ReaderWriterLock.ReleaseLock Method

Definition

Namespace:

System.Threading

Assemblies:

netstandard.dll, System.Threading.dll

Source:

ReaderWriterLock.cs

Releases the lock, regardless of the number of times the thread acquired the lock.

C#

public System.Threading.LockCookie ReleaseLock();

Returns

LockCookie

A LockCookie value representing the released lock.

Examples

The following code example shows how to use the ReleaseLock method to release the lock, regardless of how many times it has been acquired by the thread, and how to restore the state of the lock later.

This code is part of a larger example provided for the ReaderWriterLock class.

C#

// 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;

C#

// 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);
   }
}

C#

}

Remarks

ReleaseLock releases the reader lock or writer lock, regardless of the recursive lock count. To restore the state of the lock, including the lock count, pass the LockCookie to RestoreLock.

Applies to

See also

• Managed Threading
• ReaderWriterLock