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/*
* Copyright (C) 2017 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/CompletionHandler.h>
#include <wtf/MainThread.h>
#include <wtf/Ref.h>
#include <wtf/RefCounted.h>
#include <wtf/ThreadSafeRefCounted.h>
namespace WTF {
template <DestructionThread destructionThread>
class CallbackAggregatorOnThread : public ThreadSafeRefCounted<CallbackAggregatorOnThread<destructionThread>, destructionThread> {
public:
static auto create(CompletionHandler<void()>&& callback) { return adoptRef(*new CallbackAggregatorOnThread(WTFMove(callback))); }
~CallbackAggregatorOnThread()
{
ASSERT(m_wasConstructedOnMainThread == isMainThread());
if (m_callback)
m_callback();
}
private:
explicit CallbackAggregatorOnThread(CompletionHandler<void()>&& callback)
: m_callback(WTFMove(callback))
#if ASSERT_ENABLED
, m_wasConstructedOnMainThread(isMainThread())
#endif
{
}
CompletionHandler<void()> m_callback;
#if ASSERT_ENABLED
bool m_wasConstructedOnMainThread;
#endif
};
using CallbackAggregator = CallbackAggregatorOnThread<DestructionThread::Any>;
using MainRunLoopCallbackAggregator = CallbackAggregatorOnThread<DestructionThread::MainRunLoop>;
// EagerCallbackAggregator ensures a callback is executed at its first opportunity, ignoring subsequent triggers.
// It's particularly useful in situations where a callback might be triggered multiple times, but only the first
// execution is necessary. If the callback hasn't been executed by the time of the aggregator's destruction,
// it's automatically called with default parameters, ensuring a single, definitive execution.
template<typename> class EagerCallbackAggregator;
template <typename Out, typename... In>
class EagerCallbackAggregator<Out(In...)> : public ThreadSafeRefCounted<EagerCallbackAggregator<Out(In...)>> {
public:
template<typename CallableType, class = typename std::enable_if<std::is_rvalue_reference<CallableType&&>::value>::type>
static Ref<EagerCallbackAggregator> create(CallableType&& callback, In... defaultArgs)
{
return adoptRef(*new EagerCallbackAggregator(std::forward<CallableType>(callback), std::forward<In>(defaultArgs)...));
}
Out operator()(In... args)
{
if (m_callback)
return m_callback(std::forward<In>(args)...);
return Out();
}
~EagerCallbackAggregator()
{
if (m_callback)
std::apply(m_callback, WTFMove(m_defaultArgs));
}
private:
template<typename CallableType>
explicit EagerCallbackAggregator(CallableType&& callback, In... defaultArgs)
: m_callback(std::forward<CallableType>(callback))
, m_defaultArgs(std::forward<In>(defaultArgs)...)
{
}
CompletionHandler<Out(In...)> m_callback;
std::tuple<In...> m_defaultArgs;
};
} // namespace WTF
using WTF::CallbackAggregator;
using WTF::MainRunLoopCallbackAggregator;
using WTF::EagerCallbackAggregator;
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