Merge pull request #819 from brendanzagaeski/patch-1

[mono.git] / mcs / class / corlib / System.Threading / CancellationTokenSource.cs

diff --git a/mcs/class/corlib/System.Threading/CancellationTokenSource.cs b/mcs/class/corlib/System.Threading/CancellationTokenSource.cs
index fa9674e06f1b790ee30f962fd1e1736d350335e7..c5557f0446e69b7808e73a295b08c7c244d4e469 100644 (file)
--- a/mcs/class/corlib/System.Threading/CancellationTokenSource.cs
+++ b/mcs/class/corlib/System.Threading/CancellationTokenSource.cs
@@ -26,7 +26,7 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
-#if NET_4_0 || MOBILE
+#if NET_4_0
 using System.Collections.Generic;
 using System.Collections.Concurrent;
 
@@ -42,6 +42,7 @@ namespace System.Threading
                
                int currId = int.MinValue;
                ConcurrentDictionary<CancellationTokenRegistration, Action> callbacks;
+               CancellationTokenRegistration[] linkedTokens;
 
                ManualResetEvent handle;
                
@@ -60,7 +61,7 @@ namespace System.Threading
 #if NET_4_5
                        timer_callback = token => {
                                var cts = (CancellationTokenSource) token;
-                               cts.Cancel ();
+                               cts.CancelSafe ();
                        };
 #endif
                }
@@ -117,16 +118,46 @@ namespace System.Threading
                public void Cancel (bool throwOnFirstException)
                {
                        CheckDisposed ();
+                       Cancellation (throwOnFirstException);
+               }
+
+               //
+               // Don't throw ObjectDisposedException if the callback
+               // is called concurrently with a Dispose
+               //
+               public void CancelSafe ()
+               {
+                       if (!disposed)
+                               Cancellation (true);
+               }
+
+               void Cancellation (bool throwOnFirstException)
+               {
+                       if (canceled)
+                               return;
 
+                       Thread.MemoryBarrier ();
                        canceled = true;
-                       handle.Set ();
-                       
+
+                       Thread.MemoryBarrier ();
+
+                       // Dispose might be running at same time
+                       if (!disposed)
+                               handle.Set ();
+
+                       if (linkedTokens != null)
+                               UnregisterLinkedTokens ();
+
+                       var cbs = callbacks;
+                       if (cbs == null)
+                               return;
+
                        List<Exception> exceptions = null;
-                       
+
                        try {
                                Action cb;
-                               for (int id = int.MinValue + 1; id <= currId; id++) {
-                                       if (!callbacks.TryRemove (new CancellationTokenRegistration (id, this), out cb))
+                               for (int id = currId; id != int.MinValue; id--) {
+                                       if (!cbs.TryRemove (new CancellationTokenRegistration (id, this), out cb))
                                                continue;
                                        if (cb == null)
                                                continue;
@@ -145,7 +176,7 @@ namespace System.Threading
                                        }
                                }
                        } finally {
-                               callbacks.Clear ();
+                               cbs.Clear ();
                        }
 
                        if (exceptions != null)
@@ -193,12 +224,14 @@ namespace System.Threading
                                throw new ArgumentException ("Empty tokens array");
 
                        CancellationTokenSource src = new CancellationTokenSource ();
-                       Action action = src.Cancel;
+                       Action action = src.CancelSafe;
+                       var registrations = new List<CancellationTokenRegistration> (tokens.Length);
 
                        foreach (CancellationToken token in tokens) {
                                if (token.CanBeCanceled)
-                                       token.Register (action);
+                                       registrations.Add (token.Register (action));
                        }
+                       src.linkedTokens = registrations.ToArray ();
                        
                        return src;
                }
@@ -232,14 +265,29 @@ namespace System.Threading
                                disposed = true;
                                Thread.MemoryBarrier ();
 
-                               callbacks = null;
+                               if (!canceled) {
+                                       UnregisterLinkedTokens ();
+                                       callbacks = null;
+                               } else {
+                                       handle.WaitOne ();
+                               }
 #if NET_4_5
                                if (timer != null)
                                        timer.Dispose ();
 #endif
+
                                handle.Dispose ();
                        }
                }
+
+               void UnregisterLinkedTokens ()
+               {
+                       var registrations = Interlocked.Exchange (ref linkedTokens, null);
+                       if (registrations == null)
+                               return;
+                       foreach (var linked in registrations)
+                               linked.Dispose ();
+               }
                
                internal CancellationTokenRegistration Register (Action callback, bool useSynchronizationContext)
                {