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// Copyright 2016 The Bazel Authors. All rights reserved.
//
// 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 com.google.devtools.build.lib.server;
import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.runtime.CommandExecutor;
import com.google.devtools.build.lib.util.Clock;
import com.google.devtools.build.lib.util.Preconditions;
import com.google.devtools.build.lib.util.io.OutErr;
import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.stub.StreamObserver;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.lang.reflect.Field;
import java.net.InetSocketAddress;
import java.nio.channels.ServerSocketChannel;
/**
* gRPC server class.
*
* <p>Only this class should depend on gRPC so that we only need to exclude this during
* bootstrapping.
*/
public class GrpcServerImpl implements CommandServerGrpc.CommandServer, GrpcServer {
private static final String PORT_FILE = "server/grpc_port"; // relative to the output base
private final CommandExecutor commandExecutor;
private final Clock clock;
private final File portFile;
private Server server;
private int port; // mutable so that we can overwrite it if port 0 is passed in
boolean serving;
/**
* Factory class. Instantiated by reflection.
*/
public static class Factory implements GrpcServer.Factory {
@Override
public GrpcServer create(CommandExecutor commandExecutor, Clock clock, int port,
String outputBase) {
return new GrpcServerImpl(commandExecutor, clock, port, outputBase);
}
}
private GrpcServerImpl(CommandExecutor commandExecutor, Clock clock, int port,
String outputBase) {
this.commandExecutor = commandExecutor;
this.clock = clock;
this.port = port;
this.portFile = new File(outputBase + "/" + PORT_FILE);
this.serving = false;
}
public void serve() throws IOException {
Preconditions.checkState(!serving);
server = ServerBuilder.forPort(port)
.addService(CommandServerGrpc.bindService(this))
.build();
server.start();
if (port == 0) {
port = getActualServerPort();
}
PrintWriter portWriter = new PrintWriter(portFile);
portWriter.print(port);
portWriter.close();
serving = true;
}
/**
* Gets the server port the kernel bound our server to if port 0 was passed in.
*
* <p>The implementation is awful, but gRPC doesn't provide an official way to do this:
* https://github.com/grpc/grpc-java/issues/72
*/
private int getActualServerPort() {
try {
ServerSocketChannel channel =
(ServerSocketChannel) getField(server, "transportServer", "channel", "ch");
InetSocketAddress address = (InetSocketAddress) channel.getLocalAddress();
return address.getPort();
} catch (IllegalAccessException | NullPointerException | IOException e) {
throw new IllegalStateException("Cannot read server socket address from gRPC");
}
}
private static Object getField(Object instance, String... fieldNames)
throws IllegalAccessException, NullPointerException {
for (String fieldName : fieldNames) {
Field field = null;
for (Class<?> clazz = instance.getClass(); clazz != null; clazz = clazz.getSuperclass()) {
try {
field = clazz.getDeclaredField(fieldName);
break;
} catch (NoSuchFieldException e) {
// Try again with the superclass
}
}
field.setAccessible(true);
instance = field.get(instance);
}
return instance;
}
public void terminate() {
Preconditions.checkState(serving);
server.shutdownNow();
// This is Uninterruptibles#callUninterruptibly. Calling that method properly is about the same
// amount of code as implementing it ourselves.
boolean interrupted = false;
try {
while (true) {
try {
server.awaitTermination();
serving = false;
return;
} catch (InterruptedException e) {
interrupted = true;
}
}
} finally {
if (interrupted) {
Thread.currentThread().interrupt();
}
}
}
@Override
public void run(CommandProtos.Request request, StreamObserver<CommandProtos.Response> observer) {
Preconditions.checkState(serving);
commandExecutor.exec(
ImmutableList.of("version"), OutErr.SYSTEM_OUT_ERR, clock.currentTimeMillis());
CommandProtos.Response response = CommandProtos.Response.newBuilder()
.setNumber(request.getNumber() + 1)
.build();
observer.onNext(response);
observer.onCompleted();
}
}
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