Java example source code file (JSJavaThread.java)

This example Java source code file (JSJavaThread.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, iterator, javavframe, jsjavafactory, jsjavainstance, jsjavathread, jslist, list, monitorinfo, objectheap, objectmonitor, oophandle, string, stringbuffer, util

The JSJavaThread.java Java example source code

/*
 * Copyright (c) 2004, 2009, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

package sun.jvm.hotspot.utilities.soql;

import java.util.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.runtime.*;

/**
 * Wraps a JavaThread instance in the target VM.
 */
public class JSJavaThread extends JSJavaInstance {
    public JSJavaThread(Instance threadOop, JSJavaFactory fac) {
        super(threadOop, fac);
        // JavaThread retrieved from java.lang.Thread instance may be null.
        // This is the case for threads not-started and for zombies. Wherever
        // appropriate, check for null instead of resulting in NullPointerException.
        this.jthread = OopUtilities.threadOopGetJavaThread(threadOop);
    }

    public JSJavaThread(JavaThread jt, JSJavaFactory fac) {
        super((Instance) jt.getThreadObj(), fac);
        this.jthread = jt;
    }

    public String toString() {
        String name = getName();
        StringBuffer buf = new StringBuffer();
        buf.append("Thread (address=");
        buf.append(getOop().getHandle());
        buf.append(", name=");
        if (name != null) {
            buf.append(name);
        } else {
            buf.append("<unnamed>");
        }
        buf.append(')');
        return buf.toString();
    }

    protected Object getFieldValue(String name) {
        if (name.equals("name")) {
            return getName();
        } else if (name.equals("frames")) {
            return getFrames();
        } else if (name.equals("monitors")) {
            return getOwnedMonitors();
        } else {
            return super.getFieldValue(name);
        }
    }

    protected String[] getFieldNames() {
        String[] flds = super.getFieldNames();
        String[] res = new String[flds.length + 2];
        System.arraycopy(flds, 0, res, 0, flds.length);
        res[flds.length] = "frames";
        res[flds.length + 1] = "monitors";
        return res;
    }

    protected boolean hasField(String name) {
        if (name.equals("frames") || name.equals("monitors")) {
            return true;
        } else {
            return super.hasField(name);
        }
    }

    //-- Internals only below this point
    private String getName() {
        return OopUtilities.threadOopGetName(getOop());
    }

    private synchronized JSList getFrames() {
        if (framesCache == null) {
            final List list = new ArrayList(0);
            if (jthread != null) {
                JavaVFrame jvf = jthread.getLastJavaVFrameDbg();
                while (jvf != null) {
                    list.add(jvf);
                    jvf = jvf.javaSender();
                }
            }
            framesCache = factory.newJSList(list);
        }
        return framesCache;
    }

    private synchronized JSList getOwnedMonitors() {
        if (monitorsCache == null) {
            final List ownedMonitors = new ArrayList(0);
            if (jthread != null) {
                List lockedObjects = new ArrayList(); // List<OopHandle>

                ObjectMonitor waitingMonitor = jthread.getCurrentWaitingMonitor();
                OopHandle waitingObj = null;
                if (waitingMonitor != null) {
                   // save object of current wait() call (if any) for later comparison
                   waitingObj = waitingMonitor.object();
                }

                ObjectMonitor pendingMonitor = jthread.getCurrentPendingMonitor();
                OopHandle pendingObj = null;
                if (pendingMonitor != null) {
                    // save object of current enter() call (if any) for later comparison
                    pendingObj = pendingMonitor.object();
                }

                JavaVFrame frame = jthread.getLastJavaVFrameDbg();
                while (frame != null) {
                    List frameMonitors = frame.getMonitors();  // List<MonitorInfo>
                    for (Iterator miItr = frameMonitors.iterator(); miItr.hasNext(); ) {
                        MonitorInfo mi = (MonitorInfo) miItr.next();

                        if (mi.eliminated() && frame.isCompiledFrame()) {
                          continue; // skip eliminated monitor
                        }
                        OopHandle obj = mi.owner();
                        if (obj == null) {
                            // this monitor doesn't have an owning object so skip it
                            continue;
                        }

                        if (obj.equals(waitingObj)) {
                           // the thread is waiting on this monitor so it isn't really owned
                           continue;
                        }

                        if (obj.equals(pendingObj)) {
                            // the thread is pending on this monitor so it isn't really owned
                            continue;
                        }

                        boolean found = false;
                        for (Iterator loItr = lockedObjects.iterator(); loItr.hasNext(); ) {
                            // check for recursive locks
                            if (obj.equals(loItr.next())) {
                                found = true;
                                break;
                            }
                        }
                        if (found) {
                            // already have this object so don't include it
                            continue;
                        }
                        // add the owning object to our list
                        lockedObjects.add(obj);
                    }
                    frame = (JavaVFrame) frame.javaSender();
                }

                // now convert List<OopHandle> to List
                ObjectHeap heap = VM.getVM().getObjectHeap();
                for (Iterator loItr = lockedObjects.iterator(); loItr.hasNext(); ) {
                    ownedMonitors.add(heap.newOop((OopHandle)loItr.next()));
                }
            }
            monitorsCache = factory.newJSList(ownedMonitors);
        }
        return monitorsCache;
    }

    private JavaThread jthread;
    private JSList framesCache;
    private JSList monitorsCache;
}