ParallelLoopState ParallelLoopState ParallelLoopState ParallelLoopState Class

Definizione

Consente alle iterazioni dei cicli paralleli di interagire con altre iterazioni.Enables iterations of parallel loops to interact with other iterations. Un'istanza di questa classe viene resa disponibile dalla classe Parallel a ogni ciclo. Non è possibile creare istanze nel codice utente.An instance of this class is provided by the Parallel class to each loop; you can not create instances in your code.

public ref class ParallelLoopState
public class ParallelLoopState
type ParallelLoopState = class
Public Class ParallelLoopState
Ereditarietà
ParallelLoopStateParallelLoopStateParallelLoopStateParallelLoopState

Esempi

Nell'esempio seguente vengono eseguite fino a 100 iterazioni di un ciclo in parallelo.The following example executes up to 100 iterations of a loop in parallel. Ogni iterazione viene sospesa per un intervallo casuale compreso tra 1 e 1.000 millisecondi.Each iteration pauses for a random interval from 1 to 1,000 milliseconds. Un valore generato in modo casuale determina in quale iterazione del ciclo Break viene chiamato il metodo.A randomly generated value determines on which iteration of the loop the Break method is called. Come illustrato nell'output dell'esempio, nessuna iterazione il cui indice è maggiore del valore LowestBreakIteration della proprietà inizia dopo la chiamata Break al metodo.As the output from the example shows, no iterations whose index is greater than the LowestBreakIteration property value start after the call to the Break method.

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

Poiché le iterazioni del ciclo possono comunque essere eseguite quando viene chiamato il Break metodo, ogni iterazione chiama la ShouldExitCurrentIteration proprietà per verificare se un'altra iterazione ha chiamato il Break metodo.Because iterations of the loop are still likely to be executing when the Break method is called, each iteration calls the ShouldExitCurrentIteration property to check whether another iteration has called the Break method. Se il valore della proprietà trueè, l'iterazione controlla il valore LowestBreakIteration della proprietà e, se è maggiore del valore di indice dell'iterazione corrente, viene restituito immediatamente.If the property value is true, the iteration checks the value of the LowestBreakIteration property and, if it is greater than the current iteration's index value, returns immediately.

Commenti

Si noti che non è possibile creare un'istanza di questa classe.Note that you cannot instantiate an instance of this class. Viene generato automaticamente dal compilatore come argomento in una chiamata al Parallel.For metodo o. Parallel.ForEachIt is automatically generated by the compiler as an argument in a call to the Parallel.For or Parallel.ForEach method. Nell'esempio viene illustrata una situazione di questo tipo.The example provides an illustration.

I costrutti, for ad foreach esempio e C#(in For ) For Each e e (in Visual Basic), vengono eseguiti in sequenza dall'indice più basso al più alto o dal primo oggetto di un oggetto impostato sull'ultimo.Constructs such as for and foreach (in C#) and For and For Each (in Visual Basic) execute sequentially from the lowest index to the highest or from the first object in a set to the last. Al contrario, i Parallel.For metodi Parallel.ForEach e non lo sono.In contrast, the Parallel.For and Parallel.ForEach methods do not. Poiché le singole iterazioni del ciclo vengono eseguite in parallelo, possono iniziare e terminare in qualsiasi ordine.Because individual iterations of the loop run in parallel, they can begin and end in any order. La ParallelLoopState classe consente alle singole iterazioni dei cicli paralleli di interagire tra loro.The ParallelLoopState class allows individual iterations of parallel loops to interact with one another. La ParallelLoopState classe consente di:The ParallelLoopState class allows you to:

  • Uscire dall'iterazione corrente e impedire l'avvio di altre iterazioni chiamando il Stop metodo.Exit the current iteration and prevent any additional iterations from starting by calling the Stop method. Questa operazione non influisce sulle iterazioni che hanno già iniziato l'esecuzione.This does not affect iterations that have already begun execution.

  • Impedire l'esecuzione di iterazioni con un indice maggiore dell'indice corrente chiamando il Break metodo.Prevent any iterations with an index greater than the current index from executing by calling the Break method. Questa operazione non influisce sulle iterazioni che hanno già iniziato l'esecuzione.This does not affect iterations that have already begun execution.

