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pad: improve docs of get/pull_range

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Improve the docs of the get/pull_range functions, define the lifetime of the
buffer in case of errors and short reads.
Make sure the code does what the docs say.
This commit is contained in:
Wim Taymans 2012-03-20 13:14:55 +01:00
parent 7bcc3baf64
commit f9c85a53dc
3 changed files with 97 additions and 48 deletions
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83
gst/gstpad.c
View file

@ -3818,6 +3818,7 @@ gst_pad_get_range_unchecked (GstPad * pad, guint64 offset, guint size,
GstFlowReturn ret;
GstPadGetRangeFunction getrangefunc;
GstObject *parent;
GstBuffer *res_buf;
GST_PAD_STREAM_LOCK (pad);
@ -3831,11 +3832,13 @@ gst_pad_get_range_unchecked (GstPad * pad, guint64 offset, guint size,
if (G_UNLIKELY ((ret = check_sticky (pad))) != GST_FLOW_OK)
goto events_error;
res_buf = *buffer;
/* when one of the probes returns DROPPED, probe_stopped will be called
* and we skip calling the getrange function, *buffer should then contain a
* and we skip calling the getrange function, res_buf should then contain a
* valid result buffer */
PROBE_PULL (pad, GST_PAD_PROBE_TYPE_PULL | GST_PAD_PROBE_TYPE_BLOCK,
*buffer, offset, size, probe_stopped);
res_buf, offset, size, probe_stopped);
ACQUIRE_PARENT (pad, parent, no_parent);
GST_OBJECT_UNLOCK (pad);
@ -3848,7 +3851,7 @@ gst_pad_get_range_unchecked (GstPad * pad, guint64 offset, guint size,
G_GUINT64_FORMAT ", size %u",
GST_DEBUG_FUNCPTR_NAME (getrangefunc), offset, size);
ret = getrangefunc (pad, parent, offset, size, buffer);
ret = getrangefunc (pad, parent, offset, size, &res_buf);
RELEASE_PARENT (parent);
@ -3859,11 +3862,13 @@ gst_pad_get_range_unchecked (GstPad * pad, guint64 offset, guint size,
GST_OBJECT_LOCK (pad);
probed_data:
PROBE_PULL (pad, GST_PAD_PROBE_TYPE_PULL | GST_PAD_PROBE_TYPE_BUFFER,
*buffer, offset, size, probe_stopped_unref);
res_buf, offset, size, probe_stopped_unref);
GST_OBJECT_UNLOCK (pad);
GST_PAD_STREAM_UNLOCK (pad);
*buffer = res_buf;
return ret;
/* ERRORS */
@ -3910,7 +3915,7 @@ probe_stopped:
GST_CAT_LOG_OBJECT (GST_CAT_SCHEDULING, pad,
"probe returned %s", gst_flow_get_name (ret));
if (ret == GST_FLOW_CUSTOM_SUCCESS) {
if (*buffer) {
if (res_buf) {
/* the probe filled the buffer and asks us to not call the getrange
* anymore, we continue with the post probes then. */
GST_DEBUG_OBJECT (pad, "handled buffer");
@ -3936,14 +3941,13 @@ probe_stopped_unref:
ret = GST_FLOW_EOS;
GST_OBJECT_UNLOCK (pad);
GST_PAD_STREAM_UNLOCK (pad);
gst_buffer_unref (*buffer);
*buffer = NULL;
if (*buffer == NULL)
gst_buffer_unref (res_buf);
return ret;
}
get_range_failed:
{
GST_PAD_STREAM_UNLOCK (pad);
*buffer = NULL;
GST_CAT_LEVEL_LOG (GST_CAT_SCHEDULING,
(ret >= GST_FLOW_EOS) ? GST_LEVEL_INFO : GST_LEVEL_WARNING,
pad, "getrange failed, flow: %s", gst_flow_get_name (ret));
@ -3967,8 +3971,22 @@ get_range_failed:
* installed (see gst_pad_set_getrange_function()) this function returns
* #GST_FLOW_NOT_SUPPORTED.
*
* @buffer must point to a variable holding NULL or a variable that
* points to a #GstBuffer that will be filled with the result data.
* If @buffer points to a variable holding NULL, a valid new #GstBuffer will be
* placed in @buffer when this function returns #GST_FLOW_OK. The new buffer
* must be freed with gst_buffer_unref() after usage.
