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

Public Class Test
    ' Declaring the ReaderWriterLock at the class level
    ' makes it visible to all threads.
    Private Shared rwl As New ReaderWriterLock()
    ' For this example, the shared resource protected by the
    ' ReaderWriterLock is just an integer.
    Private Shared resource As Integer = 0
<span space="preserve">...

</span>    ' Shows how to request a reader lock, upgrade the
    ' reader lock to the writer lock, and downgrade to a
    ' reader lock again.
    Shared Sub UpgradeDowngrade(timeOut As Integer)
        Try
            rwl.AcquireReaderLock(timeOut)
            Try
                ' It is safe for this thread to read from
                ' the shared resource.
                Display("reads resource value " & resource)
                Interlocked.Increment(reads)
            
                ' If it is necessary to write to the resource,
                ' you must either release the reader lock and 
                ' then request the writer lock, or upgrade the
                ' reader lock. Note that 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 is 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
            
                ' When the lock has been downgraded, it is 
                ' 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 'UpgradeDowngrade
<span space="preserve">...

</span>End Class 'Test 

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

public class Test
{
    // Declaring the ReaderWriterLock at the class level
    // makes it visible to all threads.
    static ReaderWriterLock rwl = new ReaderWriterLock();
    // For this example, the shared resource protected by the
    // ReaderWriterLock is just an integer.
    static int resource = 0;
<span space="preserve">...

</span>    // Shows how to request a reader lock, upgrade the
    // reader lock to the writer lock, and downgrade to a
    // reader lock again.
    static void UpgradeDowngrade(int timeOut)
    {
        try
        {
            rwl.AcquireReaderLock(timeOut);
            try
            {
                // It is safe for this thread to read from
                // the shared resource.
                Display("reads resource value " + resource); 
                Interlocked.Increment(ref reads);

                // If it is necessary to write to the resource,
                // you must either release the reader lock and 
                // then request the writer lock, or upgrade the
                // reader lock. Note that 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 is 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);
                }

                // When the lock has been downgraded, it is 
                // 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);
        }
    }
<span space="preserve">...

</span>}

// The complete code is located in the ReaderWriterLock
// class topic.
using namespace System;
using namespace System::Threading;
public ref class Test
{
public:

   // Declaring the ReaderWriterLock at the class level
   // makes it visible to all threads.
   static ReaderWriterLock^ rwl = gcnew ReaderWriterLock;

   // For this example, the shared resource protected by the
   // ReaderWriterLock is just an integer.
   static int resource = 0;

<span space="preserve">...

</span>   // Shows how to request a reader lock, upgrade the
   // reader lock to the writer lock, and downgrade to a
   // reader lock again.
   static void UpgradeDowngrade( int timeOut )
   {
      try
      {
         rwl->AcquireReaderLock( timeOut );
         try
         {
            
            // It is safe for this thread to read from
            // the shared resource.
            Display( String::Format( "reads resource value {0}", resource ) );
            Interlocked::Increment( reads );
            
            // If it is necessary to write to the resource,
            // you must either release the reader lock and 
            // then request the writer lock, or upgrade the
            // reader lock. Note that 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 is safe for this thread to read or write
                  // from the shared resource.
                  resource = rnd->Next( 500 );
                  Display( String::Format( "writes resource value {0}", resource ) );
                  Interlocked::Increment( writes );
               }
               finally
               {
                  
                  // Ensure that the lock is released.
                  rwl->DowngradeFromWriterLock( lc );
               }

            }
            catch ( ApplicationException^ ) 
            {
               
               // The upgrade request timed out.
               Interlocked::Increment( writerTimeouts );
            }

            
            // When the lock has been downgraded, it is 
            // still safe to read from the resource.
            Display( String::Format( "reads resource value {0}", resource ) );
            Interlocked::Increment( reads );
         }
         finally
         {
            
            // Ensure that the lock is released.
            rwl->ReleaseReaderLock();
         }

      }
      catch ( ApplicationException^ ) 
      {
         
         // The reader lock request timed out.
         Interlocked::Increment( readerTimeouts );
      }

   }


<span space="preserve">...

</span>};

// The complete code is located in the ReaderWriterLock
// class topic.
import System.*;
import System.Threading.*;
import System.Threading.Thread;    

public class Test
{
    // Declaring the ReaderWriterLock at the class level
    // makes it visible to all threads.
    private static ReaderWriterLock rwl = new ReaderWriterLock();

    // For this example, the shared resource protected by the
    // ReaderWriterLock is just an integer.
    private static int resource = 0;
<span space="preserve">...

</span>    // Shows how to request a reader lock, upgrade the
    // reader lock to the writer lock, and downgrade to a
    // reader lock again.
    static void UpgradeDowngrade(int timeOut)
    {
        try {
            rwl.AcquireReaderLock(timeOut);
            try {
                // It is safe for this thread to read from
                // the shared resource.
                Display(("reads resource value " + resource));
                Interlocked.Increment(reads);

                // If it is necessary to write to the resource,
                // you must either release the reader lock and 
                // then request the writer lock, or upgrade the
                // reader lock. Note that 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 is 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);
                    }
                }
                catch (ApplicationException exp) {
                    // The upgrade request timed out.
                    Interlocked.Increment(writerTimeouts);
                }

                // When the lock has been downgraded, it is 
                // still safe to read from the resource.
                Display(("reads resource value " + resource));
                Interlocked.Increment(reads);
            }
            finally {
                // Ensure that the lock is released.
                rwl.ReleaseReaderLock();
            }
        }
        catch (ApplicationException exp) {
            // The reader lock request timed out.
            Interlocked.Increment(readerTimeouts);
        }
    } //UpgradeDowngrade
<span space="preserve">...

</span>}