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(ExecutionContext*); 39 40 // suspendIfNeeded() should be called exactly once after object construction to synchronize 41 // the suspend state with that in ExecutionContext. 42 void suspendIfNeeded(); 43 #if !ASSERT_DISABLED suspendIfNeededCalled()44 bool suspendIfNeededCalled() const { return m_suspendIfNeededCalled; } 45 #endif 46 47 // Should return true if there's any pending asynchronous activity, and so 48 // this object must not be garbage collected. 49 // 50 // Default implementation is that it returns true iff 51 // m_pendingActivityCount is non-zero. 52 virtual bool hasPendingActivity() const; 53 54 // These methods have an empty default implementation so that subclasses 55 // which don't need special treatment can skip implementation. 56 virtual void suspend(); 57 virtual void resume(); 58 virtual void stop(); 59 60 protected: 61 virtual ~ActiveDOMObject(); 62 setPendingActivity(T * thisObject)63 template<class T> void setPendingActivity(T* thisObject) 64 { 65 ASSERT(thisObject == this); 66 thisObject->ref(); 67 m_pendingActivityCount++; 68 } 69 unsetPendingActivity(T * thisObject)70 template<class T> void unsetPendingActivity(T* thisObject) 71 { 72 ASSERT(m_pendingActivityCount > 0); 73 --m_pendingActivityCount; 74 thisObject->deref(); 75 } 76 77 private: 78 unsigned m_pendingActivityCount; 79 #if !ASSERT_DISABLED 80 bool m_suspendIfNeededCalled; 81 #endif 82 }; 83 84 } // namespace WebCore 85 86 #endif // ActiveDOMObject_h 87