/* 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., 51 Franklin St, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 */

/**

 * SECTION:gstsystemclock

 * @title: 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.

 */

#include "gst_private.h"

#include "gstinfo.h"

#include "gstsystemclock.h"

#include "gstenumtypes.h"

#include "gstpoll.h"

#include "gstutils.h"

#include "glib-compat-private.h"

#include <errno.h>

#ifdef G_OS_WIN32

#  define WIN32_LEAN_AND_MEAN   /* prevents from including too many things */

#  include <windows.h>          /* QueryPerformance* stuff */

#  undef WIN32_LEAN_AND_MEAN

#  ifndef EWOULDBLOCK

#  define EWOULDBLOCK EAGAIN    /* This is just to placate gcc */

#  endif

#endif /* G_OS_WIN32 */

#ifdef __APPLE__

#include <mach/mach_time.h>

#endif

#define GET_ENTRY_STATUS(e)          ((GstClockReturn) g_atomic_int_get(&GST_CLOCK_ENTRY_STATUS(e)))

#define SET_ENTRY_STATUS(e,val)      (g_atomic_int_set(&GST_CLOCK_ENTRY_STATUS(e),(val)))

#define CAS_ENTRY_STATUS(e,old,val)  (g_atomic_int_compare_and_exchange(\

                                       (&GST_CLOCK_ENTRY_STATUS(e)), (old), (val)))

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

#undef WAIT_DEBUGGING

#define GST_SYSTEM_CLOCK_GET_COND(clock)        (&GST_SYSTEM_CLOCK_CAST(clock)->priv->entries_changed)

#define GST_SYSTEM_CLOCK_WAIT(clock)            g_cond_wait(GST_SYSTEM_CLOCK_GET_COND(clock),GST_OBJECT_GET_LOCK(clock))

#define GST_SYSTEM_CLOCK_TIMED_WAIT(clock,tv)   g_cond_timed_wait(GST_SYSTEM_CLOCK_GET_COND(clock),GST_OBJECT_GET_LOCK(clock),tv)

#define GST_SYSTEM_CLOCK_BROADCAST(clock)       g_cond_broadcast(GST_SYSTEM_CLOCK_GET_COND(clock))

struct _GstSystemClockPrivate

{

  GThread *thread;              /* thread for async notify */

  gboolean stopping;

  GList *entries;

  GCond entries_changed;

  GstClockType clock_type;

  GstPoll *timer;

  gint wakeup_count;            /* the number of entries with a pending wakeup */

  gboolean async_wakeup;        /* if the wakeup was because of a async list change */

#ifdef G_OS_WIN32

  LARGE_INTEGER start;

  LARGE_INTEGER frequency;

#endif                          /* G_OS_WIN32 */

#ifdef __APPLE__

  struct mach_timebase_info mach_timebase;

#endif

};

#define GST_SYSTEM_CLOCK_GET_PRIVATE(obj)  \

   (G_TYPE_INSTANCE_GET_PRIVATE ((obj), GST_TYPE_SYSTEM_CLOCK, \

        GstSystemClockPrivate))

#ifdef HAVE_POSIX_TIMERS

# ifdef HAVE_MONOTONIC_CLOCK

#  define DEFAULT_CLOCK_TYPE GST_CLOCK_TYPE_MONOTONIC

# else

#  define DEFAULT_CLOCK_TYPE GST_CLOCK_TYPE_REALTIME

# endif

#else

#define DEFAULT_CLOCK_TYPE GST_CLOCK_TYPE_REALTIME

#endif

enum

{

  PROP_0,

  PROP_CLOCK_TYPE,

  /* FILL ME */

};

/* the one instance of the systemclock */

static GstClock *_the_system_clock = NULL;

static gboolean _external_default_clock = FALSE;

static void gst_system_clock_dispose (GObject * object);

static void gst_system_clock_set_property (GObject * object, guint prop_id,

    const GValue * value, GParamSpec * pspec);

static void gst_system_clock_get_property (GObject * object, guint prop_id,

    GValue * value, GParamSpec * pspec);

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 void gst_system_clock_add_wakeup (GstSystemClock * sysclock);

static GMutex _gst_sysclock_mutex;

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

#define gst_system_clock_parent_class parent_class

G_DEFINE_TYPE (GstSystemClock, gst_system_clock, GST_TYPE_CLOCK);

static void

gst_system_clock_class_init (GstSystemClockClass * klass)

{

  GObjectClass *gobject_class;

