msdk: adds util functions to handle GstContext

To share GstMsdkContext with each msdk element,
it will be using GstContext.

Most common code is from gstreamer-vaapi.

https://bugzilla.gnome.org/show_bug.cgi?id=790752

sys/msdk/Makefile.am

@@ -2,6 +2,7 @@ plugin_LTLIBRARIES = libgstmsdk.la
 
 libgstmsdk_la_SOURCES = \
 	gstmsdkcontext.c \
+	gstmsdkcontextutil.c \
 	gstmsdksystemmemory.c \
 	gstmsdkvideomemory.c \
 	gstmsdkbufferpool.c \
@@ -25,6 +26,7 @@ nodist_EXTRA_libgstmsdk_la_SOURCES = not_present.cxx
 noinst_HEADERS = \
 	msdk.h \
 	gstmsdkcontext.h \
+	gstmsdkcontextutil.h \
 	gstmsdksystemmemory.h \
 	gstmsdkvideomemory.h \
 	gstmsdkbufferpool.h \

sys/msdk/gstmsdkcontextutil.c

+/* GStreamer Intel MSDK plugin
+ * Copyright (c) 2018, Intel Corporation
+ * Copyright (c) 2018, Igalia S.L.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGDECE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "gstmsdkcontextutil.h"
+
+GST_DEBUG_CATEGORY_STATIC (GST_CAT_CONTEXT);
+
+static void
+_init_context_debug (void)
+{
+#ifndef GST_DISABLE_GST_DEBUG
+  static volatile gsize _init = 0;
+
+  if (g_once_init_enter (&_init)) {
+    GST_DEBUG_CATEGORY_GET (GST_CAT_CONTEXT, "GST_CONTEXT");
+    g_once_init_leave (&_init, 1);
+  }
+#endif
+}
+
+static gboolean
+context_pad_query (const GValue * item, GValue * value, gpointer user_data)
+{
+  GstPad *const pad = g_value_get_object (item);
+  GstQuery *const query = user_data;
+
+  if (gst_pad_peer_query (pad, query)) {
+    g_value_set_boolean (value, TRUE);
+    return FALSE;
+  }
+
+  GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, pad, "context pad peer query failed");
+  return TRUE;
+}
+
+static gboolean
+_gst_context_run_query (GstElement * element, GstQuery * query,
+    GstPadDirection direction)
+{
+  GstIteratorFoldFunction const func = context_pad_query;
+  GstIterator *it;
+  GValue res = { 0 };
+
+  g_value_init (&res, G_TYPE_BOOLEAN);
+  g_value_set_boolean (&res, FALSE);
+
+  /* Ask neighbour */
+  if (direction == GST_PAD_SRC)
+    it = gst_element_iterate_src_pads (element);
+  else
+    it = gst_element_iterate_sink_pads (element);
+
+  while (gst_iterator_fold (it, func, &res, query) == GST_ITERATOR_RESYNC)
+    gst_iterator_resync (it);
+  gst_iterator_free (it);
+
+  return g_value_get_boolean (&res);
+}
+
+static gboolean
+_gst_context_get_from_query (GstElement * element, GstQuery * query,
+    GstPadDirection direction)
+{
+  GstContext *ctxt;
+
+  if (!_gst_context_run_query (element, query, direction))
+    return FALSE;
+
+  gst_query_parse_context (query, &ctxt);
+  if (!ctxt)
+    return FALSE;
+
+  GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element,
+      "found context (%" GST_PTR_FORMAT ") in %s query", ctxt,
+      direction == GST_PAD_SRC ? "downstream" : "upstream");
+
+  gst_element_set_context (element, ctxt);
+  return TRUE;
+}
+
+static void
+_gst_context_query (GstElement * element, const gchar * context_type)
+{
+  GstQuery *query;
+  GstMessage *msg;
+
+  /* 2) Query downstream with GST_QUERY_CONTEXT for the context and
+     check if downstream already has a context of the specific
+     type */
+
+  /* 3) Query upstream with GST_QUERY_CONTEXT for the context and
+     check if upstream already has a context of the specific
+     type */
+  query = gst_query_new_context (context_type);
+  if (_gst_context_get_from_query (element, query, GST_PAD_SRC))
+    goto found;
+  if (_gst_context_get_from_query (element, query, GST_PAD_SINK))
+    goto found;
+
+  /* 4) Post a GST_MESSAGE_NEED_CONTEXT message on the bus with
+     the required context types and afterwards check if an
+     usable context was set now as in 1). The message could
+     be handled by the parent bins of the element and the
+     application. */
+  GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element,
+      "posting `need-context' message");
+
+  msg = gst_message_new_need_context (GST_OBJECT_CAST (element), context_type);
+  if (!gst_element_post_message (element, msg))
+    GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element, "No bus attached");
+
+  /* Whomever responds to the need-context message performs a
+     GstElement::set_context() with the required context in which the
+     element is required to update the display_ptr */
+
+found:
+  gst_query_unref (query);
+}
+
+gboolean
+gst_msdk_context_prepare (GstElement * element, GstMsdkContext ** context_ptr)
+{
+  g_return_val_if_fail (element != NULL, FALSE);
+  g_return_val_if_fail (context_ptr != NULL, FALSE);
+
+  _init_context_debug ();
+
+  /* 1) Check if the element already has a context of the specific type. */
+  if (*context_ptr) {
+    GST_LOG_OBJECT (element, "already have a context %" GST_PTR_FORMAT,
+        *context_ptr);
+    return TRUE;
+  }
+
+  _gst_context_query (element, GST_MSDK_CONTEXT_TYPE_NAME);
+
+  if (*context_ptr)
+    GST_LOG_OBJECT (element, "found a context %" GST_PTR_FORMAT, *context_ptr);
+
+  return *context_ptr != NULL;
+}
+
+gboolean
+gst_msdk_context_get_context (GstContext * context,
+    GstMsdkContext ** msdk_context)
+{
+  const GstStructure *structure;
+  const gchar *type;
+
+  g_return_val_if_fail (GST_IS_CONTEXT (context), FALSE);
+
+  type = gst_context_get_context_type (context);
+
+  if (!g_strcmp0 (type, GST_MSDK_CONTEXT_TYPE_NAME)) {
+    structure = gst_context_get_structure (context);
+    return gst_structure_get (structure, GST_MSDK_CONTEXT_TYPE_NAME,
+        GST_TYPE_MSDK_CONTEXT, msdk_context, NULL);
+  }
+
+  return FALSE;
+}
+
+static void
+gst_msdk_context_propagate (GstElement * element, GstMsdkContext * msdk_context)
+{
+  GstContext *context;
+  GstStructure *structure;
+  GstMessage *msg;
+
+  context = gst_context_new (GST_MSDK_CONTEXT_TYPE_NAME, FALSE);
+
+  structure = gst_context_writable_structure (context);
+  gst_structure_set (structure, GST_MSDK_CONTEXT_TYPE_NAME,
+      GST_TYPE_MSDK_CONTEXT, msdk_context, NULL);
+
+  gst_element_set_context (element, context);
+
+  GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element,
+      "posting `have-context' message with MSDK context %" GST_PTR_FORMAT,
+      msdk_context);
+
+  msg = gst_message_new_have_context (GST_OBJECT_CAST (element), context);
+  if (!gst_element_post_message (element, msg)) {
+    GST_CAT_INFO_OBJECT (GST_CAT_CONTEXT, element, "No bus attached");
+  }
+}
+
+gboolean
+gst_msdk_context_ensure_context (GstElement * element, gboolean hardware)
+{
+  GstMsdkContext *msdk_context;
+
+  msdk_context = gst_msdk_context_new (hardware);
+  if (!msdk_context) {
+    GST_ERROR_OBJECT (element, "Context creation failed");
+    return FALSE;
+  }
+
+  GST_INFO_OBJECT (element, "New MSDK Context %p", msdk_context);
+
+  gst_msdk_context_propagate (element, msdk_context);
+  gst_object_unref (msdk_context);
+
+  return TRUE;
+}

