ParallelLoopState.LowestBreakIteration Propriété

Définition

Obtient l'itération la plus basse de la boucle d'où Break() a été appelé.Gets the lowest iteration of the loop from which Break() was called.

public:
 property Nullable<long> LowestBreakIteration { Nullable<long> get(); };
public Nullable<long> LowestBreakIteration { get; }
member this.LowestBreakIteration : Nullable<int64>
Public ReadOnly Property LowestBreakIteration As Nullable(Of Long)

Valeur de propriété

Itération la plus basse d'où Break() a été appelé.The lowest iteration from which Break() was called. Dans le cas d'une boucle ForEach<TSource>(Partitioner<TSource>, Action<TSource>), la valeur est basée sur un index généré en interne.In the case of a ForEach<TSource>(Partitioner<TSource>, Action<TSource>) loop, the value is based on an internally-generated index.

Exemples

L’exemple suivant exécute jusqu’à 100 itérations d’une boucle en parallèle.The following example executes up to 100 iterations of a loop in parallel. Chaque itération est suspendue pour un intervalle aléatoire compris entre 1 et 1 000 millisecondes.Each iteration pauses for a random interval from 1 to 1,000 milliseconds. Une valeur générée de manière aléatoire détermine sur quelle itération de la boucle Break la méthode est appelée.A randomly generated value determines on which iteration of the loop the Break method is called. Cela empêche les itérations dont l’index est supérieur LowestBreakIteration à la valeur de propriété de démarrer après l' Break appel à la méthode, mais elle n’affecte pas les itérations qui ont déjà commencé à s’exécuter.This prevents iterations whose index is greater than the LowestBreakIteration property value from starting after the call to the Break method, but it does not affect any iterations that have already begun executing. Pour éviter qu’ils ne se terminent, chaque ShouldExitCurrentIteration itération appelle la méthode pour vérifier si une autre Break itération a appelé la méthode.To prevent these from completing, each iteration calls the ShouldExitCurrentIteration method to check whether another iteration has called the Break method. Dans ce cas, l’itération vérifie la valeur de LowestBreakIteration la propriété et, si elle est supérieure à la valeur d’index de l’itération actuelle, est retournée immédiatement.If so, the iteration checks the value of the LowestBreakIteration property and, if it is greater than the current iteration's index value, returns immediately.

using System;
using System.Threading;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      var rnd = new Random();
      int breakIndex = rnd.Next(1, 11);
      Nullable<long> lowest = new Nullable<long>();

      Console.WriteLine("Will call Break at iteration {0}\n",
                        breakIndex);

      var result = Parallel.For(1, 101, (i, state) => {
                                            Console.WriteLine("Beginning iteration {0}", i);
                                            int delay;
                                            Monitor.Enter(rnd);
                                               delay = rnd.Next(1, 1001);
                                            Monitor.Exit(rnd);
                                            Thread.Sleep(delay);
                                            
                                            if (state.ShouldExitCurrentIteration) {
                                               if (state.LowestBreakIteration < i)
                                                  return;
                                            }

                                            if (i == breakIndex) {
                                               Console.WriteLine("Break in iteration {0}", i);
                                               state.Break();
                                               if (state.LowestBreakIteration.HasValue)
                                                  if (lowest < state.LowestBreakIteration)
                                                     lowest = state.LowestBreakIteration;
                                                  else
                                                     lowest = state.LowestBreakIteration;
                                            }