  GstClockClass *gstclock_class;

  gobject_class = (GObjectClass *) klass;

  gstclock_class = (GstClockClass *) klass;

  g_type_class_add_private (klass, sizeof (GstSystemClockPrivate));

  gobject_class->dispose = gst_system_clock_dispose;

  gobject_class->set_property = gst_system_clock_set_property;

  gobject_class->get_property = gst_system_clock_get_property;

  g_object_class_install_property (gobject_class, PROP_CLOCK_TYPE,

      g_param_spec_enum ("clock-type", "Clock type",

          "The type of underlying clock implementation used",

          GST_TYPE_CLOCK_TYPE, DEFAULT_CLOCK_TYPE,

          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  gstclock_class->get_internal_time = gst_system_clock_get_internal_time;

  gstclock_class->get_resolution = gst_system_clock_get_resolution;

  gstclock_class->wait = 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)

{

  GstSystemClockPrivate *priv;

  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);

  clock->priv = priv = GST_SYSTEM_CLOCK_GET_PRIVATE (clock);

  priv->clock_type = DEFAULT_CLOCK_TYPE;

  priv->timer = gst_poll_new_timer ();

  priv->entries = NULL;

  g_cond_init (&priv->entries_changed);

#ifdef G_OS_WIN32

  QueryPerformanceFrequency (&priv->frequency);

  /* can be 0 if the hardware does not have hardware support */

  if (priv->frequency.QuadPart != 0)

    /* we take a base time so that time starts from 0 to ease debugging */

    QueryPerformanceCounter (&priv->start);

#endif /* G_OS_WIN32 */

#ifdef __APPLE__

  mach_timebase_info (&priv->mach_timebase);

#endif

#if 0

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

  GST_OBJECT_LOCK (clock);

  gst_system_clock_start_async (clock);

  GST_OBJECT_UNLOCK (clock);

#endif

}

static void

gst_system_clock_dispose (GObject * object)

{

  GstClock *clock = (GstClock *) object;

  GstSystemClock *sysclock = GST_SYSTEM_CLOCK_CAST (clock);

  GstSystemClockPrivate *priv = sysclock->priv;

  GList *entries;

  /* else we have to stop the thread */

  GST_OBJECT_LOCK (clock);

  priv->stopping = TRUE;

  /* unschedule all entries */

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

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

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

    SET_ENTRY_STATUS (entry, GST_CLOCK_UNSCHEDULED);

  }

  GST_SYSTEM_CLOCK_BROADCAST (clock);

  gst_system_clock_add_wakeup (sysclock);

  GST_OBJECT_UNLOCK (clock);

  if (priv->thread)

    g_thread_join (priv->thread);

  priv->thread = NULL;

  GST_CAT_DEBUG (GST_CAT_CLOCK, "joined thread");

  g_list_foreach (priv->entries, (GFunc) gst_clock_id_unref, NULL);

  g_list_free (priv->entries);

  priv->entries = NULL;

  gst_poll_free (priv->timer);

  g_cond_clear (&priv->entries_changed);

  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");

  }

}

static void

gst_system_clock_set_property (GObject * object, guint prop_id,

    const GValue * value, GParamSpec * pspec)

{

  GstSystemClock *sysclock = GST_SYSTEM_CLOCK (object);

  switch (prop_id) {

    case PROP_CLOCK_TYPE:

      sysclock->priv->clock_type = (GstClockType) g_value_get_enum (value);

      GST_CAT_DEBUG (GST_CAT_CLOCK, "clock-type set to %d",

          sysclock->priv->clock_type);

      break;

    default:

      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

      break;

  }

}

static void

gst_system_clock_get_property (GObject * object, guint prop_id, GValue * value,

    GParamSpec * pspec)

{

  GstSystemClock *sysclock = GST_SYSTEM_CLOCK (object);

  switch (prop_id) {

    case PROP_CLOCK_TYPE:

      g_value_set_enum (value, sysclock->priv->clock_type);

      break;

    default:

      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

      break;

  }

}

/**

 * gst_system_clock_set_default:

 * @new_clock: (allow-none): a #GstClock

 *

 * Sets the default system clock that can be obtained with

 * gst_system_clock_obtain().

 *

 * This is mostly used for testing and debugging purposes when you

 * want to have control over the time reported by the default system

 * clock.

 *

 * MT safe.

