From: Peter Vandenabeele <peter@...>
Date: 2012-01-18T03:00:54+09:00
Subject: Re: Parsing log with date time entry

--00248c6a6566a6b4f404b6bd1ccb
Content-Type: text/plain; charset=UTF-8

On Tue, Jan 17, 2012 at 6:12 PM, Christopher Graves <gravescl@gmail.com>wrote:

> Peter Vandenabeele wrote in post #1041349:
> > On Tue, Jan 17, 2012 at 4:37 PM, Peter Vandenabeele
> > <peter@vandenabeele.com>wrote:
> >
> >>> >
> >>> Thanks Robert,
> >>>
> >>> By collect range, how would I say subtract 15 minutes from the current
> >>> time so that I can collect all matches from 14:31:02 through 14:46:02?
> >>>
> >>
> >> 1.9.3p0 :006 > Time.now.to_s
> >>  => "2012-01-17 16:36:06 +0100"
> >> 1.9.3p0 :007 > (Time.now - (15*60)).to_s
> >>  => "2012-01-17 16:21:09 +0100"
> >>
> >
> > Actually, for log files, it may be better to use uniform UTC times. So,
> > no confusion on summer/winter time or servers in different part of
> > the world etc.
> >
> > 1.9.3p0 :029 > Time.now.utc.to_s
> >  => "2012-01-17 15:43:25 UTC"
> > 1.9.3p0 :030 > (Time.now - (15*60)).utc.to_s
> >  => "2012-01-17 15:28:30 UTC"
> >
> > HTH,
> >
> > Peter
>
> Unfortunately I have no control over the format of the logs. I am trying
> to compare the current time to the string value in the logs.
> Any ideas on how to get past the crossing midnight issue?
>
> I came up with is for gathering start and end times but the above looks
> nicer.
>
> s_time = Time.now
> e_time = s_time - 900
>

Maybe s_time and e_time are swapped here ?


> Either way I now have the start time and end time so how would I make a
> range out of that counting in seconds?
>

Well, reading the Time documentation I see Time#to_f that may be a useful
number. And then, you could make a range with

s_time.to_f..e_time.to_f

Take note that comparisons on floats have their own problems
if the delta between them is very small and they are not integer.

1.9.3-p0 :001 > e_time = Time.now.utc
 => 2012-01-17 17:51:46 UTC
1.9.3-p0 :002 > s_time = e_time - 900
 => 2012-01-17 17:36:46 UTC

1.9.3-p0 :003 > range = s_time.to_f..e_time.to_f
 => 1326821806.2174225..1326822706.2174225

1.9.3-p0 :004 > log_time = Time.now.utc-300
 => 2012-01-17 17:47:22 UTC

1.9.3-p0 :007 > range === log_time.to_f
 => true # that log_time is in the range :-)

1.9.3-p0 :008 > range === Time.now.to_f
 => false # now is obviously outside the range :-)

1.9.3-p0 :009 > # but, you could simply compare times themselves ... not !
1.9.3-p0 :010 >   time_range = s_time..e_time
 => 2012-01-17 17:36:46 UTC..2012-01-17 17:51:46 UTC
1.9.3-p0 :011 > time_range === Time.now
TypeError: can't iterate from Time
    from (irb):11:in `each'
    from (irb):11:in `include?'
    from (irb):11:in `include?'
    from (irb):11:in `==='
    from (irb):11
    from /home/peterv/.rvm/rubies/ruby-1.9.3-p0/bin/irb:16:in `<main>'


Strange, obviously, for Float too ... (can't iterate from Float),
but, I can determine if a value is inside a range of Floats.
Why not for Time then ? Time has a <=> operator ...

1.9.3-p0 :014 >   range.each{|f| puts f}
TypeError: can't iterate from Float
    from (irb):14:in `each'
    from (irb):14
    from /home/peterv/.rvm/rubies/ruby-1.9.3-p0/bin/irb:16:in `<main>'


Being relatively newb, I still find it amazing that parts f the script I
> think would be the simplest turns out to be the most difficult.
>

I may have confused you even more ... (sorry for that).

I was under the impression you wanted to compare the lines
based on the string representation (in which case those issues
of midnight and mm/dd/yyyy representation etc. would play).

But if you import the date+time of each line with the code that
Robert proposed above, you end up with "clean" Time instances
that will work properly.

Sorry for the confusion ...

HTH,

Peter

--00248c6a6566a6b4f404b6bd1ccb--