                                            Console.WriteLine("Completed iteration {0}", i);
                                       });
         if (lowest.HasValue)
            Console.WriteLine("\nLowest Break Iteration: {0}", lowest);
         else
            Console.WriteLine("\nNo lowest break iteration.");
   }
}
// The example displays output like the following:
//       Will call Break at iteration 8
//
//       Beginning iteration 1
//       Beginning iteration 13
//       Beginning iteration 97
//       Beginning iteration 25
//       Beginning iteration 49
//       Beginning iteration 37
//       Beginning iteration 85
//       Beginning iteration 73
//       Beginning iteration 61
//       Completed iteration 85
//       Beginning iteration 86
//       Completed iteration 61
//       Beginning iteration 62
//       Completed iteration 86
//       Beginning iteration 87
//       Completed iteration 37
//       Beginning iteration 38
//       Completed iteration 38
//       Beginning iteration 39
//       Completed iteration 25
//       Beginning iteration 26
//       Completed iteration 26
//       Beginning iteration 27
//       Completed iteration 73
//       Beginning iteration 74
//       Completed iteration 62
//       Beginning iteration 63
//       Completed iteration 39
//       Beginning iteration 40
//       Completed iteration 40
//       Beginning iteration 41
//       Completed iteration 13
//       Beginning iteration 14
//       Completed iteration 1
//       Beginning iteration 2
//       Completed iteration 97
//       Beginning iteration 98
//       Completed iteration 49
//       Beginning iteration 50
//       Completed iteration 87
//       Completed iteration 27
//       Beginning iteration 28
//       Completed iteration 50
//       Beginning iteration 51
//       Beginning iteration 88
//       Completed iteration 14
//       Beginning iteration 15
//       Completed iteration 15
//       Completed iteration 2
//       Beginning iteration 3
//       Beginning iteration 16
//       Completed iteration 63
//       Beginning iteration 64
//       Completed iteration 74
//       Beginning iteration 75
//       Completed iteration 41
//       Beginning iteration 42
//       Completed iteration 28
//       Beginning iteration 29
//       Completed iteration 29
//       Beginning iteration 30
//       Completed iteration 98
//       Beginning iteration 99
//       Completed iteration 64
//       Beginning iteration 65
//       Completed iteration 42
//       Beginning iteration 43
//       Completed iteration 88
//       Beginning iteration 89
//       Completed iteration 51
//       Beginning iteration 52
//       Completed iteration 16
//       Beginning iteration 17
//       Completed iteration 43
//       Beginning iteration 44
//       Completed iteration 44
//       Beginning iteration 45
//       Completed iteration 99
//       Beginning iteration 4
//       Completed iteration 3
//       Beginning iteration 8
//       Completed iteration 4
//       Beginning iteration 5
//       Completed iteration 52
//       Beginning iteration 53
//       Completed iteration 75
//       Beginning iteration 76
//       Completed iteration 76
//       Beginning iteration 77
//       Completed iteration 65
//       Beginning iteration 66
//       Completed iteration 5
//       Beginning iteration 6
//       Completed iteration 89
//       Beginning iteration 90
//       Completed iteration 30
//       Beginning iteration 31
//       Break in iteration 8
//       Completed iteration 8
//       Completed iteration 6
//       Beginning iteration 7
//       Completed iteration 7
//
//       Lowest Break Iteration: 8
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim rnd As New Random()
      Dim breakIndex As Integer = rnd.Next(1, 11)
      Dim lowest As New Nullable(Of Long)()

      Console.WriteLine("Will call Break at iteration {0}", breakIndex)
      Console.WriteLine()

      Dim result = Parallel.For(1, 101, Sub(i, state)
                                            Console.WriteLine("Beginning iteration {0}", i)
                                            Dim delay As Integer
                                            Monitor.Enter(rnd)
                                               delay = rnd.Next(1, 1001)
                                            Monitor.Exit(rnd)
                                            Thread.Sleep(delay)

                                            If state.ShouldExitCurrentIteration Then
                                               If state.LowestBreakIteration < i Then
                                                  Return
                                               End If
                                            End If

                                            If i = breakIndex Then
                                               Console.WriteLine("Break in iteration {0}", i)
                                               state.Break()
                                               If state.LowestBreakIteration.HasValue Then
                                                  If lowest < state.LowestBreakIteration Then
                                                     lowest = state.LowestBreakIteration
                                                  Else
                                                     lowest = state.LowestBreakIteration
                                                  End If
                                               End If
                                            End If

