Add tearing control protocol

* 12to11-test.xml (test_surface) <committed>: New event.
* 12to11.c (XLMain): Initialize tearing control.
* Imakefile (SRCS, OBJS): Add tearing_control.c/.o.
(tearing-control-v1): New scanner target.

* compositor.h (enum _PresentationHint): New enum.
(struct _State): Add fields for tearing control.
(enum _ClientDataType): Add tearing control type.
* surface.c (SavePendingState, InternalCommit1): Handle
presentation hints.
* test.c (Commit): Send new committed event.
* tests/Imakefile (OBJS16, SRCS16): Add
tearing_control_test.c/tearing_control_test.o.
(PROGRAMS): Add tearing_control_test.
(tearing-control-v1): New scanner target.

* tests/buffer_test.c (test_names): Fix typos.
* tests/run_tests.sh (standard_tests): Add tearing_control_test.
* tests/svnignore.txt: Add tearing_control_test.
* xdg_surface.c (UpdateFrameRefreshPrediction): Return whether
or not refresh prediction is on.
(MaybeRunLateFrame): Don't clear StateLateFrame until after
SubcompositorUpdate.
(WasFrameQueued): New function.
(NoteFrame): If a frame was queued and async presentation was
requested, present now.

12to11-test.xml

@@ -178,10 +178,10 @@
 
     <event name="activated">
       <description summary="role activated">
-	The activated is sent when the xdg_activation protocol causes
+	The activated event is sent when the xdg_activation protocol
-	the surface associated with the role to be activated.  Its
+	causes the surface associated with the role to be activated.
-	parameters constitute the timestamp at which the activation
+	Its parameters constitute the timestamp at which the
-	occurred.
+	activation occurred.
 
 	If the surface that created the activation token used to
 	activate this test surface belongs to the same client that
@@ -194,6 +194,20 @@
       <arg name="activator_surface" type="object" interface="wl_surface"
 	   allow-null="true"/>
     </event>
+
+    <event name="committed">
+      <description summary="commit happened">
+	The committed event is sent immediately after the role is
+	committed, and contains some information about what choices
+	were taken by the protocol translator during presentation.
+
+	presentation_hint is the presentation hint used by the
+	protocol translator during drawing.  Its value is that of the
+	enumerator used internally, where 1 means async and 0 means
+	vsync.
+      </description>
+      <arg name="presentation_hint" type="uint"/>
+    </event>
   </interface>
 
   <interface name="test_scale_lock" version="1">

12to11.c

@@ -249,6 +249,7 @@ XLMain (int argc, char **argv)
   XLInitIdleInhibit ();
   XLInitPointerGestures ();
   XLInitXdgActivation ();
+  XLInitTearingControl ();
   XLInitTest ();
 
