AuroraRuntime/Source/Threading/Primitives/AuConditionVariable.NT.hpp
Jamie Reece Wilson 451b9025c0 [*] Fix major recent regressions
amend: 48075bfd
amend: 25b933aa
amend: f50067e6 (to be overwritten)
et al
2023-06-17 15:12:16 +01:00

84 lines
3.7 KiB
C++

/***
Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.
File: ConditionVariable.Win32.hpp
Date: 2021-6-12
Author: Reece
***/
#pragma once
#if !defined(_AURUNTIME_GENERICCV)
#include "AuConditionMutex.NT.hpp"
namespace Aurora::Threading::Primitives
{
struct ConditionVariableImpl final : IConditionVariable
{
ConditionVariableImpl(const AuSPtr<IConditionMutex> &mutex);
auline AuSPtr<IConditionMutex> GetMutex() override;
auline bool WaitForSignal(AuUInt32 timeout) override;
/*auline*/bool WaitForSignalNsEx(const std::shared_ptr<Win32ConditionMutex> &pMutex, AuUInt64 timeout);
/*auline*/bool WaitForSignalNS(AuUInt64 qwTimeout);
auline void Signal() override;
auline void Broadcast() override;
auline bool CheckOut(bool &bRet);
private:
#if defined(AURORA_FORCE_SRW_LOCKS)
CONDITION_VARIABLE winCond_;
#else
AuUInt32 wlist {};
AuUInt32 signalCount {};
#endif
std::shared_ptr<Win32ConditionMutex> mutex_;
};
struct CondVarDummy : IConditionVariable
{
private:
#if defined(AURORA_FORCE_SRW_LOCKS)
CONDITION_VARIABLE winCond_;
#else
AuUInt32 wlist {};
AuUInt32 signalCount {};
#endif
};
static const auto kSizeOfDummyCondVar = sizeof(CondVarDummy);
static const auto kBoolRequiredLateSet = true;
// Future (Reece): I got future plans
static const auto kShiftCountByBits = 8u;
// ...otherwise
// assume undefined behaviour past:
// * bit zero is used for atomic bit test and yield loops
// ( keyed events are an optimization mechanism for Windows XPs spinloop i had accidentally recreated in xenus. )
// ( originally, nt yielding sucked with the most barebones spinlock being dumb a hypervisor-unaware, smt-aware, spinner. )
// ( keyed events would then go in these spinners to serve as an early futex as early back as the year 2000 (?). )
// ( that does, in fact, mean the free-toddlers crying about how 'windows stole muh kernels totally originally idea' is entirely wrong at each sub-point. )
// ( though, keyed didn't see much use until Windows Vistas synch primitives were built on top of them. )
// ( infamously missing 100ths scale nanosecond yimeouts and an inablity to lock with a timeout. )
// ( raymond chen once claimed they didnt make it to xp because they werent fast enough )
// ( raymond chen once claimed a "con" of keyedevents were that they were linear )
// ( problem is, as far as i can tell, they didnt really change. whats worse, WakeOnAddress (windows 8+)
// ( ...inherits the issue of not having relative/abs nanosecond scale timeouts AND the issue the primitives sucking. )
// ( WakeOnAddress is nothing more than keyed events 2.0 - but with userland list keeping. )
// ( scratch the concept of how i implement WakeOnAddress with lists, how older nts waited with lists under lock, )
// ( they use hashmaps with "le meme lockless" interactions which are surly less expensive than reusing tls allocations ?! )
// ( whether or not its even faster is still up for debate. its just easier to use. )
// * bit one might be used under some niche versions of windows
// (hearsay paranoia)
// i actually have zero reason to believe windows ever implemented lock-awareness into the kernel
// i think it might be fine to skip the whole bit zero thing, but still, im going to say keep the min=2
// worst case scenario, we end up using these bits.
// ....
// =8 is future proof
// =2 is recommended
// =0 would require a bit of a require. i think this is how other people use keyed events nowadays
}
#endif