/*
 * This file is part of Deliantra, the Roguelike Realtime MMORPG.
 * 
 * Copyright (©) 2008 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
 * 
 * Deliantra 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 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
 * 
 * The authors can be reached via e-mail to <support@deliantra.net>
 */

#include "global.h"
#include "evthread.h"
#include "cfperl.h"

thread evthread;
static ev_loop *loop;

#define TICK_CYCLES 4

// the tick watcher is activated every TICK_CYCLES
ev_async tick_watcher;
EV_ATOMIC_T coroapi::cede_pending;

// the ticker runs TICK_CYCLES times as fast as the main server tick
static ev_periodic cede_watcher;

/////////////////////////////////////////////////////////////////////////////

// it is a bit silly to have to use a mutex, but contention
// is basically non-existant, favouring good mutex implementations.
static SMUTEX (evthread_mutex);
static NV next_tick;

NV get_next_tick ()
{
  SMUTEX_LOCK (evthread_mutex);
  NV retval = next_tick;
  SMUTEX_UNLOCK (evthread_mutex);
  return retval;
}

static void
cede_cb (EV_P_ ev_periodic *w, int revents)
{
  static int cycle = 0;

  if (++cycle == TICK_CYCLES)
    {
      cycle = 0;

      SMUTEX_LOCK (evthread_mutex);
      next_tick = w->at + TICK / TICK_CYCLES * (TICK_CYCLES - 1);
      SMUTEX_UNLOCK (evthread_mutex);

      ev_async_send (EV_DEFAULT_UC, &tick_watcher);
    }

  coroapi::cede_pending = 1;
}

static void
tick_cb (EV_P_ ev_async *w, int revents)
{
  cfperl_tick ();
}

/////////////////////////////////////////////////////////////////////////////

static ev_async async_watcher;
static ev_io aio1_watcher;
static ev_idle aio2_watcher;
static EV_ATOMIC_T aio_pending;

static void
aio2_cb (EV_P_ ev_idle *w, int revents)
{
  IV reqs;

  CALL_BEGIN (0);
  CALL_CALL ("IO::AIO::poll_cb", G_SCALAR);

  reqs = POPi;
  if (count > 0 && reqs < 0)
    ev_idle_start (EV_A, w);
  else
    ev_idle_stop (EV_A, w);

  CALL_END;
}

static void
async_cb (EV_P_ ev_async *w, int revents)
{
  aio2_cb (EV_A, &aio2_watcher, 0);
}

static void
aio1_cb (EV_P_ ev_io *w, int revents)
{
  char dummy[9];

  if (read (w->fd, dummy, sizeof (dummy)) > 0)
    {
      ev_async_send (EV_DEFAULT_UC, &async_watcher);
      coroapi::cede_pending = 1;
    }
}

/////////////////////////////////////////////////////////////////////////////

static void *
evthread_proc (void *arg)
{
  ev_loop (loop, 0);

  return 0;
}

void evthread_start (int aiofd)
{
  I_EV_API ("evthread");

  // main loop
  ev_async_init (&tick_watcher, tick_cb);
  ev_set_priority (&tick_watcher, 1);
  ev_async_start (EV_DEFAULT_UC, &tick_watcher);

  ev_async_init (&async_watcher, async_cb);
  ev_set_priority (&async_watcher, 1);
  ev_async_start (EV_DEFAULT_UC, &async_watcher);

  ev_idle_init (&aio2_watcher, aio2_cb);

  // secondary loop
  loop = ev_loop_new (0);

  ev_periodic_init (&cede_watcher, cede_cb, 0, TICK / TICK_CYCLES, 0);
  ev_periodic_start (loop, &cede_watcher);

  ev_io_init (&aio1_watcher, aio1_cb, aiofd, EV_READ);
  ev_io_start (loop, &aio1_watcher);

  evthread.start (evthread_proc);
}