Time Diff.cs

gistfile1.cs

void Main()
{

	var locaTime = DateTime.Now;
	
	IServiceSyncedTime ts = new SyncDateTime(new NAVTimeService());
	
	locaTime.Dump();
	
	Thread.Sleep(5000);
	ts.GetCurrentTime().Dump();
}

public interface IServiceSyncedTime
{
	void UpdateTimeDiff();
	DateTime GetCurrentTime();
}

public interface ITimeService 
{
	bool GetTime(int timeoutMisliseconds);
	DateTime ServiceTime {get; }
	long RequestMiliseconds {get;}
}

public class NAVTimeService :ITimeService {
	
	public bool GetTime(int timeoutMisliseconds)
	{
		Stopwatch st = new Stopwatch();
		st.Start();
		System.Threading.Thread.Sleep(5000);
		st.Stop();
		
		if(st.ElapsedMilliseconds > timeoutMisliseconds) return false;
		
		RequestMiliseconds  = st.ElapsedMilliseconds / 2;
		ServiceTime =  DateTime.Now;
		return true;
	}
	public long RequestMiliseconds { get; private set; }
	public DateTime ServiceTime {get; private set;}
}
public class SyncDateTime : IServiceSyncedTime
{
	public SyncDateTime(ITimeService _timeService)
	{
		this._timeService = _timeService;
	}
	
	private ITimeService _timeService;
	private TimeSpan _timeDiff = TimeSpan.MinValue;
	
	private readonly object _lock = new Object();
	public void UpdateTimeDiff()
	{
		if(_timeService.GetTime(1000))
		{
			lock(_lock)
				_timeDiff = DateTime.Now - _timeService.ServiceTime.AddMilliseconds(_timeService.RequestMiliseconds);
		}
	}
	public DateTime GetCurrentTime()
	{
		if(_timeDiff.Equals(TimeSpan.MinValue))
		{
			UpdateTimeDiff();
		}
		if(_timeDiff.Equals(TimeSpan.MinValue))
			return DateTime.Now;
		
		return DateTime.Now + -_timeDiff;
	}
}