*
* When @buffer points to a variable that points to a valid #GstBuffer, the
* buffer will be filled with the result data when this function returns
* #GST_FLOW_OK. If the provided buffer is larger than @size, only
* @size bytes will be filled in the result buffer and its size will be updated
* accordingly.
*
* Note that less than @size bytes can be returned in @buffer when, for example,
* an EOS condition is near or when @buffer is not large enough to hold @size
* bytes. The caller should check the result buffer size to get the result size.
*
* When this function returns any other result value than #GST_FLOW_OK, @buffer
* will be unchanged.
*
* This is a lowlevel function. Usualy gst_pad_pull_range() is used.
*
@ -3997,7 +4015,7 @@ gst_pad_get_range (GstPad * pad, guint64 offset, guint size,
* @buffer: (out callee-allocates): a pointer to hold the #GstBuffer, returns
* GST_FLOW_ERROR if %NULL.
*
* Pulls a @buffer from the peer pad.
* Pulls a @buffer from the peer pad or fills up a provided buffer.
*
* This function will first trigger the pad block signal if it was
* installed.
@ -4007,14 +4025,23 @@ gst_pad_get_range (GstPad * pad, guint64 offset, guint size,
* See gst_pad_get_range() for a list of return values and for the
* semantics of the arguments of this function.
*
* @buffer must point to a variable holding NULL or a variable that
* points to a #GstBuffer that will be filled with the result data.
* If @buffer points to a variable holding NULL, a valid new #GstBuffer will be
* placed in @buffer when this function returns #GST_FLOW_OK. The new buffer
* must be freed with gst_buffer_unref() after usage. When this function
* returns any other result value, @buffer will still point to NULL.
*
* When @buffer points to a variable that points to a valid #GstBuffer, the
* buffer will be filled with the result data when this function returns
* #GST_FLOW_OK. When this function returns any other result value,
* @buffer will be unchanged. If the provided buffer is larger than @size, only
* @size bytes will be filled in the result buffer and its size will be updated
* accordingly.
*
* Note that less than @size bytes can be returned in @buffer when, for example,
* an EOS condition is near or when @buffer is not large enough to hold @size
* bytes. The caller should check the result buffer size to get the result size.
*
* Returns: a #GstFlowReturn from the peer pad.
* When this function returns #GST_FLOW_OK, @buffer will contain a valid
* #GstBuffer that should be freed with gst_buffer_unref() after usage.
* @buffer may not be used or freed when any other return value than
* #GST_FLOW_OK is returned.
*
* MT safe.
*/
@ -4024,6 +4051,7 @@ gst_pad_pull_range (GstPad * pad, guint64 offset, guint size,
{
GstPad *peer;
GstFlowReturn ret;
GstBuffer *res_buf;
g_return_val_if_fail (GST_IS_PAD (pad), GST_FLOW_ERROR);
g_return_val_if_fail (GST_PAD_IS_SINK (pad), GST_FLOW_ERROR);
@ -4038,11 +4066,13 @@ gst_pad_pull_range (GstPad * pad, guint64 offset, guint size,
if (G_UNLIKELY (GST_PAD_MODE (pad) != GST_PAD_MODE_PULL))
goto wrong_mode;
res_buf = *buffer;
/* when one of the probes returns DROPPED, probe_stopped will be
* called and we skip calling the peer getrange function. *buffer should then
* contain a valid buffer */
PROBE_PULL (pad, GST_PAD_PROBE_TYPE_PULL | GST_PAD_PROBE_TYPE_BLOCK,