                                            Console.WriteLine("Completed iteration {0}", i)
                                       End Sub )
         Console.WriteLine()
         If lowest.HasValue Then
            Console.WriteLine("Lowest Break Iteration: {0}", lowest)
         Else
            Console.WriteLine("No lowest break iteration.")
         End If
   End Sub
End Module
' The example displays output like the following:
'       Will call Break at iteration 8
'
'       Beginning iteration 1
'       Beginning iteration 13
'       Beginning iteration 97
'       Beginning iteration 25
'       Beginning iteration 49
'       Beginning iteration 37
'       Beginning iteration 85
'       Beginning iteration 73
'       Beginning iteration 61
'       Completed iteration 85
'       Beginning iteration 86
'       Completed iteration 61
'       Beginning iteration 62
'       Completed iteration 86
'       Beginning iteration 87
'       Completed iteration 37
'       Beginning iteration 38
'       Completed iteration 38
'       Beginning iteration 39
'       Completed iteration 25
'       Beginning iteration 26
'       Completed iteration 26
'       Beginning iteration 27
'       Completed iteration 73
'       Beginning iteration 74
'       Completed iteration 62
'       Beginning iteration 63
'       Completed iteration 39
'       Beginning iteration 40
'       Completed iteration 40
'       Beginning iteration 41
'       Completed iteration 13
'       Beginning iteration 14
'       Completed iteration 1
'       Beginning iteration 2
'       Completed iteration 97
'       Beginning iteration 98
'       Completed iteration 49
'       Beginning iteration 50
'       Completed iteration 87
'       Completed iteration 27
'       Beginning iteration 28
'       Completed iteration 50
'       Beginning iteration 51
'       Beginning iteration 88
'       Completed iteration 14
'       Beginning iteration 15
'       Completed iteration 15
'       Completed iteration 2
'       Beginning iteration 3
'       Beginning iteration 16
'       Completed iteration 63
'       Beginning iteration 64
'       Completed iteration 74
'       Beginning iteration 75
'       Completed iteration 41
'       Beginning iteration 42
'       Completed iteration 28
'       Beginning iteration 29
'       Completed iteration 29
'       Beginning iteration 30
'       Completed iteration 98
'       Beginning iteration 99
'       Completed iteration 64
'       Beginning iteration 65
'       Completed iteration 42
'       Beginning iteration 43
'       Completed iteration 88
'       Beginning iteration 89
'       Completed iteration 51
'       Beginning iteration 52
'       Completed iteration 16
'       Beginning iteration 17
'       Completed iteration 43
'       Beginning iteration 44
'       Completed iteration 44
'       Beginning iteration 45
'       Completed iteration 99
'       Beginning iteration 4
'       Completed iteration 3
'       Beginning iteration 8
'       Completed iteration 4
'       Beginning iteration 5
'       Completed iteration 52
'       Beginning iteration 53
'       Completed iteration 75
'       Beginning iteration 76
'       Completed iteration 76
'       Beginning iteration 77
'       Completed iteration 65
'       Beginning iteration 66
'       Completed iteration 5
'       Beginning iteration 6
'       Completed iteration 89
'       Beginning iteration 90
'       Completed iteration 30
'       Beginning iteration 31
'       Break in iteration 8
'       Completed iteration 8
'       Completed iteration 6
'       Beginning iteration 7
'       Completed iteration 7
'
'       Lowest Break Iteration: 8

Notez que, étant donné LowestBreakIteration que la valeur est hors de portée en dehors de la boucle parallèle, vous devez l’assigner à une variable qui est visible en dehors de la boucle si vous souhaitez conserver sa valeur.Note that, because the LowestBreakIteration value is out of scope outside of the parallel loop, you must assign it to a variable that is visible outside of the loop if you want to preserve its value.

Remarques

Il est possible pour plusieurs itérations d’une boucle parallèle d’appeler la Break méthode.It is possible for multiple iterations of a parallel loop to call the Break method. Si c’est le cas, cette valeur est le plus petit index d’une itération Breakappelée.If they do, this value is the smallest index of an iteration that called Break. Si aucune itération de la boucle n' Breaka été appelée, nullcette propriété retourne.If no iteration of the loop called Break, this property returns null. Notez que la valeur de la propriété n’est pas affectée par Stop les appels à la méthode.Note that the property value is unaffected by calls to the Stop method.

Dans les itérations de longue durée dans lesquelles toutes les itérations après l’itération qui Break appelle la méthode n’ont pas LowestBreakIteration besoin d’être exécutées, la propriété est utilisée pour arrêter les itérations Break qui ont commencé l’exécution avant l’appel à la méthode.In long-running iterations in which all iterations after the iteration that calls the Break method need not run, the LowestBreakIteration property is used to terminate iterations that began execution before the call to the Break method. Pour arrêter les itérations dont l’index est supérieur à l’itération la plus faible de l’exécution en concurrence, vous devez effectuer les opérations suivantes:To stop iterations whose index is greater than the lowest break iteration from competing execution, you should do the following:

  1. Vérifiez si la ShouldExitCurrentIteration propriété a truela valeur.Check whether the ShouldExitCurrentIteration property is true.

  2. Quittez l’itération si son index est supérieur à la LowestBreakIteration valeur de la propriété.Exit from the iteration if its index is greater than the LowestBreakIteration property value.

Cet exemple en fournit une illustration.The example provides an illustration.

S’applique à

Voir aussi