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1 /*
2  * Copyright (c) 1998, 2013, 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.event;
27 
28 import com.sun.jdi.*;
29 
30 import java.util.Set;
31 
32 /**
33  * Several {@link Event} objects may be created at a given time by
34  * the target {@link VirtualMachine}. For example, there may be
35  * more than one {@link com.sun.jdi.request.BreakpointRequest}
36  * for a given {@link Location}
37  * or you might single step to the same location as a
38  * BreakpointRequest.  These {@link Event} objects are delivered
39  * together as an EventSet.  For uniformity, an EventSet is always used
40  * to deliver {@link Event} objects.  EventSets are delivered by
41  * the {@link EventQueue}.
42  * EventSets are unmodifiable.
43  * <P>
44  * Associated with the issuance of an event set, suspensions may
45  * have occurred in the target VM.  These suspensions correspond
46  * with the {@link #suspendPolicy() suspend policy}.
47  * To assure matching resumes occur, it is recommended,
48  * where possible,
49  * to complete the processing of an event set with
50  * {@link #resume() EventSet.resume()}.
51  * <P>
52  * The events that are grouped in an EventSet are restricted in the
53  * following ways:
54  * <P>
55  * <UL>
56  * <LI>Always singleton sets:
57  *     <UL>
58  *     <LI>{@link VMStartEvent}
59  *     <LI>{@link VMDisconnectEvent}
60  *     </UL>
61  * <LI>Only with other VMDeathEvents:
62  *     <UL>
63  *     <LI>{@link VMDeathEvent}
64  *     </UL>
65  * <LI>Only with other ThreadStartEvents for the same thread:
66  *     <UL>
67  *     <LI>{@link ThreadStartEvent}
68  *     </UL>
69  * <LI>Only with other ThreadDeathEvents for the same thread:
70  *     <UL>
71  *     <LI>{@link ThreadDeathEvent}
72  *     </UL>
73  * <LI>Only with other ClassPrepareEvents for the same class:
74  *     <UL>
75  *     <LI>{@link ClassPrepareEvent}
76  *     </UL>
77  * <LI>Only with other ClassUnloadEvents for the same class:
78  *     <UL>
79  *     <LI>{@link ClassUnloadEvent}
80  *     </UL>
81  * <LI>Only with other AccessWatchpointEvents for the same field access:
82  *     <UL>
83  *     <LI>{@link AccessWatchpointEvent}
84  *     </UL>
85  * <LI>Only with other ModificationWatchpointEvents for the same field
86  * modification:
87  *     <UL>
88  *     <LI>{@link ModificationWatchpointEvent}
89  *     </UL>
90  * <LI>Only with other ExceptionEvents for the same exception occurrance:
91  *     <UL>
92  *     <LI>{@link ExceptionEvent}
93  *     </UL>
94  * <LI>Only with other MethodExitEvents for the same method exit:
95  *     <UL>
96  *     <LI>{@link MethodExitEvent}
97  *     </UL>
98  * <LI>Only with other Monitor contended enter events for the same monitor object:
99  *     <UL>
100  *     <LI>Monitor Contended Enter Event
101  *     </UL>
102  * <LI>Only with other Monitor contended entered events for the same monitor object:
103  *     <UL>
104  *     <LI>Monitor Contended Entered Event
105  *    </UL>
106  * <LI>Only with other Monitor wait events for the same monitor object:
107  *     <UL>
108  *     <LI>Monitor Wait Event
109  *     </UL>
110  * <LI>Only with other Monitor waited events for the same monitor object:
111  *     <UL>
112  *     <LI>Monitor Waited Event
113  *     </UL>
114  * <LI>Only with other members of this group, at the same location
115  * and in the same thread:
116  *     <UL>
117  *     <LI>{@link BreakpointEvent}
118  *     <LI>{@link StepEvent}
119  *     <LI>{@link MethodEntryEvent}
120  *     </UL>
121  * </UL>
122  *
123  * @see Event
124  * @see EventQueue
125  *
126  * @author Robert Field
127  * @since  1.3
128  */
129 
130 @jdk.Exported
131 public interface EventSet extends Mirror, Set<Event> {
132 
133     /**
134      * Returns the policy used to suspend threads in the target VM
135      * for this event set. This policy is selected from the suspend
136      * policies for each event's request; the target VM chooses the
137      * policy which suspends the most threads.  The target VM
138      * suspends threads according to that policy
139      * and that policy is returned here. See
140      * {@link com.sun.jdi.request.EventRequest} for the possible
141      * policy values.
142      * <p>
143      * In rare cases, the suspend policy may differ from the requested
144      * value if a {@link ClassPrepareEvent} has occurred in a
145      * debugger system thread. See {@link ClassPrepareEvent#thread}
146      * for details.
147      *
148      * @return the suspendPolicy which is either
149      * {@link com.sun.jdi.request.EventRequest#SUSPEND_ALL SUSPEND_ALL},
150      * {@link com.sun.jdi.request.EventRequest#SUSPEND_EVENT_THREAD SUSPEND_EVENT_THREAD} or
151      * {@link com.sun.jdi.request.EventRequest#SUSPEND_NONE SUSPEND_NONE}.
152      */
suspendPolicy()153     int suspendPolicy();
154 
155     /**
156      * Return an iterator specific to {@link Event} objects.
157      */
eventIterator()158     EventIterator eventIterator();
159 
160     /**
161      * Resumes threads suspended by this event set. If the {@link #suspendPolicy}
162      * is {@link com.sun.jdi.request.EventRequest#SUSPEND_ALL}, a call
163      * to this method is equivalent to
164      * {@link com.sun.jdi.VirtualMachine#resume}. If the
165      * suspend policy is
166      * {@link com.sun.jdi.request.EventRequest#SUSPEND_EVENT_THREAD},
167      * a call to this method is equivalent to
168      * {@link com.sun.jdi.ThreadReference#resume} for the event thread.
169      * Otherwise, a call to this method is a no-op.
170      */
resume()171     void resume();
172 }
173