*buffer, offset, size, probe_stopped);
res_buf, offset, size, probe_stopped);
if (G_UNLIKELY ((peer = GST_PAD_PEER (pad)) == NULL))
goto not_linked;
@ -4051,7 +4081,7 @@ gst_pad_pull_range (GstPad * pad, guint64 offset, guint size,
pad->priv->using++;
GST_OBJECT_UNLOCK (pad);
ret = gst_pad_get_range_unchecked (peer, offset, size, buffer);
ret = gst_pad_get_range_unchecked (peer, offset, size, &res_buf);
gst_object_unref (peer);
@ -4068,10 +4098,12 @@ gst_pad_pull_range (GstPad * pad, guint64 offset, guint size,
probed_data:
PROBE_PULL (pad, GST_PAD_PROBE_TYPE_PULL | GST_PAD_PROBE_TYPE_BUFFER,
*buffer, offset, size, probe_stopped_unref);
res_buf, offset, size, probe_stopped_unref);
GST_OBJECT_UNLOCK (pad);
*buffer = res_buf;
return ret;
/* ERROR recovery here */
@ -4094,7 +4126,7 @@ probe_stopped:
GST_CAT_LOG_OBJECT (GST_CAT_SCHEDULING, pad, "pre probe returned %s",
gst_flow_get_name (ret));
if (ret == GST_FLOW_CUSTOM_SUCCESS) {
if (*buffer) {
if (res_buf) {
/* the probe filled the buffer and asks us to not forward to the peer
* anymore, we continue with the post probes then */
GST_DEBUG_OBJECT (pad, "handled buffer");
@ -4118,7 +4150,6 @@ not_linked:
}
pull_range_failed:
{
*buffer = NULL;
GST_OBJECT_UNLOCK (pad);
GST_CAT_LEVEL_LOG (GST_CAT_SCHEDULING,
(ret >= GST_FLOW_EOS) ? GST_LEVEL_INFO : GST_LEVEL_WARNING,
@ -4131,12 +4162,10 @@ probe_stopped_unref:
"post probe returned %s", gst_flow_get_name (ret));
GST_OBJECT_UNLOCK (pad);
/* if we drop here, it signals EOS */
if (ret == GST_FLOW_CUSTOM_SUCCESS) {
if (ret == GST_FLOW_CUSTOM_SUCCESS)
ret = GST_FLOW_EOS;
gst_buffer_unref (*buffer);
} else if (ret == GST_FLOW_OK)
gst_buffer_unref (*buffer);
*buffer = NULL;
if (*buffer == NULL)
gst_buffer_unref (res_buf);
return ret;
}
}

45
libs/gst/base/gstbasesrc.c
View file

@ -1379,6 +1379,7 @@ gst_base_src_default_create (GstBaseSrc * src, guint64 offset,
{
GstBaseSrcClass *bclass;
GstFlowReturn ret;
GstBuffer *res_buf;
bclass = GST_BASE_SRC_GET_CLASS (src);
@ -1390,18 +1391,22 @@ gst_base_src_default_create (GstBaseSrc * src, guint64 offset,
if (*buffer == NULL) {
/* downstream did not provide us with a buffer to fill, allocate one
* ourselves */
ret = bclass->alloc (src, offset, size, buffer);
ret = bclass->alloc (src, offset, size, &res_buf);
if (G_UNLIKELY (ret != GST_FLOW_OK))
goto alloc_failed;
} else {
res_buf = *buffer;
}
if (G_LIKELY (size > 0)) {
/* only call fill when there is a size */
ret = bclass->fill (src, offset, size, *buffer);
ret = bclass->fill (src, offset, size, res_buf);
if (G_UNLIKELY (ret != GST_FLOW_OK))
goto not_ok;
}
*buffer = res_buf;
return GST_FLOW_OK;
/* ERRORS */
@ -1419,7 +1424,8 @@ not_ok:
{
GST_DEBUG_OBJECT (src, "fill returned %d (%s)", ret,
gst_flow_get_name (ret));
gst_buffer_unref (*buffer);
if (*buffer == NULL)
gst_buffer_unref (res_buf);
return ret;
}
}
@ -2242,6 +2248,7 @@ gst_base_src_get_range (GstBaseSrc * src, guint64 offset, guint length,
GstFlowReturn ret;
GstBaseSrcClass *bclass;
GstClockReturn status;
GstBuffer *res_buf;
bclass = GST_BASE_SRC_GET_CLASS (src);
@ -2287,15 +2294,17 @@ again:
"calling create offset %" G_GUINT64_FORMAT " length %u, time %"
G_GINT64_FORMAT, offset, length, src->segment.time);
ret = bclass->create (src, offset, length, buf);
res_buf = *buf;
ret = bclass->create (src, offset, length, &res_buf);
