/* GStreamer

 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>

 *                    2004 Wim Taymans <wim@fluendo.com>

 *

 * gstsystemclock.c: Default clock, uses the system clock

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library 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

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 * Boston, MA 02111-1307, USA.

 */

/**

 * SECTION:gstsystemclock

 * @short_description: Default clock that uses the current system time

 * @see_also: #GstClock

 *

 * The GStreamer core provides a GstSystemClock based on the system time.

 * Asynchronous callbacks are scheduled from an internal thread.

 *

 * Clock implementors are encouraged to subclass this systemclock as it

 * implements the async notification.

 *

 * Subclasses can however override all of the important methods for sync and

 * async notifications to implement their own callback methods or blocking

 * wait operations.

 *

 * Last reviewed on 2006-03-08 (0.10.4)

 */

#include "gst_private.h"

#include "gstinfo.h"

#include "gstsystemclock.h"

#ifdef __SYMBIAN32__

#include <glib_global.h>

#endif

/* Define this to get some extra debug about jitter from each clock_wait */

#undef WAIT_DEBUGGING

/* the one instance of the systemclock */

static GstClock *_the_system_clock = NULL;

static void gst_system_clock_class_init (GstSystemClockClass * klass);

static void gst_system_clock_init (GstSystemClock * clock);

static void gst_system_clock_dispose (GObject * object);

static GstClockTime gst_system_clock_get_internal_time (GstClock * clock);

static guint64 gst_system_clock_get_resolution (GstClock * clock);

static GstClockReturn gst_system_clock_id_wait_jitter (GstClock * clock,

    GstClockEntry * entry, GstClockTimeDiff * jitter);

static GstClockReturn gst_system_clock_id_wait_jitter_unlocked

    (GstClock * clock, GstClockEntry * entry, GstClockTimeDiff * jitter,

    gboolean restart);

static GstClockReturn gst_system_clock_id_wait_async (GstClock * clock,

    GstClockEntry * entry);

static void gst_system_clock_id_unschedule (GstClock * clock,

    GstClockEntry * entry);

static void gst_system_clock_async_thread (GstClock * clock);

static gboolean gst_system_clock_start_async (GstSystemClock * clock);

static GStaticMutex _gst_sysclock_mutex = G_STATIC_MUTEX_INIT;

static GstClockClass *parent_class = NULL;

/* static guint gst_system_clock_signals[LAST_SIGNAL] = { 0 }; */

static void

gst_system_clock_class_init (GstSystemClockClass * klass)

{

  GObjectClass *gobject_class;

  GstClockClass *gstclock_class;

  gobject_class = (GObjectClass *) klass;

  gstclock_class = (GstClockClass *) klass;

  parent_class = g_type_class_peek_parent (klass);

  gobject_class->dispose = gst_system_clock_dispose;

  gstclock_class->get_internal_time = gst_system_clock_get_internal_time;

  gstclock_class->get_resolution = gst_system_clock_get_resolution;

  gstclock_class->wait_jitter = gst_system_clock_id_wait_jitter;

  gstclock_class->wait_async = gst_system_clock_id_wait_async;

  gstclock_class->unschedule = gst_system_clock_id_unschedule;

}

static void

gst_system_clock_init (GstSystemClock * clock)

{

  GST_OBJECT_FLAG_SET (clock,

      GST_CLOCK_FLAG_CAN_DO_SINGLE_SYNC |

      GST_CLOCK_FLAG_CAN_DO_SINGLE_ASYNC |

      GST_CLOCK_FLAG_CAN_DO_PERIODIC_SYNC |

      GST_CLOCK_FLAG_CAN_DO_PERIODIC_ASYNC);

#if 0

  /* Uncomment this to start the async clock thread straight away */

  gst_system_clock_start_async (clock);

#endif

}

static void

gst_system_clock_dispose (GObject * object)

{

  GstClock *clock = (GstClock *) object;

  GList *entries;

  /* else we have to stop the thread */

  GST_OBJECT_LOCK (clock);

  sysclock->stopping = TRUE;

  /* unschedule all entries */

  for (entries = clock->entries; entries; entries = g_list_next (entries)) {

    GstClockEntry *entry = (GstClockEntry *) entries->data;

    GST_CAT_DEBUG (GST_CAT_CLOCK, "unscheduling entry %p", entry);

    entry->status = GST_CLOCK_UNSCHEDULED;

  }

  g_list_free (clock->entries);

  clock->entries = NULL;

  GST_CLOCK_BROADCAST (clock);

  GST_OBJECT_UNLOCK (clock);

  if (sysclock->thread)

    g_thread_join (sysclock->thread);

  sysclock->thread = NULL;

  GST_CAT_DEBUG (GST_CAT_CLOCK, "joined thread");

  G_OBJECT_CLASS (parent_class)->dispose (object);

  if (_the_system_clock == clock) {

    _the_system_clock = NULL;

    GST_CAT_DEBUG (GST_CAT_CLOCK, "disposed system clock");

  }

}

/**

 * gst_system_clock_obtain:

 *

 * Get a handle to the default system clock. The refcount of the

 * clock will be increased so you need to unref the clock after

 * usage.

