On 03/08/2012 12:35 PM, sb...@cpan.org wrote:
> On 03/08/2012 02:53 PM, Bruce Ferrell wrote:
>> Just thought I'd share with the group and experience I just had. In perhaps
>> the hope of sparing others of the PITA I just went through.
>>
>> First of all, I will acknowledge I am perhaps not the best of programmers...
>> Perhaps being an understatement.
>>
>> Second of all, it is not a request for a "better way to code" this. This is
>> a recounting of some troubleshooting I just endured due to a programmer very
>> much more clever than I.
>>
>> First, allow me to present the offender(s):
>>
>> sub timestamp {
>> return strftime( "%Y-%m-%d %H:%M:%S", gmtime($_[0] || time()) );
>> }
>>
>> my $ts0 = UnixDate( Date_ConvTZ( ParseDate( timestamp()
>> ),"GMT",$tz),"%Y-%m-%d %T" );
>>
>> The original environment for this code is a Linux system running Perl 5.8.8
>> and it performed flawlessly there and was successfully transplanted to
>> 5.10.0 with no changes needed.
>> When the application containing the code above was transplanted to a system
>> running Perl 5.12.3... Well, lets just say this is where the fun began.
>>
>> When it comes to Perl installations, I long ago learned not to trust
>> Distribution provided modules so I always use CPAN to install from. Basic
>> Perl, from the Distro, sure... Add
>> on modules, not so much. Often the modules I want aren't even in the distro
>> and for module sets I use often I have little shell scripts to load the
>> necessary modules from CPAN. I
>> don't really look at it that much. Maybe not the best practice, but I'm
>> busy. I also want to say, this is code a wrote a couple of years ago. I've
>> not touched it since and have
>> since moved on to other things.
>>
>> When the report came in that important function weren't working I first had
>> to find the location of the failing code. Is it being passed it's necessary
>> data. Yep... OK, so what's
>> wrong? Any errors thrown? Nope. OK, extract the code into a test program
>> (below, suitably "cleaned" to disguise what it really is). "In circuit" the
>> code runs as a daemon and
>> errors aren't easy to get at.
>>
>> #!/usr/bin/perl -w
>>
>> use lib '../lib';
>>
>> use Common; # contains timestamp()
>>
>> use Date::Manip;
>>
>> my $graphdates='';
>>
>> $graphdates .= "&action=plot&ts2=" . UnixDate( Date_ConvTZ(
>> ParseDate( timestamp() ),"GMT",$tz),"%Y-%m-%d %T" );
>> $graphdates .= "&ts=" . UnixDate( Date_ConvTZ(DateCalc( ParseDate(
>> timestamp() ), "- 120 Minutes" ),"GMT",$tz),"%Y-%m-%d %T" );
>> my $test = UnixDate( Date_ConvTZ( ParseDate( timestamp()
>> ),"GMT",$tz),"%Y-%m-%d %T" );
>>
>> print STDERR "$test\n"
>>
>>
>> In the test program, the conversion stream works correctly. OK... Now what?
>> Maybe the module didn't install correctly?! Hand install with UNINST=1 set
>>
>> The application still misbehaves but now I have the all distribution files
>> so I dig into the docs where I find this:
>>
>> FUNCTIONAL INTERFACE (VERSION 5)
>> When using a version of perl older than 5.10, this is the only interface
>> available. This interface is documented in the Date::Manip::DM5
>> document.
>>
>> (The above should read 5.10 and below, because the code worked exactly as it
>> did under 5.8.8 at 5.10.0)
>>
>> and this:
>>
>> DATE_MANIP ENVIRONMENT VARIABLE
>> By setting the DATE_MANIP environment variable to 'DM5' before
>> running the perl script, the version 5 interface will be used.
>>
>> suffice to say, problem solved!
>>
>> insert
>>
>> export DATE_MANIP=DM5
>>
>> into the daemon startup script and enable mod_env in the apache that runs
>> other parts, adding
>>
>> SetEnv DATE_MANIP DM5
>>
>> to the apache config file.
>>
>> Now here comes my question:
>>
>> Shouldn't this have thrown SOME kind of error/warning what was going on? Is
>> silent failure a proper behavior no matter how clever the switch around is?
>> Just asking.
>>
>> Respectfully,
>> Bruce Ferrell
>
> Your report is long... but it unfortunately doesn't contain much information
> on what failed or why.
