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 * @title: GstFlowCombiner
27 * @short_description: Utility to combine multiple flow returns into one
29 * Utility struct to help handling #GstFlowReturn combination. Useful for
30 * #GstElement<!-- -->s that have multiple source pads and need to combine
31 * the different #GstFlowReturn for those pads.
33 * #GstFlowCombiner works by using the last #GstFlowReturn for all #GstPad
34 * it has in its list and computes the combined return value and provides
37 * To add a new pad to the #GstFlowCombiner use gst_flow_combiner_add_pad().
38 * The new #GstPad is stored with a default value of %GST_FLOW_OK.
40 * In case you want a #GstPad to be removed, use gst_flow_combiner_remove_pad().
42 * Please be aware that this struct isn't thread safe as its designed to be
43 * used by demuxers, those usually will have a single thread operating it.
45 * These functions will take refs on the passed #GstPad<!-- -->s.
47 * Aside from reducing the user's code size, the main advantage of using this
48 * helper struct is to follow the standard rules for #GstFlowReturn combination.
51 * * %GST_FLOW_EOS: only if all returns are EOS too
52 * * %GST_FLOW_NOT_LINKED: only if all returns are NOT_LINKED too
53 * * %GST_FLOW_ERROR or below: if at least one returns an error return
54 * * %GST_FLOW_NOT_NEGOTIATED: if at least one returns a not-negotiated return
55 * * %GST_FLOW_FLUSHING: if at least one returns flushing
56 * * %GST_FLOW_OK: otherwise
58 * %GST_FLOW_ERROR or below, GST_FLOW_NOT_NEGOTIATED and GST_FLOW_FLUSHING are
59 * returned immediately from the gst_flow_combiner_update_flow() function.
65 #include "gstflowcombiner.h"
67 struct _GstFlowCombiner
71 GstFlowReturn last_ret;
72 volatile gint ref_count;
75 GST_DEBUG_CATEGORY_STATIC (flowcombiner_dbg);
76 #define GST_CAT_DEFAULT flowcombiner_dbg
78 G_DEFINE_BOXED_TYPE_WITH_CODE (GstFlowCombiner, gst_flow_combiner,
79 (GBoxedCopyFunc) gst_flow_combiner_ref,
80 (GBoxedFreeFunc) gst_flow_combiner_unref,
81 GST_DEBUG_CATEGORY_INIT (flowcombiner_dbg, "flowcombiner", 0,
85 * gst_flow_combiner_new:
87 * Creates a new #GstFlowCombiner, use gst_flow_combiner_free() to free it.
89 * Returns: A new #GstFlowCombiner
93 gst_flow_combiner_new (void)
95 GstFlowCombiner *combiner = g_slice_new (GstFlowCombiner);
97 g_queue_init (&combiner->pads);
98 combiner->last_ret = GST_FLOW_OK;
99 combiner->ref_count = 1;
101 /* Make sure debug category is initialised */
102 gst_flow_combiner_get_type ();
108 * gst_flow_combiner_free:
109 * @combiner: the #GstFlowCombiner to free
111 * Frees a #GstFlowCombiner struct and all its internal data.
116 gst_flow_combiner_free (GstFlowCombiner * combiner)
118 gst_flow_combiner_unref (combiner);
122 * gst_flow_combiner_ref:
123 * @combiner: the #GstFlowCombiner to add a reference to.
125 * Increments the reference count on the #GstFlowCombiner.
127 * Returns: the #GstFlowCombiner.
132 gst_flow_combiner_ref (GstFlowCombiner * combiner)
134 g_return_val_if_fail (combiner != NULL, NULL);
136 g_atomic_int_inc (&combiner->ref_count);
142 * gst_flow_combiner_unref:
143 * @combiner: the #GstFlowCombiner to unreference.
145 * Decrements the reference count on the #GstFlowCombiner.
150 gst_flow_combiner_unref (GstFlowCombiner * combiner)
152 g_return_if_fail (combiner != NULL);
153 g_return_if_fail (combiner->ref_count > 0);
155 if (g_atomic_int_dec_and_test (&combiner->ref_count)) {
158 while ((pad = g_queue_pop_head (&combiner->pads)))
159 gst_object_unref (pad);
161 g_slice_free (GstFlowCombiner, combiner);
166 * gst_flow_combiner_clear:
167 * @combiner: the #GstFlowCombiner to clear
169 * Removes all pads from a #GstFlowCombiner and resets it to its initial state.
174 gst_flow_combiner_clear (GstFlowCombiner * combiner)
178 g_return_if_fail (combiner != NULL);
180 while ((pad = g_queue_pop_head (&combiner->pads)))
181 gst_object_unref (pad);
182 combiner->last_ret = GST_FLOW_OK;
186 * gst_flow_combiner_reset:
187 * @combiner: the #GstFlowCombiner to clear
189 * Reset flow combiner and all pads to their initial state without removing pads.
