#!/usr/bin/perl -w
use strict;
use threads;
use threads::shared;

# EXEMODE:   0 - system, 1 - bactic,  2 - popen   
# Try all three to compare
my $EXEMODE = 0;    

#my $XTCMD = "/usr/bin/sort testfile"; # linux test
my $XTCMD = "c:\\windows\\system32\\sort.exe testfile";  # windows test

my $queueindex : shared;
share $queueindex;

my $thearg = 0;
my $qsize  = 10;
$queueindex = 0;

sub inc_qindex
{

#   print "Locking index\n";
    lock $queueindex;
    $queueindex++;

#   print "Returning index $queueindex\n";
    return $queueindex;

}

sub dothread
{
    my ( $v, $m, @m );
    my $taskctr = 0;
    my $tmpfile = "tmp" . $thearg . ".out";
    while (1)
    {
        $v = &inc_qindex;    # get next queue item

        last if ( $v > $qsize );    # end of queue

        print "I am thread [" . $thearg . "] index = [" . $v . "]\n";

        if ( $EXEMODE eq 0 )        # this works OK
        {
            system("$XTCMD >$tmpfile");
            open XT, "$tmpfile" or die "$!: Can't open $tmpfile!";
            @m = (<XT>);
            close XT;
            $m = join( "", @m );
            print $m;               # will see this
        }

        if ( $EXEMODE eq 1 )        # this hangs
        {
            $m = `$XTCMD`;
            print $m;               # never see this
        }

        if ( $EXEMODE eq 2 )        # this also hangs
        {
            open XT, "$XTCMD|" or die "$!: trying to run $XTCMD!";
            @m = (<XT>);
            close XT;
            $m = join( "", @m );
            print $m;               # never see this
        }
        $taskctr++;
    }
    return $taskctr;

}

sub test_threaded
{
    my ( $ta, $tb, $r );
    $thearg = 1;
    $ta     = threads->new("dothread");

    $thearg = 2;
    $tb     = threads->new("dothread");

    $r = $ta->join;

    print "Thread 1 returned [$r]\n";

    $r = $tb->join;

    print "Thread 2 returned [$r]\n";

}

#dothread;      # test it unthreaded to make sure it works

test_threaded;