#!/usr/bin/perl

# ->resume is not exactly cheap (it saves/restores a LOT
# of global variables), but shouldn't be slow. just to show
# how fast it is, this little proggie compares a normal subroutine
# call with two calls of transfer in a loop.

use Coro;
use Benchmark;

$a = bless {}, main::;

# do something similar, switch two global vars and return something

sub a {
   $old = $current;
   $current = $_[0];
}

$b = new Coro sub {
   # do a little unrolling...
   while() {
      $Coro::main->resume; $Coro::main->resume; $Coro::main->resume;
   }
};

$b->resume; # the first resume is slow because it allocates all the memory

$main = $Coro::main;

#*transfer = \&Coro::_transfer;
sub transfer { Coro::_transfer($_[0], $_[1]) }

$c = Coro::_newprocess {
   while() {
      transfer($c, $main); transfer($c, $main); transfer($c, $main);
   }
};

transfer($main, $c);

timethese 100000, {
   method   => '$a->a; $a->a; $a->a; $a->a',
   resume   => '$b->resume; $b->resume',
   transfer => 'transfer($main, $c); transfer($main, $c)',
};