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zookeeper源码学习1-ZooKeeperServerMain

该方法是ZKServer单机启动时候的入口函数

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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/


/**
* This class starts and runs a standalone ZooKeeperServer.
*/
@InterfaceAudience.Public
public class ZooKeeperServerMain {

private static final Logger LOG = LoggerFactory.getLogger(ZooKeeperServerMain.class);

private static final String USAGE = "Usage: ZooKeeperServerMain configfile | port datadir [ticktime] [maxcnxns]";

// ZooKeeper server supports two kinds of connection: unencrypted and encrypted.
private ServerCnxnFactory cnxnFactory;
private ServerCnxnFactory secureCnxnFactory;
private ContainerManager containerManager;
private MetricsProvider metricsProvider;
private AdminServer adminServer;

/*
* Start up the ZooKeeper server.
*
* @param args the configfile or the port datadir [ticktime]
*/
public static void main(String[] args) {
ZooKeeperServerMain main = new ZooKeeperServerMain();
try {
main.initializeAndRun(args);
} catch (IllegalArgumentException e) {
LOG.error("Invalid arguments, exiting abnormally", e);
LOG.info(USAGE);
System.err.println(USAGE);
ZKAuditProvider.addServerStartFailureAuditLog();
ServiceUtils.requestSystemExit(ExitCode.INVALID_INVOCATION.getValue());
} catch (ConfigException e) {
LOG.error("Invalid config, exiting abnormally", e);
System.err.println("Invalid config, exiting abnormally");
ZKAuditProvider.addServerStartFailureAuditLog();
ServiceUtils.requestSystemExit(ExitCode.INVALID_INVOCATION.getValue());
} catch (DatadirException e) {
LOG.error("Unable to access datadir, exiting abnormally", e);
System.err.println("Unable to access datadir, exiting abnormally");
ZKAuditProvider.addServerStartFailureAuditLog();
ServiceUtils.requestSystemExit(ExitCode.UNABLE_TO_ACCESS_DATADIR.getValue());
} catch (AdminServerException e) {
LOG.error("Unable to start AdminServer, exiting abnormally", e);
System.err.println("Unable to start AdminServer, exiting abnormally");
ZKAuditProvider.addServerStartFailureAuditLog();
ServiceUtils.requestSystemExit(ExitCode.ERROR_STARTING_ADMIN_SERVER.getValue());
} catch (Exception e) {
LOG.error("Unexpected exception, exiting abnormally", e);
ZKAuditProvider.addServerStartFailureAuditLog();
ServiceUtils.requestSystemExit(ExitCode.UNEXPECTED_ERROR.getValue());
}
LOG.info("Exiting normally");
ServiceUtils.requestSystemExit(ExitCode.EXECUTION_FINISHED.getValue());
}

protected void initializeAndRun(String[] args) throws ConfigException, IOException, AdminServerException {
try {
ManagedUtil.registerLog4jMBeans();
} catch (JMException e) {
LOG.warn("Unable to register log4j JMX control", e);
}

ServerConfig config = new ServerConfig();
if (args.length == 1) {
config.parse(args[0]);
} else {
config.parse(args);
}

runFromConfig(config);
}

/**
* Run from a ServerConfig.
* @param config ServerConfig to use.
* @throws IOException
* @throws AdminServerException
*/
public void runFromConfig(ServerConfig config) throws IOException, AdminServerException {
LOG.info("Starting server");
FileTxnSnapLog txnLog = null;
try {
try {
metricsProvider = MetricsProviderBootstrap.startMetricsProvider(
config.getMetricsProviderClassName(),
config.getMetricsProviderConfiguration());
} catch (MetricsProviderLifeCycleException error) {
throw new IOException("Cannot boot MetricsProvider " + config.getMetricsProviderClassName(), error);
}
ServerMetrics.metricsProviderInitialized(metricsProvider);
// Note that this thread isn't going to be doing anything else,
// so rather than spawning another thread, we will just call
// run() in this thread.
// create a file logger url from the command line args
txnLog = new FileTxnSnapLog(config.dataLogDir, config.dataDir);
JvmPauseMonitor jvmPauseMonitor = null;
if (config.jvmPauseMonitorToRun) {
jvmPauseMonitor = new JvmPauseMonitor(config);
}
final ZooKeeperServer zkServer = new ZooKeeperServer(jvmPauseMonitor, txnLog, config.tickTime, config.minSessionTimeout, config.maxSessionTimeout, config.listenBacklog, null, config.initialConfig);
txnLog.setServerStats(zkServer.serverStats());

// Registers shutdown handler which will be used to know the
// server error or shutdown state changes.
final CountDownLatch shutdownLatch = new CountDownLatch(1);
zkServer.registerServerShutdownHandler(new ZooKeeperServerShutdownHandler(shutdownLatch));

// Start Admin server
adminServer = AdminServerFactory.createAdminServer();
adminServer.setZooKeeperServer(zkServer);
adminServer.start();

boolean needStartZKServer = true;
if (config.getClientPortAddress() != null) {
cnxnFactory = ServerCnxnFactory.createFactory();
cnxnFactory.configure(config.getClientPortAddress(), config.getMaxClientCnxns(), config.getClientPortListenBacklog(), false);
cnxnFactory.startup(zkServer);
// zkServer has been started. So we don't need to start it again in secureCnxnFactory.
needStartZKServer = false;
}
if (config.getSecureClientPortAddress() != null) {
secureCnxnFactory = ServerCnxnFactory.createFactory();
secureCnxnFactory.configure(config.getSecureClientPortAddress(), config.getMaxClientCnxns(), config.getClientPortListenBacklog(), true);
secureCnxnFactory.startup(zkServer, needStartZKServer);
}

containerManager = new ContainerManager(
zkServer.getZKDatabase(),
zkServer.firstProcessor,
Integer.getInteger("znode.container.checkIntervalMs", (int) TimeUnit.MINUTES.toMillis(1)),
Integer.getInteger("znode.container.maxPerMinute", 10000),
Long.getLong("znode.container.maxNeverUsedIntervalMs", 0)
);
containerManager.start();
ZKAuditProvider.addZKStartStopAuditLog();

// Watch status of ZooKeeper server. It will do a graceful shutdown
// if the server is not running or hits an internal error.
shutdownLatch.await();

shutdown();

if (cnxnFactory != null) {
cnxnFactory.join();
}
if (secureCnxnFactory != null) {
secureCnxnFactory.join();
}
if (zkServer.canShutdown()) {
zkServer.shutdown(true);
}
} catch (InterruptedException e) {
// warn, but generally this is ok
LOG.warn("Server interrupted", e);
} finally {
if (txnLog != null) {
txnLog.close();
}
if (metricsProvider != null) {
try {
metricsProvider.stop();
} catch (Throwable error) {
LOG.warn("Error while stopping metrics", error);
}
}
}
}

/**
* Shutdown the serving instance
*/
protected void shutdown() {
if (containerManager != null) {
containerManager.stop();
}
if (cnxnFactory != null) {
cnxnFactory.shutdown();
}
if (secureCnxnFactory != null) {
secureCnxnFactory.shutdown();
}
try {
if (adminServer != null) {
adminServer.shutdown();
}
} catch (AdminServerException e) {
LOG.warn("Problem stopping AdminServer", e);
}
}

// VisibleForTesting
ServerCnxnFactory getCnxnFactory() {
return cnxnFactory;
}

}