Programming C# 3.0, 5th Edition

Synchronization

At times, you might want to control access to a resource, such as an object's properties or methods, so that only one thread at a time can modify or use that resource. Your object is similar to the airplane restroom discussed earlier, and the various threads are like the people waiting in line. Synchronization is provided by a lock on the object, which helps the developer avoid having a second thread barge in on your object until the first thread is finished with it.

This section examines three synchronization mechanisms: the Interlock class, the C# lock statement, and the Monitor class. But first, you need to create a shared resource (often a file or printer); in this case, a simple integer variable: counter. You will increment counter from each of two threads.

To start, declare the member variable and initialize it to 0:

int counter = 0;

Modify the Incrementer method to increment the counter member variable:

public void Incrementer(  )
{
 try
 {
    while (counter < 1000)
    {
       int temp = counter;
       temp++; // increment

       // simulate some work in this method
       Thread.Sleep(1);

       // assign the Incremented value
       // to the counter variable
       // and display the results
       counter = temp;
       Console.WriteLine(
       "Thread {0}. Incrementer: {1}",
       Thread.CurrentThread.Name,
      counter);
    }
 }

The idea here is to simulate the work that might be done with a controlled resource. Just as you might open a file, manipulate its contents, and then close it, here, you read the value of counter into a temporary variable, ...