CountdownEvent.cs :  » 2.6.4-mono-.net-core » System.Threading » System » Threading » C# / CSharp Open Source

// CountdownEvent.cs
//
// Copyright (c) 2008 Jrmie "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;

#if NET_4_0 || BOOTSTRAP_NET_4_0

namespace System.Threading{  
  public class CountdownEvent : IDisposable
  {
    int count;
    readonly int initial;
    ManualResetEvent evt = new ManualResetEvent (false);
    
    public CountdownEvent (int count)
    {
      if (count < 0)
        throw new ArgumentOutOfRangeException ("count is negative");
      this.initial = this.count = count;
    }
    
    public bool Signal ()
    {
      return Signal (1);
    }
    
    public bool Signal (int num)
    {
      if (num <= 0)
        throw new ArgumentOutOfRangeException ("num");
      
      Action<int> check = delegate (int value) {
        if (value < 0)
        throw new InvalidOperationException ("the specified count is larger that CurrentCount");
      };
      
      int newValue;
      if (!ApplyOperation (-num, check, out newValue))
        throw new InvalidOperationException ("The event is already set");
      
      if (newValue == 0) {
        evt.Set ();
        return true;
      }
      
      return false;
    }
    
    public void AddCount ()
    {
      AddCount (1);
    }
    
    public void AddCount (int num)
    {
      if (num < 0)
        throw new ArgumentOutOfRangeException ("num");
      
      if (!TryAddCount (num))
        throw new InvalidOperationException ("The event is already set");
    }
    
    public bool TryAddCount ()
    {
      return TryAddCount (1);
    }
    
    public bool TryAddCount (int num)
    {  
      if (num < 0)
        throw new ArgumentOutOfRangeException ("num");
      
      return ApplyOperation (num, null);
    }
    
    bool ApplyOperation (int num, Action<int> doCheck)
    {
      int temp;
      return ApplyOperation (num, doCheck, out temp);
    }
      
    bool ApplyOperation (int num, Action<int> doCheck, out int newValue)
    {
      int oldCount;
      newValue = 0;
      
      do {
        oldCount = count;
        if (oldCount == 0)
          return false;
        
        newValue = oldCount + num;
        
        if (doCheck != null)
          doCheck (newValue);
      } while (Interlocked.CompareExchange (ref count, newValue, oldCount) != oldCount);
      
      return true;
    }
    
    public void Wait ()
    {
      SpinWait wait = new SpinWait ();
      while (!IsSet) {
        wait.SpinOnce ();
      }
    }
    
    public void Wait (CancellationToken token)
    {
      Wait (() => token.IsCancellationRequested);
    }
    
    public bool Wait (int timeoutMilli)
    {
      if (timeoutMilli == -1) {
        Wait ();
        return true;
      }
      
      Watch sw = Watch.StartNew ();
      long timeout = (long)timeoutMilli;
      
      bool result = Wait (() => sw.ElapsedMilliseconds > timeout);
      sw.Stop ();
      
      return result;
    }
    
    public bool Wait(TimeSpan span)
    {
      return Wait ((int)span.TotalMilliseconds);
    }
    
    public bool Wait (int timeoutMilli, CancellationToken token)
    {
      if (timeoutMilli == -1) {
        Wait ();
        return true;
      }
      
      Watch sw = Watch.StartNew ();
      long timeout = (long)timeoutMilli;
      
      bool result = Wait (() => sw.ElapsedMilliseconds > timeout || token.IsCancellationRequested);
      sw.Stop ();
      
      return result;
    }
    
    public bool Wait(TimeSpan span, CancellationToken token)
    {
      return Wait ((int)span.TotalMilliseconds, token);
    }
    
    bool Wait (Func<bool> waitPredicate)
    {
      SpinWait wait = new SpinWait ();
      
      while (!IsSet) {
        if (waitPredicate ())
          return false;
        wait.SpinOnce ();
      }
      
      return true;
    }
    
    public void Reset ()
    {
      Reset (initial);
    }
    
    public void Reset (int value)
    {
      evt.Reset ();
      Interlocked.Exchange (ref count, value);
    }
    
    public int CurrentCount {
      get {
        return count;
      }
    }
    
    public int InitialCount {
      get {
        return initial;
      }
    }
      
    public bool IsSet {
      get {
        return count == 0;
      }
    }
    
    public WaitHandle WaitHandle {
      get {
        return evt;
      }
    }

    #region IDisposable implementation 
    
    public void Dispose ()
    {
      
    }
    
    protected virtual void Dispose (bool managedRes)
    {
      
    }
    #endregion   
  }
}
#endif