content: /**
   * 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.
   */
  package org.apache.activemq.broker;
  
  import org.apache.activemq.store.PersistenceAdapter;
  import org.apache.activemq.util.ServiceStopper;
  import org.apache.activemq.util.ServiceSupport;
  import org.apache.activemq.util.ThreadPoolUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  import java.util.concurrent.ScheduledFuture;
  import java.util.concurrent.ScheduledThreadPoolExecutor;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.TimeUnit;
  
  /**
   * Helper class for working with services that requires locking
   */
  public abstract class LockableServiceSupport extends ServiceSupport implements Lockable, BrokerServiceAware {
  
      private static final Logger LOG = LoggerFactory.getLogger(LockableServiceSupport.class);
      boolean useLock = true;
      boolean stopOnError = false;
      Locker locker;
      long lockKeepAlivePeriod = 0;
      private ScheduledFuture<?> keepAliveTicket;
      protected ScheduledThreadPoolExecutor clockDaemon;
      protected BrokerService brokerService;
  
      /**
       * Initialize resources before locking
       *
       * @throws Exception
       */
      abstract public void init() throws Exception;
  
      @Override
      public void setUseLock(boolean useLock) {
          this.useLock = useLock;
      }
  
      public boolean isUseLock() {
          return this.useLock;
      }
  
      @Override
      public void setStopOnError(boolean stopOnError) {
          this.stopOnError = stopOnError;
      }
  
      public boolean isStopOnError() {
          return this.stopOnError;
      }
  
      @Override
      public void setLocker(Locker locker) throws IOException {
          this.locker = locker;
          locker.setLockable(this);
          if (this instanceof PersistenceAdapter) {
              this.locker.configure((PersistenceAdapter)this);
          }
      }
  
      public Locker getLocker() throws IOException {
          if (this.locker == null) {
              setLocker(createDefaultLocker());
          }
          return this.locker;
      }
  
      @Override
      public void setLockKeepAlivePeriod(long lockKeepAlivePeriod) {
          this.lockKeepAlivePeriod = lockKeepAlivePeriod;
      }
  
      @Override
      public long getLockKeepAlivePeriod() {
          return lockKeepAlivePeriod;
      }
  
      @Override
      public void preStart() throws Exception {
          init();
          if (useLock) {
              if (getLocker() == null) {
                  LOG.warn("No locker configured");
              } else {
                  getLocker().start();
                  if (lockKeepAlivePeriod > 0) {
                      keepAliveTicket = getScheduledThreadPoolExecutor().scheduleAtFixedRate(new Runnable() {
                          public void run() {
                              keepLockAlive();
                          }
                      }, lockKeepAlivePeriod, lockKeepAlivePeriod, TimeUnit.MILLISECONDS);
                  }
              }
          }
      }
  
      @Override
      public void postStop(ServiceStopper stopper) throws Exception {
          if (useLock) {
              if (keepAliveTicket != null) {
                  keepAliveTicket.cancel(false);
                  keepAliveTicket = null;
              }
              if (locker != null) {
                  getLocker().stop();
                  locker = null;
              }
          }
          ThreadPoolUtils.shutdown(clockDaemon);
          clockDaemon = null;
      }
  
      protected void keepLockAlive() {
          boolean stop = false;
          try {
              Locker locker = getLocker();
              if (locker != null) {
                  if (!locker.keepAlive()) {
                      stop = true;
                  }
              }
          } catch (SuppressReplyException e) {
              if (stopOnError) {
                  stop = true;
              }
              LOG.warn("locker keepAlive resulted in", e);
          } catch (IOException e) {
              if (stopOnError) {
                  stop = true;
              }
              LOG.warn("locker keepAlive resulted in", e);
          }
          if (stop) {
              stopBroker();
          }
      }
  
      protected void stopBroker() {
          // we can no longer keep the lock so lets fail
          LOG.error("{}, no longer able to keep the exclusive lock so giving up being a master", brokerService.getBrokerName());
          try {
              if( brokerService.isRestartAllowed() ) {
                  brokerService.requestRestart();
              }
              brokerService.stop();
          } catch (Exception e) {
              LOG.warn("Failure occurred while stopping broker");
          }
      }
  
      public ScheduledThreadPoolExecutor getScheduledThreadPoolExecutor() {
          if (clockDaemon == null) {
              clockDaemon = new ScheduledThreadPoolExecutor(5, new ThreadFactory() {
                  public Thread newThread(Runnable runnable) {
                      Thread thread = new Thread(runnable, "ActiveMQ Lock KeepAlive Timer");
                      thread.setDaemon(true);
                      return thread;
                  }
              });
          }
          return clockDaemon;
      }
  
      public void setScheduledThreadPoolExecutor(ScheduledThreadPoolExecutor clockDaemon) {
          this.clockDaemon = clockDaemon;
      }
  
      @Override
      public void setBrokerService(BrokerService brokerService) {
          this.brokerService = brokerService;
      }
  
      public BrokerService getBrokerService() {
          return this.brokerService;
      }
  }
  