194 gst_flow_combiner_reset (GstFlowCombiner * combiner)
198 g_return_if_fail (combiner != NULL);
200 GST_DEBUG ("Reset flow returns");
202 for (iter = combiner->pads.head; iter; iter = iter->next) {
203 GST_PAD_LAST_FLOW_RETURN (iter->data) = GST_FLOW_OK;
206 combiner->last_ret = GST_FLOW_OK;
210 gst_flow_combiner_get_flow (GstFlowCombiner * combiner)
212 GstFlowReturn cret = GST_FLOW_OK;
213 gboolean all_eos = TRUE;
214 gboolean all_notlinked = TRUE;
217 GST_DEBUG ("Combining flow returns");
219 for (iter = combiner->pads.head; iter; iter = iter->next) {
220 GstFlowReturn fret = GST_PAD_LAST_FLOW_RETURN (iter->data);
222 if (fret <= GST_FLOW_NOT_NEGOTIATED || fret == GST_FLOW_FLUSHING) {
223 GST_DEBUG ("Error flow return found, returning");
228 if (fret != GST_FLOW_NOT_LINKED) {
229 all_notlinked = FALSE;
230 if (fret != GST_FLOW_EOS)
235 cret = GST_FLOW_NOT_LINKED;
240 GST_DEBUG ("Combined flow return: %s (%d)", gst_flow_get_name (cret), cret);
245 * gst_flow_combiner_update_flow:
246 * @combiner: the #GstFlowCombiner
247 * @fret: the latest #GstFlowReturn received for a pad in this #GstFlowCombiner
249 * Computes the combined flow return for the pads in it.
251 * The #GstFlowReturn parameter should be the last flow return update for a pad
252 * in this #GstFlowCombiner. It will use this value to be able to shortcut some
253 * combinations and avoid looking over all pads again. e.g. The last combined
254 * return is the same as the latest obtained #GstFlowReturn.
256 * Returns: The combined #GstFlowReturn
260 gst_flow_combiner_update_flow (GstFlowCombiner * combiner, GstFlowReturn fret)
264 g_return_val_if_fail (combiner != NULL, GST_FLOW_ERROR);
266 if (combiner->last_ret == fret) {
270 if (fret <= GST_FLOW_NOT_NEGOTIATED || fret == GST_FLOW_FLUSHING) {
273 ret = gst_flow_combiner_get_flow (combiner);
275 combiner->last_ret = ret;
280 * gst_flow_combiner_update_pad_flow:
281 * @combiner: the #GstFlowCombiner
282 * @pad: the #GstPad whose #GstFlowReturn to update
283 * @fret: the latest #GstFlowReturn received for a pad in this #GstFlowCombiner
285 * Sets the provided pad's last flow return to provided value and computes
286 * the combined flow return for the pads in it.
288 * The #GstFlowReturn parameter should be the last flow return update for a pad
289 * in this #GstFlowCombiner. It will use this value to be able to shortcut some
290 * combinations and avoid looking over all pads again. e.g. The last combined
291 * return is the same as the latest obtained #GstFlowReturn.
293 * Returns: The combined #GstFlowReturn
297 gst_flow_combiner_update_pad_flow (GstFlowCombiner * combiner, GstPad * pad,
300 g_return_val_if_fail (pad != NULL, GST_FLOW_ERROR);
302 GST_PAD_LAST_FLOW_RETURN (pad) = fret;
304 return gst_flow_combiner_update_flow (combiner, fret);
308 * gst_flow_combiner_add_pad:
309 * @combiner: the #GstFlowCombiner
310 * @pad: (transfer none): the #GstPad that is being added
312 * Adds a new #GstPad to the #GstFlowCombiner.
317 gst_flow_combiner_add_pad (GstFlowCombiner * combiner, GstPad * pad)
319 g_return_if_fail (combiner != NULL);
320 g_return_if_fail (pad != NULL);
322 g_queue_push_head (&combiner->pads, gst_object_ref (pad));
326 * gst_flow_combiner_remove_pad:
327 * @combiner: the #GstFlowCombiner
328 * @pad: (transfer none): the #GstPad to remove
330 * Removes a #GstPad from the #GstFlowCombiner.
335 gst_flow_combiner_remove_pad (GstFlowCombiner * combiner, GstPad * pad)
337 g_return_if_fail (combiner != NULL);
338 g_return_if_fail (pad != NULL);
340 if (g_queue_remove (&combiner->pads, pad))
341 gst_object_unref (pad);