ReaderWriterLock.UpgradeToWriterLock Methode

Quelle:

ReaderWriterLock.cs

Quelle:

ReaderWriterLock.cs

Quelle:

ReaderWriterLock.cs

Quelle:

ReaderWriterLock.cs

Quelle:

ReaderWriterLock.cs

public:
 System::Threading::LockCookie UpgradeToWriterLock(int millisecondsTimeout);

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public System.Threading.LockCookie UpgradeToWriterLock(int millisecondsTimeout);

public System.Threading.LockCookie UpgradeToWriterLock(int millisecondsTimeout);

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
member this.UpgradeToWriterLock : int -> System.Threading.LockCookie

member this.UpgradeToWriterLock : int -> System.Threading.LockCookie

Public Function UpgradeToWriterLock (millisecondsTimeout As Integer) As LockCookie

Parameter

Gibt zurück

Ein LockCookie-Wert.

Attribute

UnsupportedOSPlatformAttribute

Ausnahmen

Beispiele

Im folgenden Codebeispiel wird gezeigt, wie Sie eine Lesesperre anfordern, die Lesesperre auf eine Writer-Sperre aktualisieren und erneut auf eine Lesesperre herabstufen.

Dieser Code ist Teil eines größeren Beispiels, das für die ReaderWriterLock Klasse bereitgestellt wird.

// The complete code is located in the ReaderWriterLock class topic.
using System;
using System.Threading;

public class Example
{
   static ReaderWriterLock rwl = new ReaderWriterLock();
   // Define the shared resource protected by the ReaderWriterLock.
   static int resource = 0;

' The complete code is located in the ReaderWriterLock class topic.
Imports System.Threading

Public Module Example
   Private rwl As New ReaderWriterLock()
   ' Define the shared resource protected by the ReaderWriterLock.
   Private resource As Integer = 0

// Requests a reader lock, upgrades the reader lock to the writer
// lock, and downgrades it to a reader lock again.
static void UpgradeDowngrade(Random rnd, int timeOut)
{
   try {
      rwl.AcquireReaderLock(timeOut);
      try {
         // It's safe for this thread to read from the shared resource.
         Display("reads resource value " + resource);
         Interlocked.Increment(ref reads);

         // To write to the resource, either release the reader lock and
         // request the writer lock, or upgrade the reader lock. Upgrading
         // the reader lock puts the thread in the write queue, behind any
         // other threads that might be waiting for the writer lock.
         try {
            LockCookie lc = rwl.UpgradeToWriterLock(timeOut);
            try {
               // It's safe for this thread to read or write from the shared resource.
               resource = rnd.Next(500);
               Display("writes resource value " + resource);
               Interlocked.Increment(ref writes);
            }
            finally {
               // Ensure that the lock is released.
               rwl.DowngradeFromWriterLock(ref lc);
            }
         }
         catch (ApplicationException) {
            // The upgrade request timed out.
            Interlocked.Increment(ref writerTimeouts);
         }

         // If the lock was downgraded, it's still safe to read from the resource.
         Display("reads resource value " + resource);
         Interlocked.Increment(ref reads);
      }
      finally {
         // Ensure that the lock is released.
         rwl.ReleaseReaderLock();
      }
   }
   catch (ApplicationException) {
      // The reader lock request timed out.
      Interlocked.Increment(ref readerTimeouts);
   }
}

' Requests a reader lock, upgrades the reader lock to the writer
' lock, and downgrades it to a reader lock again.
Sub UpgradeDowngrade(rnd As Random, timeOut As Integer)
   Try
      rwl.AcquireReaderLock(timeOut)
      Try
         ' It's safe for this thread to read from the shared resource.
         Display("reads resource value " & resource)
         Interlocked.Increment(reads)
         
