Proporciona operaciones atómicas para las variables compartidas por varios subprocesos.
Espacio de nombres: System.Threading
Ensamblado: mscorlib (en mscorlib.dll)
Visual Basic (Declaración)
Public NotInheritable Class Interlocked
public static class Interlocked
public ref class Interlocked abstract sealed
public final class Interlocked
public final class Interlocked
Los métodos de esta clase ayudan a proteger de los errores que pueden producirse cuando el programador cambia de contexto mientras un subproceso está actualizando una variable a la que pueden obtener acceso otros subprocesos, o cuando dos subprocesos se están ejecutando simultáneamente en procesadores distintos. Los miembros de esta clase no producen excepciones.
Los métodos Increment y Decrement aumentan o disminuyen una variable y almacenan el valor resultante en una única operación. En la mayoría de los equipos, el incremento de una variable no es una operación atómica y requiere los pasos siguientes:
-
Cargar un valor desde una variable de instancia hasta un registro.
-
Aumentar o reducir el valor.
-
Almacenar el valor en la variable de instancia.
Si no se utiliza Increment ni Decrement, un subproceso se puede adelantar después de que se hayan ejecutado los dos primeros pasos. Así, otro subproceso puede ejecutar los tres pasos. Cuando se reanuda la ejecución del primer subproceso, sobrescribe el valor de la variable de instancia y se pierde el efecto del aumento o reducción que realiza el segundo subproceso.
El método Exchange intercambia los valores de las variables especificadas atómicamente. El método CompareExchange combina dos operaciones: compara dos valores y almacena un tercer valor en una de las variables, en función del resultado de la comparación. Las operaciones de comparación e intercambio se realizan como una operación atómica.
En el ejemplo de código siguiente se muestra un mecanismo de bloqueo de recursos seguro para la ejecución de subprocesos.
Imports System
Imports System.Threading
Namespace InterlockedExchange_Example
Class MyInterlockedExchangeExampleClass
'0 for false, 1 for true.
Private Shared usingResource As Integer = 0
Private Shared currentMso As [Object]
Private Shared globalMso As New [Object]()
Private Const numThreadIterations As Integer = 5
Private Const numThreads As Integer = 10
<MTAThread> _
Shared Sub Main()
Dim myThread As Thread
Dim rnd As New Random()
Dim i As Integer
For i = 0 To numThreads - 1
myThread = New Thread(AddressOf MyThreadProc)
myThread.Name = [String].Format("Thread{0}", i + 1)
'Wait a random amount of time before starting next thread.
Thread.Sleep(rnd.Next(0, 1000))
myThread.Start()
Next i
End Sub 'Main
Private Shared Sub MyThreadProc()
Dim i As Integer
For i = 0 To numThreadIterations - 1
UseResource()
'Wait 1 second before next attempt.
Thread.Sleep(1000)
Next i
End Sub 'MyThreadProc
'A simple method that denies reentrancy.
Shared Function UseResource() As Boolean
'0 indicates that the method is not in use.
If 0 = Interlocked.Exchange(usingResource, 1) Then
Console.WriteLine("{0} acquired the lock", Thread.CurrentThread.Name)
'Code to access a resource that is not thread safe would go here.
'Simulate some work
Thread.Sleep(500)
Console.WriteLine("{0} exiting lock", Thread.CurrentThread.Name)
'Release the lock
Interlocked.Exchange(usingResource, 0)
Return True
Else
Console.WriteLine(" {0} was denied the lock", Thread.CurrentThread.Name)
Return False
End If
End Function 'UseResource
End Class 'MyInterlockedExchangeExampleClass
End Namespace 'InterlockedExchange_Example
using System;
using System.Threading;
namespace InterlockedExchange_Example
{
class MyInterlockedExchangeExampleClass
{
//0 for false, 1 for true.
private static int usingResource = 0;
private static Object currentMso;
private static Object globalMso = new Object();
private const int numThreadIterations = 5;
private const int numThreads = 10;
static void Main()
{
Thread myThread;
Random rnd = new Random();
for(int i = 0; i < numThreads; i++)
{
myThread = new Thread(new ThreadStart(MyThreadProc));
myThread.Name = String.Format("Thread{0}", i + 1);
//Wait a random amount of time before starting next thread.
Thread.Sleep(rnd.Next(0, 1000));
myThread.Start();
}
}
private static void MyThreadProc()
{
for(int i = 0; i < numThreadIterations; i++)
{
UseResource();
//Wait 1 second before next attempt.
