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 * None of these functions will take refs on the passed #GstPad<!-- -->s, it
45 * is the caller's responsibility to make sure that the #GstPad exists as long
46 * as this struct exists.
48 * Aside from reducing the user's code size, the main advantage of using this
49 * helper struct is to follow the standard rules for #GstFlowReturn combination.
52 * * %GST_FLOW_EOS: only if all returns are EOS too
53 * * %GST_FLOW_NOT_LINKED: only if all returns are NOT_LINKED too
54 * * %GST_FLOW_ERROR or below: if at least one returns an error return
55 * * %GST_FLOW_NOT_NEGOTIATED: if at least one returns a not-negotiated return
56 * * %GST_FLOW_FLUSHING: if at least one returns flushing
57 * * %GST_FLOW_OK: otherwise
59 * %GST_FLOW_ERROR or below, GST_FLOW_NOT_NEGOTIATED and GST_FLOW_FLUSHING are
60 * returned immediatelly from the gst_flow_combiner_update_flow() function.
66 #include "gstflowcombiner.h"
68 struct _GstFlowCombiner
72 GstFlowReturn last_ret;
73 volatile gint ref_count;
76 static GstFlowCombiner *gst_flow_combiner_ref (GstFlowCombiner * combiner);
77 static void gst_flow_combiner_unref (GstFlowCombiner * combiner);
79 G_DEFINE_BOXED_TYPE (GstFlowCombiner, gst_flow_combiner,
80 (GBoxedCopyFunc) gst_flow_combiner_ref,
81 (GBoxedFreeFunc) gst_flow_combiner_unref);
84 * gst_flow_combiner_new:
86 * Creates a new #GstFlowCombiner, use gst_flow_combiner_free() to free it.
88 * Returns: A new #GstFlowCombiner
92 gst_flow_combiner_new (void)
94 GstFlowCombiner *combiner = g_slice_new (GstFlowCombiner);
96 g_queue_init (&combiner->pads);
97 combiner->last_ret = GST_FLOW_OK;
98 combiner->ref_count = 1;
104 * gst_flow_combiner_free:
105 * @combiner: the #GstFlowCombiner to free
107 * Frees a #GstFlowCombiner struct and all its internal data.
112 gst_flow_combiner_free (GstFlowCombiner * combiner)
114 gst_flow_combiner_unref (combiner);
117 static GstFlowCombiner *
118 gst_flow_combiner_ref (GstFlowCombiner * combiner)
120 g_return_if_fail (combiner != NULL);
122 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_get_flow (GstFlowCombiner * combiner)
144 GstFlowReturn cret = GST_FLOW_OK;
145 gboolean all_eos = TRUE;
146 gboolean all_notlinked = TRUE;
149 GST_DEBUG ("Combining flow returns");
151 for (iter = combiner->pads.head; iter; iter = iter->next) {
152 GstFlowReturn fret = GST_PAD_LAST_FLOW_RETURN (iter->data);
154 if (fret <= GST_FLOW_NOT_NEGOTIATED || fret == GST_FLOW_FLUSHING) {
155 GST_DEBUG ("Error flow return found, returning");
160 if (fret != GST_FLOW_NOT_LINKED) {
161 all_notlinked = FALSE;
162 if (fret != GST_FLOW_EOS)
167 cret = GST_FLOW_NOT_LINKED;
172 GST_DEBUG ("Combined flow return: %s (%d)", gst_flow_get_name (cret), cret);
177 * gst_flow_combiner_update_flow:
178 * @combiner: the #GstFlowCombiner
179 * @fret: the latest #GstFlowReturn received for a pad in this #GstFlowCombiner
181 * Computes the combined flow return for the pads in it.
183 * The #GstFlowReturn paramter should be the last flow return update for a pad
184 * in this #GstFlowCombiner. It will use this value to be able to shortcut some
185 * combinations and avoid looking over all pads again. e.g. The last combined
186 * return is the same as the latest obtained #GstFlowReturn.
188 * Returns: The combined #GstFlowReturn
192 gst_flow_combiner_update_flow (GstFlowCombiner * combiner, GstFlowReturn fret)
196 g_return_val_if_fail (combiner != NULL, GST_FLOW_ERROR);
198 if (combiner->last_ret == fret) {
202 if (fret <= GST_FLOW_NOT_NEGOTIATED || fret == GST_FLOW_FLUSHING) {
205 ret = gst_flow_combiner_get_flow (combiner);
207 combiner->last_ret = ret;
212 * gst_flow_combiner_add_pad:
213 * @combiner: the #GstFlowCombiner
214 * @pad: (transfer-none): the #GstPad that is being added
216 * Adds a new #GstPad to the #GstFlowCombiner.
221 gst_flow_combiner_add_pad (GstFlowCombiner * combiner, GstPad * pad)
223 g_return_if_fail (combiner != NULL);
224 g_return_if_fail (pad != NULL);
226 g_queue_push_head (&combiner->pads, gst_object_ref (pad));
230 * gst_flow_combiner_remove_pad:
231 * @combiner: the #GstFlowCombiner
232 * @pad: (transfer-none): the #GstPad to remove
234 * Removes a #GstPad from the #GstFlowCombiner.
239 gst_flow_combiner_remove_pad (GstFlowCombiner * combiner, GstPad * pad)
241 g_return_if_fail (combiner != NULL);
242 g_return_if_fail (pad != NULL);
244 if (g_queue_remove (&combiner->pads, pad))
245 gst_object_unref (pad);