From ae04702d2381eefad0d92b0d1b8b2b0138f5a41b Mon Sep 17 00:00:00 2001
From: Seungha Yang <seungha@centricular.com>
Date: Sat, 12 Aug 2023 21:16:59 +0900
Subject: [PATCH] wasapi2: Use C++ atomic instead of GLib

Release-Acquire ordering could be faster than MemoryBarrier()

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5176>
---
 .../sys/wasapi2/gstwasapi2client.cpp          | 22 ++++++++++++++-----
 .../sys/wasapi2/gstwasapi2ringbuffer.cpp      | 12 +++++-----
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/subprojects/gst-plugins-bad/sys/wasapi2/gstwasapi2client.cpp b/subprojects/gst-plugins-bad/sys/wasapi2/gstwasapi2client.cpp
index b6b09ee0cd..89e1b507d9 100644
--- a/subprojects/gst-plugins-bad/sys/wasapi2/gstwasapi2client.cpp
+++ b/subprojects/gst-plugins-bad/sys/wasapi2/gstwasapi2client.cpp
@@ -40,6 +40,7 @@
 #include <string>
 #include <locale>
 #include <codecvt>
+#include <atomic>
 
 /* *INDENT-OFF* */
 using namespace ABI::Windows::ApplicationModel::Core;
@@ -315,7 +316,7 @@ public:
   {
     GstWasapi2Client *client = (GstWasapi2Client *) g_weak_ref_get (&client_);
     if (client) {
-      gst_wasapi2_client_set_endpoint_muted (client, !!notify->bMuted);
+      gst_wasapi2_client_set_endpoint_muted (client, notify->bMuted);
       gst_object_unref (client);
     }
     return S_OK;
@@ -349,10 +350,17 @@ enum
 #define DEFAULT_DEVICE_INDEX  -1
 #define DEFAULT_DEVICE_CLASS  GST_WASAPI2_CLIENT_DEVICE_CLASS_CAPTURE
 
+struct GstWasapi2ClientPrivate
+{
+  std::atomic < bool >is_endpoint_muted;
+};
+
 struct _GstWasapi2Client
 {
   GstObject parent;
 
+  GstWasapi2ClientPrivate *priv;
+
   GstWasapi2ClientDeviceClass device_class;
   gchar *device_id;
   gchar *device_name;
@@ -366,7 +374,6 @@ struct _GstWasapi2Client
   GMutex endpoint_volume_lock;
   IAudioEndpointVolume *audio_endpoint_volume;
   GstWasapiEndpointVolumeCallback *endpoint_volume_callback;
-  gint is_endpoint_muted;
 
   GstCaps *supported_caps;
 
@@ -481,6 +488,9 @@ gst_wasapi2_client_init (GstWasapi2Client * self)
 
   self->context = g_main_context_new ();
   self->loop = g_main_loop_new (self->context, FALSE);
+
+  self->priv = new GstWasapi2ClientPrivate ();
+  self->priv->is_endpoint_muted.store (false, std::memory_order_release);
 }
 
 static void
@@ -531,6 +541,8 @@ gst_wasapi2_client_finalize (GObject * object)
 
   g_mutex_clear (&self->endpoint_volume_lock);
 
+  delete self->priv;
+
   G_OBJECT_CLASS (parent_class)->finalize (object);
 }
 
@@ -664,7 +676,7 @@ gst_wasapi2_client_on_endpoint_volume_activated (GstWasapi2Client * self,
 
         hr = audio_endpoint_volume->GetMute (&initially_muted);
         if (gst_wasapi2_result (hr)) {
-          gst_wasapi2_client_set_endpoint_muted (self, !!initially_muted);
+          gst_wasapi2_client_set_endpoint_muted (self, initially_muted);
         }
       }
     }
@@ -679,7 +691,7 @@ gst_wasapi2_client_set_endpoint_muted (GstWasapi2Client * self, gboolean muted)
 {
   GST_DEBUG_OBJECT (self, "Audio Endpoint Volume: muted=%d", muted);
 