   /* This has to come after the rest of the initialization.  */

Imakefile

@@ -18,8 +18,8 @@ MakeSubdirs($(SUBDIRS))
 DependSubdirs($(SUBDIRS))
 #endif
 
-             SRCS = 12to11.c run.c alloc.c fns.c output.c compositor.c surface.c region.c shm.c atoms.c subcompositor.c positioner.c xdg_wm.c xdg_surface.c xdg_toplevel.c frame_clock.c xerror.c ewmh.c timer.c subsurface.c seat.c data_device.c xdg_popup.c dmabuf.c buffer.c select.c xdata.c xsettings.c dnd.c icon_surface.c primary_selection.c renderer.c picture_renderer.c explicit_synchronization.c transform.c wp_viewporter.c decoration.c text_input.c single_pixel_buffer.c drm_lease.c pointer_constraints.c time.c relative_pointer.c keyboard_shortcuts_inhibit.c idle_inhibit.c process.c fence_ring.c pointer_gestures.c test.c buffer_release.c xdg_activation.c
+             SRCS = 12to11.c run.c alloc.c fns.c output.c compositor.c surface.c region.c shm.c atoms.c subcompositor.c positioner.c xdg_wm.c xdg_surface.c xdg_toplevel.c frame_clock.c xerror.c ewmh.c timer.c subsurface.c seat.c data_device.c xdg_popup.c dmabuf.c buffer.c select.c xdata.c xsettings.c dnd.c icon_surface.c primary_selection.c renderer.c picture_renderer.c explicit_synchronization.c transform.c wp_viewporter.c decoration.c text_input.c single_pixel_buffer.c drm_lease.c pointer_constraints.c time.c relative_pointer.c keyboard_shortcuts_inhibit.c idle_inhibit.c process.c fence_ring.c pointer_gestures.c test.c buffer_release.c xdg_activation.c tearing_control.c
-             OBJS = 12to11.o run.o alloc.o fns.o output.o compositor.o surface.o region.o shm.o atoms.o subcompositor.o positioner.o xdg_wm.o xdg_surface.o xdg_toplevel.o frame_clock.o xerror.o ewmh.o timer.o subsurface.o seat.o data_device.o xdg_popup.o dmabuf.o buffer.o select.o xdata.o xsettings.o dnd.o icon_surface.o primary_selection.o renderer.o picture_renderer.o explicit_synchronization.o transform.o wp_viewporter.o decoration.o text_input.o single_pixel_buffer.o drm_lease.o pointer_constraints.o time.o relative_pointer.o keyboard_shortcuts_inhibit.o idle_inhibit.o process.o fence_ring.o pointer_gestures.o test.o buffer_release.o xdg_activation.o
+             OBJS = 12to11.o run.o alloc.o fns.o output.o compositor.o surface.o region.o shm.o atoms.o subcompositor.o positioner.o xdg_wm.o xdg_surface.o xdg_toplevel.o frame_clock.o xerror.o ewmh.o timer.o subsurface.o seat.o data_device.o xdg_popup.o dmabuf.o buffer.o select.o xdata.o xsettings.o dnd.o icon_surface.o primary_selection.o renderer.o picture_renderer.o explicit_synchronization.o transform.o wp_viewporter.o decoration.o text_input.o single_pixel_buffer.o drm_lease.o pointer_constraints.o time.o relative_pointer.o keyboard_shortcuts_inhibit.o idle_inhibit.o process.o fence_ring.o pointer_gestures.o test.o buffer_release.o xdg_activation.o tearing_control.o
        GENHEADERS = transfer_atoms.h drm_modifiers.h
            HEADER = $(GENHEADERS) compositor.h
 
@@ -106,6 +106,7 @@ ScannerTarget(idle-inhibit-unstable-v1)
 ScannerTarget(pointer-gestures-unstable-v1)
 ScannerTarget(12to11-test)
 ScannerTarget(xdg-activation-v1)
+ScannerTarget(tearing-control-v1)
 
 /* Make seat.o depend on test_seat.c, as it includes that.  Both files
    are rather special.  */

compositor.h

@@ -876,6 +876,7 @@ typedef struct _State State;
 typedef struct _FrameCallback FrameCallback;
 typedef enum _RoleType RoleType;
 typedef enum _FocusMode FocusMode;
+typedef enum _PresentationHint PresentationHint;
 
 enum _FocusMode
   {
@@ -913,12 +914,19 @@ enum
     PendingViewportSrc	    = (1 << 9),
     PendingViewportDest	    = (1 << 10),
     PendingBufferTransform  = (1 << 11),
+    PendingPresentationHint = (1 << 12),
 
     /* Flags here are stored in `pending' of the current state for
        space reasons.  */
     BufferAlreadyReleased = (1 << 19),
   };
 
+enum _PresentationHint
+  {
+    PresentationHintVsync,
+    PresentationHintAsync,
+  };
+
 struct _FrameCallback
 {
   /* The next and last callbacks.  */
@@ -968,6 +976,9 @@ struct _State
 
