alsa: allow per feature registration

Split plugin into features including
elements and device providers which
can be indiviually registered during
a static build.

More details here:

https://gitlab.freedesktop.org/gstreamer/gst-build/-/merge_requests/199
https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/661

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/merge_requests/900>

ext/alsa/gstalsaelement.c

@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) 2001 CodeFactory AB
+ * Copyright (C) 2001 Thomas Nyberg <thomas@codefactory.se>
+ * Copyright (C) 2001-2002 Andy Wingo <apwingo@eos.ncsu.edu>
+ * Copyright (C) 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
+ * Copyright (C) 2020 Huawei Technologies Co., Ltd.
+ *
+ * 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gstalsaelements.h"
+#include "gstalsadeviceprovider.h"
+
+#include <gst/gst-i18n-plugin.h>
+
+GST_DEBUG_CATEGORY (alsa_debug);
+
+/* ALSA debugging wrapper */
+/* *INDENT-OFF* */
+G_GNUC_PRINTF (5, 6)
+/* *INDENT-ON* */
+static void
+gst_alsa_error_wrapper (const char *file, int line, const char *function,
+    int err, const char *fmt, ...)
+{
+#ifndef GST_DISABLE_GST_DEBUG
+  va_list args;
+  gchar *str;
+
+  va_start (args, fmt);
+  str = g_strdup_vprintf (fmt, args);
+  va_end (args);
+  /* FIXME: use GST_LEVEL_ERROR here? Currently warning is used because we're
+   * able to catch enough of the errors that would be printed otherwise
+   */
+  gst_debug_log (alsa_debug, GST_LEVEL_WARNING, file, function, line, NULL,
+      "alsalib error: %s%s%s", str, err ? ": " : "",
+      err ? snd_strerror (err) : "");
+  g_free (str);
+#endif
+}
+
+GST_DEVICE_PROVIDER_REGISTER_DEFINE (alsadeviceprovider, "alsadeviceprovider",
+    GST_RANK_SECONDARY, GST_TYPE_ALSA_DEVICE_PROVIDER);
+
+gboolean
+alsa_element_init (GstPlugin * plugin)
+{
+  static gsize res = FALSE;
+
+  if (g_once_init_enter (&res)) {
+    GST_DEBUG_CATEGORY_INIT (alsa_debug, "alsa", 0, "alsa plugins");
+#ifdef ENABLE_NLS
+    GST_DEBUG ("binding text domain %s to locale dir %s", GETTEXT_PACKAGE,
+        LOCALEDIR);
+    bindtextdomain (GETTEXT_PACKAGE, LOCALEDIR);
+    bind_textdomain_codeset (GETTEXT_PACKAGE, "UTF-8");
+#endif
+    if (snd_lib_error_set_handler (gst_alsa_error_wrapper) != 0)
+      GST_WARNING ("failed to set alsa error handler");
+    g_once_init_leave (&res, TRUE);
+  }
+  return res;
+}

ext/alsa/gstalsaelements.h

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2020 Huawei Technologies Co., Ltd.
+ *   @Author: Julian Bouzas <julian.bouzas@collabora.com>
+ *
+ * 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.
+ */
+
+#ifndef __GST_ALSA_ELEMENTS_H__
+#define __GST_ALSA_ELEMENTS_H__
+
+#include <gst/gst.h>
+
+G_BEGIN_DECLS
+
+G_GNUC_INTERNAL gboolean alsa_element_init (GstPlugin * plugin);
+
+GST_ELEMENT_REGISTER_DECLARE (alsasrc);
+GST_ELEMENT_REGISTER_DECLARE (alsasink);
+GST_ELEMENT_REGISTER_DECLARE (alsamidisrc);
+
+GST_DEVICE_PROVIDER_REGISTER_DECLARE(alsadeviceprovider);
+
+G_END_DECLS
+
+#endif /* __GST_ALSA_ELEMENTS_H__ */

ext/alsa/gstalsamidisrc.c

@@ -42,6 +42,7 @@
 #  include "config.h"
 #endif
 
+#include "gstalsaelements.h"
 #include "gstalsamidisrc.h"
 
 GST_DEBUG_CATEGORY_STATIC (gst_alsa_midi_src_debug);
@@ -305,6 +306,10 @@ enum
 #define gst_alsa_midi_src_parent_class parent_class
 G_DEFINE_TYPE_WITH_CODE (GstAlsaMidiSrc, gst_alsa_midi_src, GST_TYPE_PUSH_SRC,
     _do_init);
+#define _do_element_init \
+    ret |= alsa_element_init (plugin);
+GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (alsamidisrc, "alsamidisrc",
+    GST_RANK_PRIMARY, GST_TYPE_ALSA_MIDI_SRC, _do_element_init);
 
 static void gst_alsa_midi_src_set_property (GObject * object, guint prop_id,
     const GValue * value, GParamSpec * pspec);

ext/alsa/gstalsaplugin.c

@@ -23,70 +23,21 @@
 #include "config.h"
 #endif
 
-#include "gstalsasink.h"
-#include "gstalsasrc.h"
-#include "gstalsamidisrc.h"
+#include "gstalsaelements.h"
 #include "gstalsadeviceprovider.h"
 