 *

 * Since: 1.4

 */

void

gst_system_clock_set_default (GstClock * new_clock)

{

  GstClock *clock;

  g_mutex_lock (&_gst_sysclock_mutex);

  clock = _the_system_clock;

  if (clock != NULL)

    g_object_unref (clock);

  if (new_clock == NULL) {

    GST_CAT_DEBUG (GST_CAT_CLOCK, "resetting default system clock");

    _external_default_clock = FALSE;

  } else {

    GST_CAT_DEBUG (GST_CAT_CLOCK, "setting new default system clock to %p",

        new_clock);

    _external_default_clock = TRUE;

    g_object_ref (new_clock);

  }

  _the_system_clock = new_clock;

  g_mutex_unlock (&_gst_sysclock_mutex);

}

/**

 * 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: (transfer full): the default clock.

 *

 * MT safe.

 */

GstClock *

gst_system_clock_obtain (void)

{

  GstClock *clock;

  g_mutex_lock (&_gst_sysclock_mutex);

  clock = _the_system_clock;

  if (clock == NULL) {

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

    g_assert (!_external_default_clock);

    clock = g_object_new (GST_TYPE_SYSTEM_CLOCK,

        "name", "GstSystemClock", NULL);

    /* Clear floating flag */

    gst_object_ref_sink (clock);

    _the_system_clock = clock;

    g_mutex_unlock (&_gst_sysclock_mutex);

  } else {

    g_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;

}

static void

gst_system_clock_remove_wakeup (GstSystemClock * sysclock)

{

  g_return_if_fail (sysclock->priv->wakeup_count > 0);

  sysclock->priv->wakeup_count--;

  GST_CAT_DEBUG (GST_CAT_CLOCK, "reading control");

  while (!gst_poll_read_control (sysclock->priv->timer)) {

    if (errno == EWOULDBLOCK) {

      /* Try again and give other threads the chance to do something */

      g_thread_yield ();

      continue;

    } else {

      /* Critical error, GstPoll will have printed a critical warning already */

      break;

    }

  }

  GST_SYSTEM_CLOCK_BROADCAST (sysclock);

  GST_CAT_DEBUG (GST_CAT_CLOCK, "wakeup count %d",

      sysclock->priv->wakeup_count);

}

static void

gst_system_clock_add_wakeup (GstSystemClock * sysclock)

{

  GST_CAT_DEBUG (GST_CAT_CLOCK, "writing control");

  gst_poll_write_control (sysclock->priv->timer);

  sysclock->priv->wakeup_count++;

  GST_CAT_DEBUG (GST_CAT_CLOCK, "wakeup count %d",

      sysclock->priv->wakeup_count);

}

static void

gst_system_clock_wait_wakeup (GstSystemClock * sysclock)

{

  while (sysclock->priv->wakeup_count > 0) {

    GST_SYSTEM_CLOCK_WAIT (sysclock);

  }

}

/* 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)

{

  GstSystemClock *sysclock = GST_SYSTEM_CLOCK_CAST (clock);

  GstSystemClockPrivate *priv = sysclock->priv;

  GstClockReturn status;

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

  GST_OBJECT_LOCK (clock);

  /* signal spinup */

  GST_SYSTEM_CLOCK_BROADCAST (clock);

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

  while (!priv->stopping) {

    GstClockEntry *entry;

    GstClockTime requested;

    GstClockReturn res;

    /* check if something to be done */

    while (priv->entries == NULL) {

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

      /* wait for work to do */

      GST_SYSTEM_CLOCK_WAIT (clock);

      GST_CAT_DEBUG (GST_CAT_CLOCK, "got signal");

      /* clock was stopping, exit */

      if (priv->stopping)

        goto exit;

    }

    /* see if we have a pending wakeup because the order of the list

     * changed. */

    if (priv->async_wakeup) {

      GST_CAT_DEBUG (GST_CAT_CLOCK, "clear async wakeup");

      gst_system_clock_remove_wakeup (sysclock);

      priv->async_wakeup = FALSE;

    }

    /* pick the next entry */

    entry = priv->entries->data;

    /* set entry status to busy before we release the clock lock */

    do {

      status = GET_ENTRY_STATUS (entry);

      /* check for unscheduled */

      if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED)) {

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

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

        goto next_entry;

      }

      /* for periodic timers, status can be EARLY from a previous run */

      if (G_UNLIKELY (status != GST_CLOCK_OK && status != GST_CLOCK_EARLY))

        GST_CAT_ERROR (GST_CAT_CLOCK, "unexpected status %d for entry %p",

            status, entry);