   /* Viewport source rectangle.  */
   double src_x, src_y, src_width, src_height;
+
+  /* The presentation hint.  Defaults to PresentationHintVsync.  */
+  PresentationHint presentation_hint;
 };
 
 typedef enum _ClientDataType ClientDataType;
@@ -987,6 +998,7 @@ enum _ClientDataType
     IdleInhibitData,
     MaxClientData,
     XdgActivationData,
+    TearingControlData,
   };
 
 struct _DestroyCallback
@@ -1889,6 +1901,10 @@ extern void XLGetTestSeat (struct wl_client *, struct wl_resource *,
 
 extern void XLInitXdgActivation (void);
 
+/* Defined in tearing_control.c.  */
+
+extern void XLInitTearingControl (void);
+
 /* Utility functions that don't belong in a specific file.  */
 
 #define ArrayElements(arr) (sizeof (arr) / sizeof (arr)[0])

surface.c

@@ -917,6 +917,10 @@ SavePendingState (Surface *surface)
     pixman_region32_copy (&surface->cached_state.opaque,
 			  &surface->pending_state.opaque);
 
+  if (surface->pending_state.pending & PendingPresentationHint)
+    surface->cached_state.presentation_hint
+      = surface->pending_state.presentation_hint;
+
   if (surface->pending_state.pending & PendingBufferScale)
     surface->cached_state.buffer_scale
       = surface->pending_state.buffer_scale;
@@ -1052,6 +1056,10 @@ InternalCommit1 (Surface *surface, State *pending)
 	}
     }
 
+  if (pending->pending & PendingPresentationHint)
+    surface->current_state.presentation_hint
+      = pending->presentation_hint;
+
   if (pending->pending & PendingBufferScale)
     {
       surface->current_state.buffer_scale = pending->buffer_scale;

test.c

@@ -226,6 +226,11 @@ Commit (Surface *surface, Role *role)
      mapped.  */
   if (test->flags & IsSurfaceMapped)
     SubcompositorUpdate (test->subcompositor);
+
+  /* And send the presentation hint.  */
+  if (test->role.resource)
+    test_surface_send_committed (test->role.resource,
+				 surface->current_state.presentation_hint);
 }
 
 static Bool

tests/Imakefile

@@ -28,6 +28,7 @@ ScannerTarget(viewporter)
 ScannerTarget(linux-dmabuf-unstable-v1)
 ScannerTarget(xdg-activation-v1)
 ScannerTarget(single-pixel-buffer-v1)
+ScannerTarget(tearing-control-v1)
 
           /* Not actually a test.  */
           SRCS1 = $(COMMONSRCS) imgview.c
@@ -60,10 +61,25 @@ ScannerTarget(single-pixel-buffer-v1)
 	 OBJS14 = $(COMMONSRCS) single_pixel_buffer_test.o
 	 SRCS15 = $(COMMONSRCS) buffer_test.c
 	 OBJS15 = $(COMMONSRCS) buffer_test.o
-       PROGRAMS = imgview simple_test damage_test transform_test viewporter_test subsurface_test scale_test seat_test dmabuf_test select_test select_helper select_helper_multiple xdg_activation_test single_pixel_buffer_test buffer_test
+	 SRCS16 = $(COMMONSRCS) tearing_control_test.c
+	 OBJS16 = $(COMMONSRCS) tearing_control_test.o
+       PROGRAMS = imgview simple_test damage_test transform_test viewporter_test subsurface_test scale_test seat_test dmabuf_test select_test select_helper select_helper_multiple xdg_activation_test single_pixel_buffer_test buffer_test tearing_control_test
 
