1 /*
2 * Copyright (c) 1999, 2017, 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.tools.jdi;
27
28 import java.lang.ref.WeakReference;
29 import java.util.ArrayList;
30 import java.util.Arrays;
31 import java.util.Iterator;
32 import java.util.List;
33
34 import com.sun.jdi.ThreadGroupReference;
35 import com.sun.jdi.ThreadReference;
36 import com.sun.jdi.VirtualMachine;
37
38 class VMState {
39 private final VirtualMachineImpl vm;
40
41 // Listeners
42 private final List<WeakReference<VMListener>> listeners = new ArrayList<>(); // synchronized (this)
43 private boolean notifyingListeners = false; // synchronized (this)
44
45 /*
46 * Certain information can be cached only when the entire VM is
47 * suspended and there are no pending resumes. The fields below
48 * are used to track whether there are pending resumes. (There
49 * is an assumption that JDWP command ids are increasing over time.)
50 */
51 private int lastCompletedCommandId = 0; // synchronized (this)
52 private int lastResumeCommandId = 0; // synchronized (this)
53
54 // This is cached only while the VM is suspended
55 private static class Cache {
56 List<ThreadGroupReference> groups = null; // cached Top Level ThreadGroups
57 List<ThreadReference> threads = null; // cached Threads
58 }
59
60 private Cache cache = null; // synchronized (this)
61 private static final Cache markerCache = new Cache();
62
63 private void disableCache() {
64 synchronized (this) {
65 cache = null;
66 }
67 }
68
69 private void enableCache() {
70 synchronized (this) {
71 cache = markerCache;
72 }
80 return cache;
81 }
82 }
83
84 VMState(VirtualMachineImpl vm) {
85 this.vm = vm;
86 }
87
88 /**
89 * Is the VM currently suspended, for the purpose of caching?
90 * Must be called synchronized on vm.state()
91 */
92 boolean isSuspended() {
93 return cache != null;
94 }
95
96 /*
97 * A JDWP command has been completed (reply has been received).
98 * Update data that tracks pending resume commands.
99 */
100 synchronized void notifyCommandComplete(int id) {
101 lastCompletedCommandId = id;
102 }
103
104 synchronized void freeze() {
105 if (cache == null && (lastCompletedCommandId >= lastResumeCommandId)) {
106 /*
107 * No pending resumes to worry about. The VM is suspended
108 * and additional state can be cached. Notify all
109 * interested listeners.
110 */
111 processVMAction(new VMAction(vm, VMAction.VM_SUSPENDED));
112 enableCache();
113 }
114 }
115
116 synchronized PacketStream thawCommand(CommandSender sender) {
117 PacketStream stream = sender.send();
118 lastResumeCommandId = stream.id();
119 thaw();
120 return stream;
121 }
122
123 /**
124 * All threads are resuming
125 */
126 void thaw() {
127 thaw(null);
128 }
129
130 /**
131 * Tell listeners to invalidate suspend-sensitive caches.
132 * If resumingThread != null, then only that thread is being
133 * resumed.
134 */
135 synchronized void thaw(ThreadReference resumingThread) {
136 if (cache != null) {
137 if ((vm.traceFlags & VirtualMachine.TRACE_OBJREFS) != 0) {
138 vm.printTrace("Clearing VM suspended cache");
|
1 /*
2 * Copyright (c) 1999, 2018, 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.tools.jdi;
27
28 import java.lang.ref.WeakReference;
29 import java.util.*;
30
31 import com.sun.jdi.ThreadGroupReference;
32 import com.sun.jdi.ThreadReference;
33 import com.sun.jdi.VirtualMachine;
34
35 class VMState {
36 private final VirtualMachineImpl vm;
37
38 // Listeners
39 private final List<WeakReference<VMListener>> listeners = new ArrayList<>(); // synchronized (this)
40 private boolean notifyingListeners = false; // synchronized (this)
41
42 /*
43 * Certain information can be cached only when the entire VM is
44 * suspended and there are no pending resumes. The field below
45 * is used to track whether there are pending resumes.
46 */
47 private final Set<Integer> pendingResumeCommands = Collections.synchronizedSet(new HashSet<>());
48
49 // This is cached only while the VM is suspended
50 private static class Cache {
51 List<ThreadGroupReference> groups = null; // cached Top Level ThreadGroups
52 List<ThreadReference> threads = null; // cached Threads
53 }
54
55 private Cache cache = null; // synchronized (this)
56 private static final Cache markerCache = new Cache();
57
58 private void disableCache() {
59 synchronized (this) {
60 cache = null;
61 }
62 }
63
64 private void enableCache() {
65 synchronized (this) {
66 cache = markerCache;
67 }
75 return cache;
76 }
77 }
78
79 VMState(VirtualMachineImpl vm) {
80 this.vm = vm;
81 }
82
83 /**
84 * Is the VM currently suspended, for the purpose of caching?
85 * Must be called synchronized on vm.state()
86 */
87 boolean isSuspended() {
88 return cache != null;
89 }
90
91 /*
92 * A JDWP command has been completed (reply has been received).
93 * Update data that tracks pending resume commands.
94 */
95 void notifyCommandComplete(int id) {
96 pendingResumeCommands.remove(id);
97 }
98
99 synchronized void freeze() {
100 if (cache == null && (pendingResumeCommands.isEmpty())) {
101 /*
102 * No pending resumes to worry about. The VM is suspended
103 * and additional state can be cached. Notify all
104 * interested listeners.
105 */
106 processVMAction(new VMAction(vm, VMAction.VM_SUSPENDED));
107 enableCache();
108 }
109 }
110
111 synchronized PacketStream thawCommand(CommandSender sender) {
112 PacketStream stream = sender.send();
113 pendingResumeCommands.add(stream.id());
114 thaw();
115 return stream;
116 }
117
118 /**
119 * All threads are resuming
120 */
121 void thaw() {
122 thaw(null);
123 }
124
125 /**
126 * Tell listeners to invalidate suspend-sensitive caches.
127 * If resumingThread != null, then only that thread is being
128 * resumed.
129 */
130 synchronized void thaw(ThreadReference resumingThread) {
131 if (cache != null) {
132 if ((vm.traceFlags & VirtualMachine.TRACE_OBJREFS) != 0) {
133 vm.printTrace("Clearing VM suspended cache");
|