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| 1 | +/* | |
| 2 | + * Copyright (c) 2000, 2010, 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 java.awt; | |
| 27 | + | |
| 28 | +import java.util.LinkedList; | |
| 29 | +import sun.awt.AppContext; | |
| 30 | +import sun.awt.SunToolkit; | |
| 31 | + | |
| 32 | +/** | |
| 33 | + * A mechanism for ensuring that a series of AWTEvents are executed in a | |
| 34 | + * precise order, even across multiple AppContexts. The nested events will be | |
| 35 | + * dispatched in the order in which their wrapping SequencedEvents were | |
| 36 | + * constructed. The only exception to this rule is if the peer of the target of | |
| 37 | + * the nested event was destroyed (with a call to Component.removeNotify) | |
| 38 | + * before the wrapping SequencedEvent was able to be dispatched. In this case, | |
| 39 | + * the nested event is never dispatched. | |
| 40 | + * | |
| 41 | + * @author David Mendenhall | |
| 42 | + */ | |
| 43 | +class SequencedEvent extends AWTEvent implements ActiveEvent { | |
| 44 | + /* | |
| 45 | + * serialVersionUID | |
| 46 | + */ | |
| 47 | + private static final long serialVersionUID = 547742659238625067L; | |
| 48 | + | |
| 49 | + private static final int ID = | |
| 50 | + java.awt.event.FocusEvent.FOCUS_LAST + 1; | |
| 51 | + private static final LinkedList list = new LinkedList(); | |
| 52 | + | |
| 53 | + private final AWTEvent nested; | |
| 54 | + private AppContext appContext; | |
| 55 | + private boolean disposed; | |
| 56 | + | |
| 57 | + /** | |
| 58 | + * Constructs a new SequencedEvent which will dispatch the specified | |
| 59 | + * nested event. | |
| 60 | + * | |
| 61 | + * @param nested the AWTEvent which this SequencedEvent's dispatch() | |
| 62 | + * method will dispatch | |
| 63 | + */ | |
| 64 | + public SequencedEvent(AWTEvent nested) { | |
| 65 | + super(nested.getSource(), ID); | |
| 66 | + this.nested = nested; | |
| 67 | + // All AWTEvents that are wrapped in SequencedEvents are (at | |
| 68 | + // least currently) implicitly generated by the system | |
| 69 | + SunToolkit.setSystemGenerated(nested); | |
| 70 | + synchronized (SequencedEvent.class) { | |
| 71 | + list.add(this); | |
| 72 | + } | |
| 73 | + } | |
| 74 | + | |
| 75 | + /** | |
| 76 | + * Dispatches the nested event after all previous nested events have been | |
| 77 | + * dispatched or disposed. If this method is invoked before all previous nested events | |
| 78 | + * have been dispatched, then this method blocks until such a point is | |
| 79 | + * reached. | |
| 80 | + * While waiting disposes nested events to disposed AppContext | |
| 81 | + * | |
| 82 | + * NOTE: Locking protocol. Since dispose() can get EventQueue lock, | |
| 83 | + * dispatch() shall never call dispose() while holding the lock on the list, | |
| 84 | + * as EventQueue lock is held during dispatching. The locks should be acquired | |
| 85 | + * in the same order. | |
| 86 | + */ | |
| 87 | + public final void dispatch() { | |
| 88 | + try { | |
| 89 | + appContext = AppContext.getAppContext(); | |
| 90 | + | |
| 91 | + if (getFirst() != this) { | |
| 92 | + if (EventQueue.isDispatchThread()) { | |
| 93 | + EventDispatchThread edt = (EventDispatchThread) | |
| 94 | + Thread.currentThread(); | |
| 95 | + edt.pumpEvents(SentEvent.ID, new Conditional() { | |
| 96 | + public boolean evaluate() { | |
| 97 | + return !SequencedEvent.this.isFirstOrDisposed(); | |
| 98 | + } | |
| 99 | + }); | |
| 100 | + } else { | |
| 101 | + while(!isFirstOrDisposed()) { | |
| 102 | + synchronized (SequencedEvent.class) { | |
| 103 | + try { | |
| 104 | + SequencedEvent.class.wait(1000); | |
| 105 | + } catch (InterruptedException e) { | |
| 106 | + break; | |
| 107 | + } | |
| 108 | + } | |
| 109 | + } | |
| 110 | + } | |
| 111 | + } | |
| 112 | + | |
| 113 | + if (!disposed) { | |
| 114 | + KeyboardFocusManager.getCurrentKeyboardFocusManager(). | |