 #include <gst/gst-i18n-plugin.h>
 
-GST_DEBUG_CATEGORY (alsa_debug);
-
-/* ALSA debugging wrapper */
-/* *INDENT-OFF* */
-G_GNUC_PRINTF (5, 6)
-/* *INDENT-ON* */
-static void
-gst_alsa_error_wrapper (const char *file, int line, const char *function,
-    int err, const char *fmt, ...)
-{
-#ifndef GST_DISABLE_GST_DEBUG
-  va_list args;
-  gchar *str;
-
-  va_start (args, fmt);
-  str = g_strdup_vprintf (fmt, args);
-  va_end (args);
-  /* FIXME: use GST_LEVEL_ERROR here? Currently warning is used because we're
-   * able to catch enough of the errors that would be printed otherwise
-   */
-  gst_debug_log (alsa_debug, GST_LEVEL_WARNING, file, function, line, NULL,
-      "alsalib error: %s%s%s", str, err ? ": " : "",
-      err ? snd_strerror (err) : "");
-  g_free (str);
-#endif
-}
-
 static gboolean
 plugin_init (GstPlugin * plugin)
 {
-  int err;
-
-  if (!gst_element_register (plugin, "alsasrc", GST_RANK_PRIMARY,
-          GST_TYPE_ALSA_SRC))
-    return FALSE;
-  if (!gst_element_register (plugin, "alsasink", GST_RANK_PRIMARY,
-          GST_TYPE_ALSA_SINK))
-    return FALSE;
-  if (!gst_element_register (plugin, "alsamidisrc", GST_RANK_PRIMARY,
-          GST_TYPE_ALSA_MIDI_SRC))
-    return FALSE;
-  if (!gst_device_provider_register (plugin, "alsadeviceprovider",
-          GST_RANK_SECONDARY, GST_TYPE_ALSA_DEVICE_PROVIDER))
-    return FALSE;
+  gboolean ret = FALSE;
 
-  GST_DEBUG_CATEGORY_INIT (alsa_debug, "alsa", 0, "alsa plugins");
-
-#ifdef ENABLE_NLS
-  GST_DEBUG ("binding text domain %s to locale dir %s", GETTEXT_PACKAGE,
-      LOCALEDIR);
-  bindtextdomain (GETTEXT_PACKAGE, LOCALEDIR);
-  bind_textdomain_codeset (GETTEXT_PACKAGE, "UTF-8");
-#endif
+  ret |= GST_DEVICE_PROVIDER_REGISTER (alsadeviceprovider, plugin);
 
-  err = snd_lib_error_set_handler (gst_alsa_error_wrapper);
-  if (err != 0)
-    GST_WARNING ("failed to set alsa error handler");
+  ret |= GST_ELEMENT_REGISTER (alsasrc, plugin);
+  ret |= GST_ELEMENT_REGISTER (alsasink, plugin);
+  ret |= GST_ELEMENT_REGISTER (alsamidisrc, plugin);
 
   return TRUE;
 }

ext/alsa/gstalsasink.c

@@ -47,6 +47,7 @@
 #include <getopt.h>
 #include <alsa/asoundlib.h>
 
+#include "gstalsaelements.h"
 #include "gstalsa.h"
 #include "gstalsasink.h"
 
@@ -72,10 +73,12 @@ enum
   PROP_LAST
 };
 
-static void gst_alsasink_init_interfaces (GType type);
+#define _do_init \
+    ret |= alsa_element_init (plugin);
 #define gst_alsasink_parent_class parent_class
-G_DEFINE_TYPE_WITH_CODE (GstAlsaSink, gst_alsasink,
-    GST_TYPE_AUDIO_SINK, gst_alsasink_init_interfaces (g_define_type_id));
+G_DEFINE_TYPE (GstAlsaSink, gst_alsasink, GST_TYPE_AUDIO_SINK);
+GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (alsasink, "alsasink", GST_RANK_PRIMARY,
+    GST_TYPE_ALSA_SINK, _do_init);
 
 static void gst_alsasink_finalise (GObject * object);
 static void gst_alsasink_set_property (GObject * object,
@@ -136,14 +139,6 @@ gst_alsasink_finalise (GObject * object)
   G_OBJECT_CLASS (parent_class)->finalize (object);
 }
 
-static void
-gst_alsasink_init_interfaces (GType type)
-{
-#if 0
-  gst_alsa_type_add_device_property_probe_interface (type);
-#endif
-}
-
 static void
 gst_alsasink_class_init (GstAlsaSinkClass * klass)
 {

ext/alsa/gstalsasrc.c

@@ -45,6 +45,7 @@
 #include <getopt.h>
 #include <alsa/asoundlib.h>
 
+#include "gstalsaelements.h"
 #include "gstalsasrc.h"
 
 #include <gst/gst-i18n-plugin.h>
@@ -70,6 +71,10 @@ enum
 
 #define gst_alsasrc_parent_class parent_class
 G_DEFINE_TYPE (GstAlsaSrc, gst_alsasrc, GST_TYPE_AUDIO_SRC);
+#define _do_init \
+    ret |= alsa_element_init (plugin);
+GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (alsasrc, "alsasrc", GST_RANK_PRIMARY,
+    GST_TYPE_ALSA_SRC, _do_init);
 
 static void gst_alsasrc_finalize (GObject * object);
 static void gst_alsasrc_set_property (GObject * object,

ext/alsa/meson.build

@@ -2,6 +2,7 @@ alsa_sources = [
   'gstalsa.c',
   'gstalsadeviceprovider.c',
   'gstalsamidisrc.c',
+  'gstalsaelement.c',
   'gstalsaplugin.c',
   'gstalsasink.c',
   'gstalsasrc.c',