/* * Copyright (C) 2008 Apple Inc. All Rights Reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */ #ifndef ActiveDOMObject_h #define ActiveDOMObject_h #include "ContextDestructionObserver.h" #include <wtf/Assertions.h> #include <wtf/Forward.h> namespace WebCore { class ActiveDOMObject : public ContextDestructionObserver { public: // The suspendIfNeeded must be called exactly once after object construction to update // the suspended state to match that of the ScriptExecutionContext. void suspendIfNeeded(); void assertSuspendIfNeededWasCalled() const; virtual bool hasPendingActivity() const; // The canSuspendForPageCache() function is used by the caller if there is a choice between suspending // and stopping. For example, a page won't be suspended and placed in the back/forward // cache if it contains any objects that cannot be suspended. // However, the suspend function will sometimes be called even if canSuspendForPageCache() returns false. // That happens in step-by-step JS debugging for example - in this case it would be incorrect // to stop the object. Exact semantics of suspend is up to the object in cases like that. enum ReasonForSuspension { JavaScriptDebuggerPaused, WillDeferLoading, PageCache, PageWillBeSuspended, DocumentWillBePaused }; virtual const char* activeDOMObjectName() const = 0; // These three functions must not have a side effect of creating or destroying // any ActiveDOMObject. That means they must not result in calls to arbitrary JavaScript. virtual bool canSuspendForPageCache() const = 0; // Returning false in canSuspendForPageCache() will prevent the page from entering the PageCache. virtual void suspend(ReasonForSuspension); virtual void resume(); // This function must not have a side effect of creating an ActiveDOMObject. // That means it must not result in calls to arbitrary JavaScript. // It can, however, have a side effect of deleting an ActiveDOMObject. virtual void stop(); template<class T> void setPendingActivity(T* thisObject) { ASSERT(thisObject == this); thisObject->ref(); ++m_pendingActivityCount; } template<class T> void unsetPendingActivity(T* thisObject) { ASSERT(m_pendingActivityCount > 0); --m_pendingActivityCount; thisObject->deref(); } protected: explicit ActiveDOMObject(ScriptExecutionContext*); virtual ~ActiveDOMObject(); private: unsigned m_pendingActivityCount; #if !ASSERT_DISABLED bool m_suspendIfNeededWasCalled; #endif }; #if ASSERT_DISABLED inline void ActiveDOMObject::assertSuspendIfNeededWasCalled() const { } #endif } // namespace WebCore #endif // ActiveDOMObject_h