1/* 2 * Copyright (C) 2008 Apple Inc. All Rights Reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR 17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 * 25 */ 26 27#ifndef ActiveDOMObject_h 28#define ActiveDOMObject_h 29 30#include "ContextDestructionObserver.h" 31#include <wtf/Assertions.h> 32#include <wtf/Forward.h> 33 34namespace WebCore { 35 36class ActiveDOMObject : public ContextDestructionObserver { 37public: 38 ActiveDOMObject(ScriptExecutionContext*); 39 40 // suspendIfNeeded() should be called exactly once after object construction to synchronize 41 // the suspend state with that in ScriptExecutionContext. 42 void suspendIfNeeded(); 43#if !ASSERT_DISABLED 44 bool suspendIfNeededCalled() const { return m_suspendIfNeededCalled; } 45#endif 46 47 virtual bool hasPendingActivity() const; 48 49 // canSuspend() is used by the caller if there is a choice between suspending and stopping. 50 // For example, a page won't be suspended and placed in the back/forward cache if it has 51 // the objects that can not be suspended. 52 // However, 'suspend' can be called even if canSuspend() would return 'false'. That 53 // happens in step-by-step JS debugging for example - in this case it would be incorrect 54 // to stop the object. Exact semantics of suspend is up to the object then. 55 enum ReasonForSuspension { 56 JavaScriptDebuggerPaused, 57 WillDeferLoading, 58 DocumentWillBecomeInactive, 59 PageWillBeSuspended 60 }; 61 virtual bool canSuspend() const; 62 virtual void suspend(ReasonForSuspension); 63 virtual void resume(); 64 virtual void stop(); 65 66 template<class T> void setPendingActivity(T* thisObject) 67 { 68 ASSERT(thisObject == this); 69 thisObject->ref(); 70 m_pendingActivityCount++; 71 } 72 73 template<class T> void unsetPendingActivity(T* thisObject) 74 { 75 ASSERT(m_pendingActivityCount > 0); 76 --m_pendingActivityCount; 77 thisObject->deref(); 78 } 79 80protected: 81 virtual ~ActiveDOMObject(); 82 83private: 84 unsigned m_pendingActivityCount; 85#if !ASSERT_DISABLED 86 bool m_suspendIfNeededCalled; 87#endif 88}; 89 90} // namespace WebCore 91 92#endif // ActiveDOMObject_h 93