319 lines
10 KiB
C++
319 lines
10 KiB
C++
/***
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Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.
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File: AuMutex.NT.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 "AuMutex.Generic.hpp"
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#include "SMTYield.hpp"
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#include "../AuWakeInternal.hpp"
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#if !defined(_AURUNTIME_GENERICMUTEX)
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#include "AuMutex.NT.hpp"
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#include "AuConditionMutex.NT.hpp"
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#include <Time/Time.hpp>
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#if !defined(NTSTATUS_TIMEOUT)
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#define NTSTATUS_TIMEOUT 0x102
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#endif
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namespace Aurora::Threading::Primitives
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{
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MutexImpl::MutexImpl()
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{
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if (!pWaitOnAddress)
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{
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#if defined(AURORA_FORCE_SRW_LOCKS)
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::InitializeSRWLock(&this->atomicHolder_);
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::InitializeConditionVariable(&this->wakeup_);
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#endif
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}
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this->state_ = 0;
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}
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MutexImpl::~MutexImpl()
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{
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}
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bool MutexImpl::HasOSHandle(AuMach &mach)
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{
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return false;
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}
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bool MutexImpl::TryLock()
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{
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return DoTryIf([=]()
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{
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return AuAtomicTestAndSet(&this->state_, 0) == 0;
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});
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}
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bool MutexImpl::HasLockImplementation()
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{
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return true;
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}
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void MutexImpl::SlowLock()
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{
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auto status = LockNS(0);
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SysAssert(status, "Couldn't lock Mutex object");
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}
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bool MutexImpl::LockMS(AuUInt64 uTimeout)
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{
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if (AuAtomicTestAndSet(&this->state_, 0) == 0)
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{
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return true;
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}
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return LockNS(AuMSToNS<AuUInt64>(uTimeout));
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}
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bool MutexImpl::LockNS(AuUInt64 uTimeout)
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{
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bool returnValue = false;
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if (TryLock())
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{
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return true;
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}
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AuUInt64 uStartTime = Time::SteadyClockNS();
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AuUInt64 uEndTime = uTimeout ? uStartTime + uTimeout : 0;
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int iYieldCounter {};
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if (gUseNativeWaitMutex)
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{
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auto state = this->state_;
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while (::_interlockedbittestandset((volatile LONG *)&this->state_, 0) != 0)
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{
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if (!InternalLTSWaitOnAddressHighRes((void *)&this->state_, &state, sizeof(this->state_), uEndTime))
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{
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return false;
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}
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state = this->state_;
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}
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return true;
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}
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else
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{
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#if defined(AURORA_FORCE_SRW_LOCKS)
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::AcquireSRWLockShared(&this->atomicHolder_);
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BOOL status = false;
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while (!this->TryLock())
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{
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AuUInt32 uTimeoutMS = INFINITE;
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if (uTimeout != 0)
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{
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uStartTime = Time::SteadyClockNS();
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if (uStartTime >= uEndTime)
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{
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goto exitWin32;
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}
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uTimeoutMS = AuNSToMS<AuInt64>(uEndTime - uStartTime);
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}
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if (!uTimeoutMS)
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{
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::ReleaseSRWLockShared(&this->atomicHolder_);
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SMPPause();
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AuThreading::ContextYield();
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::AcquireSRWLockShared(&this->atomicHolder_);
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}
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else
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{
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(void)SleepConditionVariableSRW(&this->wakeup_, &this->atomicHolder_, uTimeoutMS, CONDITION_VARIABLE_LOCKMODE_SHARED);
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}
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}
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returnValue = true;
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exitWin32:
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::ReleaseSRWLockShared(&this->atomicHolder_);
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#else
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if (!uTimeout)
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{
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while (!TryLock())
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{
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auto &uValueRef = this->state_;
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auto uValue = uValueRef | 1;
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if (AuAtomicCompareExchange(&uValueRef, uValue + kFutexBitWait, uValue) == uValue)
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{
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pNtWaitForKeyedEvent(gKeyedEventHandle, (void *)&uValueRef, 0, NULL);
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AuAtomicSub(&uValueRef, kFutexBitWake);
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}
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}
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return true;
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}
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else
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{
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auto &uValueRef = this->state_;
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returnValue = true;
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auto uEndTimeSteady = AuTime::SteadyClockNS() + uTimeout;
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auto uEndTimeWall = AuTime::CurrentClockNS() + uTimeout;
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bool bFailed {};
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while (bFailed || (!TryLock()))
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{
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auto uValue = uValueRef | 1;
