/*

 * Copyright (c) 1998, 2011, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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 com.sun.tools.jdi;

import com.sun.jdi.*;

import java.util.*;

public class ThreadGroupReferenceImpl extends ObjectReferenceImpl

    implements ThreadGroupReference, VMListener

{

    // Cached components that cannot change

    String name;

    ThreadGroupReference parent;

    boolean triedParent;

    // This is cached only while the VM is suspended

    private static class Cache extends ObjectReferenceImpl.Cache {

        JDWP.ThreadGroupReference.Children kids = null;

    }

    protected ObjectReferenceImpl.Cache newCache() {

        return new Cache();

    }

    ThreadGroupReferenceImpl(VirtualMachine aVm,long aRef) {

        super(aVm,aRef);

        vm.state().addListener(this);

    }

    protected String description() {

        return "ThreadGroupReference " + uniqueID();

    }

    public String name() {

        if (name == null) {

            // Does not need synchronization, since worst-case

            // static info is fetched twice (Thread group name

            // cannot change)

            try {

                name = JDWP.ThreadGroupReference.Name.

                                     process(vm, this).groupName;

            } catch (JDWPException exc) {

                throw exc.toJDIException();

            }

        }

        return name;

    }

    public ThreadGroupReference parent() {

        if (!triedParent) {

            // Does not need synchronization, since worst-case

            // static info is fetched twice (Thread group parent cannot

            // change)

            try {

                parent = JDWP.ThreadGroupReference.Parent.

                                 process(vm, this).parentGroup;

                triedParent = true;

            } catch (JDWPException exc) {

                throw exc.toJDIException();

            }

        }

       return parent;

    }

    public void suspend() {

        for (ThreadReference thread : threads()) {

            thread.suspend();

        }

        for (ThreadGroupReference threadGroup : threadGroups()) {

            threadGroup.suspend();

        }

    }

    public void resume() {

        for (ThreadReference thread : threads()) {

            thread.resume();

        }

        for (ThreadGroupReference threadGroup : threadGroups()) {

            threadGroup.resume();

        }

    }

    private JDWP.ThreadGroupReference.Children kids() {

        JDWP.ThreadGroupReference.Children kids = null;

        try {

            Cache local = (Cache)getCache();

            if (local != null) {

                kids = local.kids;

            }

            if (kids == null) {

                kids = JDWP.ThreadGroupReference.Children

                                                  .process(vm, this);

                if (local != null) {

                    local.kids = kids;

                    if ((vm.traceFlags & VirtualMachine.TRACE_OBJREFS) != 0) {

                        vm.printTrace(description() +

                                      " temporarily caching children ");

                    }

                }

            }

        } catch (JDWPException exc) {

            throw exc.toJDIException();

        }

        return kids;

    }

    public List<ThreadReference> threads() {

        return Arrays.asList((ThreadReference[])kids().childThreads);

    }

    public List<ThreadGroupReference> threadGroups() {

        return Arrays.asList((ThreadGroupReference[])kids().childGroups);

    }

    public String toString() {

        return "instance of " + referenceType().name() +

               "(name='" + name() + "', " + "id=" + uniqueID() + ")";

    }

    byte typeValueKey() {

        return JDWP.Tag.THREAD_GROUP;

    }

}