Horse Race for linux!

[i5513]

Hi Monks,

With AnyEvent and TermScreen modules, I would like to share with you a 100 lines script which emulate a race horse, I think it is funny :-).

#!/usr/bin/perl -w
use strict;

my $nhorses=10;
my $finished=AnyEvent->condvar;

require Term::Screen;
use AnyEvent;

sub status
{
    my ($scr,$string) = @_;
    $scr->at ($nhorses,0)->clreol->reverse->bold->puts ("$string")->no
+rmal;
}

sub next_step
{
    my ($scr,$horses) = @_;
    my $max_jump=4;
    
    foreach my $horse (keys %$horses)
    {
        my $step=int(rand($max_jump)); $horses->{$horse}+=$step;
        if ($step == $max_jump-1 and (int (rand (20)) == 19))
        {
            $horses->{$horse}+=$max_jump-1;
            status $scr, "Wowwww $horse went to infinity!!";
        }
    }

    if (int(rand(10)) == 9)
    {
        status $scr,  "Horses delayed: ". join (",", 
                ((sort {$horses->{$a} <=> $horses->{$b}}
                    keys %$horses)[0..2]));
    }
}

sub draw_horses
{
    my ($scr,$horses) = @_;
    $scr-> at ( $_-1,$horses->{$_}-length $horses->{$_}+1)->puts($_) 
        foreach sort { $a <=> $b } keys %$horses;
}

sub draw_end
{
    my ($scr,$horses) = @_;
    $scr-> at ( $_-1,49)->puts("|") foreach keys %$horses;
}

sub clean_horses
{
    my ($scr,$horses) = @_;
    $scr-> at ( $_-1, $horses->{$_}-length $horses->{$_}+1)
        -> puts(" " x length $_) foreach sort { $a <=> $b } keys %$hor
+ses;
}

sub race_finished
{
    my ($scr,$horses) = @_;
    my @winers = grep {$horses->{$_} > 50} (keys %$horses);

    if (scalar @winers > 0)
    {
        status $scr, "And the winner is: ".
            $winers[int(rand(scalar @winers))]."\r\n";
        return 1;
    }
    return 0;
}

sub init_screen
{
    my ($horses) = @_;
    my $scr = new Term::Screen;
    unless ($scr) { die "Something's wrong\n"; }
    $scr->clrscr();    system ("stty isig"); system ("tput civis");
    draw_horses ($scr,$horses); draw_end ($scr, $horses);
    status $scr, "Ready ..."; sleep 1; status $scr, "Stady ..."; sleep
+ 1;
    status $scr, "Go! ..."; 
    return $scr;
}

sub update_screen
{
    my ($scr,$horses) = @_;
    clean_horses ($scr,$horses);
    next_step ($scr,$horses);
    draw_horses ($scr, $horses);
    $finished -> send if (scalar race_finished($scr,$horses));
}

my $w = AnyEvent->signal (signal => "INT", cb => 
    sub { system("tput cvvis"); print "Finished before the end\n"; exi
+t 1 });
my %horses= map { $_ => 0 } (1..$nhorses);
my $scr=init_screen (\%horses);
my $hr = AnyEvent->timer (after => 2, interval => 1, 
        cb => sub {update_screen ($scr,\%horses); });
$finished->recv;

I hope this script is ok for this section ... and other monks enjoy with the game. I even hacked an telnet server running that horse race using inet and IO::Socket::INET, but I cannot publish it online :-)

Could be many improvements to the game:

Allow bets

using festival if available

Adding ondemand telnet server

Rewrite without Term::Screen / AnyEvent dependencies ?

Please share your comments about the code if you see things done in the wrong way ! thanks!

Regards,
PD: It would be nice to see my patches https://rt.cpan.org/Public/Bug/Display.html?id=75858 and https://rt.cpan.org/Public/Bug/Display.html?id=75862 applied to Term::Screen module, so less tput / stty hacks have to be used.

[zentara]

See Gtk2 ....needs thread testing on a multi-threaded computer for a GUI version of a horse race. :-)

[i5513]

Greatful, thanks a lot, I will take a look to the code ! I get a seg fault, while horses are running, some races works fine some others not.

$ LANG=C perl horses_gtk 
*** glibc detected *** perl: realloc(): invalid pointer: 0x�&#6
+5533;�
3 ***
*** unhandled exception in callback:
***   `<span foreground="bl...' is not of type Gtk2::Widget at horses_
+gtk line 209.
***  ignoring at horses_gtk line 228.
Abortado (`core' generado)
$ LANG=C perl horses_gtk  
Violación de segmento (`core' generado)
$ file core 
core: ELF 64-bit LSB core file x86-64, version 1 (SYSV), SVR4-style, f
+rom 'perl horses_gtk'
$ ls -lh core 
-rw------- 1 user group 80M abr  2 15:36 core

[zentara]

Thanks for the report. Its been a while since I tested it. I just ran it a few times myself, and am getting similar failures. I'll work at it and report any fixes I can find.

Update: I believe it is a locking problem, as I try to lock a hash acting as a container variable, as in lock $track{$tr}{'go'};

I was counting on each track to have it's own shared variable, so I thought locking would not be a problem. It didn't seem to matter on a single cpu computer, but now I have a multi-core computer, and it matters. Furthermore, I thought I could lock a portion of the shared hash container %track, but I read in perldoc threads::shared that it causes errors.

From perldoc threads::shared:

 You cannot lock the individual elements of a container variable:

             my %hash :shared;
             $hash{'foo'} = 'bar';
             #lock($hash{'foo'});          # Error
             lock(%hash);                  # Works

           If you need more fine-grained control over shared variable 
+access, see Thread::Semaphore.

So it seems this code needs a re-write to make locking work.

[zentara]

See Re: Gtk2 ....needs thread testing on a multi-threaded computer for some better code, but not yet perfect. :-)