/*
 * 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]
 *
 * CDDL HEADER END
 *
 *
 *      Portions Copyright 2006 Sun Microsystems, Inc.
 */
package org.opends.server.monitors;



import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.Map;

import org.opends.server.api.MonitorProvider;
import org.opends.server.config.ConfigEntry;
import org.opends.server.config.ConfigException;
import org.opends.server.core.DirectoryServer;
import org.opends.server.core.InitializationException;
import org.opends.server.protocols.asn1.ASN1OctetString;
import org.opends.server.types.Attribute;
import org.opends.server.types.AttributeType;
import org.opends.server.types.AttributeValue;

import static org.opends.server.loggers.Debug.*;



/**
 * This class defines a Directory Server monitor provider that can be used to
 * obtain a stack trace from all server threads that are currently defined in
 * the JVM.
 */
public class StackTraceMonitorProvider
       extends MonitorProvider
{
  /**
   * The fully-qualified name of this class for debugging purposes.
   */
  private static final String CLASS_NAME =
       "org.opends.server.monitors.StackTraceMonitorProvider";



  /**
   * Initializes this monitor provider.
   */
  public StackTraceMonitorProvider()
  {
    super("Stack Trace Monitor Provider");

    // No initialization should be performed here.
  }



  /**
   * Initializes this monitor provider based on the information in the provided
   * configuration entry.
   *
   * @param  configEntry  The configuration entry that contains the information
   *                      to use to initialize this monitor provider.
   *
   * @throws  ConfigException  If an unrecoverable problem arises in the
   *                           process of performing the initialization.
   *
   * @throws  InitializationException  If a problem occurs during initialization
   *                                   that is not related to the server
   *                                   configuration.
   */
  public void initializeMonitorProvider(ConfigEntry configEntry)
         throws ConfigException, InitializationException
  {
    assert debugEnter(CLASS_NAME, "initializeMonitorProvider",
                      String.valueOf(configEntry));

    // No initialization is required.
  }



  /**
   * Retrieves the name of this monitor provider.  It should be unique among all
   * monitor providers, including all instances of the same monitor provider.
   *
   * @return  The name of this monitor provider.
   */
  public String getMonitorInstanceName()
  {
    assert debugEnter(CLASS_NAME, "getMonitorInstanceName");

    return "JVM Stack Trace";
  }



  /**
   * Retrieves the length of time in milliseconds that should elapse between
   * calls to the <CODE>updateMonitorData()</CODE> method.  A negative or zero
   * return value indicates that the <CODE>updateMonitorData()</CODE> method
   * should not be periodically invoked.
   *
   * @return  The length of time in milliseconds that should elapse between
   *          calls to the <CODE>updateMonitorData()</CODE> method.
   */
  public long getUpdateInterval()
  {
    assert debugEnter(CLASS_NAME, "getUpdateInterval");

    // This monitor does not need to run periodically.
    return 0;
  }



  /**
   * Performs any processing periodic processing that may be desired to update
   * the information associated with this monitor.  Note that best-effort
   * attempts will be made to ensure that calls to this method come
   * <CODE>getUpdateInterval()</CODE> milliseconds apart, but no guarantees will
   * be made.
   */
  public void updateMonitorData()
  {
    assert debugEnter(CLASS_NAME, "updateMonitorData");

    // This monitor does not need to run periodically.
    return;
  }



  /**
   * Retrieves a set of attributes containing monitor data that should be
   * returned to the client if the corresponding monitor entry is requested.
   *
   * @return  A set of attributes containing monitor data that should be
   *          returned to the client if the corresponding monitor entry is
   *          requested.
   */
  public ArrayList<Attribute> getMonitorData()
  {
    assert debugEnter(CLASS_NAME, "getMonitorData");


    Map<Thread,StackTraceElement[]> threadStacks = Thread.getAllStackTraces();
    ArrayList<Attribute> attrs = new ArrayList<Attribute>();

    int i=0;
    for (Thread t : threadStacks.keySet())
    {
      String prefix = "thread-" + i + "-";

      // Create an attribute for the thread name.
      attrs.add(createAttribute(prefix + "name", t.getName()));

      // Create an attribute for the thread ID.
      attrs.add(createAttribute(prefix + "id:", String.valueOf(t.getId())));

      // Create an attribute for the thread priority.
      attrs.add(createAttribute(prefix + "priority",
                                String.valueOf(t.getPriority())));

      // Create an attribute for the current thread state.
      attrs.add(createAttribute(prefix + "state", t.getState().toString()));

      // Create an attribute for the thread group.
      ThreadGroup threadGroup = t.getThreadGroup();
      if (threadGroup != null)
      {
        attrs.add(createAttribute(prefix + "group", threadGroup.getName()));
      }

      // Create an attribute for the stack trace.
      StackTraceElement[] stackElements = threadStacks.get(t);
      if (stackElements != null)
      {
        int j=0;
        for (StackTraceElement e : stackElements)
        {
          StringBuilder trace = new StringBuilder();

          trace.append(e.getClassName());
          trace.append(".");
          trace.append(e.getMethodName());
          trace.append("(");
          trace.append(e.getFileName());
          trace.append(":");
          trace.append(e.getLineNumber());
          trace.append(")");

          if (e.isNativeMethod())
          {
            trace.append(" -- Native method");
          }

          attrs.add(createAttribute(prefix + "stack-frame-" + j,
                                    trace.toString()));
          j++;
        }
      }

      i++;
    }

    return attrs;
  }



  /**
   * Constructs an attribute using the provided information.  It will have the
   * default syntax.
   *
   * @param  name   The name to use for the attribute.
   * @param  value  The value to use for the attribute.
   *
   * @return  The attribute created from the provided information.
   */
  private Attribute createAttribute(String name, String value)
  {
    assert debugEnter(CLASS_NAME, "createAttribute", String.valueOf(name),
                      String.valueOf(value));

    AttributeType attrType = DirectoryServer.getDefaultAttributeType(name);

    ASN1OctetString encodedValue = new ASN1OctetString(value);
    LinkedHashSet<AttributeValue> values = new LinkedHashSet<AttributeValue>(1);

    try
    {
      values.add(new AttributeValue(encodedValue,
                                    attrType.normalize(encodedValue)));
    }
    catch (Exception e)
    {
      assert debugException(CLASS_NAME, "createAttribute", e);

      values.add(new AttributeValue(encodedValue, encodedValue));
    }

    return new Attribute(attrType, name, values);
  }
}