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systemclock: move to GCond waiting

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This commit is contained in:
Matthew Waters 2020-04-14 14:48:20 +10:00
parent 88f0312624
commit 2c8a65745c
1 changed files with 48 additions and 125 deletions
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173
gst/gstsystemclock.c
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@ -68,9 +68,12 @@
/* Define this to get some extra debug about jitter from each clock_wait */
#undef WAIT_DEBUGGING
#define GST_SYSTEM_CLOCK_GET_LOCK(clock) GST_OBJECT_GET_LOCK(clock)
#define GST_SYSTEM_CLOCK_LOCK(clock) g_mutex_lock(GST_SYSTEM_CLOCK_GET_LOCK(clock))
#define GST_SYSTEM_CLOCK_UNLOCK(clock) g_mutex_unlock(GST_SYSTEM_CLOCK_GET_LOCK(clock))
#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_WAIT(clock) g_cond_wait(GST_SYSTEM_CLOCK_GET_COND(clock),GST_SYSTEM_CLOCK_GET_LOCK(clock))
#define GST_SYSTEM_CLOCK_WAIT_UNTIL(clock,us) g_cond_wait_until(GST_SYSTEM_CLOCK_GET_COND(clock),GST_SYSTEM_CLOCK_GET_LOCK(clock),us)
#define GST_SYSTEM_CLOCK_BROADCAST(clock) g_cond_broadcast(GST_SYSTEM_CLOCK_GET_COND(clock))
struct _GstSystemClockPrivate
@ -82,9 +85,6 @@ struct _GstSystemClockPrivate
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 frequency;
@ -135,7 +135,6 @@ 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;
@ -184,7 +183,6 @@ gst_system_clock_init (GstSystemClock * clock)
clock->priv = priv = gst_system_clock_get_instance_private (clock);
priv->clock_type = DEFAULT_CLOCK_TYPE;
priv->timer = gst_poll_new_timer ();
priv->entries = NULL;
g_cond_init (&priv->entries_changed);
@ -203,9 +201,9 @@ gst_system_clock_init (GstSystemClock * clock)
#if 0
/* Uncomment this to start the async clock thread straight away */
GST_OBJECT_LOCK (clock);
GST_SYSTEM_CLOCK_LOCK (clock);
gst_system_clock_start_async (clock);
GST_OBJECT_UNLOCK (clock);
GST_SYSTEM_CLOCK_UNLOCK (clock);
#endif
}
@ -218,7 +216,7 @@ gst_system_clock_dispose (GObject * object)
GList *entries;
/* else we have to stop the thread */
GST_OBJECT_LOCK (clock);
GST_SYSTEM_CLOCK_LOCK (clock);
priv->stopping = TRUE;
/* unschedule all entries */
for (entries = priv->entries; entries; entries = g_list_next (entries)) {
@ -228,8 +226,7 @@ gst_system_clock_dispose (GObject * object)
SET_ENTRY_STATUS (entry, GST_CLOCK_UNSCHEDULED);
}
GST_SYSTEM_CLOCK_BROADCAST (clock);
gst_system_clock_add_wakeup (sysclock);
GST_OBJECT_UNLOCK (clock);
GST_SYSTEM_CLOCK_UNLOCK (clock);
if (priv->thread)
g_thread_join (priv->thread);
@ -240,7 +237,6 @@ gst_system_clock_dispose (GObject * object)
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);
@ -364,46 +360,6 @@ gst_system_clock_obtain (void)
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.
@ -424,7 +380,7 @@ gst_system_clock_async_thread (GstClock * clock)
GstClockReturn status;
GST_CAT_DEBUG (GST_CAT_CLOCK, "enter system clock thread");
GST_OBJECT_LOCK (clock);
GST_SYSTEM_CLOCK_LOCK (clock);
/* signal spinup */
GST_SYSTEM_CLOCK_BROADCAST (clock);
/* now enter our (almost) infinite loop */
@ -444,14 +400,6 @@ gst_system_clock_async_thread (GstClock * clock)
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;
@ -475,8 +423,6 @@ gst_system_clock_async_thread (GstClock * clock)
* statuses */
} while (G_UNLIKELY (!CAS_ENTRY_STATUS (entry, status, GST_CLOCK_BUSY)));
GST_OBJECT_UNLOCK (clock);
requested = entry->time;
/* now wait for the entry */
@ -484,8 +430,6 @@ gst_system_clock_async_thread (GstClock * clock)
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 */
@ -499,10 +443,10 @@ gst_system_clock_async_thread (GstClock * clock)
GST_CAT_DEBUG (GST_CAT_CLOCK, "async entry %p timed out", entry);
if (entry->func) {
/* unlock before firing the callback */
GST_OBJECT_UNLOCK (clock);
GST_SYSTEM_CLOCK_UNLOCK (clock);
entry->func (clock, entry->time, (GstClockID) entry,
entry->user_data);
GST_OBJECT_LOCK (clock);
GST_SYSTEM_CLOCK_LOCK (clock);
}
if (entry->type == GST_CLOCK_ENTRY_PERIODIC) {
GST_CAT_DEBUG (GST_CAT_CLOCK, "updating periodic entry %p", entry);
@ -545,7 +489,7 @@ gst_system_clock_async_thread (GstClock * clock)
exit:
/* signal exit */
GST_SYSTEM_CLOCK_BROADCAST (clock);
GST_OBJECT_UNLOCK (clock);
GST_SYSTEM_CLOCK_UNLOCK (clock);
GST_CAT_DEBUG (GST_CAT_CLOCK, "exit system clock thread");
}
@ -652,24 +596,6 @@ gst_system_clock_get_resolution (GstClock * clock)
#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
@ -688,20 +614,21 @@ 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;
gint64 mono_ts;
status = GET_ENTRY_STATUS (entry);
if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED)) {
gst_system_clock_cleanup_unscheduled (sysclock, entry);
entry->unscheduled = TRUE;
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);
mono_ts = g_get_monotonic_time ();
/* get the time of the entry */
entryt = GST_CLOCK_ENTRY_TIME (entry);
@ -724,11 +651,11 @@ gst_system_clock_id_wait_jitter_unlocked (GstClock * clock,
#endif
while (TRUE) {
gint pollret;
gboolean waitret;
/* 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);
/* now wait on the entry, it either times out or the cond is signalled.
