116 lines
3.3 KiB
C#
116 lines
3.3 KiB
C#
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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
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#if SILVERLIGHT
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using System;
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namespace System.Threading
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{
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//Monitor based implementation of Semaphore
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//that mimicks the .NET Semaphore class (System.Threading.Semaphore)
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internal sealed class Semaphore : IDisposable
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{
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private int m_currentCount;
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private int m_maximumCount;
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private object m_lockObject;
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private bool m_disposed;
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public Semaphore(int initialCount, int maximumCount)
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{
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if (initialCount < 0)
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{
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throw new ArgumentOutOfRangeException("initialCount", "Non-negative number required.");
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}
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if (maximumCount < 1)
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{
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throw new ArgumentOutOfRangeException("maximumCount", "Positive number required.");
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}
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if (initialCount > maximumCount)
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{
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throw new ArgumentException("Initial count must be smaller than maximum");
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}
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m_currentCount = initialCount;
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m_maximumCount = maximumCount;
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m_lockObject = new object();
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}
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public int Release()
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{
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return this.Release(1);
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}
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public int Release(int releaseCount)
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{
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if (releaseCount < 1)
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{
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throw new ArgumentOutOfRangeException("releaseCount", "Positive number required.");
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}
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if (m_disposed)
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{
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throw new ObjectDisposedException("Semaphore");
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}
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var oldCount = default(int);
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lock (m_lockObject)
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{
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oldCount = m_currentCount;
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if (releaseCount + m_currentCount > m_maximumCount)
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{
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throw new ArgumentOutOfRangeException("releaseCount", "Amount of releases would overflow maximum");
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}
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m_currentCount += releaseCount;
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//PulseAll makes sure all waiting threads get queued for acquiring the lock
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//Pulse would only queue one thread.
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Monitor.PulseAll(m_lockObject);
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}
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return oldCount;
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}
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public bool WaitOne()
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{
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return WaitOne(Timeout.Infinite);
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}
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public bool WaitOne(int millisecondsTimeout)
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{
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if (m_disposed)
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{
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throw new ObjectDisposedException("Semaphore");
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}
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lock (m_lockObject)
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{
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while (m_currentCount == 0)
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{
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if (!Monitor.Wait(m_lockObject, millisecondsTimeout))
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{
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return false;
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}
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}
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m_currentCount--;
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return true;
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}
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}
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public bool WaitOne(TimeSpan timeout)
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{
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return WaitOne((int)timeout.TotalMilliseconds);
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}
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public void Close()
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{
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Dispose();
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}
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public void Dispose()
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{
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//the .NET CLR semaphore does not release waits upon dispose
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//so we don't do that either.
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m_disposed = true;
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m_lockObject = null;
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}
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}
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}
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#endif
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