub;
import io.grpc.examples.helloworld.GreeterGrpc.GreeterStub;
import io.grpc.examples.helloworld.HelloReply;
import io.grpc.examples.helloworld.HelloRequest;
import io.grpc.stub.StreamObserver;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import javax.annotation.Nullable;
/**
* Shows how to extract error information from a failed RPC.
*/
public class ErrorHandlingClient {
public static void main(String [] args) throws Exception {
new ErrorHandlingClient().run();
}
private ManagedChannel channel;
void run() throws Exception {
// Port 0 means that the operating system will pick an available port to use.
Server server = Grpc.newServerBuilderForPort(0, InsecureServerCredentials.create())
.addService(new GreeterGrpc.GreeterImplBase() {
@Override
public void sayHello(HelloRequest request, StreamObserver<HelloReply> responseObserver) {
// The server will always fail, and we'll see this failure on client-side. The exception is
// not sent to the client, only the status code (i.e., INTERNAL) and description.
responseObserver.onError(Status.INTERNAL
.withDescription("Eggplant Xerxes Crybaby Overbite Narwhal").asRuntimeException());
}
}).build().start();
channel = Grpc.newChannelBuilderForAddress(
"localhost", server.getPort(), InsecureChannelCredentials.create()).build();
blockingCall();
futureCallDirect();
futureCallCallback();
asyncCall();
advancedAsyncCall();
channel.shutdown();
server.shutdown();
channel.awaitTermination(1, TimeUnit.SECONDS);
server.awaitTermination();
}
void blockingCall() {
GreeterBlockingStub stub = GreeterGrpc.newBlockingStub(channel);
try {
stub.sayHello(HelloRequest.newBuilder().setName("Bart").build());
} catch (Exception e) {
Status status = Status.fromThrowable(e);
Verify.verify(status.getCode() == Status.Code.INTERNAL);
Verify.verify(status.getDescription().contains("Eggplant"));
// Cause is not transmitted over the wire.
}
}
void futureCallDirect() {
GreeterFutureStub stub = GreeterGrpc.newFutureStub(channel);
ListenableFuture<HelloReply> response =
stub.sayHello(HelloRequest.newBuilder().setName("Lisa").build());
try {
response.get();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new RuntimeException(e);
} catch (ExecutionException e) {
Status status = Status.fromThrowable(e.getCause());
Verify.verify(status.getCode() == Status.Code.INTERNAL);
Verify.verify(status.getDescription().contains("Xerxes"));
// Cause is not transmitted over the wire.
}
}
void futureCallCallback() {
GreeterFutureStub stub = GreeterGrpc.newFutureStub(channel);
ListenableFuture<HelloReply> response =
stub.sayHello(HelloRequest.newBuilder().setName("Maggie").build());
final CountDownLatch latch = new CountDownLatch(1);
Futures.addCallback(
response,
new FutureCallback<HelloReply>() {
@Override
public void onSuccess(@Nullable HelloReply result) {
// Won't be called, since the server in this example always fails.
}
@Override
public void onFailure(Throwable t) {
Status status = Status.fromThrowable(t);
Verify.verify(status.getCode() == Status.Code.INTERNAL);
Verify.verify(status.getDescription().contains("Crybaby"));
// Cause is not transmitted over the wire..
latch.countDown();
}
},
directExecutor());
if (!Uninterruptibles.awaitUninterruptibly(latch, 1, TimeUnit.SECONDS)) {
throw new RuntimeException("timeout!");
}
}
void asyncCall() {
GreeterStub stub = GreeterGrpc.newStub(channel);
HelloRequest request = HelloRequest.newBuilder().setName("Homer").build();
final CountDownLatch latch = new CountDownLatch(1);
StreamObserver<HelloReply> responseObserver = new StreamObserver<HelloReply>() {
@Override
public void onNext(HelloReply value) {
// Won't be called.
}
@Override
public void onError(Throwable t) {
Status status = Status.fromThrowable(t);
Verify.verify(status.getCode() == Status.Code.INTERNAL);
Verify.verify(status.getDescription().contains("Overbite"));
// Cause is not transmitted over the wire..
latch.countDown();
}
@Override
public void onCompleted() {
// Won't be called, since the server in this example always fails.
}
};
stub.sayHello(request, responseObserver);
if (!Uninterruptibles.awaitUninterruptibly(latch, 1, TimeUnit.SECONDS)) {
throw new RuntimeException("timeout!");
}
}
/**
* This is more advanced and does not make use of the stub. You should not normally need to do
* this, but here is how you would.
*/
void advancedAsyncCall() {
ClientCall<HelloRequest, HelloReply> call =
channel.newCall(GreeterGrpc.getSayHelloMethod(), CallOptions.DEFAULT);
final CountDownLatch latch = new CountDownLatch(1);
call.start(new ClientCall.Listener<HelloReply>() {
@Override
public void onClose(Status status, Metadata trailers) {
Verify.verify(status.getCode() == Status.Code.INTERNAL);
Verify.verify(status.getDescription().contains("Narwhal"));
// Cause is not transmitted over the wire.
latch.countDown();
}
}, new Metadata());
call.sendMessage(HelloRequest.newBuilder().setName("Marge").build());
call.halfClose();
if (!Uninterruptibles.awaitUninterruptibly(latch, 1, TimeUnit.SECONDS)) {
throw new RuntimeException("timeout!");
}
}
}