LowLevelMonitor.cs

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using System.Runtime.InteropServices;
 
namespace System.Threading;
 
[StructLayout(LayoutKind.Auto)]
internal struct LowLevelMonitor
{
    internal struct Monitor
    {
        public Interop.Kernel32.CRITICAL_SECTION _criticalSection;
 
        public Interop.Kernel32.CONDITION_VARIABLE _conditionVariable;
    }
 
    private unsafe Monitor* _pMonitor;
 
    public void Dispose()
    {
        DisposeCore();
    }
 
    public void Acquire()
    {
        AcquireCore();
    }
 
    public void Release()
    {
        ReleaseCore();
    }
 
    public void Wait()
    {
        WaitCore();
    }
 
    public void Signal_Release()
    {
        Signal_ReleaseCore();
    }
 
    public unsafe void Initialize()
    {
        _pMonitor = (Monitor*)(void*)Marshal.AllocHGlobal(sizeof(Monitor));
        Interop.Kernel32.InitializeCriticalSection(&_pMonitor->_criticalSection);
        Interop.Kernel32.InitializeConditionVariable(&_pMonitor->_conditionVariable);
    }
 
    private unsafe void DisposeCore()
    {
        if (_pMonitor != null)
        {
            Interop.Kernel32.DeleteCriticalSection(&_pMonitor->_criticalSection);
            Marshal.FreeHGlobal((IntPtr)_pMonitor);
            _pMonitor = null;
        }
    }
 
    private unsafe void AcquireCore()
    {
        Interop.Kernel32.EnterCriticalSection(&_pMonitor->_criticalSection);
    }
 
    private unsafe void ReleaseCore()
    {
        Interop.Kernel32.LeaveCriticalSection(&_pMonitor->_criticalSection);
    }
 
    private void WaitCore()
    {
        WaitCore(-1);
    }
 
    private unsafe bool WaitCore(int timeoutMilliseconds)
    {
        return Interop.Kernel32.SleepConditionVariableCS(&_pMonitor->_conditionVariable, &_pMonitor->_criticalSection, timeoutMilliseconds);
    }
 
    private unsafe void Signal_ReleaseCore()
    {
        Interop.Kernel32.WakeConditionVariable(&_pMonitor->_conditionVariable);
        Interop.Kernel32.LeaveCriticalSection(&_pMonitor->_criticalSection);
    }
}