Item7811: SERVERTIME to be in local time; DISPLAYTIME and log time stamps to observe {DisplayTimeValues}

Display of times in TWiki metacode

Should these matters be platform related, my platform is 'CentOS Linux release 7.3.1611 (Core)'

Problem description

• Tested using the following TWiki metacode with $TWiki::cfg{DisplayTimeValues} = 'localtime'; in LocalSite.cfg.

DISPLAYTIME is %DISPLAYTIME%.  SERVERTIME is %SERVERTIME%.  DATE is %DATE%.  GMTIME is %GMTIME%

• Result: I get times rendered in GMT for the 3 above times. This is correct for GMTIME but not for DISPLAYTIME and maybe not for SERVERTIME?

Problem analysis

The following code in sub formatTime {} in lib/TWiki/Time.pm is relevant.

 
   210      } else {
   211          my $tzSave;
   212          if ( $outputTimeZone ) {
   213              $tzSave = $ENV{TZ};
   214              $ENV{TZ} = $outputTimeZone;
   215              tzset();
   216          }

Commenting out line 214 & 215 as a hack fixes the problem.

• Result: I get times rendered in BST for DISPLAYTIME and SERVERTIME and in GMT for GMTIME which is correct.

If not set explicitly in the code $outputTimeZone is set to $TWiki::cfg{DisplayTimeValues} from LocalSite.cfg. Looking at the man page for tzset on my system suggests localtime (or gmtime as suggested in lib/TWiki.spec) is not a valid value for this environment variable, which is intended to code an explicit/geographical timezone spec, eg. Europe/London.

• Uncommented/restored the code in lib/TWiki/Time.pm and changed LocalSite.cfg item to read $TWiki::cfg{DisplayTimeValues} = ':/etc/localtime'; where /etc/localtime -> /usr/share/zoneinfo/Europe/London on my system.

• Result: I get times rendered in BST for DISPLAYTIME and in GMT for SERVERTIME and GMTIME which is better.

• Conclusion: This is acceptable but is this the intended behaviour? Maybe the entry in lib/TWiki.spec needs amending?

Display of times in TWiki logs (eg. data/log201705.txt and data/debug.txt)

Problem description

The logs are always timestamped in GMT. Looking at the code (see below) this seems to be intended. At least on the Unix systems I have administered most things (syslog,Apache etc.) always log in local time, which to my mind makes the TWiki logs slightly confusing.

Problem analysis

The following code in sub _writeReport{} in lib/TWiki.pm is relevant.

  2354  sub _writeReport {
  2355      my ( $this, $log, $message ) = @_;
  2356  
  2357      if ( $log ) {
  2358          require TWiki::Time;
  2359          my $time =
  2360            TWiki::Time::formatTime( time(), '$year$mo', 'gmtime');
  2361          $log =~ s/%DATE%/$time/go;
  2362          $time = TWiki::Time::formatTime( time(), '$year-$mo-$day - $hour:$min:$sec', 'gmtime' );

Replacing both instances of 'gmtime' with undef makes the formatTime() call use the timezone value $TWiki::cfg{DisplayTimeValues} specified in LocalSite.cfg, which as changed above makes the logs timestamps render in BST. Could this (being able to set the timezone for logs) be considered as a feature request for future TWiki releases? I notice there are many other calls to formatTime() and other functions within the TWiki code which specify gmtime as an argument and I can see that for certain internal uses this makes sense. Maybe a more holistic approach to timezone handling rather than the two issues I've brought up is needed...

-- TWiki:Main/TomCrane - 2017-05-16

Thanks for the thorough description of the symptoms and analysis. It seems that this item is closely related to Item7752 (same root cause, different observations). I fully agree with Maybe a more holistic approach to timezone handling [...] is needed.

-- TWiki:Main.HaraldJoerg - 2017-05-18

TWiki::_writeReport() now omits the third argument of TWiki::TIme::formatTime(). TWikibug:Item7752 is already taken care of. So you can have time stamps in log files in local time if you set $TWiki::cfg{DisplayTimeValues} "servertime".

-- TWiki:Main.HideyoImazu - 2017-06-01