package TGrep;
use strict;
use threads;
use Thread::Queue;

our $WORKERS = 4;

sub g_proxy {
    my( $code, $Qin, $Qout ) = @_;

    $Qout->enqueue( $code->() ? $_ : ()  ) while local $_ = $Qin->dequeue;
    $Qout->enqueue( undef );
}

sub tgrep(&@) {
    my $workers = $WORKERS;
    my $code = shift;
    my( $Qin, $Qout ) = map Thread::Queue->new, 1..2;
    async( \&g_proxy, $code, $Qin, $Qout )->detach for 1 .. $workers;
    $Qin->enqueue( map{ ref $_[0] ? @{ $_ } : $_ } @_ );
    $Qin->enqueue( (undef) x $workers );
    my @results;
    push @results, $_ while $_ = $Qout->dequeue;
    return wantarray ? @results : \@results;
}

sub import {
    no strict 'refs';
    my $pkg = caller;
    *{ $pkg . '::' . $_ } = *{ $_ } for qw[ tgrep ];
}

1;

##</code><code>##

#! perl -slw
use strict;
use TGrep;
use Time::HiRes qw[ time ];

our $N //= 1e3;

my $start = time;
my @a = tgrep{ $_ % 5 == 0 } [ 1..$N ];
printf "Took %.9f seconds\n", time() -$start;
print scalar @a;

__END__
C:\test>t-tgrep -N=1e5
Took 3.830074787 seconds
20000

##</code><code>##

$t=time; 
my @a = grep{ $_%5 == 0 } 1 .. 1e6; 
print time-$t;;
0.18144702911377