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/*
* 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.
*
*/
#pragma once
#include "ContextDestructionObserver.h"
#include "TaskSource.h"
#include <wtf/AbstractRefCounted.h>
#include <wtf/Assertions.h>
#include <wtf/CancellableTask.h>
#include <wtf/Forward.h>
#include <wtf/Function.h>
#include <wtf/RefCounted.h>
#include <wtf/Threading.h>
namespace WebCore {
class Document;
class Event;
class EventLoopTaskGroup;
class EventTarget;
enum class ReasonForSuspension : uint8_t {
JavaScriptDebuggerPaused,
WillDeferLoading,
BackForwardCache,
PageWillBeSuspended,
};
class WEBCORE_EXPORT ActiveDOMObject : public AbstractRefCounted, 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;
void didMoveToNewDocument(Document&);
// This function is used by JS bindings to determine if the JS wrapper should be kept alive or not.
bool hasPendingActivity() const { return m_pendingActivityInstanceCount || virtualHasPendingActivity(); }
// However, the suspend function will sometimes be called even if canSuspendForDocumentSuspension() 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.
// These 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 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>
class PendingActivity : public RefCounted<PendingActivity<T>> {
public:
explicit PendingActivity(T& thisObject)
: m_thisObject(thisObject)
{
++(m_thisObject->m_pendingActivityInstanceCount);
}
~PendingActivity()
{
ASSERT(m_thisObject->m_pendingActivityInstanceCount > 0);
--(m_thisObject->m_pendingActivityInstanceCount);
}
private:
Ref<T> m_thisObject;
};
template<class T> Ref<PendingActivity<T>> makePendingActivity(T& thisObject)
{
ASSERT(&thisObject == this);
return adoptRef(*new PendingActivity<T>(thisObject));
}
bool isContextStopped() const;
bool isAllowedToRunScript() const;
template<typename T>
static void queueTaskKeepingObjectAlive(T& object, TaskSource source, Function<void ()>&& task)
{
// Calls the template member function outside of lambda init-captures to work around a MSVC bug.
auto activity = object.ActiveDOMObject::makePendingActivity(object);
object.queueTaskInEventLoop(source, [protectedObject = Ref { object }, activity = WTFMove(activity), task = WTFMove(task)] () {
task();
});
}
template<typename T>
static void queueCancellableTaskKeepingObjectAlive(T& object, TaskSource source, TaskCancellationGroup& cancellationGroup, Function<void()>&& task)
{
CancellableTask cancellableTask(cancellationGroup, WTFMove(task));
// Calls the template member function outside of lambda init-captures to work around a MSVC bug.
auto activity = object.ActiveDOMObject::makePendingActivity(object);
object.queueTaskInEventLoop(source, [protectedObject = Ref { object }, activity = WTFMove(activity), cancellableTask = WTFMove(cancellableTask)]() mutable {
cancellableTask();
});
}
template<typename EventTargetType>
static void queueTaskToDispatchEvent(EventTargetType& target, TaskSource source, Ref<Event>&& event)
{
target.queueTaskToDispatchEventInternal(target, source, WTFMove(event));
}
template<typename EventTargetType>
static void queueCancellableTaskToDispatchEvent(EventTargetType& target, TaskSource source, TaskCancellationGroup& cancellationGroup, Ref<Event>&& event)
{
target.queueCancellableTaskToDispatchEventInternal(target, source, cancellationGroup, WTFMove(event));
}
protected:
explicit ActiveDOMObject(ScriptExecutionContext*);
explicit ActiveDOMObject(Document*);
explicit ActiveDOMObject(Document&);
virtual ~ActiveDOMObject();
private:
enum CheckedScriptExecutionContextType { CheckedScriptExecutionContext };
ActiveDOMObject(ScriptExecutionContext*, CheckedScriptExecutionContextType);
// This is used by subclasses to indicate that they have pending activity, meaning that they would
// like the JS wrapper to stay alive (because they may still fire JS events).
virtual bool virtualHasPendingActivity() const { return false; }
void queueTaskInEventLoop(TaskSource, Function<void ()>&&);
void queueTaskToDispatchEventInternal(EventTarget&, TaskSource, Ref<Event>&&);
void queueCancellableTaskToDispatchEventInternal(EventTarget&, TaskSource, TaskCancellationGroup&, Ref<Event>&&);
uint64_t m_pendingActivityInstanceCount { 0 };
#if ASSERT_ENABLED
bool m_suspendIfNeededWasCalled { false };
Ref<Thread> m_creationThread { Thread::current() };
#endif
friend class ActiveDOMObjectEventDispatchTask;
};
#if !ASSERT_ENABLED
inline void ActiveDOMObject::assertSuspendIfNeededWasCalled() const
{
}
#endif
} // namespace WebCore
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