--- /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);
+}