[browser][MT] use regular POSIX portable threadpool (#99836)

src/coreclr/System.Private.CoreLib/src/System/Threading/LowLevelLifoSemaphore.Unix.cs

@@ -11,7 +11,7 @@ namespace System.Threading
     /// <summary>
     /// A LIFO semaphore implemented using the PAL's semaphore with uninterruptible waits.
     /// </summary>
-    internal sealed partial class LowLevelLifoSemaphore : LowLevelLifoSemaphoreBase, IDisposable
+    internal sealed partial class LowLevelLifoSemaphore : IDisposable
     {
         private Semaphore? _semaphore;
 
@@ -34,7 +34,7 @@ public bool WaitCore(int timeoutMs)
         [LibraryImport(RuntimeHelpers.QCall, EntryPoint = "WaitHandle_CorWaitOnePrioritizedNative")]
         private static partial int WaitNative(SafeWaitHandle handle, int timeoutMs);
 
-        protected override void ReleaseCore(int count)
+        private void ReleaseCore(int count)
         {
             Debug.Assert(_semaphore != null);
             Debug.Assert(count > 0);

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Threading/LowLevelLifoSemaphore.Unix.cs

@@ -9,7 +9,7 @@ namespace System.Threading
     /// A LIFO semaphore.
     /// Waits on this semaphore are uninterruptible.
     /// </summary>
-    internal sealed partial class LowLevelLifoSemaphore : LowLevelLifoSemaphoreBase, IDisposable
+    internal sealed partial class LowLevelLifoSemaphore : IDisposable
     {
         private WaitSubsystem.WaitableObject _semaphore;
 
@@ -27,7 +27,7 @@ private bool WaitCore(int timeoutMs)
             return WaitSubsystem.Wait(_semaphore, timeoutMs, false, true) == WaitHandle.WaitSuccess;
         }
 
-        protected override void ReleaseCore(int count)
+        private void ReleaseCore(int count)
         {
             WaitSubsystem.ReleaseSemaphore(_semaphore, count);
         }

src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems

@@ -2685,7 +2685,6 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.ThreadCounts.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.WaitThread.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.WorkerThread.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.WorkerThread.NonBrowser.cs" Condition="'$(TargetsBrowser)' != 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.WorkerTracking.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.Unix.cs" Condition="'$(TargetsUnix)' == 'true' or ('$(TargetsBrowser)' == 'true' and '$(FeatureWasmManagedThreads)' != 'true') or '$(TargetsWasi)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\PortableThreadPool.Windows.cs" Condition="'$(TargetsWindows)' == 'true'" />
@@ -2697,7 +2696,6 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\RegisteredWaitHandle.Windows.cs" Condition="'$(TargetsWindows)' == 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\RegisteredWaitHandle.Unix.cs" Condition="'$(TargetsWindows)' != 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\RegisteredWaitHandle.Portable.cs" />
-    <Compile Include="$(MSBuildThisFileDirectory)System\Threading\LowLevelLifoSemaphoreBase.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\ThreadPoolBoundHandle.Portable.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\ThreadPoolBoundHandle.Unix.cs" Condition="'$(TargetsWindows)' != 'true'" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Threading\ThreadPoolBoundHandle.Windows.cs" Condition="'$(TargetsWindows)' == 'true'" />

src/libraries/System.Private.CoreLib/src/System/Threading/LowLevelLifoSemaphore.Windows.cs

@@ -50,7 +50,7 @@ public bool WaitCore(int timeoutMs)
             return success;
         }
 
-        protected override void ReleaseCore(int count)
+        private void ReleaseCore(int count)
         {
             Debug.Assert(count > 0);
 

src/libraries/System.Private.CoreLib/src/System/Threading/LowLevelLifoSemaphore.cs

