Simplify Parallel.ForEach loop execution

diff --git a/mcs/class/corlib/System.Threading.Tasks/Parallel.cs b/mcs/class/corlib/System.Threading.Tasks/Parallel.cs
index 94d5926639492bd46ebed451252a2e60c48791b2..1891be5b9095da84e3de1f1cd89f451fb41b4343 100644 (file)
--- a/mcs/class/corlib/System.Threading.Tasks/Parallel.cs
+++ b/mcs/class/corlib/System.Threading.Tasks/Parallel.cs
@@ -258,33 +258,25 @@ namespace System.Threading.Tasks
 
                        IList<IEnumerator<TSource>> slices = enumerable (num);
 
-                       int sliceIndex = 0;
-
-                       Func<ParallelLoopState, bool> cancellationTokenTest = (s) => {
-                               if (options != null && options.CancellationToken.IsCancellationRequested) {
-                                       s.Stop ();
-                                       return true;
-                               }
-                               return false;
-                       };
+                       int sliceIndex = -1;
 
                        Action workerMethod = delegate {
-                               IEnumerator<TSource> slice = slices[Interlocked.Increment (ref sliceIndex) - 1];
+                               IEnumerator<TSource> slice = slices[Interlocked.Increment (ref sliceIndex)];
 
-                               TLocal local = (init != null) ? init () : default (TLocal);
+                               TLocal local = init ();
                                ParallelLoopState state = new ParallelLoopState (infos);
                                int workIndex = bag.GetNextIndex ();
+                               CancellationToken token = options.CancellationToken;
 
                                try {
                                        bool cont = true;
                                        TSource element;
 
                                        while (cont) {
-                                               if (infos.IsStopped)
+                                               if (infos.IsStopped || infos.IsBroken.Value)
                                                        return;
 
-                                               if (cancellationTokenTest (state))
-                                                       return;
+                                               token.ThrowIfCancellationRequested ();
 
                                                for (int i = 0; i < bagCount && (cont = slice.MoveNext ()); i++) {
                                                        bag.Add (workIndex, slice.Current);
@@ -294,25 +286,22 @@ namespace System.Threading.Tasks
                                                        if (infos.IsStopped)
                                                                return;
 
-                                                       if (cancellationTokenTest (state))
-                                                               return;
+                                                       token.ThrowIfCancellationRequested ();
 
                                                        local = action (element, state, local);
                                                }
                                        }
 
                                        while (bag.TrySteal (workIndex, out element)) {
-                                               if (infos.IsStopped)
-                                                       return;
-
-                                               if (cancellationTokenTest (state))
-                                                       return;
+                                               token.ThrowIfCancellationRequested ();
 
                                                local = action (element, state, local);
+
+                                               if (infos.IsStopped || infos.IsBroken.Value)
+                                                       return;
                                        }
                                } finally {
-                                       if (destruct != null)
-                                               destruct (local);
+                                       destruct (local);
                                }
                        };