Locking by string. Is this safe/sane?

Question

I need to lock a section of code by string. Of course the following code is hideously unsafe:

lock(\"http://someurl\")
{
    //bla
}

So I\'

Answer 1

This is how I implemented this locking schema:

public class KeyLocker
{
    private class KeyLock
    {
        public int Count;
    }

    private readonly Dictionary keyLocks = new Dictionary();

    public T ExecuteSynchronized(TKey key, Func function)
    {
        KeyLock keyLock =  null;
        try
        {              
            lock (keyLocks)
            {
                if (!keyLocks.TryGetValue(key, out keyLock))
                {
                    keyLock = new KeyLock();
                    keyLocks.Add(key, keyLock);
                }
                keyLock.Count++;
            }
            lock (keyLock)
            {
                return function(key);
            }
        }
        finally
        {         
            lock (keyLocks)
            {
                if (keyLock != null && --keyLock.Count == 0) keyLocks.Remove(key);
            }
        }
    }

    public void ExecuteSynchronized(TKey key, Action action)
    {
        this.ExecuteSynchronized(key, k =>
        {
            action(k);
            return true;
        });
    }
}

And used like this:

private locker = new KeyLocker();
......

void UseLocker()
{
     locker.ExecuteSynchronized("some string", () => DoSomething());
}