Hi, ----- Original Message ----- From: "Stewart, Robert" <Robert.Stewart@sig.com> To: <boost@lists.boost.org> Sent: Thursday, March 18, 2010 4:18 PM Subject: Re: [boost] [log] Boost.Log Formal Review
sam.gundry@gmail.com wrote:
A concern, which again Andrey has mentioned during this review, is the speed of Boost.DateTime formatting. From our comparisons, it is about 3-5x slower than log4cxx. Is it possible to have a bare-minimum date time formatter similar to log4cxx's implemented? I wrote a quick little wrapper using a customised strftime (for microseconds) with the most basic caching (which log4cxx's formatter uses) and performance was comparable.
In our logging library, date/time formatting was likewise too sluggish. I now track midnight as a time_t, with the date string, and then compute the current time relative to midnight, do a little math, and the result is a very fast computation of the current time. Of course, I also have to determine if the current time is more than 24 hours since the cached midnight to detect when the cached values must be updated.
In Boost.Chrono there is a class t24_hours which is a view of a boost::chrono::duration<Rep, Period> providing accesors functions for number of days, hours, minutes, seconds and nanoseconds. Boost.Chrono provides also a formatter with a default format "%d days(s) %h:%m:%s.%n\n", where a.. %d : days b.. %h : hours c.. %m : minutes d.. %s : seconds e.. %n : nanoseconds The interface of basic_24_hours_formatter is quite specific to the needs of Stopwatches, but we can make an interface that is more adapted to your needs. More info at https://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction#Boost.Chron... The files related are: /boost/chrono/t24_hours.hpp /boost/chrono/t24_hours_formatter.hpp /libs/chrono/example/t24_hours_example.cpp I will appreciate if you can tell me what is missing and how the interface can change so you can get waht you need. Thanks, Vicente