93 lines
3.0 KiB
C++
93 lines
3.0 KiB
C++
/*
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* Copyright (C) 2021 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <wtf/Function.h>
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#include <wtf/UniqueRef.h>
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#include <wtf/WeakPtr.h>
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namespace WTF {
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class CancellableTask;
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class TaskCancellationGroup : public CanMakeWeakPtr<TaskCancellationGroup> {
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public:
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TaskCancellationGroup() : m_impl(makeUniqueRef<Impl>()) { }
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void cancel() { m_impl->cancel(); }
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bool hasPendingTask() const { return m_impl->hasPendingTask(); }
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private:
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friend class CancellableTask;
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class Impl : public CanMakeWeakPtr<Impl> {
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WTF_MAKE_FAST_ALLOCATED;
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public:
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void cancel() { weakPtrFactory().revokeAll(); }
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bool hasPendingTask() const { return weakPtrFactory().weakPtrCount(); }
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};
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class Handle {
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public:
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bool isCancelled() const { return !m_impl; }
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void clear() { m_impl = nullptr; }
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private:
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friend class TaskCancellationGroup;
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explicit Handle(Impl& impl) : m_impl(makeWeakPtr(impl)) { }
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WeakPtr<Impl> m_impl;
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};
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Handle createHandle() { return Handle { m_impl }; }
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UniqueRef<Impl> m_impl;
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};
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class CancellableTask {
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public:
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CancellableTask(TaskCancellationGroup&, Function<void()>&&);
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void operator()();
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private:
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TaskCancellationGroup::Handle m_cancellationGroup;
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Function<void()> m_task;
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};
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inline CancellableTask::CancellableTask(TaskCancellationGroup& cancellationGroup, Function<void()>&& task)
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: m_cancellationGroup(cancellationGroup.createHandle())
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, m_task(WTFMove(task))
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{ }
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inline void CancellableTask::operator()()
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{
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if (m_cancellationGroup.isCancelled())
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return;
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m_cancellationGroup.clear();
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m_task();
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}
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} // namespace WTF
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using WTF::CancellableTask;
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using WTF::TaskCancellationGroup;
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