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// Copyright 2014 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.Iterables;
import com.google.devtools.build.lib.runtime.BlazeCommandDispatcher.LockingMode;
import com.google.devtools.build.lib.runtime.BlazeCommandDispatcher.ShutdownMethod;
import com.google.devtools.build.lib.util.Preconditions;
import com.google.devtools.build.lib.util.io.OutErr;
import java.util.List;
import java.util.logging.Logger;
/**
* An RPCService is a Java object that can process RPC requests. Requests may
* be of the form:
* <pre>
* blaze <blaze-arguments>
* </pre>
* Requests are delegated to the ServerCommand instance provided
* to the constructor.
*/
public final class RPCService {
private static final Logger LOG = Logger.getLogger(RPCService.class.getName());
private final ServerCommand appCommand;
private ShutdownMethod shutdown = ShutdownMethod.NONE;
public RPCService(ServerCommand appCommand) {
this.appCommand = appCommand;
}
/**
* The {@link #executeRequest(List, OutErr, long)} method may
* throw this exception if a command is unknown to the RPC service.
*/
public static class UnknownCommandException extends Exception {
private static final long serialVersionUID = 1L;
UnknownCommandException(String command) {
super("Unknown command: " + command);
}
}
/**
* Executes the request; returns Unix like return codes (0 means success). May
* also throw arbitrary exceptions.
*/
public int executeRequest(List<String> request,
OutErr outErr,
long firstContactTime) throws Exception {
if (shutdown != ShutdownMethod.NONE) {
throw new IllegalStateException("Received request after shutdown.");
}
String command = Iterables.getFirst(request, "");
if (appCommand != null && command.equals("blaze")) { // an application request
// Blocking is done in the client for AF_UNIX communications, so if blockForLock would block,
// something went wrong
int result = appCommand.exec(
request.subList(1, request.size()), outErr, LockingMode.ERROR_OUT, "AF_UNIX client",
firstContactTime);
ShutdownMethod commandShutdown = appCommand.shutdown();
if (commandShutdown != ShutdownMethod.NONE) { // an application shutdown request
shutdown(commandShutdown);
}
return result;
} else {
throw new UnknownCommandException(command);
}
}
/**
* After executing this function, further requests will fail, and
* {@link #getShutdown()} will the shutdown method passed in.
*/
public void shutdown(ShutdownMethod method) {
Preconditions.checkState(method != ShutdownMethod.NONE);
if (shutdown != ShutdownMethod.NONE) {
return;
}
LOG.info("RPC Service: shutting down ...");
shutdown = method;
}
/**
* Has this service been shutdown. If so, any call to
* {@link #executeRequest(List, OutErr, long)} will result in an
* {@link IllegalStateException}
*/
public ShutdownMethod getShutdown() {
return shutdown;
}
}
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