[gnome-remote-desktop] session-rdp: Handle all graphics operations in a separate thread

[Jonas Ådahl <jadahl src gnome org>]

commit 0ecacc677e1523b80541c85a8e865347e9eaa5c3
Author: Pascal Nowack <Pascal Nowack gmx de>
Date:   Tue Aug 24 12:12:49 2021 +0200

    session-rdp: Handle all graphics operations in a separate thread
    
    Currently, all graphics operations happen in the main thread, which
    means that remote input is delayed until the current graphics
    operation, such as encoding frame content for example, is done.
    On very slow servers or with the raw bitmaps path in the legacy path,
    this highly reduces the input responsiveness, as the main thread can
    become fully occupied.
    
    So, run all graphics operations in a separate thread, while the main
    thread takes care of pushing the input events to mutter.

 src/grd-session-rdp.c | 76 +++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 56 insertions(+), 20 deletions(-)
---
diff --git a/src/grd-session-rdp.c b/src/grd-session-rdp.c
index 8435ab2..195767b 100644
--- a/src/grd-session-rdp.c
+++ b/src/grd-session-rdp.c
@@ -42,6 +42,10 @@
 #include "grd-settings.h"
 #include "grd-stream.h"
 
+#ifdef HAVE_NVENC
+#include "grd-rdp-nvenc.h"
+#endif /* HAVE_NVENC */
+
 #define DISCRETE_SCROLL_STEP 10.0
 
 typedef enum _RdpPeerFlag
@@ -124,6 +128,9 @@ struct _GrdSessionRdp
   HANDLE start_event;
   HANDLE stop_event;
 
+  GThread *graphics_thread;
+  GMainContext *graphics_context;
+
   GrdRdpSurface *rdp_surface;
   Pointer *last_pointer;
   GHashTable *pointer_cache;
@@ -1632,7 +1639,7 @@ rdp_peer_post_connect (freerdp_peer *peer)
 
       rdp_peer_context->graphics_pipeline =
         grd_rdp_graphics_pipeline_new (session_rdp,
-                                       NULL,
+                                       session_rdp->graphics_context,
                                        rdp_peer_context->vcm,
                                        session_rdp->stop_event,
                                        peer->context,
@@ -1907,6 +1914,27 @@ socket_thread_func (gpointer data)
   return NULL;
 }
 
+static gpointer
+graphics_thread_func (gpointer data)
+{
+  GrdSessionRdp *session_rdp = data;
+
+#ifdef HAVE_NVENC
+  if (session_rdp->rdp_nvenc)
+    grd_rdp_nvenc_push_cuda_context (session_rdp->rdp_nvenc);
+#endif /* HAVE_NVENC */
+
+  while (WaitForSingleObject (session_rdp->stop_event, 0) == WAIT_TIMEOUT)
+    g_main_context_iteration (session_rdp->graphics_context, TRUE);
+
+#ifdef HAVE_NVENC
+  if (session_rdp->rdp_nvenc)
+    grd_rdp_nvenc_pop_cuda_context (session_rdp->rdp_nvenc);
+#endif /* HAVE_NVENC */
+
+  return NULL;
+}
+
 GrdSessionRdp *
 grd_session_rdp_new (GrdRdpServer      *rdp_server,
                      GSocketConnection *connection,
@@ -1946,24 +1974,13 @@ grd_session_rdp_new (GrdRdpServer      *rdp_server,
 #ifdef HAVE_NVENC
   session_rdp->rdp_nvenc = rdp_nvenc;
 #endif /* HAVE_NVENC */
-  session_rdp->start_event = CreateEvent (NULL, TRUE, FALSE, NULL);
-  session_rdp->stop_event = CreateEvent (NULL, TRUE, FALSE, NULL);
 
   session_rdp->socket_thread = g_thread_new ("RDP socket thread",
                                              socket_thread_func,
                                              session_rdp);
-  if (!session_rdp->socket_thread)
-    {
-      g_warning ("Failed to create socket thread");
-
-      g_clear_pointer (&session_rdp->stop_event, CloseHandle);
-      g_clear_pointer (&session_rdp->start_event, CloseHandle);
-      g_object_unref (connection);
-      g_free (password);
-      g_free (username);
-
-      return NULL;
-    }
+  session_rdp->graphics_thread = g_thread_new ("RDP graphics thread",
+                                               graphics_thread_func,
+                                               session_rdp);
 
   init_rdp_session (session_rdp, username, password);
 