Thread.Sleep(1000);
}
}
//A simple method that denies reentrancy.
static bool UseResource()
{
//0 indicates that the method is not in use.
if(0 == Interlocked.Exchange(ref usingResource, 1))
{
Console.WriteLine("{0} acquired the lock", Thread.CurrentThread.Name);
//Code to access a resource that is not thread safe would go here.
//Simulate some work
Thread.Sleep(500);
Console.WriteLine("{0} exiting lock", Thread.CurrentThread.Name);
//Release the lock
Interlocked.Exchange(ref usingResource, 0);
return true;
}
else
{
Console.WriteLine(" {0} was denied the lock", Thread.CurrentThread.Name);
return false;
}
}
}
}
using namespace System;
using namespace System::Threading;
const int numThreads = 10;
const int numThreadIterations = 5;
ref class MyInterlockedExchangeExampleClass
{
public:
static void MyThreadProc()
{
for ( int i = 0; i < numThreadIterations; i++ )
{
UseResource();
//Wait 1 second before next attempt.
Thread::Sleep( 1000 );
}
}
private:
//A simple method that denies reentrancy.
static bool UseResource()
{
//0 indicates that the method is not in use.
if ( 0 == Interlocked::Exchange( usingResource, 1 ) )
{
Console::WriteLine( " {0} acquired the lock", Thread::CurrentThread->Name );
//Code to access a resource that is not thread safe would go here.
//Simulate some work
Thread::Sleep( 500 );
Console::WriteLine( " {0} exiting lock", Thread::CurrentThread->Name );
//Release the lock
Interlocked::Exchange( usingResource, 0 );
return true;
}
else
{
Console::WriteLine( " {0} was denied the lock", Thread::CurrentThread->Name );
return false;
}
}
//0 for false, 1 for true.
static int usingResource;
static Object^ globalMso = gcnew Object;
};
int main()
{
Thread^ myThread;
Random^ rnd = gcnew Random;
for ( int i = 0; i < numThreads; i++ )
{
myThread = gcnew Thread( gcnew ThreadStart( MyInterlockedExchangeExampleClass::MyThreadProc ) );
myThread->Name = String::Format( "Thread {0}", i + 1 );
//Wait a random amount of time before starting next thread.
Thread::Sleep( rnd->Next( 0, 1000 ) );
myThread->Start();
}
}
package InterlockedExchange_Example ;
import System .* ;
import System.Threading .* ;
import System.Threading.Thread;
class MyInterlockedExchangeExampleClass
{
//0 for false, 1 for true.
private static int usingResource = 0;
private static Object currentMso;
private static Object globalMso = new Object();
private static int numThreadIterations = 5;
private static int numThreads = 10;
public static void main(String[] args)
{
Thread myThread;
Random rnd = new Random();
for (int i = 0; i < numThreads; i++) {
myThread = new Thread(new ThreadStart(MyThreadProc));
myThread.set_Name(String.Format("Thread{0}",
String.valueOf(i + 1)));
//Wait a random amount of time before starting next thread.
Thread.Sleep(rnd.Next(0, 1000));
myThread.Start();
}
} //main
private static void MyThreadProc()
{
for (int i = 0; i < numThreadIterations; i++) {
UseResource();
//Wait 1 second before next attempt.
Thread.Sleep(1000);
}
} //MyThreadProc
//A simple method that denies reentrancy.
static boolean UseResource()
{
//0 indicates that the method is not in use.
if (0 == Interlocked.Exchange(usingResource, 1)) {
Console.WriteLine("{0} acquired the lock",
Thread.get_CurrentThread().get_Name());
//Code to access a resource that is not thread safe would go here.
//Simulate some work
Thread.Sleep(500);
Console.WriteLine("{0} exiting lock",
Thread.get_CurrentThread().get_Name());
//Release the lock
Interlocked.Exchange(usingResource, 0);
return true;
}
else {
Console.WriteLine(" {0} was denied the lock",
Thread.get_CurrentThread().get_Name());
return false;
}
} //UseResource
} //MyInterlockedExchangeExampleClass
System.Object
System.Threading.Interlocked
Seguridad para subprocesos
Este tipo es seguro para la ejecución de subprocesos.
Windows 98, Windows 2000 Service Pack 4, Windows CE, Windows Millennium, Windows Mobile para Pocket PC, Windows Mobile para Smartphone, Windows Server 2003, Windows XP Media Center, Windows XP Professional x64, Windows XP SP2, Windows XP Starter
Microsoft .NET Framework 3.0 es compatible con Windows Vista, Microsoft Windows XP SP2 y Windows Server 2003 SP1.
.NET Framework
Compatible con: 3.0, 2.0, 1.1, 1.0
.NET Compact Framework
Compatible con: 2.0, 1.0
XNA Framework
Compatible con: 1.0