  • Determinare se si è verificata un'eccezione in qualsiasi iterazione del ciclo recuperando il IsExceptional valore della proprietà.Determine whether an exception has occurred in any loop iteration by retrieving the value of the IsExceptional property.

  • Determinare se un'iterazione del ciclo ha chiamato il Stop metodo recuperando il valore IsStopped della proprietà.Determine whether any iteration of the loop has called the Stop method by retrieving the value of the IsStopped property. È possibile utilizzare questa proprietà per restituire le iterazioni del ciclo avviate prima della chiamata al Stop metodo, ma che sono ancora in esecuzione.You can use this property to return from iterations of the loop that started before the call to the Stop method but are still executing.

  • Determinare se un'iterazione del ciclo ha chiamato il Break metodo Stop o oppure ha generato un'eccezione recuperando il valore della ShouldExitCurrentIteration proprietà.Determine whether any iteration of the loop has called the Break or Stop method or has thrown an exception by retrieving the value of the ShouldExitCurrentIteration property.

  • Uscire da un'iterazione a esecuzione prolungata il cui indice è maggiore dell'indice di un'iterazione in cui è stato chiamato break recuperando LowestBreakIteration il valore della proprietà.Exit from a long-running iteration whose index is greater than the index of an iteration in which Break was called by retrieving the value of the LowestBreakIteration property.

Proprietà

IsExceptional IsExceptional IsExceptional IsExceptional

Ottiene un valore che indica se un'iterazione del ciclo ha generato un'eccezione che non è stata gestita da tale iterazione.Gets whether any iteration of the loop has thrown an exception that went unhandled by that iteration.

IsStopped IsStopped IsStopped IsStopped

Ottiene un valore che indica se un'iterazione del ciclo ha chiamato il metodo Stop().Gets whether any iteration of the loop has called the Stop() method.

LowestBreakIteration LowestBreakIteration LowestBreakIteration LowestBreakIteration

Ottiene il numero di iterazione minimo del ciclo da cui è stato chiamato l'oggetto Break().Gets the lowest iteration of the loop from which Break() was called.

ShouldExitCurrentIteration ShouldExitCurrentIteration ShouldExitCurrentIteration ShouldExitCurrentIteration

Ottiene un valore che indica se terminare l'iterazione corrente del ciclo in base alle richieste fatte da questa o da altre iterazioni.Gets whether the current iteration of the loop should exit based on requests made by this or other iterations.

Metodi

Break() Break() Break() Break()

Comunica che il ciclo Parallel deve interrompere l'esecuzione delle iterazioni dopo l'iterazione corrente non appena il sistema lo richiede.Communicates that the Parallel loop should cease execution of iterations beyond the current iteration at the system's earliest convenience.

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Determina se l'oggetto specificato è uguale all'oggetto corrente.Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Funge da funzione hash predefinita.Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

Ottiene l'oggetto Type dell'istanza corrente.Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Crea una copia superficiale dell'oggetto Object corrente.Creates a shallow copy of the current Object.

(Inherited from Object)
Stop() Stop() Stop() Stop()

Comunica che il ciclo Parallel deve interrompere l'esecuzione non appena il sistema lo richieda.Communicates that the Parallel loop should cease execution at the system's earliest convenience.

ToString() ToString() ToString() ToString()

Restituisce una stringa che rappresenta l'oggetto corrente.Returns a string that represents the current object.

(Inherited from Object)

Si applica a

Thread safety

Un' ParallelLoopState istanza è destinata all'uso solo all'interno del corpo del ciclo al quale è stata fornita un'istanza.A ParallelLoopState instance is meant to be used only within the body of the loop to which an instance was provided. Non è sicuro usare un'istanza fornita ParallelLoopState dopo che il ciclo associato termina, né è possibile passarlo esplicitamente ad altri thread e far accedere a tali thread in qualsiasi momento.It is not safe to use a provided ParallelLoopState instance after the associated loop ends, nor is it safe to explicitly hand it off to other threads and have those threads access it at any time. Viene fornita ParallelLoopState un'istanza diversa a ogni thread incluso in un ciclo.A different ParallelLoopState instance will be provided to each thread involved in a loop.

Vedi anche