gstreamer/libs/gst/base/gstflowcombiner.c

267 lines
7.2 KiB
C
Raw Normal View History

/* GStreamer
*
* Copyright (C) 2014 Samsung Electronics. All rights reserved.
* Author: Thiago Santos <ts.santos@sisa.samsung.com>
*
* gstflowcombiner.c: utility to combine multiple flow returns into a single one
*
* 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., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
/**
* SECTION:gstflowcombiner
* @short_description: Utility to combine multiple flow returns into one
*
* Utility struct to help handling #GstFlowReturn combination. Useful for
* #GstElement<!-- -->s that have multiple source pads and need to combine
* the different #GstFlowReturn for those pads.
*
* #GstFlowCombiner works by using the last #GstFlowReturn for all #GstPad
* it has in its list and computes the combined return value and provides
* it to the caller.
*
* To add a new pad to the #GstFlowCombiner use gst_flow_combiner_add_pad().
* The new #GstPad is stored with a default value of %GST_FLOW_OK.
*
* In case you want a #GstPad to be removed, use gst_flow_combiner_remove_pad().
*
* Please be aware that this struct isn't thread safe as its designed to be
* used by demuxers, those usually will have a single thread operating it.
*
* These functions will take refs on the passed #GstPad<!-- -->s.
*
* Aside from reducing the user's code size, the main advantage of using this
* helper struct is to follow the standard rules for #GstFlowReturn combination.
* These rules are:
*
* * %GST_FLOW_EOS: only if all returns are EOS too
* * %GST_FLOW_NOT_LINKED: only if all returns are NOT_LINKED too
* * %GST_FLOW_ERROR or below: if at least one returns an error return
* * %GST_FLOW_NOT_NEGOTIATED: if at least one returns a not-negotiated return
* * %GST_FLOW_FLUSHING: if at least one returns flushing
* * %GST_FLOW_OK: otherwise
*
* %GST_FLOW_ERROR or below, GST_FLOW_NOT_NEGOTIATED and GST_FLOW_FLUSHING are
* returned immediatelly from the gst_flow_combiner_update_flow() function.
*
* Since: 1.4
*/
#include <gst/gst.h>
#include "gstflowcombiner.h"
struct _GstFlowCombiner
{
GQueue pads;
GstFlowReturn last_ret;
volatile gint ref_count;
};
static GstFlowCombiner *gst_flow_combiner_ref (GstFlowCombiner * combiner);
static void gst_flow_combiner_unref (GstFlowCombiner * combiner);
G_DEFINE_BOXED_TYPE (GstFlowCombiner, gst_flow_combiner,
(GBoxedCopyFunc) gst_flow_combiner_ref,
(GBoxedFreeFunc) gst_flow_combiner_unref);
/**
* gst_flow_combiner_new:
*
* Creates a new #GstFlowCombiner, use gst_flow_combiner_free() to free it.
*
* Returns: A new #GstFlowCombiner
* Since: 1.4
*/
GstFlowCombiner *
gst_flow_combiner_new (void)
{
GstFlowCombiner *combiner = g_slice_new (GstFlowCombiner);
g_queue_init (&combiner->pads);
combiner->last_ret = GST_FLOW_OK;
combiner->ref_count = 1;
return combiner;
}
/**
* gst_flow_combiner_free:
* @combiner: the #GstFlowCombiner to free
*
* Frees a #GstFlowCombiner struct and all its internal data.
*
* Since: 1.4
*/
void
gst_flow_combiner_free (GstFlowCombiner * combiner)
{
gst_flow_combiner_unref (combiner);
}
static GstFlowCombiner *
gst_flow_combiner_ref (GstFlowCombiner * combiner)
{
g_return_val_if_fail (combiner != NULL, NULL);
g_atomic_int_inc (&combiner->ref_count);
return combiner;
}
static void
gst_flow_combiner_unref (GstFlowCombiner * combiner)
{
g_return_if_fail (combiner != NULL);
g_return_if_fail (combiner->ref_count > 0);
if (g_atomic_int_dec_and_test (&combiner->ref_count)) {
GstPad *pad;
while ((pad = g_queue_pop_head (&combiner->pads)))
gst_object_unref (pad);
g_slice_free (GstFlowCombiner, combiner);
}
}
/**
* gst_flow_combiner_clear:
* @combiner: the #GstFlowCombiner to clear
*
* Removes all pads from a #GstFlowCombiner and resets it to its initial state.