sys/msdk/gstmsdkcontextutil.h

+/* GStreamer Intel MSDK plugin
+ * Copyright (c) 2018, Intel Corporation
+ * Copyright (c) 2018, Igalia S.L.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGDECE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef GST_MSDK_CONTEXT_UTIL_H
+#define GST_MSDK_CONTEXT_UTIL_H
+
+#include "msdk.h"
+#include "gstmsdkcontext.h"
+#ifndef _WIN32
+#include <va/va.h>
+#endif
+
+#define GST_MSDK_CONTEXT_TYPE_NAME "gst.msdk.Context"
+
+G_BEGIN_DECLS
+
+gboolean
+gst_msdk_context_prepare (GstElement * element, GstMsdkContext ** context_ptr);
+
+gboolean
+gst_msdk_context_get_context (GstContext * context, GstMsdkContext ** msdk_context);
+
+gboolean
+gst_msdk_context_ensure_context (GstElement * element, gboolean hardware);
+
+G_END_DECLS
+
+#endif /* GST_MSDK_CONTEXT_UTIL_H */

sys/msdk/meson.build

 msdk_sources = [
   'gstmsdk.c',
   'gstmsdkcontext.c',
+  'gstmsdkcontextutil.c',
   'gstmsdksystemmemory.c',
   'gstmsdkvideomemory.c',
   'gstmsdkbufferpool.c',