http://qs321.pair.com?node_id=203519

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Could potentially receive more than one socket connection per second. Need to capture the exact date/time the connection is made because a file will be created with the date/combo as part of the filename. Here's what I've come up with so far, feel free to offer any improvements: 
#!/usr/bin/perl -w

use Time::HiRes qw(time);
use strict;

# using time from Time::HiRes to obtain fractions...
my $now = time; 
my ($secs, $fract) = ($now =~ /(\d+)\.(\d+)/);

# convert $secs to YYYYMMDDHHMMSS...
my ($sec, $min, $hr, $day, $mon, $yr) = (localtime($secs))[0,1,2,3,4,5
+];
my $new = sprintf "%04d%02d%02d%02d%02d%02d", $yr + 1900, $mon + 1, $d
+ay, $hr, $min, $sec;

# combine the fraction from Time::HiRes::time to $new...
print "Exact time is: $new$fract\n";

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This works but seems like a hack. Is there a better way to do what I need?

Replies are listed 'Best First'.
Re: Obtaining The Exact Time
by sauoq (Abbot) on Oct 08, 2002 at 00:19 UTC
    Need to capture the exact date/time the connection is made because a file will be created with the date/combo as part of the filename.

    Using Time::HiRes to ensure unique filenames is probably overkill. It would be easier and cleaner to simply increment a counter for each connection created within the same second. I would use something like:

    {
    my ($t,$c);
    sub unique_timestamp {
       my $time = time;
       $c++;
       $c = 0 unless $time == $t;
       $t = $time;
       my ($s,$m,$h,$D,$M,$Y) = (localtime($time))[0..5]; 
       sprintf "%04d%02d%02d%02d%02d%02d%03d",
                $Y+1900, $M+1, $D, $h, $m, $s, $c;
   }
}


# To see that work... 
for (1..100) { 
    print unique_timestamp, "\n"; 
    sleep rand 2; 
}

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    If you could have more than 1000 connections in a second, you may wish to increase that %03d in the sprintf to %04d or something. This code avoids the use of a module and parsing out fractional seconds. It also results in sequential unique stamps that are the same length.

    -sauoq
"My two cents aren't worth a dime.";
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Re: Obtaining The Exact Time
by Russ (Deacon) on Oct 08, 2002 at 00:08 UTC
    If you want a unique filename, combine the timestamp with the process ID of the fork handling the connection...

    Your question asks how to get the exact time, but I would be more worried about a guaranteed unique value.

    Russ
    Brainbench 'Most Valuable Professional' for Perl

    P.S. Look at POSIX::strftime. I think 

    my $Now = strftime('%Y%m%d', localtime)

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    is much prettier to use than 
    ($sec, $min, ...) = (localtime())[0..5];
$Now = sprintf('%4d%2d%2d', $sec, $min...);

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[select]

      I agree that he should be more concerned with a unique value.

      However, he didn't say that he was forking and, even if he is, he may well be handling some setup prior to the fork.

      -sauoq
"My two cents aren't worth a dime.";
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Re: Obtaining The Exact Time
by Zaxo (Archbishop) on Oct 08, 2002 at 00:45 UTC

    POSIX strftime will help with formatting a string from the localtime($secs) call without all the extra variables. All you need is to give it a format string and the localtime call. The strftime man page details the format string conventions available.

    After Compline,
    Zaxo

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Re: Obtaining The Exact Time
by fglock (Vicar) on Oct 08, 2002 at 00:15 UTC

    Date::Tie might help a bit with fractional times.

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Re: Obtaining The Exact Time
by cacharbe (Curate) on Oct 08, 2002 at 12:23 UTC
    Just as a "Thinking Outside the Box" exercise, you can always get the time from the NIST, available from any and all of the mirrors mentioned here. 
    use strict;
my $host = '129.6.15.28';
my $port = '13';
my $sock = IO::Socket::INET->new(PeerAddr => $host,
                                 PeerPort => $port,
                                 Proto => 'TCP');  
die "Couldn't connect to $host on $port: $!\n" unless $sock;
scalar <$sock>;
my $time = scalar <$sock>;
$sock->close;  

print $time."\n";

# $time has the format:
#JJJJJ YR-MO-DA HH:MM:SS TT L H msADV UTC(NIST) OTM

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    *shrug* It just happens to be something I'm working on for another project.

    C-.

    ---
    Flex the Geek

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