>
> When I run your script (with the addition of the line setting $tz and a
> couple prints):
>
> #!/usr/bin/perl
>
> use POSIX qw(strftime);
> use Date::Manip;
>
> sub timestamp {
> return strftime( "%Y-%m-%d %H:%M:%S", gmtime($_[0] || time()) );
> }
>
> my $tz = "America/New_York";
>
> my $st = timestamp();
> print "$st\n";
>
> my $ts0 = UnixDate( Date_ConvTZ( ParseDate( $st ),"GMT",$tz),"%Y-%m-%d %T"
> );
>
> print "$ts0\n";
>
> it seems to work fine. You didn't tell me what $tz should be, so I just used
> my local timezone, and the result of this is that it prints out the current
> time (which is
> correct). I ran it with both perl 5.10.1 and 5.14.2.
>
> So, I can't tell what you expected it to produce, or what it did produce
> based on your report. If you fill in some/all of this information, I may be
> able to help more.
>
> However, I can provide a little information which may help.
>
> You've updated from Date::Manip 5.xx to 6.xx. That's a major upgrade with a
> few backwards incompatible changes (not many... but there are a couple). You
> may want to read the
> Date::Manip::Migration5to6 man page. It talks about a change to the
> Date_ConvTZ function, but it doesn't appear to me that that is what it
> getting you since you are using 3
> arguments. Still, there may be some change in there that's impacting you.
>
> Of course, you can use the the workaround of setting DATE_MANIP=DM5 (which
> means that you continue to use the 5.xx version of Date::Manip), but if
> you're doing any kind of
> timezone handling (which you are), you'd be well served to switch to 6.xx .
> 5.xx does NOT handle timezones well.
>
> As far as your question:
>
> shouldn't this have thrown SOME kind of error/waring
>
> the answer is: I don't know since I can't be sure of what failed. Frankly,
> if Date_ConvTZ returns nothing, it means that there was an error on the
> input, so if you check your
> return value, it DOES signal an error. At that point, handling the error
> really falls to the calling program... not the module, since I can't possibly
> know what the result of an
> error should be.
>
>
> Anyway, if you want to provide me with some information about how this script
> failed, I'll be happy to look into it more.
>
>
The failure, I thought was clear. Nothing is is returned in the running code.
In the test code on the "bad" system:
./test.pl
2012-03-08 13:07:25
I get a return?! BTW, the environment variable isn't set. See why I'm now
squirrel bait?
cpan[1]> i Date::Manip
Reading '/root/.cpan/Metadata'
Database was generated on Thu, 08 Mar 2012 07:13:59 GMT
Module id = Date::Manip
DESCRIPTION Complete date/time manipulation package
CPAN_USERID SBECK (Sullivan Beck <sb...@cpan.org>)
CPAN_VERSION 6.31
CPAN_FILE S/SB/SBECK/Date-Manip-6.31.tar.gz
UPLOAD_DATE 2012-03-01
DSLIP_STATUS RdpOp (released,developer,perl,object-oriented,Standard-Perl)
MANPAGE Date::Manip - Date manipulation routines
INST_FILE /usr/lib/perl5/site_perl/5.12.3/Date/Manip.pm
INST_VERSION 6.31
My apologies for the lack of information. If $tz isn't defined, the function
defaults to GMT. $tz is in fact a timezone entry, in the case of the failing
system, "CST5CDT" and
that really works on 5.10.0 and below... with 5.4.
I just re-looked at the cpan entry on the "good" system
cpan[2]> i Date::Manip
Module id = Date::Manip
DESCRIPTION Complete date/time manipulation package
CPAN_USERID SBECK (Sullivan Beck <sb...@cpan.org>)n
CPAN_VERSION 6.31
CPAN_FILE S/SB/SBECK/Date-Manip-6.31.tar.gz
DSLIP_STATUS RdpOp (released,developer,perl,object-oriented,Standard-Perl)
MANPAGE Date::Manip - date manipulation routines
INST_FILE /usr/lib/perl5/vendor_perl/5.10.0/Date/Manip.pm
INST_VERSION 5.54
You're right, I do have 5 installed there. I blasted publicly, so I get to
apologize just as publicly. Mea Culpa. My only excuse is coding/debugging
from 2am my time and for
many days actually. And that's a poor excuse too.
Since I didn't say it initially, I have to now. Thanks for the code. It DOES
make my life better.
Respectfully,
Bruce Ferrell
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