3 * Copyright (C) 2014 Samsung Electronics. All rights reserved.
4 * Author: Thiago Santos <ts.santos@sisa.samsung.com>
6 * gstflowcombiner.c: utility to combine multiple flow returns into a single one
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Library General Public
10 * License as published by the Free Software Foundation; either
11 * version 2 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Library General Public License for more details.
18 * You should have received a copy of the GNU Library General Public
19 * License along with this library; if not, write to the
20 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
21 * Boston, MA 02110-1301, USA.
25 * SECTION:gstflowcombiner
26 * @short_description: Utility to combine multiple flow returns into one
28 * Utility struct to help handling #GstFlowReturn combination. Useful for
29 * #GstElement<!-- -->s that have multiple source pads and need to combine
30 * the different #GstFlowReturn for those pads.
32 * #GstFlowCombiner works by using the last #GstFlowReturn for all #GstPad
33 * it has in its list and computes the combined return value and provides
36 * To add a new pad to the #GstFlowCombiner use gst_flow_combiner_add_pad().
37 * The new #GstPad is stored with a default value of %GST_FLOW_OK.
39 * In case you want a #GstPad to be removed, use gst_flow_combiner_remove_pad().
41 * Please be aware that this struct isn't thread safe as its designed to be
42 * used by demuxers, those usually will have a single thread operating it.
44 * These functions will take refs on the passed #GstPad<!-- -->s.
46 * Aside from reducing the user's code size, the main advantage of using this
47 * helper struct is to follow the standard rules for #GstFlowReturn combination.
50 * * %GST_FLOW_EOS: only if all returns are EOS too
51 * * %GST_FLOW_NOT_LINKED: only if all returns are NOT_LINKED too
52 * * %GST_FLOW_ERROR or below: if at least one returns an error return
53 * * %GST_FLOW_NOT_NEGOTIATED: if at least one returns a not-negotiated return
54 * * %GST_FLOW_FLUSHING: if at least one returns flushing
55 * * %GST_FLOW_OK: otherwise
57 * %GST_FLOW_ERROR or below, GST_FLOW_NOT_NEGOTIATED and GST_FLOW_FLUSHING are
58 * returned immediatelly from the gst_flow_combiner_update_flow() function.
64 #include "gstflowcombiner.h"
66 struct _GstFlowCombiner
70 GstFlowReturn last_ret;
71 volatile gint ref_count;
74 static GstFlowCombiner *gst_flow_combiner_ref (GstFlowCombiner * combiner);
75 static void gst_flow_combiner_unref (GstFlowCombiner * combiner);
77 G_DEFINE_BOXED_TYPE (GstFlowCombiner, gst_flow_combiner,
78 (GBoxedCopyFunc) gst_flow_combiner_ref,
79 (GBoxedFreeFunc) gst_flow_combiner_unref);
82 * gst_flow_combiner_new:
84 * Creates a new #GstFlowCombiner, use gst_flow_combiner_free() to free it.
86 * Returns: A new #GstFlowCombiner
90 gst_flow_combiner_new (void)
92 GstFlowCombiner *combiner = g_slice_new (GstFlowCombiner);
94 g_queue_init (&combiner->pads);
95 combiner->last_ret = GST_FLOW_OK;
96 combiner->ref_count = 1;
102 * gst_flow_combiner_free:
103 * @combiner: the #GstFlowCombiner to free
105 * Frees a #GstFlowCombiner struct and all its internal data.
110 gst_flow_combiner_free (GstFlowCombiner * combiner)
112 gst_flow_combiner_unref (combiner);
115 static GstFlowCombiner *
116 gst_flow_combiner_ref (GstFlowCombiner * combiner)
118 g_return_val_if_fail (combiner != NULL, NULL);
120 g_atomic_int_inc (&combiner->ref_count);
126 gst_flow_combiner_unref (GstFlowCombiner * combiner)
128 g_return_if_fail (combiner != NULL);
129 g_return_if_fail (combiner->ref_count > 0);
131 if (g_atomic_int_dec_and_test (&combiner->ref_count)) {
134 while ((pad = g_queue_pop_head (&combiner->pads)))
135 gst_object_unref (pad);
137 g_slice_free (GstFlowCombiner, combiner);
142 * gst_flow_combiner_clear:
143 * @combiner: the #GstFlowCombiner to clear
145 * Removes all pads from a #GstFlowCombiner and resets it to its initial state.
