WaitHandle-Klasse
Kapselt betriebssystemspezifische Objekte, die auf exklusiven Zugriff auf gemeinsam genutzte Ressourcen warten.
Namespace: System.Threading
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
<ComVisibleAttribute(True)> _
Public MustInherit Class WaitHandle
Inherits MarshalByRefObject
Implements IDisposable
'Usage
Dim instance As WaitHandle
[ComVisibleAttribute(true)]
public abstract class WaitHandle : MarshalByRefObject, IDisposable
[ComVisibleAttribute(true)]
public ref class WaitHandle abstract : public MarshalByRefObject, IDisposable
/** @attribute ComVisibleAttribute(true) */
public abstract class WaitHandle extends MarshalByRefObject implements IDisposable
ComVisibleAttribute(true)
public abstract class WaitHandle extends MarshalByRefObject implements IDisposable
Hinweise
Diese Klasse wird i. d. R. als Basisklasse für Synchronisierungsobjekte verwendet. Von WaitHandle abgeleitete Klassen definieren einen Signalisierungsmechanismus, um das Aufnehmen oder Freigeben von Zugriff auf gemeinsam genutzte Ressourcen anzugeben, verwenden jedoch die geerbten WaitHandle-Methoden zum Blockieren während des Wartens auf den Zugriff auf gemeinsam genutzte Ressourcen.
Verwenden Sie die statischen Methoden dieser Klasse zur Blockierung eines Threads, bis ein oder mehrere Synchronisierungsobjekte ein Signal empfangen.
Beispiel
Im folgenden Codebeispiel wird veranschaulicht, wie zwei Threads Hintergrundaufgaben ausführen können, während der Hauptthread mithilfe der WaitAny-Methode und der WaitAll-Methode der WaitHandle-Klasse darauf wartet, dass die Aufgaben abgeschlossen werden.
Imports System
Imports System.Threading
NotInheritable Public Class App
' Define an array with two AutoResetEvent WaitHandles.
Private Shared waitHandles() As WaitHandle = _
{New AutoResetEvent(False), New AutoResetEvent(False)}
' Define a random number generator for testing.
Private Shared r As New Random()
<MTAThreadAttribute> _
Public Shared Sub Main()
' Queue two tasks on two different threads;
' wait until all tasks are completed.
Dim dt As DateTime = DateTime.Now
Console.WriteLine("Main thread is waiting for BOTH tasks to complete.")
ThreadPool.QueueUserWorkItem(AddressOf DoTask, waitHandles(0))
ThreadPool.QueueUserWorkItem(AddressOf DoTask, waitHandles(1))
WaitHandle.WaitAll(waitHandles)
' The time shown below should match the longest task.
Console.WriteLine("Both tasks are completed (time waited={0})", _
(DateTime.Now - dt).TotalMilliseconds)
' Queue up two tasks on two different threads;
' wait until any tasks are completed.
dt = DateTime.Now
Console.WriteLine()
Console.WriteLine("The main thread is waiting for either task to complete.")
ThreadPool.QueueUserWorkItem(AddressOf DoTask, waitHandles(0))
ThreadPool.QueueUserWorkItem(AddressOf DoTask, waitHandles(1))
Dim index As Integer = WaitHandle.WaitAny(waitHandles)
' The time shown below should match the shortest task.
Console.WriteLine("Task {0} finished first (time waited={1}).", _
index + 1,(DateTime.Now - dt).TotalMilliseconds)
End Sub 'Main
Shared Sub DoTask(ByVal state As [Object])
Dim are As AutoResetEvent = CType(state, AutoResetEvent)
Dim time As Integer = 1000 * r.Next(2, 10)
Console.WriteLine("Performing a task for {0} milliseconds.", time)
Thread.Sleep(time)
are.Set()
End Sub 'DoTask
End Class 'App
' This code produces output similar to the following:
'
' Main thread is waiting for BOTH tasks to complete.
' Performing a task for 7000 milliseconds.
' Performing a task for 4000 milliseconds.
' Both tasks are completed (time waited=7064.8052)
'
' The main thread is waiting for either task to complete.
' Performing a task for 2000 milliseconds.
' Performing a task for 2000 milliseconds.
' Task 1 finished first (time waited=2000.6528).
using System;
using System.Threading;
public sealed class App
{
// Define an array with two AutoResetEvent WaitHandles.
static WaitHandle[] waitHandles = new WaitHandle[]
{
new AutoResetEvent(false),
new AutoResetEvent(false)
};
// Define a random number generator for testing.
static Random r = new Random();
static void Main()
{
// Queue up two tasks on two different threads;
// wait until all tasks are completed.
