C# Monitor.Exit方法代码示例

//引入命名空间
using System;
using System.Threading;
using System.Collections.Generic;
using System.Text;

class SafeQueue<T>
{
   // A queue that is protected by Monitor.
   private Queue<T> m_inputQueue = new Queue<T>();

   // Lock the queue and add an element.
   public void Enqueue(T qValue)
   {
      // Request the lock, and block until it is obtained.
      Monitor.Enter(m_inputQueue);
      try
      {
         // When the lock is obtained, add an element.
         m_inputQueue.Enqueue(qValue);
      }
      finally
      {
         // Ensure that the lock is released.
         Monitor.Exit(m_inputQueue);
      }
   }

   // Try to add an element to the queue: Add the element to the queue 
   // only if the lock is immediately available.
   public bool TryEnqueue(T qValue)
   {
      // Request the lock.
      if (Monitor.TryEnter(m_inputQueue))
      {
         try
         {
            m_inputQueue.Enqueue(qValue);
         }
         finally
         {
            // Ensure that the lock is released.
            Monitor.Exit(m_inputQueue);
         }
         return true;
      }
      else
      {
         return false;
      }
   }

   // Try to add an element to the queue: Add the element to the queue 
   // only if the lock becomes available during the specified time
   // interval.
   public bool TryEnqueue(T qValue, int waitTime)
   {
      // Request the lock.
      if (Monitor.TryEnter(m_inputQueue, waitTime))
      {
         try
         {
            m_inputQueue.Enqueue(qValue);
         }
         finally
         {
            // Ensure that the lock is released.
            Monitor.Exit(m_inputQueue);
         }
         return true;
      }
      else
      {
         return false;
      }
   }

   // Lock the queue and dequeue an element.
   public T Dequeue()
   {
      T retval;

      // Request the lock, and block until it is obtained.
      Monitor.Enter(m_inputQueue);
      try
      {
         // When the lock is obtained, dequeue an element.
         retval = m_inputQueue.Dequeue();
      }
      finally
      {
         // Ensure that the lock is released.
         Monitor.Exit(m_inputQueue);
      }

      return retval;
   }

   // Delete all elements that equal the given object.
   public int Remove(T qValue)
   {
      int removedCt = 0;

      // Wait until the lock is available and lock the queue.
      Monitor.Enter(m_inputQueue);
      try
      {
         int counter = m_inputQueue.Count;
         while (counter > 0)
            // Check each element.
         {
            T elem = m_inputQueue.Dequeue();
            if (!elem.Equals(qValue))
            {
               m_inputQueue.Enqueue(elem);
            }
            else
            {
               // Keep a count of items removed.
               removedCt += 1;
            }
            counter = counter - 1;
         }
      }
      finally
      {
         // Ensure that the lock is released.
         Monitor.Exit(m_inputQueue);
      }

      return removedCt;
   }

   // Print all queue elements.
   public string PrintAllElements()
   {
      StringBuilder output = new StringBuilder();

      // Lock the queue.
      Monitor.Enter(m_inputQueue);
      try
      {
         foreach( T elem in m_inputQueue )
         {
            // Print the next element.
            output.AppendLine(elem.ToString());
         }
      }
      finally
      {
         // Ensure that the lock is released.
         Monitor.Exit(m_inputQueue);
      }

      return output.ToString();
   }
}

public class Example
{
   private static SafeQueue<int> q = new SafeQueue<int>();
   private static int threadsRunning = 0;
   private static int[][] results = new int[3][];

   static void Main()
   {
      Console.WriteLine("Working...");

      for(int i = 0; i < 3; i++)
      {
         Thread t = new Thread(ThreadProc);
         t.Start(i);
         Interlocked.Increment(ref threadsRunning);
      }
   }

   private static void ThreadProc(object state)
   {
      DateTime finish = DateTime.Now.AddSeconds(10);
      Random rand = new Random();
      int[] result = { 0, 0, 0, 0, 0, 0, 0, 0, 0 };
      int threadNum = (int) state;

      while (DateTime.Now < finish)

      {
         int what = rand.Next(250);
         int how = rand.Next(100);

         if (how < 16)
         {
            q.Enqueue(what);
            result[(int)ThreadResultIndex.EnqueueCt] += 1;
         }
         else if (how < 32)
         {
            if (q.TryEnqueue(what))
            {
               result[(int)ThreadResultIndex.TryEnqueueSucceedCt] += 1;
            }
            else
            {
               result[(int)ThreadResultIndex.TryEnqueueFailCt] += 1;
            }
         }
         else if (how < 48)
         {
            // Even a very small wait significantly increases the success 
            // rate of the conditional enqueue operation.
            if (q.TryEnqueue(what, 10))
            {
               result[(int)ThreadResultIndex.TryEnqueueWaitSucceedCt] += 1;
            }
            else
            {
               result[(int)ThreadResultIndex.TryEnqueueWaitFailCt] += 1;
            }
         }
         else if (how < 96)
         {
            result[(int)ThreadResultIndex.DequeueCt] += 1;
            try
            {
               q.Dequeue();
            }
            catch
            {
               result[(int)ThreadResultIndex.DequeueExCt] += 1;
            }
         }
         else
         {
            result[(int)ThreadResultIndex.RemoveCt] += 1;
            result[(int)ThreadResultIndex.RemovedCt] += q.Remove(what);
         }         
      }

