[gnome-remote-desktop] rdp-buffer-pool: Unmap buffer resources with low priority GSource

[Jonas Ådahl <jadahl src gnome org>]

commit 1a7b1fe7602b9b652b14c40fd427275da0d704b0
Author: Pascal Nowack <Pascal Nowack gmx de>
Date:   Sun Jan 9 23:38:23 2022 +0100

    rdp-buffer-pool: Unmap buffer resources with low priority GSource
    
    With the previously added APIs, add a new low priority GSource to unmap
    all untaken buffers.
    This ensures that the latency of the first two frames, introduced by
    the mapping operations, after the system being idle is smaller than
    the unmap operations before this change.
    
    A run of the GSource is queued, as soon as a buffer is returned.

 src/grd-rdp-buffer-pool.c | 50 ++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 5 deletions(-)
---
diff --git a/src/grd-rdp-buffer-pool.c b/src/grd-rdp-buffer-pool.c
index 05bed058..6327f0e8 100644
--- a/src/grd-rdp-buffer-pool.c
+++ b/src/grd-rdp-buffer-pool.c
@@ -47,6 +47,8 @@ struct _GrdRdpBufferPool
   GSource *resize_pool_source;
   uint32_t minimum_pool_size;
 
+  GSource *unmap_source;
+
   GMutex pool_mutex;
   GHashTable *buffer_table;
   uint32_t buffers_taken;
@@ -189,6 +191,7 @@ grd_rdp_buffer_pool_release_buffer (GrdRdpBufferPool *buffer_pool,
 {
   BufferInfo *buffer_info;
   gboolean queue_pool_resize;
+  gboolean queue_unmap;
 
   g_mutex_lock (&buffer_pool->pool_mutex);
   if (!g_hash_table_lookup_extended (buffer_pool->buffer_table, buffer,
@@ -201,10 +204,13 @@ grd_rdp_buffer_pool_release_buffer (GrdRdpBufferPool *buffer_pool,
   --buffer_pool->buffers_taken;
 
   queue_pool_resize = should_resize_buffer_pool (buffer_pool);
+  queue_unmap = buffer_has_mapped_data (buffer);
   g_mutex_unlock (&buffer_pool->pool_mutex);
 
   if (queue_pool_resize)
     g_source_set_ready_time (buffer_pool->resize_pool_source, 0);
+  if (queue_unmap)
+    g_source_set_ready_time (buffer_pool->unmap_source, 0);
 }
 
 static gboolean
@@ -228,7 +234,28 @@ resize_buffer_pool (gpointer user_data)
 }
 
 static gboolean
-resize_pool_source_dispatch (GSource     *source,
+unmap_untaken_buffers (gpointer user_data)
+{
+  GrdRdpBufferPool *buffer_pool = user_data;
+  GHashTableIter iter;
+  GrdRdpBuffer *buffer;
+  BufferInfo *buffer_info;
+
+  g_mutex_lock (&buffer_pool->pool_mutex);
+  g_hash_table_iter_init (&iter, buffer_pool->buffer_table);
+  while (g_hash_table_iter_next (&iter, (gpointer *) &buffer,
+                                        (gpointer *) &buffer_info))
+    {
+      if (!buffer_info->buffer_taken)
+        grd_rdp_buffer_unmap_resources (buffer);
+    }
+  g_mutex_unlock (&buffer_pool->pool_mutex);
+
+  return G_SOURCE_CONTINUE;
+}
+
+static gboolean
+buffer_pool_source_dispatch (GSource     *source,
                              GSourceFunc  callback,
                              gpointer     user_data)
 {
@@ -237,9 +264,9 @@ resize_pool_source_dispatch (GSource     *source,
   return callback (user_data);
 }
 
-static GSourceFuncs resize_pool_source_funcs =
+static GSourceFuncs buffer_pool_source_funcs =
 {
-  .dispatch = resize_pool_source_dispatch,
+  .dispatch = buffer_pool_source_dispatch,
 };
 
 static gboolean
@@ -270,13 +297,21 @@ grd_rdp_buffer_pool_new (GrdEglThread     *egl_thread,
   buffer_pool->cuda_stream = cuda_stream;
   buffer_pool->minimum_pool_size = minimum_size;
 
-  buffer_pool->resize_pool_source = g_source_new (&resize_pool_source_funcs,
-                                                 sizeof (GSource));
+  buffer_pool->resize_pool_source = g_source_new (&buffer_pool_source_funcs,
+                                                  sizeof (GSource));
   g_source_set_callback (buffer_pool->resize_pool_source,
                          resize_buffer_pool, buffer_pool, NULL);
   g_source_set_ready_time (buffer_pool->resize_pool_source, -1);
   g_source_attach (buffer_pool->resize_pool_source, NULL);
 
+  buffer_pool->unmap_source = g_source_new (&buffer_pool_source_funcs,
+                                            sizeof (GSource));
+  g_source_set_callback (buffer_pool->unmap_source,
+                         unmap_untaken_buffers, buffer_pool, NULL);
+  g_source_set_priority (buffer_pool->unmap_source, G_PRIORITY_LOW);
+  g_source_set_ready_time (buffer_pool->unmap_source, -1);
+  g_source_attach (buffer_pool->unmap_source, NULL);
+
   if (!fill_buffer_pool (buffer_pool))
     return NULL;
 
@@ -310,6 +345,11 @@ grd_rdp_buffer_pool_dispose (GObject *object)
 {
   GrdRdpBufferPool *buffer_pool = GRD_RDP_BUFFER_POOL (object);
 
+  if (buffer_pool->unmap_source)
+    {
+      g_source_destroy (buffer_pool->unmap_source);
+      g_clear_pointer (&buffer_pool->unmap_source, g_source_unref);
+    }
   if (buffer_pool->resize_pool_source)
     {
       g_source_destroy (buffer_pool->resize_pool_source);