Question

I have the code:

internal static class IdCounter
{
    [ThreadStatic]
    private static int _id = 0;

    static IdCounter()
    {

    }

    public static int Id
    {
        get
        {
            lock(typeof(IdCounter))
            {
                return _id++;
            }
        }
    }
}

public abstract class Request
{
    protected Request(int requestId)
    {
        RequestId = IdCounter.Id;
    }
}

On the second call, i receive RequestId equals 2, not 1, where is the problem? I tried to use Thread.SetData, but result is the same.

Answer 1

Are you checking the value of IdCounter.Id in the debugger? This will evaluate the property, which will increment it.

Modifying operations in property gets are a bad idea.

Also:

• Using a type instance for locking is a bad idea (the guidelines recommend against it as it can cause problems in some scenarios), instead allocate an instance of Object to lock on.
• If _id is ThreadStatic each thread has its own instance, so there is no need to lock anyway.