/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE
 * or https://OpenDS.dev.java.net/OpenDS.LICENSE.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE.  If applicable,
 * add the following below this CDDL HEADER, with the fields enclosed
 * by brackets "[]" replaced with your own identifying information:
 *      Portions Copyright [yyyy] [name of copyright owner]
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 * CDDL HEADER END
 *
 *
 *      Copyright 2009-2010 Sun Microsystems, Inc.
 *      Portions Copyright 2011-2013 ForgeRock AS
 */
package org.opends.server.replication.server;

import java.io.IOException;

import org.opends.server.api.DirectoryThread;
import org.opends.server.loggers.debug.DebugTracer;
import org.opends.server.replication.protocol.MonitorMsg;

import static org.opends.server.loggers.debug.DebugLogger.*;

/**
 * This thread regularly publishes monitoring information:
 * - it sends monitoring messages regarding the direct topology (directly
 *   connected DSs and RSs) to the connected RSs
 * - it sends monitoring messages regarding the whole topology (also includes
 *   the local RS) to the connected DSs
 * Note: as of today, monitoring messages mainly contains the server state of
 * the entities.
 */
public class MonitoringPublisher extends DirectoryThread
{

  private volatile boolean shutdown = false;

  /**
   * The tracer object for the debug logger.
   */
  private static final DebugTracer TRACER = getTracer();

  /** The replication domain we send monitoring for. */
  private final ReplicationServerDomain domain;

  /** Sleep time (in ms) before sending new monitoring messages. */
  private volatile long period;

  /** Whether the thread is terminated. */
  private volatile boolean done = false;

  private final Object shutdownLock = new Object();

  /**
   * Create a monitoring publisher.
   * @param replicationServerDomain The ReplicationServerDomain the monitoring
   *        publisher is for.
   * @param period The sleep time to use
   */
  public MonitoringPublisher(ReplicationServerDomain replicationServerDomain,
    long period)
  {
    super("Replication server RS("
        + replicationServerDomain.getLocalRSServerId()
        + ") monitor publisher for domain \""
        + replicationServerDomain.getBaseDn() + "\"");

    this.domain = replicationServerDomain;
    this.period = period;
  }

  /**
   * Run method for the monitoring publisher.
   */
  @Override
  public void run()
  {
    if (debugEnabled())
    {
      TRACER.debugInfo(getMessage("Monitoring publisher starting."));
    }

    try
    {
      while (!shutdown)
      {
        synchronized (shutdownLock)
        {
          if (!shutdown)
          {
            shutdownLock.wait(period);
          }
        }

        // Send global topology information to peer DSs
        final int senderId = domain.getLocalRSServerId();
        final MonitorMsg monitorMsg =
            domain.createGlobalTopologyMonitorMsg(senderId, 0);

        for (ServerHandler serverHandler : domain.getConnectedDSs().values())
        {
          monitorMsg.setDestination(serverHandler.getServerId());
          try
          {
            serverHandler.send(monitorMsg);
          }
          catch (IOException e)
          {
            // Server is disconnecting ? Forget it
          }
        }
      }
    }
    catch (InterruptedException e)
    {
      TRACER.debugInfo(getMessage(
          "Monitoring publisher has been interrupted while sleeping."));
    }

    done = true;
    TRACER.debugInfo(getMessage("Monitoring publisher is terminated."));
  }



  /**
   * Stops the thread.
   */
  public void shutdown()
  {
    synchronized (shutdownLock)
    {
      shutdown = true;
      shutdownLock.notifyAll();

      if (debugEnabled())
      {
        TRACER.debugInfo(getMessage("Shutting down monitoring publisher."));
      }
    }
  }

  /**
   * Waits for thread death. If not terminated within 2 seconds,
   * forces interruption
   */
  public void waitForShutdown()
  {
    try
    {
      int FACTOR = 40; // Wait for 2 seconds before interrupting the thread
      int n = 0;
      while (!done && isAlive())
      {
        Thread.sleep(50);
        n++;
        if (n >= FACTOR)
        {
          TRACER.debugInfo(getMessage("Interrupting monitoring publisher."));
          interrupt();
        }
      }
    } catch (InterruptedException e)
    {
      // exit the loop if this thread is interrupted.
    }
  }

  /**
   * Sets the period value.
   * @param period The new period value.
   */
  public void setPeriod(long period)
  {
    if (debugEnabled())
    {
      TRACER.debugInfo(getMessage(
          "Monitoring publisher changing period value to " + period));
    }

    this.period = period;
  }

  private String getMessage(String message)
  {
    return "In RS " + domain.getLocalRSServerId() + ", for base dn "
        + domain.getBaseDn() + ": " + message;
  }
}