#!/usr/bin/perl

use strict;
use warnings;

# Requires MCE 1.830. Fixes MCE::Relay stalling from setting $/.

use MCE::Loop 1.830;

my $mbnum = $ARGV[0] or die "usage: $0 mbnum\n";

my @ldif_files = qw(
    /path/to/file1.ldif.bz2
    /path/to/file2.ldif.bz2
    /path/to/file3.ldif.bz2
);

MCE::Loop->init(
    max_workers => scalar @ldif_files,
    chunk_size  => 1,
    init_relay  => ''
);

mce_loop {
    # my ($mce, $chunk_ref, $chunk_id) = @_;
    # When chunk_size 1 is specified, $_ contains
    # the same value as $chunk_ref->[0].

    my ($file, $ret) = ($_, '');

    # Must localize $/ to not stall MCE, fixed in 1.830.
    # Localizing $/ is recommended, but fixed MCE if not.

    local $/ = "";

    open my $fh, "-|", "/usr/bin/bzcat $file"
        or warn "open error ($file): $!";

    if (defined fileno($fh)) {
        while (<$fh>) {
            if (/uid=$mbnum/m) {
                $ret  = "## $file\n";
                $ret .= $_;
                last;
            }
        }
        close $fh;
    }

    # Relay is beneficial for running a code block serially
    # and orderly. The init_relay option enables MCE::Relay.
    # All participating workers must call relay. Here, workers
    # write to STDOUT orderly starting with chunk_id 1.

    MCE::relay { print $ret };

} \@ldif_files;

MCE::Loop->finish;