1   /*
    2    * Copyright (c) 1998, 2006, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   
   26   package com.sun.jdi;
   27   
   28   import java.util.List;
   29   
   30   /**
   31    * A thread group object from the target VM.
   32    * A ThreadGroupReference is an {@link ObjectReference} with additional
   33    * access to threadgroup-specific information from the target VM.
   34    *
   35    * @author Robert Field
   36    * @author Gordon Hirsch
   37    * @author James McIlree
   38    * @since  1.3
   39    */
   40   public interface ThreadGroupReference extends ObjectReference
   41   {
   42       /**
   43        * Returns the name of this thread group.
   44        *
   45        * @return the string containing the thread group name.
   46        */
   47       String name();
   48   
   49       /**
   50        * Returns the parent of this thread group.
   51        *
   52        * @return a {@link ThreadGroupReference} mirroring the parent of this
   53        * thread group in the target VM, or null if this is a top-level
   54        * thread group.
   55        */
   56       ThreadGroupReference parent();
   57   
   58       /**
   59        * Suspends all threads in this thread group. Each thread
   60        * in this group and in all of its subgroups will be
   61        * suspended as described in {@link ThreadReference#suspend}.
   62        * This is not guaranteed to be an atomic
   63        * operation; if the target VM is not interrupted at the time
   64        * this method is
   65        * called, it is possible that new threads will be created
   66        * between the time that threads are enumerated and all of them
   67        * have been suspended.
   68        * @throws VMCannotBeModifiedException if the VirtualMachine is read-only - see {@link VirtualMachine#canBeModified()}.
   69        */
   70       void suspend();
   71   
   72       /**
   73        * Resumes all threads in this thread group. Each thread
   74        * in this group and in all of its subgroups will be
   75        * resumed as described in {@link ThreadReference#resume}.
   76        * @throws VMCannotBeModifiedException if the VirtualMachine is read-only - see {@link VirtualMachine#canBeModified()}.
   77        */
   78       void resume();
   79   
   80       /**
   81        * Returns a List containing a {@link ThreadReference} for each live thread
   82        * in this thread group. Only the live threads in this immediate thread group
   83        * (and not its subgroups) are returned.  A thread is alive if it
   84        * has been started and has not yet been stopped.
   85        *
   86        * @return a List of {@link ThreadReference} objects mirroring the
   87        * live threads from this thread group in the target VM.
   88        */
   89       List<ThreadReference> threads();
   90   
   91       /**
   92        * Returns a List containing each active {@link ThreadGroupReference} in this
   93        * thread group. Only the active thread groups in this immediate thread group
   94        * (and not its subgroups) are returned.
   95        * See <a href="{@docRoot}/../../../../api/java/lang/ThreadGroup.html">java.lang.ThreadGroup</a>
   96        * for information about 'active' ThreadGroups.
   97        * @return a List of {@link ThreadGroupReference} objects mirroring the
   98        * active thread groups from this thread group in the target VM.
   99        */
  100       List<ThreadGroupReference> threadGroups();
  101   }