      /* mark the entry as busy but watch out for intermediate unscheduled

       * statuses */

    } while (G_UNLIKELY (!CAS_ENTRY_STATUS (entry, status, GST_CLOCK_BUSY)));

    GST_OBJECT_UNLOCK (clock);

    requested = entry->time;

    /* now wait for the entry */

    res =

        gst_system_clock_id_wait_jitter_unlocked (clock, (GstClockID) entry,

        NULL, FALSE);

    GST_OBJECT_LOCK (clock);

    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 */

        GST_CAT_DEBUG (GST_CAT_CLOCK, "async entry %p timed out", 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) {

          GST_CAT_DEBUG (GST_CAT_CLOCK, "updating periodic entry %p", entry);

          /* adjust time now */

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

          /* and resort the list now */

          priv->entries =

              g_list_sort (priv->entries, gst_clock_id_compare_func);

          /* and restart */

          continue;

        } else {

          GST_CAT_DEBUG (GST_CAT_CLOCK, "moving to next entry");

          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);

        /* we set the entry back to the OK state. This is needed so that the

         * _unschedule() code can see if an entry is currently being waited

         * on (when its state is BUSY). */

        SET_ENTRY_STATUS (entry, GST_CLOCK_OK);

        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 */

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

    gst_clock_id_unref ((GstClockID) entry);

  }

exit:

  /* signal exit */

  GST_SYSTEM_CLOCK_BROADCAST (clock);

  GST_OBJECT_UNLOCK (clock);

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

}

#ifdef HAVE_POSIX_TIMERS

static inline clockid_t

clock_type_to_posix_id (GstClockType clock_type)

{

#ifdef HAVE_MONOTONIC_CLOCK

  if (clock_type == GST_CLOCK_TYPE_MONOTONIC)

    return CLOCK_MONOTONIC;

  else

#endif

    return CLOCK_REALTIME;

}

#endif

/* MT safe */

static GstClockTime

gst_system_clock_get_internal_time (GstClock * clock)

{

#if defined __APPLE__

  GstSystemClock *sysclock = GST_SYSTEM_CLOCK_CAST (clock);

  uint64_t mach_t = mach_absolute_time ();

  return gst_util_uint64_scale (mach_t, sysclock->priv->mach_timebase.numer,

      sysclock->priv->mach_timebase.denom);

#else

#ifdef G_OS_WIN32

  GstSystemClock *sysclock = GST_SYSTEM_CLOCK_CAST (clock);

  if (sysclock->priv->frequency.QuadPart != 0) {

    LARGE_INTEGER now;

    /* we prefer the highly accurate performance counters on windows */

    QueryPerformanceCounter (&now;;

    return gst_util_uint64_scale (now.QuadPart - sysclock->priv->start.QuadPart,

        GST_SECOND, sysclock->priv->frequency.QuadPart);

  } else

#endif /* G_OS_WIN32 */

#if !defined HAVE_POSIX_TIMERS || !defined HAVE_CLOCK_GETTIME

  {

    GTimeVal timeval;

    g_get_current_time (&timeval);

    return GST_TIMEVAL_TO_TIME (timeval);

  }

#else

  {

    GstSystemClock *sysclock = GST_SYSTEM_CLOCK_CAST (clock);

    clockid_t ptype;

    struct timespec ts;

    ptype = clock_type_to_posix_id (sysclock->priv->clock_type);

    if (G_UNLIKELY (clock_gettime (ptype, &ts)))

      return GST_CLOCK_TIME_NONE;

    return GST_TIMESPEC_TO_TIME (ts);

  }

#endif

#endif /* __APPLE__ */

}

static guint64

gst_system_clock_get_resolution (GstClock * clock)

{

#if defined __APPLE__

  GstSystemClock *sysclock = GST_SYSTEM_CLOCK_CAST (clock);

  return gst_util_uint64_scale (GST_NSECOND,

      sysclock->priv->mach_timebase.numer, sysclock->priv->mach_timebase.denom);

#else

#ifdef G_OS_WIN32

  GstSystemClock *sysclock = GST_SYSTEM_CLOCK_CAST (clock);

  if (sysclock->priv->frequency.QuadPart != 0) {

    return GST_SECOND / sysclock->priv->frequency.QuadPart;

  } else

#endif /* G_OS_WIN32 */

#if defined(HAVE_POSIX_TIMERS) && defined(HAVE_CLOCK_GETTIME)

  {

    GstSystemClock *sysclock = GST_SYSTEM_CLOCK_CAST (clock);

    clockid_t ptype;

    struct timespec ts;

    ptype = clock_type_to_posix_id (sysclock->priv->clock_type);

    if (G_UNLIKELY (clock_getres (ptype, &ts)))

      return GST_CLOCK_TIME_NONE;

    return GST_TIMESPEC_TO_TIME (ts);

  }

#else

  {

    return 1 * GST_USECOND;

  }

#endif

#endif /* __APPLE__ */

}

static inline void

gst_system_clock_cleanup_unscheduled (GstSystemClock * sysclock,

    GstClockEntry * entry)

{

  /* try to clean up.