/* The create function could be unlocked because we have a pending EOS. It's
* possible that we have a valid buffer from create that we need to
* discard when the create function returned _OK. */
if (G_UNLIKELY (g_atomic_int_get (&src->priv->pending_eos))) {
if (ret == GST_FLOW_OK) {
gst_buffer_unref (*buf);
*buf = NULL;
if (*buf == NULL)
gst_buffer_unref (res_buf);
}
goto eos;
}
@ -2305,14 +2314,14 @@ again:
/* no timestamp set and we are at offset 0, we can timestamp with 0 */
if (offset == 0 && src->segment.time == 0
&& GST_BUFFER_TIMESTAMP (*buf) == -1 && !src->is_live) {
&& GST_BUFFER_TIMESTAMP (res_buf) == -1 && !src->is_live) {
GST_DEBUG_OBJECT (src, "setting first timestamp to 0");
*buf = gst_buffer_make_writable (*buf);
GST_BUFFER_TIMESTAMP (*buf) = 0;
res_buf = gst_buffer_make_writable (res_buf);
GST_BUFFER_TIMESTAMP (res_buf) = 0;
}
/* now sync before pushing the buffer */
status = gst_base_src_do_sync (src, *buf);
status = gst_base_src_do_sync (src, res_buf);
/* waiting for the clock could have made us flushing */
if (G_UNLIKELY (src->priv->flushing))
@ -2331,8 +2340,9 @@ again:
/* this case is triggered when we were waiting for the clock and
* it got unlocked because we did a state change. In any case, get rid of
* the buffer. */
gst_buffer_unref (*buf);
*buf = NULL;
if (*buf == NULL)
gst_buffer_unref (res_buf);
if (!src->live_running) {
/* We return WRONG_STATE when we are not running to stop the dataflow also
* get rid of the produced buffer. */
@ -2352,11 +2362,14 @@ again:
GST_ELEMENT_ERROR (src, CORE, CLOCK,
(_("Internal clock error.")),
("clock returned unexpected return value %d", status));
gst_buffer_unref (*buf);
*buf = NULL;
if (*buf == NULL)
gst_buffer_unref (res_buf);
ret = GST_FLOW_ERROR;
break;
}
if (G_LIKELY (ret == GST_FLOW_OK))
*buf = res_buf;
return ret;
/* ERROR */
@ -2396,8 +2409,8 @@ reached_num_buffers:
flushing:
{
GST_DEBUG_OBJECT (src, "we are flushing");
gst_buffer_unref (*buf);
*buf = NULL;
if (*buf == NULL)
gst_buffer_unref (res_buf);
return GST_FLOW_FLUSHING;
}
eos:

17
plugins/elements/gstqueue2.c
View file

@ -1161,7 +1161,11 @@ gst_queue2_create_read (GstQueue2 * queue, guint64 offset, guint length,
GstFlowReturn ret = GST_FLOW_OK;
/* allocate the output buffer of the requested size */
buf = gst_buffer_new_allocate (NULL, length, NULL);
if (*buffer == NULL)
buf = gst_buffer_new_allocate (NULL, length, NULL);
else
buf = *buffer;
gst_buffer_map (buf, &info, GST_MAP_WRITE);
data = info.data;
@ -1289,21 +1293,24 @@ hit_eos:
{
GST_DEBUG_OBJECT (queue, "EOS hit and we don't have any requested data");
gst_buffer_unmap (buf, &info);
gst_buffer_unref (buf);
if (*buffer == NULL)
gst_buffer_unref (buf);
return GST_FLOW_EOS;
}
out_flushing:
{
GST_DEBUG_OBJECT (queue, "we are flushing");
gst_buffer_unmap (buf, &info);
gst_buffer_unref (buf);
if (*buffer == NULL)
gst_buffer_unref (buf);
return GST_FLOW_FLUSHING;
}
read_error:
{
GST_DEBUG_OBJECT (queue, "we have a read error");
gst_buffer_unmap (buf, &info);
gst_buffer_unref (buf);
if (*buffer == NULL)
gst_buffer_unref (buf);
return ret;
}
}
@ -1322,7 +1329,7 @@ gst_queue2_read_item_from_file (GstQueue2 * queue)
queue->starting_segment = NULL;
} else {
GstFlowReturn ret;
GstBuffer *buffer;
GstBuffer *buffer = NULL;
guint64 reading_pos;
reading_pos = queue->current->reading_pos;