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/*
* Copyright (C) 2021 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. AND ITS CONTRIBUTORS ``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 ITS 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 <wtf/Function.h>
#include <wtf/UniqueRef.h>
#include <wtf/WeakPtr.h>
namespace WTF {
class CancellableTask;
class TaskCancellationGroup : public CanMakeWeakPtr<TaskCancellationGroup> {
public:
TaskCancellationGroup() : m_impl(makeUniqueRef<Impl>()) { }
void cancel() { m_impl->cancel(); }
bool hasPendingTask() const { return m_impl->hasPendingTask(); }
private:
friend class CancellableTask;
class Impl : public CanMakeWeakPtr<Impl> {
WTF_MAKE_FAST_ALLOCATED;
public:
void cancel() { weakPtrFactory().revokeAll(); }
bool hasPendingTask() const { return weakPtrFactory().weakPtrCount(); }
};
class Handle {
public:
bool isCancelled() const { return !m_impl; }
void clear() { m_impl = nullptr; }
private:
friend class TaskCancellationGroup;
explicit Handle(Impl& impl) : m_impl(impl) { }
WeakPtr<Impl> m_impl;
};
Handle createHandle() { return Handle { m_impl }; }
UniqueRef<Impl> m_impl;
};
class CancellableTask {
public:
CancellableTask(TaskCancellationGroup&, Function<void()>&&);
void operator()();
private:
TaskCancellationGroup::Handle m_cancellationGroup;
Function<void()> m_task;
};
inline CancellableTask::CancellableTask(TaskCancellationGroup& cancellationGroup, Function<void()>&& task)
: m_cancellationGroup(cancellationGroup.createHandle())
, m_task(WTFMove(task))
{ }
inline void CancellableTask::operator()()
{
if (m_cancellationGroup.isCancelled())
return;
m_cancellationGroup.clear();
m_task();
}
} // namespace WTF
using WTF::CancellableTask;
using WTF::TaskCancellationGroup;
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