   * The unschedule function managed to set the status to

   * unscheduled. We now take the lock and mark the entry as unscheduled.

   * This makes sure that the unschedule function doesn't perform a

   * wakeup anymore. If the unschedule function has a change to perform

   * the wakeup before us, we clean up here */

  GST_OBJECT_LOCK (sysclock);

  entry->unscheduled = TRUE;

  if (entry->woken_up) {

    gst_system_clock_remove_wakeup (sysclock);

  }

  GST_OBJECT_UNLOCK (sysclock);

}

/* synchronously wait on the given GstClockEntry.

 *

 * We do this by blocking on the global GstPoll timer with

 * the requested timeout. This allows us to unblock the

 * entry by writing on the control fd.

 *

 * Note that writing the global GstPoll 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.

 *

 * MT safe.

 */

static GstClockReturn

gst_system_clock_id_wait_jitter_unlocked (GstClock * clock,

    GstClockEntry * entry, GstClockTimeDiff * jitter, gboolean restart)

{

  GstSystemClock *sysclock = GST_SYSTEM_CLOCK_CAST (clock);

  GstClockTime entryt, now;

  GstClockTimeDiff diff;

  GstClockReturn status;

  status = GET_ENTRY_STATUS (entry);

  if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED)) {

    gst_system_clock_cleanup_unscheduled (sysclock, entry);

    return GST_CLOCK_UNSCHEDULED;

  }

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

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

  now = gst_clock_get_time (clock);

  /* get the time of the entry */

  entryt = GST_CLOCK_ENTRY_TIME (entry);

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

   * wait */

  diff = GST_CLOCK_DIFF (now, entryt);

  if (G_LIKELY (jitter))

    *jitter = -diff;

  GST_CAT_DEBUG (GST_CAT_CLOCK, "entry %p"

      " time %" GST_TIME_FORMAT

      " now %" GST_TIME_FORMAT

      " diff (time-now) %" G_GINT64_FORMAT,

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

  if (G_LIKELY (diff > 0)) {

#ifdef WAIT_DEBUGGING

    GstClockTime final;

#endif

    while (TRUE) {

      gint pollret;

      /* now wait on the entry, it either times out or the fd is written. The

       * status of the entry is BUSY only around the poll. */

      pollret = gst_poll_wait (sysclock->priv->timer, diff);

      /* get the new status, mark as DONE. We do this so that the unschedule

       * function knows when we left the poll and doesn't need to wakeup the

       * poll anymore. */

      do {

        status = GET_ENTRY_STATUS (entry);

        /* we were unscheduled, exit immediately */

        if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED))

          break;

        if (G_UNLIKELY (status != GST_CLOCK_BUSY))

          GST_CAT_ERROR (GST_CAT_CLOCK, "unexpected status %d for entry %p",

              status, entry);

      } while (G_UNLIKELY (!CAS_ENTRY_STATUS (entry, status, GST_CLOCK_DONE)));

      GST_CAT_DEBUG (GST_CAT_CLOCK, "entry %p unlocked, status %d, ret %d",

          entry, status, pollret);

      if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED)) {

        gst_system_clock_cleanup_unscheduled (sysclock, entry);

        goto done;

      } else {

        if (G_UNLIKELY (pollret != 0)) {

          /* some other id got unlocked */

          if (!restart) {

            /* this can happen if the entry got unlocked because of an async

             * entry was added to the head of the async queue. */

            GST_CAT_DEBUG (GST_CAT_CLOCK, "wakeup waiting for entry %p", entry);

            goto done;

          }

          /* wait till all the entries got woken up */

          GST_OBJECT_LOCK (sysclock);

          gst_system_clock_wait_wakeup (sysclock);

          GST_OBJECT_UNLOCK (sysclock);

          GST_CAT_DEBUG (GST_CAT_CLOCK, "entry %p needs to be restarted",

              entry);