-  g_atomic_int_set (&self->is_endpoint_muted, muted);
+  self->priv->is_endpoint_muted.store (muted, std::memory_order_release);
 }
 
 /* *INDENT-OFF* */
@@ -1287,5 +1299,5 @@ gst_wasapi2_client_is_endpoint_muted (GstWasapi2Client * client)
 {
   g_return_val_if_fail (GST_IS_WASAPI2_CLIENT (client), FALSE);
 
-  return g_atomic_int_get (&client->is_endpoint_muted);
+  return client->priv->is_endpoint_muted.load (std::memory_order_acquire);
 }
diff --git a/subprojects/gst-plugins-bad/sys/wasapi2/gstwasapi2ringbuffer.cpp b/subprojects/gst-plugins-bad/sys/wasapi2/gstwasapi2ringbuffer.cpp
index f60eca9542..b4648a4f09 100644
--- a/subprojects/gst-plugins-bad/sys/wasapi2/gstwasapi2ringbuffer.cpp
+++ b/subprojects/gst-plugins-bad/sys/wasapi2/gstwasapi2ringbuffer.cpp
@@ -22,6 +22,7 @@
 #include <mfapi.h>
 #include <wrl.h>
 #include <memory>
+#include <atomic>
 
 GST_DEBUG_CATEGORY_STATIC (gst_wasapi2_ring_buffer_debug);
 #define GST_CAT_DEFAULT gst_wasapi2_ring_buffer_debug
@@ -141,6 +142,7 @@ private:
 struct GstWasapi2RingBufferPrivate
 {
   std::shared_ptr<GstWasapi2RingBufferPtr> obj_ptr;
+  std::atomic<bool> monitor_device_mute;
 };
 /* *INDENT-ON* */
 
@@ -186,8 +188,6 @@ struct _GstWasapi2RingBuffer
   gboolean mute_changed;
   gboolean volume_changed;
 
-  gboolean monitor_device_mute;
-
   GstCaps *supported_caps;
 
   GstWasapi2RingBufferPrivate *priv;
@@ -254,6 +254,7 @@ gst_wasapi2_ring_buffer_init (GstWasapi2RingBuffer * self)
 
   self->priv = new GstWasapi2RingBufferPrivate ();
   self->priv->obj_ptr = std::make_shared < GstWasapi2RingBufferPtr > (self);
+  self->priv->monitor_device_mute.store (false, std::memory_order_release);
 }
 
 static void
@@ -484,7 +485,7 @@ gst_wasapi2_ring_buffer_read (GstWasapi2RingBuffer * self)
   gint segment;
   guint8 *readptr;
   gint len;
-  gboolean is_device_muted;
+  bool is_device_muted;
 
   if (!capture_client) {
     GST_ERROR_OBJECT (self, "IAudioCaptureClient is not available");
@@ -498,7 +499,8 @@ gst_wasapi2_ring_buffer_read (GstWasapi2RingBuffer * self)
     goto out;
   }
 
-  is_device_muted = g_atomic_int_get (&self->monitor_device_mute) &&
+  is_device_muted =
+      self->priv->monitor_device_mute.load (std::memory_order_acquire) &&
       gst_wasapi2_client_is_endpoint_muted (self->client);
 
   to_read_bytes = to_read * GST_AUDIO_INFO_BPF (info);
@@ -1517,5 +1519,5 @@ gst_wasapi2_ring_buffer_set_device_mute_monitoring (GstWasapi2RingBuffer * buf,
 {
   g_return_if_fail (GST_IS_WASAPI2_RING_BUFFER (buf));
 
-  g_atomic_int_set (&buf->monitor_device_mute, value);
+  buf->priv->monitor_device_mute.store (value, std::memory_order_release);
 }