#! /usr/bin/perl
### -*-cperl-*-
###
### Job distribution for discrete logs
###
### (c) 2017 Mark Wooding
###

###----- Licensing notice ---------------------------------------------------
###
### This file is part of Rhodes, a distributed discrete-log finder.
###
### Rhodes is free software; you can redistribute it and/or modify
### it under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2 of the License, or
### (at your option) any later version.
###
### Rhodes is distributed in the hope that it will be useful,
### but WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
### GNU General Public License for more details.
###
### You should have received a copy of the GNU General Public License
### along with Rhodes; if not, write to the Free Software Foundation,
### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

use POSIX qw(:sys_wait_h);

@ARGV == 2 or die "usage: $0 DIR WORKERS";
my ($DIR, $WORKERS) = @ARGV;

open my $fh, "<", $WORKERS or die "open($WORKERS): $!";
my @W = ();
my @C = ();
my %P = ();
my @F = ();
while (<$fh>) {
  next unless /^\s*[^#]/;
  my ($w, $n, @c) = split;
  for (my $i = 0; $i < $n; $i++) {
    push @W, "$w#$i";
    push @C, \@c;
  }
}
for (my $i = 0; $i < @W; $i++) { push @F, $i; }

sub state {
  system "./rhodes", "done", $DIR;
  if ($? == 0) { return 'DONE'; }
  elsif ($? == 512) { return 'IDLE'; }
  elsif ($? != 256) { die "job broken: done rc = $?"; }
  else { $STATE = 'BUSY'; }
}

my $STATE = 'BUSY';
my $RUN = 0;
while ($RUN || $STATE ne 'DONE') {
  if ($STATE ne 'DONE') { $STATE = state; }
  while (@F && $STATE eq 'BUSY') {
    my $i = shift @F;
    print "## -> $W[$i]\n";
    defined (my $kid = fork) or die "fork: $!";
    if (!$kid) {
      exec "./rhodes", "step", $DIR, @{$C[$i]};
      die "exec: $!";
    }
    $P{$kid} = $i;
    $RUN++;
    $STATE = state;
  }

  my $kid = waitpid -1, 0;
  while ($kid > 0) {
    next unless exists $P{$kid};
    my $i = $P{$kid};
    print "## <- $W[$i] rc = $?\n";
    push @F, $i; $RUN--;
    $kid = waitpid -1, WNOHANG;
  }
}