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if (!bFailed &&
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AuTime::SteadyClockNS() >= uEndTimeSteady)
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{
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returnValue = TryLock();
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break;
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}
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if (bFailed || AuAtomicCompareExchange(&uValueRef, uValue + kFutexBitWait, uValue) == uValue)
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{
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auto uTargetTimeNt = AuTime::ConvertTimestampNs(uEndTimeWall);
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LARGE_INTEGER word;
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word.QuadPart = uTargetTimeNt;
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auto uStatus = pNtWaitForKeyedEvent(gKeyedEventHandle, (void *)&this->state_, 0, &word);
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if (uStatus == NTSTATUS_TIMEOUT)
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{
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auto uWWaiters = this->state_ & ~kFutexBitWake;
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if (uWWaiters >= kFutexBitWait && AuAtomicCompareExchange(&this->state_, uWWaiters - kFutexBitWait, uWWaiters) == uWWaiters)
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{
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continue;
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}
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else
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{
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bFailed = true;
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continue;
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}
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}
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else
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{
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AuAtomicSub(&uValueRef, kFutexBitWake);
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SysAssertDbg(uStatus == 0);
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}
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}
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bFailed = false;
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}
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}
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#endif
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return returnValue;
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}
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}
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void MutexImpl::Unlock()
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{
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if (gUseNativeWaitMutex)
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{
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this->state_ = 0;
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pWakeByAddressSingle((void *)&this->state_);
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}
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else
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{
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#if defined(AURORA_FORCE_SRW_LOCKS)
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::AcquireSRWLockExclusive(&this->atomicHolder_);
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this->state_ = 0;
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::ReleaseSRWLockExclusive(&this->atomicHolder_);
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::WakeAllConditionVariable(&this->wakeup_);
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#else
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auto &uValueRef = this->state_;
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#if defined(AURORA_ARCH_X86) || defined(AURORA_ARCH_X64)
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// Intel 64 and IA - 32 Architectures Software Developer's Manual, Volume 3A: Section: 8.2.3.1
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*(AuUInt8 *)&uValueRef = 0;
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// From this point onwards, our thread could be subject to StoreLoad re-ordering
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// ...but it should not matter.
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// Given the memory model of x86[64], we can only really expect to be out of order during an unfenced load operation, which in this class, can only be expected under this function before the CAS.
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// No other place reads.
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// Re-ordering race condition 1: one thread wins an atomic bit set, that we dont catch until the CAS, resulting in: a slow implicit fence under the cas, a mm_pause stall, a compare, and a return
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// alt: uValueRef reads zero, resulting in a preemptive return while no threads need to be awoken
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// Re-ordering race condition 2: we unlock, multiple threads enter ::Lock(), we somehow read `uValue = uValueRef` as zero, and then the first atomic bitsetandtest winner thread signals the keyed mutex
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// I fail to see how:
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// *byte = 0; | |
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// | interlocked atomicbitset | interlocked atomicbitset fail
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// | [logic] | interlocked atomic set kFutexBitWait
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// | *byte = 0; | yield
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// | auto uValue =[acquire]= uValueRef
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// ...would result in the second thread missing the third threads atomic set kFutexBitWait (cst (?) on the account of 8.2.3.1, 8.2.3.8, etc)
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// Also note: mfence is far too expensive and the _ReadWriteBarrier() intrinsics do absolutely nothing
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#else
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InterlockedAndRelease((volatile LONG *)&uValueRef, ~0xFF);
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#endif
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while (true)
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{
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auto uValue = uValueRef;
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//
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if (uValue < kFutexBitWait)
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{
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return;
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}
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// StoreLoad race-conditions here cannot result in a return
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// We should see StoreLoads of at least our *pByte = 0
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// or we should at least see the CST of kFutexBitWait being applied
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if (uValue & 1)
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{
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return;
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}
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if (uValue & kFutexBitWake)
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{
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// StoreLoad paranoia
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if (AuAtomicCompareExchange(&uValueRef, uValue, uValue) == uValue)
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{
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return;
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}
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else
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{
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SMPPause();
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continue;
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}
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}
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if (AuAtomicCompareExchange(&uValueRef, uValue - kFutexBitWait + kFutexBitWake, uValue) == uValue)
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{
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pNtReleaseKeyedEvent(gKeyedEventHandle, (void *)&uValueRef, 0, NULL);
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return;
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}
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SMPPause();
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}
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#endif
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}
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}
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AUKN_SYM IHyperWaitable *MutexNew()
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{
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return _new MutexImpl();
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}
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AUKN_SYM void MutexRelease(IHyperWaitable *pMutex)
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{
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AuSafeDelete<MutexImpl *>(pMutex);
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}
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AUROXTL_INTERFACE_SOO_SRC_EX(AURORA_SYMBOL_EXPORT, Mutex, MutexImpl)
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}
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#endif |