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basesrc: Make locking of the segment a bit more strict and update documentation

Browse source 
Updating the segment values must only be done while holding the
STREAM_LOCK and OBJECT_LOCK. This means, reading can be done as
long as one of them is held, not both, which removes some lock-unlock
blocks from performance critical code paths.

Also document, that gst_base_src_set_format() *must* be called in
states <= READY and add an assertion for this. Changing the format
later will completely mess up the segment information.
This commit is contained in:
Sebastian Dröge 2010-02-12 14:49:52 +01:00
parent 8d1c45f513
commit fae502056f
2 changed files with 11 additions and 21 deletions
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29
libs/gst/base/gstbasesrc.c
View file

@ -553,12 +553,15 @@ gst_base_src_is_live (GstBaseSrc * src)
* If a format of GST_FORMAT_BYTES is set, the element will be able to
* operate in pull mode if the #GstBaseSrc.is_seekable() returns TRUE.
*
* This function must only be called in states < %GST_STATE_PAUSED.
*
* Since: 0.10.1
*/
void
gst_base_src_set_format (GstBaseSrc * src, GstFormat format)
{
g_return_if_fail (GST_IS_BASE_SRC (src));
g_return_if_fail (GST_STATE (src) <= GST_STATE_READY);
GST_OBJECT_LOCK (src);
gst_segment_init (&src->segment, format);
@ -1340,9 +1343,7 @@ gst_base_src_perform_seek (GstBaseSrc * src, GstEvent * event, gboolean unlock)
* copy the current segment info into the temp segment that we can actually
* attempt the seek with. We only update the real segment if the seek suceeds. */
if (!seekseg_configured) {
GST_OBJECT_LOCK (src);
memcpy (&seeksegment, &src->segment, sizeof (GstSegment));
GST_OBJECT_UNLOCK (src);
/* now configure the final seek segment */
if (event) {
@ -1383,7 +1384,6 @@ gst_base_src_perform_seek (GstBaseSrc * src, GstEvent * event, gboolean unlock)
* are not yet providing data as we still have the STREAM_LOCK. */
gst_pad_push_event (src->srcpad, tevent);
} else if (res && src->data.ABI.running) {
GST_OBJECT_LOCK (src);
/* we are running the current segment and doing a non-flushing seek,
* close the segment first based on the last_stop. */
GST_DEBUG_OBJECT (src, "closing running segment %" G_GINT64_FORMAT
@ -1397,7 +1397,6 @@ gst_base_src_perform_seek (GstBaseSrc * src, GstEvent * event, gboolean unlock)
src->segment.rate, src->segment.applied_rate, src->segment.format,
src->segment.start, src->segment.last_stop, src->segment.time);
gst_event_set_seqnum (src->priv->close_segment, seqnum);
GST_OBJECT_UNLOCK (src);
}
/* The subclass must have converted the segment to the processing format
@ -1957,6 +1956,7 @@ no_sync:
}
}
/* Called with STREAM_LOCK and LIVE_LOCK */
static gboolean
gst_base_src_update_length (GstBaseSrc * src, guint64 offset, guint * length)
{
@ -1967,12 +1967,10 @@ gst_base_src_update_length (GstBaseSrc * src, guint64 offset, guint * length)
bclass = GST_BASE_SRC_GET_CLASS (src);
GST_OBJECT_LOCK (src);
format = src->segment.format;
stop = src->segment.stop;
/* get total file size */
size = (guint64) src->segment.duration;
GST_OBJECT_UNLOCK (src);
/* only operate if we are working with bytes */
if (format != GST_FORMAT_BYTES)
@ -2000,10 +1998,6 @@ gst_base_src_update_length (GstBaseSrc * src, guint64 offset, guint * length)
if (!bclass->get_size (src, &size))
size = -1;
GST_OBJECT_LOCK (src);
gst_segment_set_duration (&src->segment, GST_FORMAT_BYTES, size);
GST_OBJECT_UNLOCK (src);
/* make sure we don't exceed the configured segment stop
* if it was set */
if (stop != -1)
@ -2022,9 +2016,10 @@ gst_base_src_update_length (GstBaseSrc * src, guint64 offset, guint * length)
}
}
/* keep track of current position. segment is in bytes, we checked
* that above. */
/* keep track of current position and update duration.
* segment is in bytes, we checked that above. */
GST_OBJECT_LOCK (src);
gst_segment_set_duration (&src->segment, GST_FORMAT_BYTES, size);
gst_segment_set_last_stop (&src->segment, GST_FORMAT_BYTES, offset);
GST_OBJECT_UNLOCK (src);
@ -2316,7 +2311,6 @@ gst_base_src_loop (GstPad * pad)
blocksize = src->blocksize;
GST_OBJECT_LOCK (src);
/* if we operate in bytes, we can calculate an offset */
if (src->segment.format == GST_FORMAT_BYTES) {
position = src->segment.last_stop;
@ -2333,7 +2327,6 @@ gst_base_src_loop (GstPad * pad)
}
} else
position = -1;
GST_OBJECT_UNLOCK (src);
GST_LOG_OBJECT (src, "next_ts %" GST_TIME_FORMAT " size %lu",
GST_TIME_ARGS (position), blocksize);
@ -2374,7 +2367,6 @@ gst_base_src_loop (GstPad * pad)
g_list_free (tags);
}
GST_OBJECT_LOCK (src);
/* figure out the new position */
switch (src->segment.format) {
case GST_FORMAT_BYTES:
@ -2437,9 +2429,10 @@ gst_base_src_loop (GstPad * pad)
/* when going reverse, all buffers are DISCONT */
src->priv->discont = TRUE;
}
GST_OBJECT_LOCK (src);
gst_segment_set_last_stop (&src->segment, src->segment.format, position);
}
GST_OBJECT_UNLOCK (src);
}
if (G_UNLIKELY (src->priv->discont)) {
buf = gst_buffer_make_metadata_writable (buf);
@ -2487,11 +2480,9 @@ pause:
gint64 last_stop;
/* perform EOS logic */
GST_OBJECT_LOCK (src);
flag_segment = (src->segment.flags & GST_SEEK_FLAG_SEGMENT) != 0;
format = src->segment.format;
last_stop = src->segment.last_stop;
GST_OBJECT_UNLOCK (src);
if (flag_segment) {
GstMessage *message;
@ -2664,9 +2655,7 @@ gst_base_src_start (GstBaseSrc * basesrc)
GST_OBJECT_FLAG_SET (basesrc, GST_BASE_SRC_STARTED);
GST_OBJECT_LOCK (basesrc);
format = basesrc->segment.format;
GST_OBJECT_UNLOCK (basesrc);
/* figure out the size */
if (format == GST_FORMAT_BYTES) {

3
libs/gst/base/gstbasesrc.h
View file

@ -91,8 +91,9 @@ struct _GstBaseSrc {
GstClockID clock_id; /* for syncing */
GstClockTime end_time;
/* MT-protected (with STREAM_LOCK) */
/* MT-protected (with STREAM_LOCK *and* OBJECT_LOCK) */
GstSegment segment;
/* MT-protected (with STREAM_LOCK) */
gboolean need_newsegment;
guint64 offset; /* current offset in the resource, unused */