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// SemaphoreSlim.cs
//
// Copyright (c) 2008 Jérémie "Garuma" Laval
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
//
using System;
using System.Diagnostics;
#if NET_4_5
using System.Threading.Tasks;
#endif
#if NET_4_0
namespace System.Threading
{
[System.Diagnostics.DebuggerDisplayAttribute ("Current Count = {currCount}")]
public class SemaphoreSlim : IDisposable
{
const int spinCount = 10;
const int deepSleepTime = 20;
readonly int maxCount;
int currCount;
bool isDisposed;
EventWaitHandle handle;
public SemaphoreSlim (int initialCount) : this (initialCount, int.MaxValue)
{
}
public SemaphoreSlim (int initialCount, int maxCount)
{
if (initialCount < 0 || initialCount > maxCount || maxCount < 0)
throw new ArgumentOutOfRangeException ("The initialCount argument is negative, initialCount is greater than maxCount, or maxCount is not positive.");
this.maxCount = maxCount;
this.currCount = initialCount;
this.handle = new ManualResetEvent (initialCount > 0);
}
public void Dispose ()
{
Dispose(true);
}
protected virtual void Dispose (bool disposing)
{
isDisposed = true;
}
void CheckState ()
{
if (isDisposed)
throw new ObjectDisposedException ("The SemaphoreSlim has been disposed.");
}
public int CurrentCount {
get {
return currCount;
}
}
public int Release ()
{
return Release(1);
}
public int Release (int releaseCount)
{
CheckState ();
if (releaseCount < 1)
throw new ArgumentOutOfRangeException ("releaseCount", "releaseCount is less than 1");
// As we have to take care of the max limit we resort to CAS
int oldValue, newValue;
do {
oldValue = currCount;
newValue = (currCount + releaseCount);
newValue = newValue > maxCount ? maxCount : newValue;
} while (Interlocked.CompareExchange (ref currCount, newValue, oldValue) != oldValue);
handle.Set ();
return oldValue;
}
public void Wait ()
{
Wait (CancellationToken.None);
}
public bool Wait (TimeSpan timeout)
{
return Wait ((int)timeout.TotalMilliseconds, CancellationToken.None);
}
public bool Wait (int millisecondsTimeout)
{
return Wait (millisecondsTimeout, CancellationToken.None);
}
public void Wait (CancellationToken cancellationToken)
{
Wait (-1, cancellationToken);
}
public bool Wait (TimeSpan timeout, CancellationToken cancellationToken)
{
CheckState();
return Wait ((int)timeout.TotalMilliseconds, cancellationToken);
}
public bool Wait (int millisecondsTimeout, CancellationToken cancellationToken)
{
CheckState ();
if (millisecondsTimeout < -1)
throw new ArgumentOutOfRangeException ("millisecondsTimeout",
"millisecondsTimeout is a negative number other than -1");
Watch sw = Watch.StartNew ();
Func<bool> stopCondition = () => millisecondsTimeout >= 0 && sw.ElapsedMilliseconds > millisecondsTimeout;
do {
bool shouldWait;
int result;
do {
cancellationToken.ThrowIfCancellationRequested ();
if (stopCondition ())
return false;
shouldWait = true;
result = currCount;
if (result > 0)
shouldWait = false;
else
break;
} while (Interlocked.CompareExchange (ref currCount, result - 1, result) != result);
if (!shouldWait) {
if (result == 1)
handle.Reset ();
break;
}
SpinWait wait = new SpinWait ();
while (Thread.VolatileRead (ref currCount) <= 0) {
cancellationToken.ThrowIfCancellationRequested ();
if (stopCondition ())
return false;
if (wait.Count > spinCount)
handle.WaitOne (Math.Min (Math.Max (millisecondsTimeout - (int)sw.ElapsedMilliseconds, 1), deepSleepTime));
else
wait.SpinOnce ();
}
} while (true);
return true;
}
public WaitHandle AvailableWaitHandle {
get {
return handle;
}
}
#if NET_4_5
public Task WaitAsync ()
{
return Task.Factory.StartNew (() => Wait ());
}
public Task WaitAsync (CancellationToken cancellationToken)
{
return Task.Factory.StartNew (() => Wait (cancellationToken), cancellationToken);
}
public Task<bool> WaitAsync (int millisecondsTimeout)
{
return Task.Factory.StartNew (() => Wait (millisecondsTimeout));
}
public Task<bool> WaitAsync (TimeSpan timeout)
{
return Task.Factory.StartNew (() => Wait (timeout));
}
public Task<bool> WaitAsync (int millisecondsTimeout, CancellationToken cancellationToken)
{
return Task.Factory.StartNew (() => Wait (millisecondsTimeout, cancellationToken), cancellationToken);
}
public Task<bool> WaitAsync (TimeSpan timeout, CancellationToken cancellationToken)
{
return Task.Factory.StartNew (() => Wait (timeout, cancellationToken), cancellationToken);
}
#endif
}
}
#endif
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