        } else {

          GST_CAT_DEBUG (GST_CAT_CLOCK, "entry %p unlocked after timeout",

              entry);

        }

        /* reschedule if gst_poll_wait returned early or we have to reschedule after

         * an unlock*/

        now = gst_clock_get_time (clock);

        diff = GST_CLOCK_DIFF (now, entryt);

        if (diff <= 0) {

          /* timeout, this is fine, we can report success now */

          if (G_UNLIKELY (!CAS_ENTRY_STATUS (entry, GST_CLOCK_DONE,

                      GST_CLOCK_OK))) {

            status = GET_ENTRY_STATUS (entry);

            if (status != GST_CLOCK_UNSCHEDULED)

              GST_CAT_ERROR (GST_CAT_CLOCK, "unexpected status %d for entry %p",

                  status, entry);

            goto done;

          } else {

            status = GST_CLOCK_OK;

          }

          GST_CAT_DEBUG (GST_CAT_CLOCK,

              "entry %p finished, diff %" G_GINT64_FORMAT, entry, diff);

#ifdef WAIT_DEBUGGING

          final = gst_system_clock_get_internal_time (clock);

          GST_CAT_DEBUG (GST_CAT_CLOCK, "Waited for %" G_GINT64_FORMAT

              " got %" G_GINT64_FORMAT " diff %" G_GINT64_FORMAT

              " %g target-offset %" G_GINT64_FORMAT " %g", entryt, now,

              now - entryt,

              (double) (GstClockTimeDiff) (now - entryt) / GST_SECOND,

              (final - target),

              ((double) (GstClockTimeDiff) (final - target)) / GST_SECOND);

#endif

          goto done;

        } else {

          GST_CAT_DEBUG (GST_CAT_CLOCK,

              "entry %p restart, diff %" G_GINT64_FORMAT, entry, diff);

          /* we are going to poll again, set status back to busy */

          do {

            status = GET_ENTRY_STATUS (entry);

            /* we were unscheduled, exit immediately */

            if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED))

              goto done;

            if (G_UNLIKELY (status != GST_CLOCK_DONE))

              GST_CAT_ERROR (GST_CAT_CLOCK, "unexpected status %d for entry %p",

                  status, entry);

          } while (G_UNLIKELY (!CAS_ENTRY_STATUS (entry, status,

                      GST_CLOCK_BUSY)));

        }

      }

    }

  } else {

    /* we are right on time or too late */

    if (G_UNLIKELY (diff == 0)) {

      if (G_UNLIKELY (!CAS_ENTRY_STATUS (entry, status, GST_CLOCK_OK))) {

        status = GET_ENTRY_STATUS (entry);

        if (G_LIKELY (status == GST_CLOCK_UNSCHEDULED))

          gst_system_clock_cleanup_unscheduled (sysclock, entry);

        else

          GST_CAT_ERROR (GST_CAT_CLOCK, "unexpected status %d for entry %p",

              status, entry);

      } else {

        status = GST_CLOCK_OK;

      }

    } else {

      if (G_UNLIKELY (!CAS_ENTRY_STATUS (entry, status, GST_CLOCK_EARLY))) {

        status = GET_ENTRY_STATUS (entry);

        if (G_LIKELY (status == GST_CLOCK_UNSCHEDULED))

          gst_system_clock_cleanup_unscheduled (sysclock, entry);

        else

          GST_CAT_ERROR (GST_CAT_CLOCK, "unexpected status %d for entry %p",

              status, entry);

      } else {

        status = GST_CLOCK_EARLY;

      }

    }

  }

done:

  return status;

}

static GstClockReturn

gst_system_clock_id_wait_jitter (GstClock * clock, GstClockEntry * entry,

    GstClockTimeDiff * jitter)

{

  GstClockReturn status;

  do {

    status = GET_ENTRY_STATUS (entry);

    /* stop when we are unscheduled */

    if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED))

      return status;

    if (G_UNLIKELY (status != GST_CLOCK_OK))

      GST_CAT_ERROR (GST_CAT_CLOCK, "unexpected status %d for entry %p",

          status, entry);

    /* mark the entry as busy but watch out for intermediate unscheduled

     * statuses */

  } while (G_UNLIKELY (!CAS_ENTRY_STATUS (entry, status, GST_CLOCK_BUSY)));

  return gst_system_clock_id_wait_jitter_unlocked (clock, entry, jitter, TRUE);

}

/* 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;