Instance constructor sets a static member, is it thread safe?

Question

I am re-factoring some code and am wondering about the use of a lock in the instance constructor.

public class MyClass {

    private static Int32 counter = 0;
    private Int32 myCount;

    public MyClass() {

        lock(this) {
            counter++;
            myCount = counter;
        }
    }
}

Please confirm

1. Instance constructors are thread-safe.
2. The lock statement prevents access to that code block, not to the static 'counter' member.

If the intent of the original programmer were to have each instance know its 'count', how would I synchronize access to the 'counter' member to ensure that another thread isn't new'ing a MyClass and changing the count before this one sets its count?

FYI - This class is not a singleton. Instances must simply be aware of their number.

Answer 1

If you are only incrementing a number, there is a special class (Interlocked) for just that...

http://msdn.microsoft.com/en-us/library/system.threading.interlocked.increment.aspx

Interlocked.Increment Method

Increments a specified variable and stores the result, as an atomic operation.

System.Threading.Interlocked.Increment(myField);

More information about threading best practices...

http://msdn.microsoft.com/en-us/library/1c9txz50.aspx