This is a faster pattern converter for the "yyyy-MM-dd hh:mm:ss tt" pattern. I
use this primarily with my NHibernate logger in DEBUG mode because I want to
see what NHibernate is doing but I don't necessarily care about timings down to
the millisecond when its writing out its generated sql and building objects.
When I use this pattern converter my app doesn't feel slow when NHibenrate
DEBUG logging is enabled:
public class NoMillisecondsPatternConverter : PatternLayoutConverter
{
private long nextSecond;
private string cachedTimeStamp;
protected override void Convert(TextWriter writer, LoggingEvent
loggingEvent)
{
if (loggingEvent.TimeStamp.Ticks > nextSecond)
{
cachedTimeStamp = loggingEvent.TimeStamp.ToString("yyyy-MM-dd
hh:mm:ss tt");
nextSecond = loggingEvent.TimeStamp.Ticks +
TimeSpan.TicksPerSecond; // ???
}
writer.Write(cachedTimeStamp);
}
}
Here's a simplistic benchmark that compares the two:
class Program
{
static void Main(string[] args)
{
runner(new SimpleDateFormatter("yyyy-MM-dd hh:mm:ss tt"));
runner(new NoMillisecondsDateFormatter());
}
public static void runner(IDateFormatter dateFormatter)
{
StubTextWriter writer = new StubTextWriter();
Console.Write(dateFormatter + ": ");
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
for (int i = 0; i < 10000000; i++)
{
dateFormatter.FormatDate(DateTime.Now, writer);
}
stopwatch.Stop();
Console.WriteLine(stopwatch.ElapsedMilliseconds);
}
}
log4net.DateFormatter.SimpleDateFormatter: 17185
ConsoleApplication1.NoMillisecondsDateFormatter: 3561
NoMillisecondsDateFormatter is about 80% faster by not showing the milliseconds.
This is how you use the code:
<layout type="log4net.Layout.PatternLayout">
<converter>
<name value="date" />
<type value="Company.Logging.NoMillisecondsPatternConverter,
Company.Logging" />
</converter>
<conversionPattern value="%5level %date (%logger) - %message%newline" />
</layout>
or you could create a custom pattern layout to more easily share the converter:
<layout type="Company.Logging.MoMillisecondsPatternLayout">
<conversionPattern value="%5level %date (%logger) - %message%newline" />
</layout>
Log4net uses a similiar caching approach with the built-in date formatters:
%date{DATE}, %date{ABSOLUTE}, etc. Those are much faster than using your own
predefined layout because they cache most of the slow changing components of
the logging event's TimeStamp like year, month, day, hour, minute, and second
then only calculate the millisecond when generating the string.
This is interesting article about faster ways of formatting time by calculating
the offsets manually:
Performance Quiz: Fastest way to format time
http://geekswithblogs.net/akraus1/archive/2006/04/23/76146.aspx