| 115 | + setCurrentSequencedEvent(this); | |
| 116 | + Toolkit.getEventQueue().dispatchEvent(nested); | |
| 117 | + } | |
| 118 | + } finally { | |
| 119 | + dispose(); | |
| 120 | + } | |
| 121 | + } | |
| 122 | + | |
| 123 | + /** | |
| 124 | + * true only if event exists and nested source appContext is disposed. | |
| 125 | + */ | |
| 126 | + private final static boolean isOwnerAppContextDisposed(SequencedEvent se) { | |
| 127 | + if (se != null) { | |
| 128 | + Object target = se.nested.getSource(); | |
| 129 | + if (target instanceof Component) { | |
| 130 | + return ((Component)target).appContext.isDisposed(); | |
| 131 | + } | |
| 132 | + } | |
| 133 | + return false; | |
| 134 | + } | |
| 135 | + | |
| 136 | + /** | |
| 137 | + * Sequenced events are dispatched in order, so we cannot dispatch | |
| 138 | + * until we are the first sequenced event in the queue (i.e. it's our | |
| 139 | + * turn). But while we wait for our turn to dispatch, the event | |
| 140 | + * could have been disposed for a number of reasons. | |
| 141 | + */ | |
| 142 | + public final boolean isFirstOrDisposed() { | |
| 143 | + if (disposed) { | |
| 144 | + return true; | |
| 145 | + } | |
| 146 | + // getFirstWithContext can dispose this | |
| 147 | + return this == getFirstWithContext() || disposed; | |
| 148 | + } | |
| 149 | + | |
| 150 | + private final synchronized static SequencedEvent getFirst() { | |
| 151 | + return (SequencedEvent)list.getFirst(); | |
| 152 | + } | |
| 153 | + | |
| 154 | + /* Disposes all events from disposed AppContext | |
| 155 | + * return first valid event | |
| 156 | + */ | |
| 157 | + private final static SequencedEvent getFirstWithContext() { | |
| 158 | + SequencedEvent first = getFirst(); | |
| 159 | + while(isOwnerAppContextDisposed(first)) { | |
| 160 | + first.dispose(); | |
| 161 | + first = getFirst(); | |
| 162 | + } | |
| 163 | + return first; | |
| 164 | + } | |
| 165 | + | |
| 166 | + /** | |
| 167 | + * Disposes of this instance. This method is invoked once the nested event | |
| 168 | + * has been dispatched and handled, or when the peer of the target of the | |
| 169 | + * nested event has been disposed with a call to Component.removeNotify. | |
| 170 | + * | |
| 171 | + * NOTE: Locking protocol. Since SunToolkit.postEvent can get EventQueue lock, | |
| 172 | + * it shall never be called while holding the lock on the list, | |
| 173 | + * as EventQueue lock is held during dispatching and dispatch() will get | |
| 174 | + * lock on the list. The locks should be acquired in the same order. | |
| 175 | + */ | |
| 176 | + final void dispose() { | |
| 177 | + synchronized (SequencedEvent.class) { | |
| 178 | + if (disposed) { | |
| 179 | + return; | |
| 180 | + } | |
| 181 | + if (KeyboardFocusManager.getCurrentKeyboardFocusManager(). | |
| 182 | + getCurrentSequencedEvent() == this) { | |
| 183 | + KeyboardFocusManager.getCurrentKeyboardFocusManager(). | |
| 184 | + setCurrentSequencedEvent(null); | |
| 185 | + } | |
| 186 | + disposed = true; | |
| 187 | + } | |
| 188 | + // Wake myself up | |
| 189 | + if (appContext != null) { | |
| 190 | + SunToolkit.postEvent(appContext, new SentEvent()); | |
| 191 | + } | |
| 192 | + | |
| 193 | + SequencedEvent next = null; | |
| 194 | + | |
| 195 | + synchronized (SequencedEvent.class) { | |
| 196 | + SequencedEvent.class.notifyAll(); | |
| 197 | + | |
| 198 | + if (list.getFirst() == this) { | |
| 199 | + list.removeFirst(); | |
| 200 | + | |
| 201 | + if (!list.isEmpty()) { | |
| 202 | + next = (SequencedEvent)list.getFirst(); | |
| 203 | + } | |
| 204 | + } else { | |
| 205 | + list.remove(this); | |
| 206 | + } | |
| 207 | + } | |
| 208 | + // Wake up waiting threads | |
| 209 | + if (next != null && next.appContext != null) { | |
| 210 | + SunToolkit.postEvent(next.appContext, new SentEvent()); | |
| 211 | + } | |
| 212 | + } | |
| 213 | +} | |