#! perl # MANDATORY

# this extension swaps out maps and resets them, in essence managing
# the reset/swap policy of the server.
# it also contains the map prefetching logic

#our $DEACTIVATE_TIMEOUT =   20; # number of seconds after which maps get deactivated to save cpu
our $SWAP_TIMEOUT       = $cf::CFG{swap_timeout}      || 300; # number of seconds after which inactive maps get swapped out
our $SCHEDULE_INTERVAL  = $cf::CFG{schedule_interval} ||  .8; # time the map scheduler sleeps between runs
our $SAVE_TIMEOUT       = $cf::CFG{save_timeout}      ||  30; # save maps every n seconds
our $SWAP_LOAD1         = $cf::CFG{swap_load1}        ||  .1; # start aggressively swapping at this load
our $SWAP_LOAD2         = $cf::CFG{swap_load2}        ||  .4; # swap as fast as possible at this load

cf::async_ext {
   $Coro::current->prio (Coro::PRIO_MIN);
   # load the header of swapped-out maps.
   # this is not a correctness issue, it simply saves diskspace
   # because old files will get cleaned up on reset time
   Coro::Timer::sleep 1;

   my $files = Coro::AIO::aio_readdir $cf::TMPDIR;

   for my $map (@$files) {
      utf8::decode $map;
      next if $map =~ /\.(?:pst|meta)$/;
      cf::map::find $map;
      cf::wait_for_tick;
   }

   #TODO: should also preload random maps...
};

our $SCHEDULER = cf::async_ext {
   while () {
      Coro::Event::do_timer (after => $SCHEDULE_INTERVAL)
         unless $cf::LOADAVG > $SWAP_LOAD2;

      # this weird form of iteration over values is used because
      # the hash changes underneath us frequently, and for
      # keeps a direct reference to the value without (in 5.8 perls)
      # keeping a reference, so this is prone to crashes or worse.
      my @maps = keys %cf::MAP;
      for (@maps) {
         my $map = $cf::MAP{$_}
            or next;
         $map->valid or next;

         eval {
            # not yet, because maps might become visible to players nearby
            # we need to remove the map from %cf::MAP and all tiled map links
#         if ($last_access + $DEACTIVATE_TIMEOUT <= $cf::RUNTIME) {
#            $map->deactivate;
#            delete $map->{active};
#         }
            if ($map->should_reset) {
               $map->reset;
            } elsif ($map->in_memory == cf::MAP_IN_MEMORY) {
               my $max_idle = cf::clamp +(cf::lerp $cf::LOADAVG, $SWAP_LOAD1, $SWAP_LOAD2, $SWAP_TIMEOUT, 0), 0, $SWAP_TIMEOUT;

               if ($map->last_access + $max_idle <= $cf::RUNTIME && !$map->players) {
                  $map->swap_out;
                  cf::wait_for_tick unless $cf::LOADAVG > $SWAP_LOAD2;
               } elsif ($map->{last_save} + $SAVE_TIMEOUT <= $cf::RUNTIME) {
                  $map->save;
                  cf::wait_for_tick unless $cf::LOADAVG > $SWAP_LOAD2;
               }
            }
         };
         warn $@ if $@;
         cf::cede_to_tick;
      };
   }
};

$SCHEDULER->prio (-2);