@@ -11,13 +11,29 @@ namespace System.Threading
     /// A LIFO semaphore.
     /// Waits on this semaphore are uninterruptible.
     /// </summary>
-    internal sealed partial class LowLevelLifoSemaphore : LowLevelLifoSemaphoreBase, IDisposable
+    internal sealed partial class LowLevelLifoSemaphore : IDisposable
     {
+        private CacheLineSeparatedCounts _separated;
+
+        private readonly int _maximumSignalCount;
+        private readonly int _spinCount;
+        private readonly Action _onWait;
+
         private const int SpinSleep0Threshold = 10;
 
         public LowLevelLifoSemaphore(int initialSignalCount, int maximumSignalCount, int spinCount, Action onWait)
-            : base(initialSignalCount, maximumSignalCount, spinCount, onWait)
         {
+            Debug.Assert(initialSignalCount >= 0);
+            Debug.Assert(initialSignalCount <= maximumSignalCount);
+            Debug.Assert(maximumSignalCount > 0);
+            Debug.Assert(spinCount >= 0);
+
+            _separated = default;
+            _separated._counts.SignalCount = (uint)initialSignalCount;
+            _maximumSignalCount = maximumSignalCount;
+            _spinCount = spinCount;
+            _onWait = onWait;
+
             Create(maximumSignalCount);
         }
 