* The status of the entry is BUSY only around the wait. */
waitret = GST_SYSTEM_CLOCK_WAIT_UNTIL (clock, mono_ts + (diff / 1000));
/* 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
@ -743,14 +670,14 @@ gst_system_clock_id_wait_jitter_unlocked (GstClock * clock,
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);
GST_CAT_DEBUG (GST_CAT_CLOCK, "entry %p unlocked, status %d",
entry, status);
if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED)) {
gst_system_clock_cleanup_unscheduled (sysclock, entry);
entry->unscheduled = TRUE;
goto done;
} else {
if (G_UNLIKELY (pollret != 0)) {
if (waitret) {
/* some other id got unlocked */
if (!restart) {
/* this can happen if the entry got unlocked because of an async
@ -759,11 +686,6 @@ gst_system_clock_id_wait_jitter_unlocked (GstClock * clock,
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 {
@ -771,7 +693,7 @@ gst_system_clock_id_wait_jitter_unlocked (GstClock * clock,
entry);
}
/* reschedule if gst_poll_wait returned early or we have to reschedule after
/* reschedule if gst_cond_wait_until returned early or we have to reschedule after
* an unlock*/
now = gst_clock_get_time (clock);
diff = GST_CLOCK_DIFF (now, entryt);
@ -826,7 +748,7 @@ gst_system_clock_id_wait_jitter_unlocked (GstClock * clock,
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);
entry->unscheduled = TRUE;
else
GST_CAT_ERROR (GST_CAT_CLOCK, "unexpected status %d for entry %p",
status, entry);
@ -837,7 +759,7 @@ gst_system_clock_id_wait_jitter_unlocked (GstClock * clock,
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);
entry->unscheduled = TRUE;
else
GST_CAT_ERROR (GST_CAT_CLOCK, "unexpected status %d for entry %p",
status, entry);
@ -855,12 +777,16 @@ gst_system_clock_id_wait_jitter (GstClock * clock, GstClockEntry * entry,
GstClockTimeDiff * jitter)
{
GstClockReturn status;
GST_SYSTEM_CLOCK_LOCK (clock);
do {
status = GET_ENTRY_STATUS (entry);
/* stop when we are unscheduled */
if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED))
if (G_UNLIKELY (status == GST_CLOCK_UNSCHEDULED)) {
GST_SYSTEM_CLOCK_UNLOCK (clock);
return status;
}
if (G_UNLIKELY (status != GST_CLOCK_OK))
GST_CAT_ERROR (GST_CAT_CLOCK, "unexpected status %d for entry %p",
@ -870,7 +796,11 @@ gst_system_clock_id_wait_jitter (GstClock * clock, GstClockEntry * entry,
* statuses */
} while (G_UNLIKELY (!CAS_ENTRY_STATUS (entry, status, GST_CLOCK_BUSY)));
return gst_system_clock_id_wait_jitter_unlocked (clock, entry, jitter, TRUE);
status =
gst_system_clock_id_wait_jitter_unlocked (clock, entry, jitter, TRUE);
GST_SYSTEM_CLOCK_UNLOCK (clock);
return status;
}
/* Start the async clock thread. Must be called with the object lock
@ -923,7 +853,7 @@ 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);
GST_SYSTEM_CLOCK_LOCK (clock);
/* Start the clock async thread if needed */
if (G_UNLIKELY (!gst_system_clock_start_async (sysclock)))
goto thread_error;
@ -959,18 +889,15 @@ gst_system_clock_id_wait_async (GstClock * clock, GstClockEntry * entry)
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_CAT_DEBUG (GST_CAT_CLOCK,
"head entry was busy. Wakeup async thread");
GST_SYSTEM_CLOCK_BROADCAST (clock);
}
}
}
GST_OBJECT_UNLOCK (clock);
GST_SYSTEM_CLOCK_UNLOCK (clock);
return GST_CLOCK_OK;
@ -978,12 +905,12 @@ gst_system_clock_id_wait_async (GstClock * clock, GstClockEntry * entry)
thread_error:
{
/* Could not start the async clock thread */
GST_OBJECT_UNLOCK (clock);
GST_SYSTEM_CLOCK_UNLOCK (clock);
return GST_CLOCK_ERROR;
}
was_unscheduled:
{
GST_OBJECT_UNLOCK (clock);
GST_SYSTEM_CLOCK_UNLOCK (clock);
return GST_CLOCK_UNSCHEDULED;
}
}
@ -998,14 +925,11 @@ was_unscheduled:
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);
GST_SYSTEM_CLOCK_LOCK (clock);
/* change the entry status to unscheduled */
do {
status = GET_ENTRY_STATUS (entry);
@ -1018,10 +942,9 @@ gst_system_clock_id_unschedule (GstClock * clock, GstClockEntry * entry)
* 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;
if (!entry->unscheduled) {
GST_SYSTEM_CLOCK_BROADCAST (clock);
}
}
GST_OBJECT_UNLOCK (clock);
GST_SYSTEM_CLOCK_UNLOCK (clock);
}