How can I efficiently match many different regex patterns in Perl?

Question

I have a growing list of regular expressions that I am using to parse through log files searching for \"interesting\" error and debug statements. I\'m currently breaking th

Answer 1

One possible solution is to let the regex state machine do the checking of alternatives for you. You'll have to benchmark to see if the result is noticeably more efficient, but it will certainly be more maintainable.

First, you'd maintain a file containing one pattern of interest per line.

Failed in routing out
Agent .+ failed
Record Not Exist in DB

Then you'd read in that file at the beginning of your run, and construct a large regular expression using the "alternative" operator, "|"

open(PATTERNS,";
close PATTERNS or die $!;
chomp @patterns;
$matcher = join('|', @patterns);

while () {
    print if $_ =~ $matcher;
}