/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2006-2010 Sun Microsystems, Inc.
 * Portions Copyright 2014-2015 ForgeRock AS.
 */
package org.opends.server.monitors;

import static org.opends.server.util.CollectionUtils.*;

import java.util.List;
import java.util.Map;
import java.util.TreeMap;

import org.forgerock.opendj.config.server.ConfigException;
import org.opends.server.admin.std.server.StackTraceMonitorProviderCfg;
import org.opends.server.api.MonitorProvider;
import org.opends.server.types.Attribute;
import org.opends.server.types.AttributeBuilder;
import org.opends.server.types.InitializationException;

/**
 * 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<StackTraceMonitorProviderCfg>
{
  @Override
  public void initializeMonitorProvider(
                   StackTraceMonitorProviderCfg configuration)
         throws ConfigException, InitializationException
  {
    // No initialization is required.
  }

  @Override
  public String getMonitorInstanceName()
  {
    return "JVM Stack Trace";
  }

  @Override
  public List<Attribute> getMonitorData()
  {
    Map<Thread,StackTraceElement[]> threadStacks = Thread.getAllStackTraces();

    // Re-arrange all of the elements by thread ID so that there is some logical order.
    TreeMap<Long,Map.Entry<Thread,StackTraceElement[]>> orderedStacks = new TreeMap<>();
    for (Map.Entry<Thread,StackTraceElement[]> e : threadStacks.entrySet())
    {
      orderedStacks.put(e.getKey().getId(), e);
    }

    AttributeBuilder builder = new AttributeBuilder("jvmThread");
    for (Map.Entry<Thread,StackTraceElement[]> e : orderedStacks.values())
    {
      Thread t                          = e.getKey();
      StackTraceElement[] stackElements = e.getValue();

      long id = t.getId();
      builder.add("id=" + id + " ---------- " + t.getName() + " ----------");

      // Create an attribute for the stack trace.
      if (stackElements != null)
      {
        for (int j=0; j < stackElements.length; j++)
        {
          StringBuilder buffer = new StringBuilder();
          buffer.append("id=");
          buffer.append(id);
          buffer.append(" frame[");
          buffer.append(j);
          buffer.append("]=");

          buffer.append(stackElements[j].getClassName());
          buffer.append(".");
          buffer.append(stackElements[j].getMethodName());
          buffer.append("(");
          buffer.append(stackElements[j].getFileName());
          buffer.append(":");
          if (stackElements[j].isNativeMethod())
          {
            buffer.append("native");
          }
          else
          {
            buffer.append(stackElements[j].getLineNumber());
          }
          buffer.append(")");

          builder.add(buffer.toString());
        }
      }
    }

    return newArrayList(builder.toAttribute());
  }
}