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 "core/dom/ContextLifecycleObserver.h" 31 #include "wtf/Assertions.h" 32 #include "wtf/Forward.h" 33 34 namespace WebCore { 35 36 class ActiveDOMObject : public ContextLifecycleObserver { 37 public: 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 }; 60 virtual bool canSuspend() const; 61 virtual void suspend(ReasonForSuspension); 62 virtual void resume(); 63 virtual void stop(); 64 65 template<class T> void setPendingActivity(T* thisObject) 66 { 67 ASSERT(thisObject == this); 68 thisObject->ref(); 69 m_pendingActivityCount++; 70 } 71 72 template<class T> void unsetPendingActivity(T* thisObject) 73 { 74 ASSERT(m_pendingActivityCount > 0); 75 --m_pendingActivityCount; 76 thisObject->deref(); 77 } 78 79 protected: 80 virtual ~ActiveDOMObject(); 81 82 private: 83 unsigned m_pendingActivityCount; 84 #if !ASSERT_DISABLED 85 bool m_suspendIfNeededCalled; 86 #endif 87 }; 88 89 } // namespace WebCore 90 91 #endif // ActiveDOMObject_h 92