96 lines
2.3 KiB
C++
96 lines
2.3 KiB
C++
/***
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Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.
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File: ConditionEx.cpp
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Date: 2021-6-12
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Author: Reece
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***/
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#include <Source/RuntimeInternal.hpp>
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#include "ConditionEx.hpp"
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#include "Mutex.Generic.hpp"
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#include "Semaphore.Generic.hpp"
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namespace Aurora::Threading::Primitives
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{
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// Implementing Condition Variables with Semaphores, Andrew Birrell, MSFT
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// Subsitute semaphore count = 1 with a spinlock and...
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class SemaphoreConditionVariableImpl : public ConditionEx
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{
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public:
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SemaphoreConditionVariableImpl();
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void WaitForSignal(Aurora::Threading::IWaitable *waitable) override;
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void WaitForSignal() override;
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void Signal() override;
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void Broadcast() override;
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private:
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std::atomic<AuUInt> waiters_;
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Semaphore s_, h_;
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SpinLock x_;
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};
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SemaphoreConditionVariableImpl::SemaphoreConditionVariableImpl() : s_(0), h_(0)
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{
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}
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void SemaphoreConditionVariableImpl::WaitForSignal(Aurora::Threading::IWaitable *waitable)
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{
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x_.Lock();
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waiters_++;
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x_.Unlock();
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if (waitable)
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{
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waitable->Unlock();
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}
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s_.Lock();
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h_.Unlock();
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if (waitable)
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{
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waitable->Lock();
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}
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}
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void SemaphoreConditionVariableImpl::WaitForSignal()
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{
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WaitForSignal(nullptr);
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}
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void SemaphoreConditionVariableImpl::Signal()
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{
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x_.Lock();
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if (waiters_ > 0)
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{
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waiters_--;
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s_.Unlock(); // 1 may pass
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h_.Lock(); // finish operation - wait for the alive signal back
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}
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x_.Unlock();
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}
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void SemaphoreConditionVariableImpl::Broadcast()
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{
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x_.Lock();
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s_.Unlock(waiters_); // all may pass at once
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for (auto i = 0; i < waiters_; i++)
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{
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h_.Lock(); // finish operation - wait for the alive signal back
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}
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waiters_ = 0;
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x_.Unlock();
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}
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AUKN_SYM ConditionEx *FeaturefulConditionNew()
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{
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return _new SemaphoreConditionVariableImpl();
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}
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AUKN_SYM void FeaturefulConditionRelease(ConditionEx *semaphore)
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{
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SafeDelete<SemaphoreConditionVariableImpl *>(semaphore);
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}
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} |