/**

  * Copyright 2009 Martin Vysny.

  *

  * This file is part of WebVM.

  *

  * WebVM is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, either version 3 of the License, or

  * (at your option) any later version.

  *

  * WebVM is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  * GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License

  * along with WebVM.  If not, see <http://www.gnu.org/licenses/>.

  */

 package sk.baka.webvm;

 import java.lang.management.ManagementFactory;

 import java.lang.management.ThreadInfo;

 import java.lang.management.ThreadMXBean;

 import java.util.ArrayList;

 import java.util.List;

 import org.apache.wicket.markup.html.basic.Label;

 import org.apache.wicket.markup.html.list.ListItem;

 import org.apache.wicket.markup.html.list.ListView;

 import org.apache.wicket.model.IModel;

 import org.apache.wicket.model.LoadableDetachableModel;

 /**

  * Performs and displays a full thread dump.

  * @author vyzivus

  */

 public final class ThreadDump extends WebVMPage {

     private static final long serialVersionUID = 1L;

     /**

      * Constructor.

      */

     public ThreadDump() {

         border.add(new ThreadListView("threadList", new ThreadListModel()));

     }

     /**

      * Provides a list of all VM threads.

      */

     private static class ThreadListModel extends LoadableDetachableModel<List<ThreadInfo>> {

         private static final long serialVersionUID = 1L;

         @Override

         protected List<ThreadInfo> load() {

             final ThreadMXBean bean = ManagementFactory.getThreadMXBean();

             final ThreadInfo[] info = bean.getThreadInfo(bean.getAllThreadIds(), Integer.MAX_VALUE);

             final List<ThreadInfo> result = new ArrayList<ThreadInfo>(info.length);

             for (final ThreadInfo i : info) {

                 if (i != null) {

                     result.add(i);

                 }

             }

             return result;

         }

     }

     /**

      * Wicket ListView which displays a thread list.

      */

     private static class ThreadListView extends ListView<ThreadInfo> {

         public ThreadListView(String id, IModel<? extends List<? extends ThreadInfo>> model) {

             super(id, model);

         }

         private static final long serialVersionUID = 1L;

         @Override

         protected void populateItem(final ListItem<ThreadInfo> item) {

             final ThreadInfo info = item.getModelObject();

             item.add(new Label("threadName", getThreadMetadata(info)));

             item.add(new Label("threadStacktrace", getThreadStacktrace(info)));

         }

     }

     /**

      * Shows a basic thread info: thread ID, whether the thread is native, suspended, etc.

      * @param info the thread info.

      * @return pretty-printed thread info.

      */

     public static String getThreadMetadata(final ThreadInfo info) {

         final StringBuilder sb = new StringBuilder();

         sb.append("0x");

         sb.append(Long.toHexString(info.getThreadId()));

         sb.append(" [");

         sb.append(info.getThreadName());

         sb.append("] ");

         sb.append(info.getThreadState().toString());

         if (info.isInNative()) {

             sb.append(", in native");

         }

         if (info.isSuspended()) {

             sb.append(", suspended");

         }

         final String lockName = info.getLockName();

         if (lockName != null) {

             sb.append(", locked on [");

             sb.append(lockName);

             sb.append("]");

             sb.append(" owned by thread ");

             sb.append(info.getLockOwnerId());

             sb.append(" [");

             sb.append(info.getLockOwnerName());

             sb.append("]");

         }

         return sb.toString();

     }

     /**

      * Pretty-prints a thread stacktrace, similar to {@link Throwable#printStackTrace()} except that it handles nulls correctly.

      * @param info

      * @return string representation of the stacktrace.

      */

     public static String getThreadStacktrace(final ThreadInfo info) {

         final StringBuilder sb = new StringBuilder();

         final StackTraceElement[] stack = info.getStackTrace();

         if (stack == null) {

             sb.append("  stack trace not available");

         } else if (stack.length == 0) {

             sb.append("  stack trace is empty");

         } else {

             for (final StackTraceElement ste : stack) {

                 sb.append("  at ");

                 sb.append(ste.toString());

                 sb.append('\n');

             }

         }

         return sb.toString();

     }

 }