DateTime dt = DateTime.Now;
Console.WriteLine("Main thread is waiting for BOTH tasks to complete.");
ThreadPool.QueueUserWorkItem(new WaitCallback(DoTask), waitHandles[0]);
ThreadPool.QueueUserWorkItem(new WaitCallback(DoTask), waitHandles[1]);
WaitHandle.WaitAll(waitHandles);
// The time shown below should match the longest task.
Console.WriteLine("Both tasks are completed (time waited={0})",
(DateTime.Now - dt).TotalMilliseconds);
// Queue up two tasks on two different threads;
// wait until any tasks are completed.
dt = DateTime.Now;
Console.WriteLine();
Console.WriteLine("The main thread is waiting for either task to complete.");
ThreadPool.QueueUserWorkItem(new WaitCallback(DoTask), waitHandles[0]);
ThreadPool.QueueUserWorkItem(new WaitCallback(DoTask), waitHandles[1]);
int index = WaitHandle.WaitAny(waitHandles);
// The time shown below should match the shortest task.
Console.WriteLine("Task {0} finished first (time waited={1}).",
index + 1, (DateTime.Now - dt).TotalMilliseconds);
}
static void DoTask(Object state)
{
AutoResetEvent are = (AutoResetEvent) state;
int time = 1000 * r.Next(2, 10);
Console.WriteLine("Performing a task for {0} milliseconds.", time);
Thread.Sleep(time);
are.Set();
}
}
// This code produces output similar to the following:
//
// Main thread is waiting for BOTH tasks to complete.
// Performing a task for 7000 milliseconds.
// Performing a task for 4000 milliseconds.
// Both tasks are completed (time waited=7064.8052)
//
// The main thread is waiting for either task to complete.
// Performing a task for 2000 milliseconds.
// Performing a task for 2000 milliseconds.
// Task 1 finished first (time waited=2000.6528).
using namespace System;
using namespace System::Threading;
public ref class WaitHandleExample
{
// Define a random number generator for testing.
private:
static Random^ random = gcnew Random();
public:
static void DoTask(Object^ state)
{
AutoResetEvent^ autoReset = (AutoResetEvent^) state;
int time = 1000 * random->Next(2, 10);
Console::WriteLine("Performing a task for {0} milliseconds.", time);
Thread::Sleep(time);
autoReset->Set();
}
};
int main()
{
// Define an array with two AutoResetEvent WaitHandles.
array<WaitHandle^>^ handles = gcnew array<WaitHandle^> {
gcnew AutoResetEvent(false), gcnew AutoResetEvent(false)};
// Queue up two tasks on two different threads;
// wait until all tasks are completed.
DateTime timeInstance = DateTime::Now;
Console::WriteLine("Main thread is waiting for BOTH tasks to " +
"complete.");
ThreadPool::QueueUserWorkItem(
gcnew WaitCallback(WaitHandleExample::DoTask), handles[0]);
ThreadPool::QueueUserWorkItem(
gcnew WaitCallback(WaitHandleExample::DoTask), handles[1]);
WaitHandle::WaitAll(handles);
// The time shown below should match the longest task.
Console::WriteLine("Both tasks are completed (time waited={0})",
(DateTime::Now - timeInstance).TotalMilliseconds);
// Queue up two tasks on two different threads;
// wait until any tasks are completed.
timeInstance = DateTime::Now;
Console::WriteLine();
Console::WriteLine("The main thread is waiting for either task to " +
"complete.");
ThreadPool::QueueUserWorkItem(
gcnew WaitCallback(WaitHandleExample::DoTask), handles[0]);
ThreadPool::QueueUserWorkItem(
gcnew WaitCallback(WaitHandleExample::DoTask), handles[1]);
int index = WaitHandle::WaitAny(handles);
// The time shown below should match the shortest task.
Console::WriteLine("Task {0} finished first (time waited={1}).",
index + 1, (DateTime::Now - timeInstance).TotalMilliseconds);
}
// This code produces the following sample output.
//
// Main thread is waiting for BOTH tasks to complete.
// Performing a task for 7000 milliseconds.
// Performing a task for 4000 milliseconds.
// Both tasks are completed (time waited=7064.8052)
// The main thread is waiting for either task to complete.
// Performing a task for 2000 milliseconds.
// Performing a task for 2000 milliseconds.
// Task 1 finished first (time waited=2000.6528).
Vererbungshierarchie
System.Object
System.MarshalByRefObject
System.Threading.WaitHandle
System.Threading.EventWaitHandle
System.Threading.Mutex
System.Threading.Semaphore
Threadsicherheit
Dieser Typ ist threadsicher.
Plattformen
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, Windows Mobile für Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0
.NET Compact Framework
Unterstützt in: 2.0, 1.0
Siehe auch
Referenz
WaitHandle-Member
System.Threading-Namespace