 *

 * Returns: the default clock.

 *

 * MT safe.

 */

#ifdef __SYMBIAN32__

EXPORT_C

#endif

GstClock *

gst_system_clock_obtain (void)

{

  GstClock *clock;

  g_static_mutex_lock (&_gst_sysclock_mutex);

  clock = _the_system_clock;

  if (clock == NULL) {

    GST_CAT_DEBUG (GST_CAT_CLOCK, "creating new static system clock");

    clock = g_object_new (GST_TYPE_SYSTEM_CLOCK,

        "name", "GstSystemClock", NULL);

    /* we created the global clock; take ownership so

     * we can hand out instances later */

    _the_system_clock = clock;

    g_static_mutex_unlock (&_gst_sysclock_mutex);

  } else {

    g_static_mutex_unlock (&_gst_sysclock_mutex);

    GST_CAT_DEBUG (GST_CAT_CLOCK, "returning static system clock");

  }

  /* we ref it since we are a clock factory. */

  gst_object_ref (clock);

  return clock;

}

/* this thread reads the sorted clock entries from the queue.

 *

 * It waits on each of them and fires the callback when the timeout occurs.

 *

 * When an entry in the queue was canceled before we wait for it, it is

 * simply skipped.

 *

 * When waiting for an entry, it can become canceled, in that case we don't

 * call the callback but move to the next item in the queue.

 *

 * MT safe.

 */

static void

gst_system_clock_async_thread (GstClock * clock)

{

  GST_CAT_DEBUG (GST_CAT_CLOCK, "enter system clock thread");

  GST_OBJECT_LOCK (clock);

  /* signal spinup */

  GST_CLOCK_BROADCAST (clock);

  /* now enter our (almost) infinite loop */

  while (!sysclock->stopping) {

    GstClockEntry *entry;

    GstClockTime requested;

    GstClockReturn res;

    /* check if something to be done */

    while (clock->entries == NULL) {

      GST_CAT_DEBUG (GST_CAT_CLOCK, "no clock entries, waiting..");

      /* wait for work to do */

      GST_CLOCK_WAIT (clock);

      GST_CAT_DEBUG (GST_CAT_CLOCK, "got signal");

      /* clock was stopping, exit */

      if (sysclock->stopping)

        goto exit;

    }

    /* pick the next entry */

    entry = clock->entries->data;

    /* if it was unscheduled, just move on to the next entry */

    if (entry->status == GST_CLOCK_UNSCHEDULED) {

      GST_CAT_DEBUG (GST_CAT_CLOCK, "entry %p was unscheduled", entry);

      goto next_entry;

    }

    requested = entry->time;

    /* now wait for the entry, we already hold the lock */

    res =

        gst_system_clock_id_wait_jitter_unlocked (clock, (GstClockID) entry,

        NULL, FALSE);

    switch (res) {

      case GST_CLOCK_UNSCHEDULED:

        /* entry was unscheduled, move to the next */

        GST_CAT_DEBUG (GST_CAT_CLOCK, "async entry %p unscheduled", entry);

        goto next_entry;

      case GST_CLOCK_OK:

      case GST_CLOCK_EARLY:

      {

        /* entry timed out normally, fire the callback and move to the next

         * entry */

        if (entry->func) {

          /* unlock before firing the callback */

          GST_OBJECT_UNLOCK (clock);

          entry->func (clock, entry->time, (GstClockID) entry,

              entry->user_data);

          GST_OBJECT_LOCK (clock);

        }

        if (entry->type == GST_CLOCK_ENTRY_PERIODIC) {

          /* adjust time now */

          entry->time = requested + entry->interval;

          /* and resort the list now */

          clock->entries =

              g_list_sort (clock->entries, gst_clock_id_compare_func);

          /* and restart */

          continue;

        } else {

          goto next_entry;

        }

      }

      case GST_CLOCK_BUSY:

        /* somebody unlocked the entry but is was not canceled, This means that

         * either a new entry was added in front of the queue or some other entry

         * was canceled. Whatever it is, pick the head entry of the list and

         * continue waiting. */

        GST_CAT_DEBUG (GST_CAT_CLOCK, "async entry %p needs restart", entry);

        continue;

      default:

        GST_CAT_DEBUG (GST_CAT_CLOCK,

            "strange result %d waiting for %p, skipping", res, entry);

        g_warning ("%s: strange result %d waiting for %p, skipping",

            GST_OBJECT_NAME (clock), res, entry);

        goto next_entry;

    }

  next_entry:

    /* we remove the current entry and unref it */

    clock->entries = g_list_remove (clock->entries, entry);

    gst_clock_id_unref ((GstClockID) entry);

  }

exit:

  /* signal exit */

  GST_CLOCK_BROADCAST (clock);

  GST_OBJECT_UNLOCK (clock);

  GST_CAT_DEBUG (GST_CAT_CLOCK, "exit system clock thread");

}

/* MT safe */

static GstClockTime

gst_system_clock_get_internal_time (GstClock * clock)

{

  GTimeVal timeval;

  g_get_current_time (&timeval);

  return GST_TIMEVAL_TO_TIME (timeval);

}

static guint64

gst_system_clock_get_resolution (GstClock * clock)

{

  return 1 * GST_USECOND;

}

/* synchronously wait on the given GstClockEntry.

 *

 * We do this by blocking on the global clock GCond variable with

 * the requested time as a timeout. This allows us to unblock the

 * entry by signaling the GCond variable.

 *

 * Note that signaling the global GCond unlocks all waiting entries. So

 * we need to check if an unlocked entry has changed when it unlocks.

 *

 * Entries that arrive too late are simply not waited on and a

 * GST_CLOCK_EARLY result is returned.

 *

 * should be called with LOCK held.

 *

 * MT safe.

 */

static GstClockReturn

gst_system_clock_id_wait_jitter_unlocked (GstClock * clock,

    GstClockEntry * entry, GstClockTimeDiff * jitter, gboolean restart)

{

  GstClockTimeDiff diff;

  /* need to call the overridden method because we want to sync against the time

   * of the clock, whatever the subclass uses as a clock. */

  real = GST_CLOCK_GET_CLASS (clock)->get_internal_time (clock);

  entryt = GST_CLOCK_ENTRY_TIME (entry);

  if (jitter) {

    *jitter = GST_CLOCK_DIFF (entryt, now);

  }

  /* the diff of the entry with the clock is the amount of time we have to

   * wait */

  diff = entryt - now;

  GST_CAT_DEBUG (GST_CAT_CLOCK, "entry %p"

      " now %" GST_TIME_FORMAT

      " real %" GST_TIME_FORMAT

      entry,

      GST_TIME_ARGS (entryt), GST_TIME_ARGS (now), GST_TIME_ARGS (real), diff);

  if (diff > 0) {

#ifdef WAIT_DEBUGGING

#endif

#ifdef WAIT_DEBUGGING

#endif

          break;

      }

    }

  } else if (diff == 0) {

    entry->status = GST_CLOCK_OK;

  } else {

    entry->status = GST_CLOCK_EARLY;

  }

  return entry->status;

}

static GstClockReturn

gst_system_clock_id_wait_jitter (GstClock * clock, GstClockEntry * entry,

    GstClockTimeDiff * jitter)

{

  GstClockReturn ret;

  GST_OBJECT_LOCK (clock);

  ret = gst_system_clock_id_wait_jitter_unlocked (clock, entry, jitter, TRUE);

  GST_OBJECT_UNLOCK (clock);

  return ret;

}

/* Start the async clock thread. Must be called with the object lock

 * held */

static gboolean

gst_system_clock_start_async (GstSystemClock * clock)

{

  GError *error = NULL;

    return TRUE;                /* Thread already running. Nothing to do */

  clock->thread = g_thread_create ((GThreadFunc) gst_system_clock_async_thread,

      clock, TRUE, &error);

    goto no_thread;

  /* wait for it to spin up */

  GST_CLOCK_WAIT (clock);

  return TRUE;

  /* ERRORS */

no_thread:

  {

    g_warning ("could not create async clock thread: %s", error->message);

  }

  return FALSE;

}

/* Add an entry to the list of pending async waits. The entry is inserted

 * in sorted order. If we inserted the entry at the head of the list, we

 * need to signal the thread as it might either be waiting on it or waiting

 * for a new entry.

 *

 * MT safe.

 */

static GstClockReturn

gst_system_clock_id_wait_async (GstClock * clock, GstClockEntry * entry)

{

  GST_CAT_DEBUG (GST_CAT_CLOCK, "adding async entry %p", entry);

  GST_OBJECT_LOCK (clock);

  /* Start the clock async thread if needed */

    goto thread_error;