--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/gstreamer_core/gst/gstsystemclock.c Thu Dec 17 08:53:32 2009 +0200
@@ -0,0 +1,566 @@
+/* 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 }; */
+#ifdef __SYMBIAN32__
+EXPORT_C
+#endif
+
+
+GType
+gst_system_clock_get_type (void)
+{
+ static GType clock_type = 0;
+
+ if (G_UNLIKELY (clock_type == 0)) {
+ static const GTypeInfo clock_info = {
+ sizeof (GstSystemClockClass),
+ NULL,
+ NULL,
+ (GClassInitFunc) gst_system_clock_class_init,
+ NULL,
+ NULL,
+ sizeof (GstSystemClock),
+ 0,
+ (GInstanceInitFunc) gst_system_clock_init,
+ NULL
+ };
+
+ clock_type = g_type_register_static (GST_TYPE_CLOCK, "GstSystemClock",
+ &clock_info, 0);
+ }
+ return clock_type;
+}
+
+static void
+gst_system_clock_class_init (GstSystemClockClass * klass)
+{
+ GObjectClass *gobject_class;
+ GstObjectClass *gstobject_class;
+ GstClockClass *gstclock_class;
+
+ gobject_class = (GObjectClass *) klass;
+ gstobject_class = (GstObjectClass *) 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_CLOCK_LOCK (clock);
+ gst_system_clock_start_async (clock);
+ GST_CLOCK_UNLOCK (clock);
+#endif
+}
+
+static void
+gst_system_clock_dispose (GObject * object)
+{
+ GstClock *clock = (GstClock *) object;
+
+ GstSystemClock *sysclock = GST_SYSTEM_CLOCK (clock);
+ 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 */
+ gst_object_ref (clock);
+ gst_object_sink (GST_OBJECT (clock));
+
+ _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)
+{
+ GstSystemClock *sysclock = GST_SYSTEM_CLOCK (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 */
+ GST_CAT_DEBUG (GST_CAT_CLOCK, "async entry %p unlocked", 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)
+{
+ GstClockTime entryt, real, now, target;
+ 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);
+
+ now = gst_clock_adjust_unlocked (clock, real);
+ 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;
+ /* Our GCond implementation expects an absolute time against the system clock
+ * as a timeout value. We use our internal time to get the system time and add
+ * the expected timeout to it, this gives us the absolute time of the
+ * timeout. */
+ target = gst_system_clock_get_internal_time (clock) + diff;
+
+ GST_CAT_DEBUG (GST_CAT_CLOCK, "entry %p"
+ " target %" GST_TIME_FORMAT
+ " entry %" GST_TIME_FORMAT
+ " now %" GST_TIME_FORMAT
+ " real %" GST_TIME_FORMAT
+ " diff (entry-now) %" G_GINT64_FORMAT,
+ entry,
+ GST_TIME_ARGS (target),
+ GST_TIME_ARGS (entryt), GST_TIME_ARGS (now), GST_TIME_ARGS (real), diff);
+
+ if (diff > 0) {
+ GTimeVal tv;
+
+#ifdef WAIT_DEBUGGING
+ GstClockTime result, final;
+#endif
+
+ GST_TIME_TO_TIMEVAL (target, tv);
+
+ while (TRUE) {
+ /* now wait on the entry, it either times out or the cond is signaled. */
+ if (!GST_CLOCK_TIMED_WAIT (clock, &tv)) {
+ /* timeout, this is fine, we can report success now */
+ GST_CAT_DEBUG (GST_CAT_CLOCK, "entry %p unlocked after timeout", entry);
+ entry->status = GST_CLOCK_OK;
+
+#ifdef WAIT_DEBUGGING
+ real = GST_CLOCK_GET_CLASS (clock)->get_internal_time (clock);
+ result = gst_clock_adjust_unlocked (clock, real);
+ 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, result,
+ result - entryt,
+ (double) (GstClockTimeDiff) (result - entryt) / GST_SECOND,
+ (final - target),
+ ((double) (GstClockTimeDiff) (final - target)) / GST_SECOND);
+#endif
+ break;
+ } else {
+ /* the waiting is interrupted because the GCond was signaled. This can
+ * be because this or some other entry was unscheduled. */
+ GST_CAT_DEBUG (GST_CAT_CLOCK, "entry %p unlocked with signal", entry);
+ /* if the entry is unscheduled, we can stop waiting for it, else we
+ * continue our while loop. */
+ if (entry->status == GST_CLOCK_UNSCHEDULED)
+ break;
+ /* else restart if we must */
+ if (!restart)
+ break;
+
+ /* 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, "continue waiting for entry %p", entry);
+ }
+ }
+ } 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;
+
+ if (clock->thread != NULL)
+ return TRUE; /* Thread already running. Nothing to do */
+
+ clock->thread = g_thread_create ((GThreadFunc) gst_system_clock_async_thread,
+ clock, TRUE, &error);
+ if (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 */
+ if (!gst_system_clock_start_async (GST_SYSTEM_CLOCK (clock)))
+ goto thread_error;
+
+ /* need to take a ref */
+ gst_clock_id_ref ((GstClockID) entry);
+ /* insert the entry in sorted order */
+ clock->entries = g_list_insert_sorted (clock->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 (clock->entries->data == entry) {
+ GST_CAT_DEBUG (GST_CAT_CLOCK, "async entry added to head, sending signal");
+ /* this will wake up _all_ entries waiting for the clock because we have
+ * only one cond for all entries (makes allocation faster). Entries that
+ * have not timed out will have their status set to BUSY and should continue
+ * to wait. In the case of the async ones, the new head entry should be
+ * taken and waited for. */
+ GST_CLOCK_BROADCAST (clock);
+ }
+ GST_OBJECT_UNLOCK (clock);
+
+ return GST_CLOCK_OK;
+
+thread_error:
+ /* Could not start the async clock thread */
+ return GST_CLOCK_ERROR;
+}
+
+/* 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)
+{
+ GST_CAT_DEBUG (GST_CAT_CLOCK, "unscheduling entry %p", entry);
+
+ GST_OBJECT_LOCK (clock);
+ /* mark entry as unscheduled, then wake up all entries. The entries that did
+ * not timeout will be woken up but immediatly go to sleep again because their
+ * status would still be busy. */
+ entry->status = GST_CLOCK_UNSCHEDULED;
+ GST_CAT_DEBUG (GST_CAT_CLOCK, "sending signal");
+ GST_CLOCK_BROADCAST (clock);
+ GST_OBJECT_UNLOCK (clock);
+}