LockCookie 結構

定義

命名空間:

System.Threading

組件:

netstandard.dll, System.Threading.dll

來源:

LockCookie.cs

定義實作單一寫入器/多讀取器語意的鎖定。 這是實值型別。

public value class LockCookie : IEquatable<System::Threading::LockCookie>

public struct LockCookie : IEquatable<System.Threading.LockCookie>

type LockCookie = struct

Public Structure LockCookie
Implements IEquatable(Of LockCookie)

繼承

Object

ValueType

LockCookie

實作

IEquatable<LockCookie>

範例

以下範例說明如何請求讀取鎖、將讀取鎖升級為寫入鎖定，並儲存 LockCookie。 接著它會用 降 LockCookie 級回讀取鎖。

此程式碼是該類別更大 ReaderWriterLock 範例的一部分。

// 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

方法

名稱	Description
Equals(LockCookie)	表示目前實例是否等於指定的 LockCookie。
Equals(Object)	表示指定物件是否為 且 LockCookie 等於當前實例。
GetHashCode()	傳回這個實例的哈希碼。

操作員

名稱	Description
Equality(LockCookie, LockCookie)	表示兩個 LockCookie 結構是否相等。
Inequality(LockCookie, LockCookie)	表示兩個 LockCookie 結構是否不相等。

執行緒安全性

此類型是安全線程。

另請參閱

• ReaderWriterLock
• 管理的執行緒
• Reader-Writer 鎖