/* 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;
GstSystemClockPrivate *priv = clock->priv;
if (G_LIKELY (priv->thread != NULL))
return TRUE; /* Thread already running. Nothing to do */
priv->thread = g_thread_try_new ("GstSystemClock",
(GThreadFunc) gst_system_clock_async_thread, clock, &error);
if (G_UNLIKELY (error))
goto no_thread;
/* wait for it to spin up */
GST_SYSTEM_CLOCK_WAIT (clock);
return TRUE;
/* ERRORS */
no_thread:
{
g_warning ("could not create async clock thread: %s", error->message);
g_error_free (error);
}
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)
{
GstSystemClock *sysclock;
GstSystemClockPrivate *priv;
GstClockEntry *head;
sysclock = GST_SYSTEM_CLOCK_CAST (clock);
priv = sysclock->priv;
GST_CAT_DEBUG (GST_CAT_CLOCK, "adding async entry %p", entry);
GST_OBJECT_LOCK (clock);
/* Start the clock async thread if needed */
if (G_UNLIKELY (!gst_system_clock_start_async (sysclock)))
goto thread_error;
if (G_UNLIKELY (GET_ENTRY_STATUS (entry) == GST_CLOCK_UNSCHEDULED))
goto was_unscheduled;
if (priv->entries)
head = priv->entries->data;
else
head = NULL;
/* need to take a ref */
gst_clock_id_ref ((GstClockID) entry);
/* insert the entry in sorted order */
priv->entries = g_list_insert_sorted (priv->entries, entry,
gst_clock_id_compare_func);
/* only need to send the signal if the entry was added to the
* front, else the thread is just waiting for another entry and
* will get to this entry automatically. */
if (priv->entries->data == entry) {
GST_CAT_DEBUG (GST_CAT_CLOCK, "async entry added to head %p", head);
if (head == NULL) {
/* the list was empty before, signal the cond so that the async thread can
* start taking a look at the queue */
GST_CAT_DEBUG (GST_CAT_CLOCK, "first entry, sending signal");
GST_SYSTEM_CLOCK_BROADCAST (clock);
} else {
GstClockReturn status;
status = GET_ENTRY_STATUS (head);
GST_CAT_DEBUG (GST_CAT_CLOCK, "head entry %p status %d", head, status);
if (status == GST_CLOCK_BUSY) {
GST_CAT_DEBUG (GST_CAT_CLOCK, "head entry is busy");
/* the async thread was waiting for an entry, unlock the wait so that it
* looks at the new head entry instead, we only need to do this once */
if (!priv->async_wakeup) {
GST_CAT_DEBUG (GST_CAT_CLOCK, "wakeup async thread");
priv->async_wakeup = TRUE;
gst_system_clock_add_wakeup (sysclock);
}
}
}
}
GST_OBJECT_UNLOCK (clock);
return GST_CLOCK_OK;
/* ERRORS */
thread_error:
{
/* Could not start the async clock thread */
GST_OBJECT_UNLOCK (clock);
return GST_CLOCK_ERROR;
}
was_unscheduled:
{
GST_OBJECT_UNLOCK (clock);
return GST_CLOCK_UNSCHEDULED;
}
}
/* unschedule an entry. This will set the state of the entry to GST_CLOCK_UNSCHEDULED
* and will signal any thread waiting for entries to recheck their entry.
* We cannot really decide if the signal is needed or not because the entry
* could be waited on in async or sync mode.
*
* MT safe.
*/
static void
gst_system_clock_id_unschedule (GstClock * clock, GstClockEntry * entry)
{
GstSystemClock *sysclock;
GstClockReturn status;
sysclock = GST_SYSTEM_CLOCK_CAST (clock);
GST_CAT_DEBUG (GST_CAT_CLOCK, "unscheduling entry %p", entry);
GST_OBJECT_LOCK (clock);
/* change the entry status to unscheduled */
do {
status = GET_ENTRY_STATUS (entry);
} while (G_UNLIKELY (!CAS_ENTRY_STATUS (entry, status,
GST_CLOCK_UNSCHEDULED)));
if (G_LIKELY (status == GST_CLOCK_BUSY)) {
/* the entry was being busy, wake up all entries so that they recheck their
* status. We cannot wake up just one entry because allocating such a
* datastructure for each entry would be too heavy and unlocking an entry
* is usually done when shutting down or some other exceptional case. */
GST_CAT_DEBUG (GST_CAT_CLOCK, "entry was BUSY, doing wakeup");
if (!entry->unscheduled && !entry->woken_up) {
gst_system_clock_add_wakeup (sysclock);
entry->woken_up = TRUE;
}
}
GST_OBJECT_UNLOCK (clock);
}