150 gst_flow_combiner_clear (GstFlowCombiner * combiner)
154 g_return_if_fail (combiner != NULL);
156 while ((pad = g_queue_pop_head (&combiner->pads)))
157 gst_object_unref (pad);
158 combiner->last_ret = GST_FLOW_OK;
162 * gst_flow_combiner_reset:
163 * @combiner: the #GstFlowCombiner to clear
165 * Removes all pads from a #GstFlowCombiner and resets it to its initial state.
170 gst_flow_combiner_reset (GstFlowCombiner * combiner)
174 g_return_if_fail (combiner != NULL);
176 GST_DEBUG ("Reset flow returns");
178 for (iter = combiner->pads.head; iter; iter = iter->next) {
179 GST_PAD_LAST_FLOW_RETURN (iter->data) = GST_FLOW_OK;
182 combiner->last_ret = GST_FLOW_OK;
186 gst_flow_combiner_get_flow (GstFlowCombiner * combiner)
188 GstFlowReturn cret = GST_FLOW_OK;
189 gboolean all_eos = TRUE;
190 gboolean all_notlinked = TRUE;
193 GST_DEBUG ("Combining flow returns");
195 for (iter = combiner->pads.head; iter; iter = iter->next) {
196 GstFlowReturn fret = GST_PAD_LAST_FLOW_RETURN (iter->data);
198 if (fret <= GST_FLOW_NOT_NEGOTIATED || fret == GST_FLOW_FLUSHING) {
199 GST_DEBUG ("Error flow return found, returning");
204 if (fret != GST_FLOW_NOT_LINKED) {
205 all_notlinked = FALSE;
206 if (fret != GST_FLOW_EOS)
211 cret = GST_FLOW_NOT_LINKED;
216 GST_DEBUG ("Combined flow return: %s (%d)", gst_flow_get_name (cret), cret);
221 * gst_flow_combiner_update_flow:
222 * @combiner: the #GstFlowCombiner
223 * @fret: the latest #GstFlowReturn received for a pad in this #GstFlowCombiner
225 * Computes the combined flow return for the pads in it.
227 * The #GstFlowReturn parameter should be the last flow return update for a pad
228 * in this #GstFlowCombiner. It will use this value to be able to shortcut some
229 * combinations and avoid looking over all pads again. e.g. The last combined
230 * return is the same as the latest obtained #GstFlowReturn.
232 * Returns: The combined #GstFlowReturn
236 gst_flow_combiner_update_flow (GstFlowCombiner * combiner, GstFlowReturn fret)
240 g_return_val_if_fail (combiner != NULL, GST_FLOW_ERROR);
242 if (combiner->last_ret == fret) {
246 if (fret <= GST_FLOW_NOT_NEGOTIATED || fret == GST_FLOW_FLUSHING) {
249 ret = gst_flow_combiner_get_flow (combiner);
251 combiner->last_ret = ret;
256 * gst_flow_combiner_add_pad:
257 * @combiner: the #GstFlowCombiner
258 * @pad: (transfer none): the #GstPad that is being added
260 * Adds a new #GstPad to the #GstFlowCombiner.
265 gst_flow_combiner_add_pad (GstFlowCombiner * combiner, GstPad * pad)
267 g_return_if_fail (combiner != NULL);
268 g_return_if_fail (pad != NULL);
270 g_queue_push_head (&combiner->pads, gst_object_ref (pad));
274 * gst_flow_combiner_remove_pad:
275 * @combiner: the #GstFlowCombiner
276 * @pad: (transfer none): the #GstPad to remove
278 * Removes a #GstPad from the #GstFlowCombiner.
283 gst_flow_combiner_remove_pad (GstFlowCombiner * combiner, GstPad * pad)
285 g_return_if_fail (combiner != NULL);
286 g_return_if_fail (pad != NULL);
288 if (g_queue_remove (&combiner->pads, pad))
289 gst_object_unref (pad);