Class that locks on objects in a dictionary by key.

KeyLocker.cs

public class KeyLocker : IDisposable
{
    private static readonly ConcurrentDictionary<object, object> Locks = new ConcurrentDictionary<object, object>();
    private readonly object _locker;

    public KeyLocker(object key)
    {
        _locker = Locks.GetOrAdd(key, new object());
        Monitor.Enter(_locker);
    }

    public void Dispose()
    {
        Monitor.Exit(_locker);
    }
}