#!/usr/bin/perl

use v5.24;
use warnings;
use JSON::XS;
use Benchmark 'cmpthese';

my @kwlist = qw(foo bar baz qux q0 q1 q2 q3 q4 q5 q6 q7 q8 q9);
my %kwhash = map {($_, 0)} @kwlist;
my $kwre = join('|',@kwlist);
#my @items = getfromdb("select id,text from table"); # I have a sub that does this
my @items = ([1, '{"foo":0}'], [2, '{"foo":0,"qux":0}'],
    [3, '{"foo":0}'], [4, '{"baz":0}'], [5, '{"twx":0}']); # Wildly guessed data

sub var1 {
    foreach my $i (0..$#items) {
        my ($id,$text) = @{$items[$i]};
        my $count = 0;
        while($text =~ /$kwre/g) {
            $count++;
        }
    }
}

sub var2 {
    foreach my $i (0..$#items) {
        my ($id,$temp) = @{$items[$i]};
        my $kws = decode_json($temp);
        my $count = 0;
        foreach my $k (@kwlist) {
            if (defined($kws->{$k})) {
                $count++;
            }
        }
    }
}

sub var3 {
    foreach my $item (@items) {
        my (undef,$text) = @$item;
        my $kws = decode_json($text);
        my $count = 0;
        $count += exists $kwhash{$_} for keys %$kws;
    }
}

cmpthese(0, {
        var1 => \&var1,
        var2 => \&var2,
        var3 => \&var3,
    });

__DATA__

         Rate var2 var1 var3
var2 176400/s   -- -31% -38%
var1 254510/s  44%   -- -11%
var3 285034/s  62%  12%   --