         ' To write to the resource, either release the reader lock and
         ' request the writer lock, or upgrade the reader lock. Upgrading
         ' the reader lock puts the thread in the write queue, behind any
         ' other threads that might be waiting for the writer lock.
         Try
            Dim lc As LockCookie = rwl.UpgradeToWriterLock(timeOut)
            Try
               ' It's safe for this thread to read or write from the shared resource.
               resource = rnd.Next(500)
               Display("writes resource value " & resource)
               Interlocked.Increment(writes)
            Finally
               ' Ensure that the lock is released.
               rwl.DowngradeFromWriterLock(lc)
            End Try
         Catch ex As ApplicationException
            ' The upgrade request timed out.
            Interlocked.Increment(writerTimeouts)
         End Try
         
         ' If the lock was downgraded, it's still safe to read from the resource.
         Display("reads resource value " & resource)
         Interlocked.Increment(reads)
      Finally
         ' Ensure that the lock is released.
         rwl.ReleaseReaderLock()
      End Try
   Catch ex As ApplicationException
      ' The reader lock request timed out.
      Interlocked.Increment(readerTimeouts)
   End Try
End Sub

}

End Module

Hinweise

Wenn ein Thread die Lesesperre aufruft UpgradeToWriterLock , wird unabhängig von der Sperranzahl losgelassen, und der Thread wechselt zum Ende der Warteschlange für die Writer-Sperre. Daher können andere Threads in die Ressource schreiben, bevor dem Thread, der das Upgrade angefordert hat, die Writer-Sperre gewährt wird.

Rufen Sie DowngradeFromWriterLock zum Wiederherstellen des Sperrzustands mithilfe der LockCookie zurückgegebenen von UpgradeToWriterLock. Verwenden Sie dies LockCookie nicht mit RestoreLock.

Wenn ein Thread keine Lesesperre aufweist, verwenden UpgradeToWriterLockSie nicht . Verwenden Sie stattdessen AcquireWriterLock.

Gültige Timeoutwerte finden Sie unter ReaderWriterLock.

Weitere Informationen

• Verwaltetes Thread-Management
• Readerwriterlock

Quelle:

ReaderWriterLock.cs

Quelle:

ReaderWriterLock.cs

Quelle:

ReaderWriterLock.cs

Quelle:

ReaderWriterLock.cs

Quelle:

ReaderWriterLock.cs

public:
 System::Threading::LockCookie UpgradeToWriterLock(TimeSpan timeout);

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public System.Threading.LockCookie UpgradeToWriterLock(TimeSpan timeout);

public System.Threading.LockCookie UpgradeToWriterLock(TimeSpan timeout);

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
member this.UpgradeToWriterLock : TimeSpan -> System.Threading.LockCookie

member this.UpgradeToWriterLock : TimeSpan -> System.Threading.LockCookie

Public Function UpgradeToWriterLock (timeout As TimeSpan) As LockCookie

Parameter

Gibt zurück

Ein LockCookie-Wert.

Attribute

UnsupportedOSPlatformAttribute

Ausnahmen

Hinweise

Wenn ein Thread die Lesesperre aufruft UpgradeToWriterLock , wird unabhängig von der Sperranzahl losgelassen, und der Thread wechselt zum Ende der Warteschlange für die Writer-Sperre. Daher können andere Threads in die Ressource schreiben, bevor dem Thread, der das Upgrade angefordert hat, die Writer-Sperre gewährt wird.

Rufen Sie DowngradeFromWriterLock zum Wiederherstellen des Sperrzustands mithilfe der LockCookie zurückgegebenen von UpgradeToWriterLock. Verwenden Sie dies LockCookie nicht mit RestoreLock.

Wenn ein Thread keine Lesesperre aufweist, verwenden UpgradeToWriterLockSie nicht . Verwenden Sie stattdessen AcquireWriterLock.

Gültige Timeoutwerte finden Sie unter ReaderWriterLock.

Weitere Informationen

• Verwaltetes Thread-Management
• Readerwriterlock