*
* Since: 1.6
*/
void
gst_flow_combiner_clear (GstFlowCombiner * combiner)
{
GstPad *pad;
g_return_if_fail (combiner != NULL);
while ((pad = g_queue_pop_head (&combiner->pads)))
gst_object_unref (pad);
combiner->last_ret = GST_FLOW_OK;
}
static GstFlowReturn
gst_flow_combiner_get_flow (GstFlowCombiner * combiner)
{
GstFlowReturn cret = GST_FLOW_OK;
gboolean all_eos = TRUE;
gboolean all_notlinked = TRUE;
GList *iter;
GST_DEBUG ("Combining flow returns");
for (iter = combiner->pads.head; iter; iter = iter->next) {
GstFlowReturn fret = GST_PAD_LAST_FLOW_RETURN (iter->data);
if (fret <= GST_FLOW_NOT_NEGOTIATED || fret == GST_FLOW_FLUSHING) {
GST_DEBUG ("Error flow return found, returning");
cret = fret;
goto done;
}
if (fret != GST_FLOW_NOT_LINKED) {
all_notlinked = FALSE;
if (fret != GST_FLOW_EOS)
all_eos = FALSE;
}
}
if (all_notlinked)
cret = GST_FLOW_NOT_LINKED;
else if (all_eos)
cret = GST_FLOW_EOS;
done:
GST_DEBUG ("Combined flow return: %s (%d)", gst_flow_get_name (cret), cret);
return cret;
}
/**
* gst_flow_combiner_update_flow:
* @combiner: the #GstFlowCombiner
* @fret: the latest #GstFlowReturn received for a pad in this #GstFlowCombiner
*
* Computes the combined flow return for the pads in it.
*
* The #GstFlowReturn paramter should be the last flow return update for a pad
* in this #GstFlowCombiner. It will use this value to be able to shortcut some
* combinations and avoid looking over all pads again. e.g. The last combined
* return is the same as the latest obtained #GstFlowReturn.
*
* Returns: The combined #GstFlowReturn
* Since: 1.4
*/
GstFlowReturn
gst_flow_combiner_update_flow (GstFlowCombiner * combiner, GstFlowReturn fret)
{
GstFlowReturn ret;
g_return_val_if_fail (combiner != NULL, GST_FLOW_ERROR);
if (combiner->last_ret == fret) {
return fret;
}
if (fret <= GST_FLOW_NOT_NEGOTIATED || fret == GST_FLOW_FLUSHING) {
ret = fret;
} else {
ret = gst_flow_combiner_get_flow (combiner);
}
combiner->last_ret = ret;
return ret;
}
/**
* gst_flow_combiner_add_pad:
* @combiner: the #GstFlowCombiner
* @pad: (transfer none): the #GstPad that is being added
*
* Adds a new #GstPad to the #GstFlowCombiner.
*
* Since: 1.4
*/
void
gst_flow_combiner_add_pad (GstFlowCombiner * combiner, GstPad * pad)
{
g_return_if_fail (combiner != NULL);
g_return_if_fail (pad != NULL);
g_queue_push_head (&combiner->pads, gst_object_ref (pad));
}
/**
* gst_flow_combiner_remove_pad:
* @combiner: the #GstFlowCombiner
* @pad: (transfer none): the #GstPad to remove
*
* Removes a #GstPad from the #GstFlowCombiner.
*
* Since: 1.4
*/
void
gst_flow_combiner_remove_pad (GstFlowCombiner * combiner, GstPad * pad)
{
g_return_if_fail (combiner != NULL);
g_return_if_fail (pad != NULL);
if (g_queue_remove (&combiner->pads, pad))
gst_object_unref (pad);
}