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

#if NET_4_0 || BOOTSTRAP_NET_4_0
// 
// CancellationTokenSource.cs
//  
// Author:
//       Jrmie "Garuma" Laval <jeremie.laval@gmail.com>
// 
// Copyright (c) 2009 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;
using System.Collections.Generic;

namespace System.Threading{
  
  public sealed class CancellationTokenSource : IDisposable
  {
    volatile bool canceled;
    volatile bool processed;
    
    int currId = int.MinValue;
    
    Dictionary<CancellationTokenRegistration, Action> callbacks
      = new Dictionary<CancellationTokenRegistration, Action> ();
    
    ManualResetEvent handle = new ManualResetEvent (false);
    
    object syncRoot = new object ();
    
    internal static readonly CancellationTokenSource NoneSource = new CancellationTokenSource ();
    
    public void Cancel ()
    {
      Cancel (false);
    }
    
    // If parameter is true we throw exception as soon as they appear otherwise we aggregate them
    public void Cancel (bool throwOnFirst)
    {
      canceled = true;
      handle.Set ();
      
      List<Exception> exceptions = null;
      if (!throwOnFirst)
        exceptions = new List<Exception> ();
      
      lock (callbacks) {
        foreach (KeyValuePair<CancellationTokenRegistration, Action> item in callbacks) {
          if (throwOnFirst) {
            item.Value ();
          } else {
            try {
              item.Value ();
            } catch (Exception e) {
              exceptions.Add (e);
            }
          }
        }
      }
      
      processed = true;
      
      if (exceptions != null && exceptions.Count > 0)
        throw new AggregateException (exceptions);
    }
    
    public void Dispose ()
    {
      
    }
    
    public static CancellationTokenSource CreateLinkedTokenSource (CancellationToken token1, CancellationToken token2)
    {
      return CreateLinkedTokenSource (new CancellationToken[] { token1, token2 });
    }
    
    public static CancellationTokenSource CreateLinkedTokenSource (params CancellationToken[] tokens)
    {
      CancellationTokenSource src = new CancellationTokenSource ();
      Action action = src.Cancel;
      
      foreach (CancellationToken token in tokens)
        token.Register (action);
      
      return src;
    }
    
    public CancellationToken Token {
      get {
        return CreateToken ();
      }
    }
    
    public bool IsCancellationRequested {
      get {
        return canceled;
      }
    }
    
    internal WaitHandle WaitHandle {
      get {
        return handle;
      }
    }
    
    internal CancellationTokenRegistration Register (Action callback, bool useSynchronizationContext)
    {
      CancellationTokenRegistration tokenReg = GetTokenReg ();
      if (canceled) {
        callback ();
      } else {
        bool temp = false;
        lock (syncRoot) {
          if (!(temp = canceled))
            callbacks.Add (tokenReg, callback);
        }
        if (temp)
          callback ();
      }
      
      return tokenReg;
    }
    
    internal void RemoveCallback (CancellationTokenRegistration tokenReg)
    {
      if (!canceled) {
        lock (syncRoot) {
          if (!canceled) {
            callbacks.Remove (tokenReg);
            return;
          }
        }
      }
      
      SpinWait sw = new SpinWait ();
      while (!processed)
        sw.SpinOnce ();
      
    }
    
    internal void ThrowIfCancellationRequested ()
    {
      if (canceled)
        throw new OperationCanceledException (CreateToken ());
    }
    
    CancellationTokenRegistration GetTokenReg ()
    {
      CancellationTokenRegistration registration
        = new CancellationTokenRegistration (Interlocked.Increment (ref currId), this);
      
      return registration;
    }
    
    CancellationToken CreateToken ()
    {
      CancellationToken tk = new CancellationToken (canceled);
      tk.Source = this;
      
      return tk;
    }
  }
}
#endif