@@ -185,5 +201,178 @@ private bool WaitForSignal(int timeoutMs)
                 }
             }
         }
+
+        public void Release(int releaseCount)
+        {
+            Debug.Assert(releaseCount > 0);
+            Debug.Assert(releaseCount <= _maximumSignalCount);
+
+            int countOfWaitersToWake;
+            Counts counts = _separated._counts;
+            while (true)
+            {
+                Counts newCounts = counts;
+
+                // Increase the signal count. The addition doesn't overflow because of the limit on the max signal count in constructor.
+                newCounts.AddSignalCount((uint)releaseCount);
+
+                // Determine how many waiters to wake, taking into account how many spinners and waiters there are and how many waiters
+                // have previously been signaled to wake but have not yet woken
+                countOfWaitersToWake =
+                    (int)Math.Min(newCounts.SignalCount, (uint)counts.WaiterCount + counts.SpinnerCount) -
+                    counts.SpinnerCount -
+                    counts.CountOfWaitersSignaledToWake;
+                if (countOfWaitersToWake > 0)
+                {
+                    // Ideally, limiting to a maximum of releaseCount would not be necessary and could be an assert instead, but since
+                    // WaitForSignal() does not have enough information to tell whether a woken thread was signaled, and due to the cap
+                    // below, it's possible for countOfWaitersSignaledToWake to be less than the number of threads that have actually
+                    // been signaled to wake.
+                    if (countOfWaitersToWake > releaseCount)
+                    {
+                        countOfWaitersToWake = releaseCount;
+                    }
+
+                    // Cap countOfWaitersSignaledToWake to its max value. It's ok to ignore some woken threads in this count, it just
+                    // means some more threads will be woken next time. Typically, it won't reach the max anyway.
+                    newCounts.AddUpToMaxCountOfWaitersSignaledToWake((uint)countOfWaitersToWake);
+                }
+
+                Counts countsBeforeUpdate = _separated._counts.InterlockedCompareExchange(newCounts, counts);
+                if (countsBeforeUpdate == counts)
+                {
+                    Debug.Assert(releaseCount <= _maximumSignalCount - counts.SignalCount);
+                    if (countOfWaitersToWake > 0)
+                        ReleaseCore(countOfWaitersToWake);
+                    return;
+                }
+
+                counts = countsBeforeUpdate;
+            }
+        }
+
+        private struct Counts : IEquatable<Counts>
+        {
+            private const byte SignalCountShift = 0;
+            private const byte WaiterCountShift = 32;
+            private const byte SpinnerCountShift = 48;
+            private const byte CountOfWaitersSignaledToWakeShift = 56;
+
+            private ulong _data;
+
+            private Counts(ulong data) => _data = data;
+
+            private uint GetUInt32Value(byte shift) => (uint)(_data >> shift);
+            private void SetUInt32Value(uint value, byte shift) =>
+                _data = (_data & ~((ulong)uint.MaxValue << shift)) | ((ulong)value << shift);
+            private ushort GetUInt16Value(byte shift) => (ushort)(_data >> shift);
+            private void SetUInt16Value(ushort value, byte shift) =>
+                _data = (_data & ~((ulong)ushort.MaxValue << shift)) | ((ulong)value << shift);
+            private byte GetByteValue(byte shift) => (byte)(_data >> shift);
+            private void SetByteValue(byte value, byte shift) =>
+                _data = (_data & ~((ulong)byte.MaxValue << shift)) | ((ulong)value << shift);
+
+            public uint SignalCount
+            {
+                get => GetUInt32Value(SignalCountShift);
+                set => SetUInt32Value(value, SignalCountShift);
+            }
+
+            public void AddSignalCount(uint value)
+            {
+                Debug.Assert(value <= uint.MaxValue - SignalCount);
+                _data += (ulong)value << SignalCountShift;
+            }
+
+            public void IncrementSignalCount() => AddSignalCount(1);
+
+            public void DecrementSignalCount()
+            {
+                Debug.Assert(SignalCount != 0);
+                _data -= (ulong)1 << SignalCountShift;
+            }
+
+            public ushort WaiterCount
+            {
+                get => GetUInt16Value(WaiterCountShift);
+                set => SetUInt16Value(value, WaiterCountShift);
+            }
+
+            public void IncrementWaiterCount()
+            {
+                Debug.Assert(WaiterCount < ushort.MaxValue);
+                _data += (ulong)1 << WaiterCountShift;
+            }
+
+            public void DecrementWaiterCount()
+            {
+                Debug.Assert(WaiterCount != 0);
+                _data -= (ulong)1 << WaiterCountShift;
+            }
+
+            public void InterlockedDecrementWaiterCount()
+            {
+                var countsAfterUpdate = new Counts(Interlocked.Add(ref _data, unchecked((ulong)-1) << WaiterCountShift));
+                Debug.Assert(countsAfterUpdate.WaiterCount != ushort.MaxValue); // underflow check
+            }
+
+            public byte SpinnerCount
+            {
+                get => GetByteValue(SpinnerCountShift);
+                set => SetByteValue(value, SpinnerCountShift);
+            }
+
+            public void IncrementSpinnerCount()
+            {
+                Debug.Assert(SpinnerCount < byte.MaxValue);
+                _data += (ulong)1 << SpinnerCountShift;
+            }
+
+            public void DecrementSpinnerCount()
+            {
+                Debug.Assert(SpinnerCount != 0);
+                _data -= (ulong)1 << SpinnerCountShift;
+            }
+
+            public byte CountOfWaitersSignaledToWake
+            {
+                get => GetByteValue(CountOfWaitersSignaledToWakeShift);
+                set => SetByteValue(value, CountOfWaitersSignaledToWakeShift);
+            }
+
+            public void AddUpToMaxCountOfWaitersSignaledToWake(uint value)
+            {
+                uint availableCount = (uint)(byte.MaxValue - CountOfWaitersSignaledToWake);
+                if (value > availableCount)
+                {
+                    value = availableCount;
+                }
+                _data += (ulong)value << CountOfWaitersSignaledToWakeShift;
+            }
+
+            public void DecrementCountOfWaitersSignaledToWake()
+            {
+                Debug.Assert(CountOfWaitersSignaledToWake != 0);
+                _data -= (ulong)1 << CountOfWaitersSignaledToWakeShift;
+            }
+
+            public Counts InterlockedCompareExchange(Counts newCounts, Counts oldCounts) =>
+                new Counts(Interlocked.CompareExchange(ref _data, newCounts._data, oldCounts._data));
+
+            public static bool operator ==(Counts lhs, Counts rhs) => lhs.Equals(rhs);
+            public static bool operator !=(Counts lhs, Counts rhs) => !lhs.Equals(rhs);
+
+            public override bool Equals([NotNullWhen(true)] object? obj) => obj is Counts other && Equals(other);
+            public bool Equals(Counts other) => _data == other._data;
+            public override int GetHashCode() => (int)_data + (int)(_data >> 32);
+        }
+
+        [StructLayout(LayoutKind.Sequential)]
+        private struct CacheLineSeparatedCounts
+        {
+            private readonly Internal.PaddingFor32 _pad1;
+            public Counts _counts;
+            private readonly Internal.PaddingFor32 _pad2;
+        }
     }
 }