1 /*
  2  * Copyright (c) 1998, 2021, 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
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  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. Virtual threads are not considered live threads in
 83      * a thread group and are not included. Only the live threads in this
 84      * immediate thread group (and not its subgroups) are returned. A thread is
 85      * alive if it has been started and has not yet been stopped.
 86      *
 87      * @return a List of {@link ThreadReference} objects mirroring the
 88      * live threads from this thread group in the target VM.
 89      */
 90     List<ThreadReference> threads();
 91 
 92     /**
 93      * Returns a List containing a {@link ThreadGroupReference} for each
 94      * subgroup. Only the thread groups in this immediate thread group (and
 95      * not its subgroups) are returned.
 96      *
 97      * @return a List of {@link ThreadGroupReference} objects mirroring the
 98      * thread groups from this thread group in the target VM.
 99      */
100     List<ThreadGroupReference> threadGroups();
101 }