@@ -2014,6 +2031,15 @@ grd_session_rdp_stop (GrdSession *session)
         rdp_peer_context->network_autodetection);
     }
 
+  if (session_rdp->graphics_thread)
+    {
+      g_assert (session_rdp->graphics_context);
+      g_assert (WaitForSingleObject (session_rdp->stop_event, 0) != WAIT_TIMEOUT);
+
+      g_main_context_wakeup (session_rdp->graphics_context);
+      g_clear_pointer (&session_rdp->graphics_thread, g_thread_join);
+    }
+
   g_clear_object (&session_rdp->pipewire_stream);
 
   g_clear_object (&rdp_peer_context->clipboard_rdp);
@@ -2050,9 +2076,6 @@ grd_session_rdp_stop (GrdSession *session)
                                clear_pointer_bitmap,
                                NULL);
 
-  g_clear_pointer (&session_rdp->stop_event, CloseHandle);
-  g_clear_pointer (&session_rdp->start_event, CloseHandle);
-
   g_clear_handle_id (&session_rdp->close_session_idle_id, g_source_remove);
 }
 
@@ -2094,6 +2117,7 @@ grd_session_rdp_stream_ready (GrdSession *session,
                               GrdStream  *stream)
 {
   GrdSessionRdp *session_rdp = GRD_SESSION_RDP (session);
+  GMainContext *graphics_context = session_rdp->graphics_context;
   uint32_t pipewire_node_id;
   uint16_t refresh_rate;
   g_autoptr (GError) error = NULL;
@@ -2101,7 +2125,7 @@ grd_session_rdp_stream_ready (GrdSession *session,
   pipewire_node_id = grd_stream_get_pipewire_node_id (stream);
   refresh_rate = session_rdp->rdp_surface->refresh_rate;
   session_rdp->pipewire_stream = grd_rdp_pipewire_stream_new (session_rdp,
-                                                              NULL,
+                                                              graphics_context,
                                                               pipewire_node_id,
                                                               refresh_rate,
                                                               &error);
@@ -2147,10 +2171,16 @@ grd_session_rdp_dispose (GObject *object)
       g_clear_pointer (&session_rdp->pending_encode_source, g_source_unref);
     }
 
+  g_assert (!session_rdp->graphics_thread);
+  g_clear_pointer (&session_rdp->graphics_context, g_main_context_unref);
+
   g_clear_pointer (&session_rdp->pressed_unicode_keys, g_hash_table_unref);
   g_clear_pointer (&session_rdp->pressed_keys, g_hash_table_unref);
   g_clear_pointer (&session_rdp->pointer_cache, g_hash_table_unref);
 
+  g_clear_pointer (&session_rdp->stop_event, CloseHandle);
+  g_clear_pointer (&session_rdp->start_event, CloseHandle);
+
   G_OBJECT_CLASS (grd_session_rdp_parent_class)->dispose (object);
 }
 
@@ -2210,6 +2240,9 @@ static GSourceFuncs pending_encode_source_funcs =
 static void
 grd_session_rdp_init (GrdSessionRdp *session_rdp)
 {
+  session_rdp->start_event = CreateEvent (NULL, TRUE, FALSE, NULL);
+  session_rdp->stop_event = CreateEvent (NULL, TRUE, FALSE, NULL);
+
   session_rdp->pointer_cache = g_hash_table_new (NULL, are_pointer_bitmaps_equal);
   session_rdp->pressed_keys = g_hash_table_new (NULL, NULL);
   session_rdp->pressed_unicode_keys = g_hash_table_new (NULL, NULL);
@@ -2221,12 +2254,15 @@ grd_session_rdp_init (GrdSessionRdp *session_rdp)
 
   session_rdp->rdp_event_queue = grd_rdp_event_queue_new (session_rdp);
 
+  session_rdp->graphics_context = g_main_context_new ();
+
   session_rdp->pending_encode_source = g_source_new (&pending_encode_source_funcs,
                                                      sizeof (GSource));
   g_source_set_callback (session_rdp->pending_encode_source,
                          encode_pending_frames, session_rdp, NULL);
   g_source_set_ready_time (session_rdp->pending_encode_source, -1);
-  g_source_attach (session_rdp->pending_encode_source, NULL);
+  g_source_attach (session_rdp->pending_encode_source,
+                   session_rdp->graphics_context);
 }
 
 static void