ReaderWriterLock.RestoreLock(LockCookie) 메서드

정의

네임스페이스:

System.Threading

어셈블리:

netstandard.dll, System.Threading.dll

Source:

ReaderWriterLock.cs

스레드의 잠금 상태를 호출 ReleaseLock()하기 전의 상태로 복원합니다.

public:
 void RestoreLock(System::Threading::LockCookie % lockCookie);

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public void RestoreLock(ref System.Threading.LockCookie lockCookie);

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
member this.RestoreLock : LockCookie -> unit

Public Sub RestoreLock (ByRef lockCookie As LockCookie)

매개 변수

lockCookie

LockCookie

에 의해 반환된 LockCookieA ReleaseLock() 입니다.

특성

UnsupportedOSPlatformAttribute

예외

NullReferenceException

주소 lockCookie 는 null 포인터입니다.

예제

다음 코드 예제에서는 메서드를 사용하여 ReleaseLock 스레드에서 잠금을 획득한 횟수와 관계없이 잠금을 해제하는 방법과 나중에 잠금 상태를 복원하는 방법을 보여 줍니다.

이 코드는 클래스에 제공된 더 큰 예제의 ReaderWriterLock 일부입니다.

// 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

// Release all locks and later restores the lock state.
// Uses sequence numbers to determine whether another thread has
// obtained a writer lock since this thread last accessed the resource.
static void ReleaseRestore(Random rnd, int timeOut)
{
   int lastWriter;

   try {
      rwl.AcquireReaderLock(timeOut);
      try {
         // It's safe for this thread to read from the shared resource,
         // so read and cache the resource value.
         int resourceValue = resource;     // Cache the resource value.
         Display("reads resource value " + resourceValue);
         Interlocked.Increment(ref reads);

         // Save the current writer sequence number.
         lastWriter = rwl.WriterSeqNum;

         // Release the lock and save a cookie so the lock can be restored later.
         LockCookie lc = rwl.ReleaseLock();

         // Wait for a random interval and then restore the previous state of the lock.
         Thread.Sleep(rnd.Next(250));
         rwl.RestoreLock(ref lc);

         // Check whether other threads obtained the writer lock in the interval.
         // If not, then the cached value of the resource is still valid.
         if (rwl.AnyWritersSince(lastWriter)) {
            resourceValue = resource;
            Interlocked.Increment(ref reads);
            Display("resource has changed " + resourceValue);
         }
         else {
            Display("resource has not changed " + resourceValue);
         }
      }
      finally {
         // Ensure that the lock is released.
         rwl.ReleaseReaderLock();
      }
   }
   catch (ApplicationException) {
      // The reader lock request timed out.
      Interlocked.Increment(ref readerTimeouts);
   }
}

' Release all locks and later restores the lock state.
' Uses sequence numbers to determine whether another thread has
' obtained a writer lock since this thread last accessed the resource.
Sub ReleaseRestore(rnd As Random ,timeOut As Integer)
   Dim lastWriter As Integer
   
   Try
      rwl.AcquireReaderLock(timeOut)
      Try
         ' It's safe for this thread to read from the shared resource,
         ' so read and cache the resource value.
         Dim resourceValue As Integer = resource
         Display("reads resource value " & resourceValue)
         Interlocked.Increment(reads)
         
         ' Save the current writer sequence number.
         lastWriter = rwl.WriterSeqNum
         
         ' Release the lock and save a cookie so the lock can be restored later.
         Dim lc As LockCookie = rwl.ReleaseLock()
         
         ' Wait for a random interval and then restore the previous state of the lock.
         Thread.Sleep(rnd.Next(250))
         rwl.RestoreLock(lc)
        
         ' Check whether other threads obtained the writer lock in the interval.
         ' If not, then the cached value of the resource is still valid.
         If rwl.AnyWritersSince(lastWriter) Then
            resourceValue = resource
            Interlocked.Increment(reads)
            Display("resource has changed " & resourceValue)
         Else
            Display("resource has not changed " & resourceValue)
         End If
      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

설명

복원된 RestoreLock 상태에는 재귀 잠금 수가 포함됩니다.

스레드는 다른 스레드가 기록기 잠금을 획득한 후 판독기 잠금을 복원하려고 시도하거나 다른 스레드가 판독기 잠금 또는 기록기 잠금을 획득한 후 기록기 잠금을 복원하려고 하는 경우 차단합니다. RestoreLock 제한 시간을 허용하지 않으므로 교착 상태가 발생하지 않도록 주의해야 합니다.

주의

호출 RestoreLock하기 전에 호출 이후 획득한 모든 잠금을 해제했는지 확인합니다 ReleaseLock. 예를 들어 스레드는 판독기 잠금을 획득한 다음 이전 기록기 잠금을 복원하려고 하면 교착 상태가 발생합니다. IsReaderLockHeld 이러한 추가 잠금을 사용하고 IsWriterLockHeld 검색합니다.

에서 LockCookie반환된 을 UpgradeToWriterLock 사용하지 마세요.

추가 정보

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