/*
* Copyright 2014 the original author or 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 org.springframework.xd.dirt.zookeeper;
import java.io.File;
import java.lang.reflect.Method;
import java.util.Properties;
import java.util.UUID;
import org.apache.zookeeper.server.ServerConfig;
import org.apache.zookeeper.server.ZooKeeperServerMain;
import org.apache.zookeeper.server.quorum.QuorumPeerConfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.SmartLifecycle;
import org.springframework.util.ErrorHandler;
import org.springframework.util.SocketUtils;
/**
* Helper class to start an embedded instance of standalone (non clustered) ZooKeeper.
*
* NOTE: at least an external standalone server (if not an ensemble) are recommended, even for
* {@link org.springframework.xd.dirt.server.SingleNodeApplication}
*
* @author Patrick Peralta
* @author Mark Fisher
* @author David Turanski
*/
public class EmbeddedZooKeeper implements SmartLifecycle {
/**
* Logger.
*/
private static final Logger logger = LoggerFactory.getLogger(EmbeddedZooKeeper.class);
/**
* ZooKeeper client port. This will be determined dynamically upon startup.
*/
private final int clientPort;
/**
* Whether to auto-start. Default is true.
*/
private boolean autoStartup = true;
/**
* Lifecycle phase. Default is 0.
*/
private int phase = 0;
/**
* Thread for running the ZooKeeper server.
*/
private volatile Thread zkServerThread;
/**
* ZooKeeper server.
*/
private volatile ZooKeeperServerMain zkServer;
/**
* {@link ErrorHandler} to be invoked if an Exception is thrown from the ZooKeeper server thread.
*/
private ErrorHandler errorHandler;
/**
* Construct an EmbeddedZooKeeper with a random port.
*/
public EmbeddedZooKeeper() {
clientPort = SocketUtils.findAvailableTcpPort();
}
/**
* Construct an EmbeddedZooKeeper with the provided port.
*
* @param clientPort port for ZooKeeper server to bind to
*/
public EmbeddedZooKeeper(int clientPort) {
this.clientPort = clientPort;
}
/**
* Returns the port that clients should use to connect to this embedded server.
*
* @return dynamically determined client port
*/
public int getClientPort() {
return this.clientPort;
}
/**
* Specify whether to start automatically. Default is true.
*
* @param autoStartup whether to start automatically
*/
public void setAutoStartup(boolean autoStartup) {
this.autoStartup = autoStartup;
}
/**
* {@inheritDoc}
*/
@Override
public boolean isAutoStartup() {
return this.autoStartup;
}
/**
* Specify the lifecycle phase for the embedded server.
*
* @param phase the lifecycle phase
*/
public void setPhase(int phase) {
this.phase = phase;
}
/**
* {@inheritDoc}
*/
@Override
public int getPhase() {
return this.phase;
}
/**
* {@inheritDoc}
*/
@Override
public boolean isRunning() {
return (zkServerThread != null);
}
/**
* Start the ZooKeeper server in a background thread.
* <p>
* Register an error handler via {@link #setErrorHandler} in order to handle
* any exceptions thrown during startup or execution.
*/
@Override
public synchronized void start() {
if (zkServerThread == null) {
zkServerThread = new Thread(new ServerRunnable(), "ZooKeeper Server Starter");
zkServerThread.setDaemon(true);
zkServerThread.start();
}
}
/**
* Shutdown the ZooKeeper server.
*/
@Override
public synchronized void stop() {
if (zkServerThread != null) {
// The shutdown method is protected...thus this hack to invoke it.
// This will log an exception on shutdown; see
// https://issues.apache.org/jira/browse/ZOOKEEPER-1873 for details.
try {
Method shutdown = ZooKeeperServerMain.class.getDeclaredMethod("shutdown");
shutdown.setAccessible(true);
shutdown.invoke(zkServer);
}
catch (Exception e) {
throw ZooKeeperUtils.wrapThrowable(e);
}
// It is expected that the thread will exit after
// the server is shutdown; this will block until
// the shutdown is complete.
try {
zkServerThread.join(5000);
zkServerThread = null;
}
catch (InterruptedException e) {
Thread.currentThread().interrupt();
logger.warn("Interrupted while waiting for embedded ZooKeeper to exit");
// abandoning zk thread
zkServerThread = null;
}
}
}
/**
* Stop the server if running and invoke the callback when complete.
*/
@Override
public void stop(Runnable callback) {
stop();
callback.run();
}
/**
* Provide an {@link ErrorHandler} to be invoked if an Exception is thrown from the ZooKeeper server thread. If none
* is provided, only error-level logging will occur.
*
* @param errorHandler the {@link ErrorHandler} to be invoked
*/
public void setErrorHandler(ErrorHandler errorHandler) {
this.errorHandler = errorHandler;
}
/**
* Runnable implementation that starts the ZooKeeper server.
*/
private class ServerRunnable implements Runnable {
@Override
public void run() {
try {
Properties properties = new Properties();
File file = new File(System.getProperty("java.io.tmpdir")
+ File.separator + UUID.randomUUID());
file.deleteOnExit();
properties.setProperty("dataDir", file.getAbsolutePath());
properties.setProperty("clientPort", String.valueOf(clientPort));
QuorumPeerConfig quorumPeerConfig = new QuorumPeerConfig();
quorumPeerConfig.parseProperties(properties);
zkServer = new ZooKeeperServerMain();
ServerConfig configuration = new ServerConfig();
configuration.readFrom(quorumPeerConfig);
zkServer.runFromConfig(configuration);
}
catch (Exception e) {
if (errorHandler != null) {
errorHandler.handleError(e);
}
else {
logger.error("Exception running embedded ZooKeeper", e);
}
}
}
}
}