      results[threadNum] = result;

      if (0 == Interlocked.Decrement(ref threadsRunning))      
      {
         StringBuilder sb = new StringBuilder(
            "                               Thread 1 Thread 2 Thread 3    Total\n");

         for(int row = 0; row < 9; row++)
         {
            int total = 0;
            sb.Append(titles[row]);

            for(int col = 0; col < 3; col++)
            {
               sb.Append(String.Format("{0,9}", results[col][row]));
               total += results[col][row];
            }

            sb.AppendLine(String.Format("{0,9}", total));
         }

         Console.WriteLine(sb.ToString());
      }
   }

   private static string[] titles = {
      "Enqueue                       ", 
      "TryEnqueue succeeded          ", 
      "TryEnqueue failed             ", 
      "TryEnqueue(T, wait) succeeded ", 
      "TryEnqueue(T, wait) failed    ", 
      "Dequeue attempts              ", 
      "Dequeue exceptions            ", 
      "Remove operations             ", 
      "Queue elements removed        "};

   private enum ThreadResultIndex
   {
      EnqueueCt, 
      TryEnqueueSucceedCt, 
      TryEnqueueFailCt, 
      TryEnqueueWaitSucceedCt, 
      TryEnqueueWaitFailCt, 
      DequeueCt, 
      DequeueExCt, 
      RemoveCt, 
      RemovedCt
   };
}

/*
Code revised from Book published by 
(C) Copyright 1992-2006 by Deitel & Associates, Inc. and
Pearson Education, Inc. All Rights Reserved.  

*/


using System;
using System.Threading;

public class SynchronizedBuffer
{
   private int buffer = -1; 

   private int occupiedBufferCount = 0;  

   public int Buffer
   {      
      get
      { 
         Monitor.Enter( this );

         if ( occupiedBufferCount == 0 )
         {
            Console.WriteLine(Thread.CurrentThread.Name + " tries to read." );
            DisplayState( "Buffer empty. " +Thread.CurrentThread.Name + " waits." );
            Monitor.Wait( this );
         } 
         --occupiedBufferCount;    
                              
         DisplayState( Thread.CurrentThread.Name + " reads " + buffer );

         Monitor.Pulse( this );
         int bufferCopy = buffer;

         Monitor.Exit( this );

         return bufferCopy;
      }
      set
      {
         Monitor.Enter( this );
         if ( occupiedBufferCount == 1 )
         {
            Console.WriteLine(Thread.CurrentThread.Name + " tries to write." );
            DisplayState( "Buffer full. " + Thread.CurrentThread.Name + " waits." );
            Monitor.Wait( this );
         }
         buffer = value;

         ++occupiedBufferCount;

         DisplayState( Thread.CurrentThread.Name + " writes " + buffer );
         Monitor.Pulse( this );

         Monitor.Exit( this );
      } 
   }

   public void DisplayState( string operation )
   {
      Console.WriteLine( "{0,-35}{1,-9}{2}\n",operation, buffer, occupiedBufferCount );
   }

   static void Main( string[] args )
   {
      SynchronizedBuffer shared = new SynchronizedBuffer();
      Random random = new Random();

      Console.WriteLine( "{0,-35}{1,-9}{2}\n","Operation", "Buffer", "Occupied Count" );
      shared.DisplayState( "Initial state" );

      Producer producer = new Producer( shared, random );
      Consumer consumer = new Consumer( shared, random );

      Thread producerThread = new Thread( new ThreadStart( producer.Produce ) );
      producerThread.Name = "Producer";

      Thread consumerThread = new Thread( new ThreadStart( consumer.Consume ) );
      consumerThread.Name = "Consumer";

      producerThread.Start();
      consumerThread.Start();
   }
}

public class Consumer
{
   private SynchronizedBuffer sharedLocation;
   private Random randomSleepTime;

   public Consumer( SynchronizedBuffer shared, Random random )
   {
      sharedLocation = shared;
      randomSleepTime = random;
   }

   public void Consume()
   {
      int sum = 0;

      for ( int count = 1; count <= 10; count++ )
      {
         Thread.Sleep( randomSleepTime.Next( 1, 1001 ) );
         sum += sharedLocation.Buffer;
      }

      Console.WriteLine("{0} read values totaling: {1}.\nTerminating {0}.",Thread.CurrentThread.Name, sum );
   }
}

public class Producer 
{
   private SynchronizedBuffer sharedLocation;
   private Random randomSleepTime;

   public Producer( SynchronizedBuffer shared, Random random )
   {
      sharedLocation = shared;
      randomSleepTime = random;
   }
   public void Produce()
   {
      for ( int count = 1; count <= 10; count++ ) 
      {
         Thread.Sleep( randomSleepTime.Next( 1, 1001 ) );
         sharedLocation.Buffer = count; 
      }
      Console.WriteLine( "{0} done producing.\nTerminating {0}.",Thread.CurrentThread.Name );
   }
}