[+] A small header only futex

Include/Aurora/Threading/Waitables/FutexWaitable.hpp

@@ -0,0 +1,150 @@
+/***
+    Copyright (C) 2023 J Reece Wilson (a/k/a "Reece"). All rights reserved.
+
+    File: FutexWaitable.hpp
+    Date: 2023-08-19
+    Author: Reece
+***/
+#pragma once
+
+#include "../WakeOnAddress.hpp"
+#include "../SpinTime.hpp"
+
+namespace Aurora::Threading::Waitables
+{
+    struct FutexWaitable final : IWaitable
+    {
+        inline constexpr FutexWaitable()
+        {}
+
+        AU_NO_COPY_NO_MOVE(FutexWaitable);
+
+        inline bool TryLock() override
+        {
+            if (AuAtomicTestAndSet(&this->uAtomicState, 0u))
+            {
+                return true;
+            }
+
+        #if defined(AURORA_ARCH_X86) || defined(AURORA_ARCH_X64)
+            for (AU_ITERATE_N(i, AuUInt(1u) << AuUInt(Threading::GetSpinCountTimeout())))
+            {
+                _mm_pause();
+
+                if (AuAtomicTestAndSet(&this->uAtomicState, 0u))
+                {
+                    return true;
+                }
+            }
+        #else
+            static const AuUInt32 kRef { 1 };
+            if (TryWaitOnAddress(&this->uAtomicState, &kRef, sizeof(kRef)))
+            {
+                if (AuAtomicTestAndSet(&this->uAtomicState, 0u))
+                {
+                    return true;
+                }
+            }
+        #endif
+
+            return false;
+        }
+
+        inline bool HasOSHandle(AuMach &mach) override
+        {
+            return false;
+        }
+
+        inline bool HasLockImplementation() override
+        {
+            return true;
+        }
+
+        inline void Unlock() override
+        {
+            this->uAtomicState = 0;
+
+            if (auto uSleeping = this->uAtomicSleeping)
+            {
+                WakeOnAddress(&this->uAtomicState);
+            }
+        }
+
+        inline void Lock() override
+        {
+            static const AuUInt32 kRef { 1 };
+
+            while (!TryLock())
+            {
+                AuAtomicAdd(&this->uAtomicSleeping, 1u);
+                WaitOnAddress(&this->uAtomicState, &kRef, sizeof(kRef), 0);
+                AuAtomicSub(&this->uAtomicSleeping, 1u);
+            }
+        }
+
+        inline bool LockMS(AuUInt64 qwTimeout) override
+        {
+            return LockNS(AuMSToNS<AuUInt64>(qwTimeout));
+        }
+
+        inline bool LockAbsMS(AuUInt64 qwTimeout) override
+        {
+            return LockAbsNS(AuMSToNS<AuUInt64>(qwTimeout));
+        }
+
+        inline bool LockNS(AuUInt64 qwTimeout) override
+        {
+            static const AuUInt32 kRef { 1 };
+            if (AuAtomicTestAndSet(&this->uAtomicState, 0u))
+            {
+                return true;
+            }
+
+            auto qwEndTime = Time::SteadyClockNS() + qwTimeout;
+
+            while (!TryLock())
+            {
+                bool bStatus {};
+
+                AuAtomicAdd(&this->uAtomicSleeping, 1u);
+                bStatus = WaitOnAddressSteady(&this->uAtomicState, &kRef, sizeof(kRef), qwEndTime);
+                AuAtomicSub(&this->uAtomicSleeping, 1u);
+
+                if (!bStatus)
+                {
+                    return TryLock();
+                }
+            }
+
+            return true;
+        }
+
+        inline bool LockAbsNS(AuUInt64 qwTimeoutAbs) override
+        {
+            static const AuUInt32 kRef { 1 };
+            if (AuAtomicTestAndSet(&this->uAtomicState, 0u))
+            {
+                return true;
+            }
+
+            while (!TryLock())
+            {
+                bool bStatus {};
+
+                AuAtomicAdd(&this->uAtomicSleeping, 1u);
+                bStatus = WaitOnAddressSteady(&this->uAtomicState, &kRef, sizeof(kRef), qwTimeoutAbs);
+                AuAtomicSub(&this->uAtomicSleeping, 1u);
+
+                if (!bStatus)
+                {
+                    return TryLock();
+                }
+            }
+
+            return true;
+        }
+
+        AuUInt32 uAtomicState {};
+        AuUInt32 uAtomicSleeping {};
+    };
+}

Include/Aurora/Threading/Waitables/Waitables.hpp

@@ -9,3 +9,4 @@
 
 #include "CBWaitable.hpp"
 #include "BooleanWaitable.hpp"
+#include "FutexWaitable.hpp"