I have a log file. It could be hundreds of megabytes and thousands of lines. The contents would look something like this: 
0000HA-00001 begin

[download]
Any number of lines here possibly including another begin. 
0000HA-00001 doing-work

[download]
Any number of lines here possibly including another begin. 
0000HA-00002 complete

[download]
File continues.

For each line containing serial number and begin I have to find the matching, doing-work and complete entries. If the matching entries do not exist report it.

My code (untested)

#!/usr/bin/perl

use strict;
use warnings;

my (@entries, $x, $doing,
    $complete);

open FH, "logfile";
while <FH>{
    if (m/(\w{6}-\w{5})\s+begin/){
        push @entries, $1;
    }
}
close FH;

foreach $x (@entries){
    open FH, "logfile";
    while <FH>{
            if (m/$x\s+doing-work/){
                $doing = 1;
            }       
            if (m/$x\s+complete/){
                $complete = 1;
            }       
    }
    close FH;

    if ($doing == 1 && $complete == 1){
        $doing = 0;
        $complete = 0;
        next;   
    
    #failed !
    }else{  
        push @failed, $x;
    }
}

print "These entries have failed\n";
foreach $x (@entries){
    print $x."\n";
}

[download]

This invovles going through the log file many times. Is there a more efficient way?

Neil Watson
watson-wilson.ca

In reply to Efficiently parsing a large file by neilwatson

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