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[*] c111dee8 cont. Simplification of if (SignalSpuriously()) AddWatcher() continued

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This commit is contained in:
Reece Wilson 2024-02-14 01:01:25 +00:00
parent 11e18d462a
commit 03623dfa48
2 changed files with 2 additions and 40 deletions
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41
Source/Threading/Primitives/AuConditionVariable.NT.cpp
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@ -164,7 +164,7 @@ namespace Aurora::Threading::Primitives
// (NT 5-6.1) Unblocks one race condition, where another thread checks out our signal, and we return with nothing. // (NT 5-6.1) Unblocks one race condition, where another thread checks out our signal, and we return with nothing.
// Normal execution of the blocked thread can continue, so long as we trigger the keyed event as though this thread was signaled. // Normal execution of the blocked thread can continue, so long as we trigger the keyed event as though this thread was signaled.
// This is only relevant in an edge case of multi-waiters spinning, rapid signaling, and the IOU being hit once. Do this instead of ticketing. // This is only relevant in an edge case of multi-waiters spinning, rapid signaling, and the IOU being hit once. Do this instead of ticketing.
this->SignalSpuriously(); pNtReleaseKeyedEvent(gKeyedEventHandle, (void *)&this->wlist, FALSE, nullptr);
} }
} }
} }
@ -221,7 +221,7 @@ namespace Aurora::Threading::Primitives
if (!gUseNativeWaitCondvar) if (!gUseNativeWaitCondvar)
{ {
this->SignalSpuriously(); pNtReleaseKeyedEvent(gKeyedEventHandle, (void *)&this->wlist, FALSE, nullptr);
} }
} }
} }
@ -334,43 +334,6 @@ namespace Aurora::Threading::Primitives
#endif #endif
} }
void ConditionVariableNT::SignalSpuriously()
{
#if !defined(AURORA_FORCE_SRW_LOCKS)
auto original = this->wlist;
auto expected = original;
expected = expected >> kShiftCountByBits;
if (expected)
{
// INTENTIONAL: Missing this->signalCount atomic increment to force another AddWaiter under successful keyedevent return
while (expected)
{
// INTENTIONAL: Removed the -1 so we dont have to rewatch the condvar, potentially missing a signal in the process
if (AuAtomicCompareExchange(&this->wlist, (expected << kShiftCountByBits) /*intentional clear*/, original) == original)
{
if (!gUseNativeWaitCondvar)
{
pNtReleaseKeyedEvent(gKeyedEventHandle, (void *)&this->wlist, FALSE, nullptr);
}
// INTENTIONAL: Removal of modernt branch. We err on the side of caution by failing awake, then its up to the last waking
// thread up process to block again. So long as wlist represents all the waiting threads, it doesn't matter,
// we will continue to be signalable withouts signal being lost or any thread blocking.
return;
}
original = this->wlist;
expected = original >> kShiftCountByBits;
}
}
#else
::WakeConditionVariable(&this->winCond_);
#endif
}
void ConditionVariableNT::Signal() void ConditionVariableNT::Signal()
{ {
#if !defined(AURORA_FORCE_SRW_LOCKS) #if !defined(AURORA_FORCE_SRW_LOCKS)

1
Source/Threading/Primitives/AuConditionVariable.NT.hpp
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@ -19,7 +19,6 @@ namespace Aurora::Threading::Primitives
bool WaitForSignalNsEx(Win32ConditionMutex *pMutex, AuUInt64 timeout, bool bSpin = true); bool WaitForSignalNsEx(Win32ConditionMutex *pMutex, AuUInt64 timeout, bool bSpin = true);
void Signal(); void Signal();
auline void SignalSpuriously();
void Broadcast(); void Broadcast();
void BroadcastN(AuUInt32 nBroadcast); void BroadcastN(AuUInt32 nBroadcast);