 /* Make all objects depend on HEADER.  */
 $(OBJS1): $(HEADER)
+$(OBJS2): $(HEADER)
+$(OBJS3): $(HEADER)
+$(OBJS4): $(HEADER)
+$(OBJS5): $(HEADER)
+$(OBJS6): $(HEADER)
+$(OBJS7): $(HEADER)
+$(OBJS8): $(HEADER)
+$(OBJS9): $(HEADER)
+$(OBJS10): $(HEADER)
+$(OBJS13): $(HEADER)
+$(OBJS14): $(HEADER)
+$(OBJS15): $(HEADER)
+$(OBJS16): $(HEADER)
 
 /* And depend on all sources and headers.  */
 depend:: $(HEADER) $(COMMONSRCS)
@@ -83,11 +99,13 @@ NormalProgramTarget(select_helper_multiple,$(OBJS12),NullParameter,$(XLIB),NullP
 NormalProgramTarget(xdg_activation_test,$(OBJS13),NullParameter,$(LOCAL_LIBRARIES),NullParameter)
 NormalProgramTarget(single_pixel_buffer_test,$(OBJS14),NullParameter,$(LOCAL_LIBRARIES),NullParameter)
 NormalProgramTarget(buffer_test,$(OBJS15),NullParameter,$(LOCAL_LIBRARIES),NullParameter)
+NormalProgramTarget(tearing_control_test,$(OBJS16),NullParameter,$(LOCAL_LIBRARIES),NullParameter)
 DependTarget3($(SRCS1),$(SRCS2),$(SRCS3))
 DependTarget3($(SRCS4),$(SRCS5),$(SRCS6))
 DependTarget3($(SRCS7),$(SRCS8),$(SRCS9))
 DependTarget3($(SRCS10),$(SRCS11),$(SRCS12))
 DependTarget3($(SRCS13),$(SRCS14),$(SRCS15))
+DependTarget3($(SRCS16),NullParameter,NullParameter)
 
 all:: $(PROGRAMS)
 

tests/buffer_test.c

@@ -30,7 +30,7 @@ enum test_kind
 static const char *test_names[] =
   {
     "buffer_release",
-    "buffer_destroy_kind",
+    "buffer_destroy",
   };
 
 #define LAST_TEST	BUFFER_DESTROY_KIND

tests/run_tests.sh

@@ -23,6 +23,7 @@ declare -a standard_tests=(
     simple_test damage_test transform_test viewporter_test
     subsurface_test scale_test seat_test dmabuf_test
     xdg_activation_test single_pixel_buffer_test buffer_test
+    tearing_control_test
 )
 
 make -C . "${standard_tests[@]}"

tests/svnignore.txt

@@ -15,6 +15,7 @@ select_helper_multiple
 xdg_activation_test
 single_pixel_buffer_test
 buffer_test
+tearing_control_test
 imgview
 reject.dump
 Makefile

xdg_surface.c

@@ -276,7 +276,7 @@ RunFrameCallbacksConditionally (XdgRole *role)
     role->state |= StatePendingFrameCallback;
 }
 
-static void
+static Bool
 UpdateFrameRefreshPrediction (XdgRole *role)
 {
   int desync_children;
@@ -296,7 +296,11 @@ UpdateFrameRefreshPrediction (XdgRole *role)
 	XLFrameClockSetPredictRefresh (role->clock);
       else
 	XLFrameClockDisablePredictRefresh (role->clock);
+
+      return desync_children > 0;
     }
+
+  return False;
 }
 
 static void
@@ -862,15 +866,15 @@ MaybeRunLateFrame (XdgRole *role)
 
   if (role->state & StateLateFrame)
     {
-      /* Clear the late frame flag.  */
-      role->state &= ~StateLateFrame;
-
       if (role->state & StateLateFrameAcked)
 	XLFrameClockUnfreeze (role->clock);
 
       /* Now apply the state in the late frame.  */
       SubcompositorUpdate (role->subcompositor);
 
+      /* Clear the late frame flag.  */
+      role->state &= ~StateLateFrame;
+
       /* Return True, as a new update has started.  */
       return True;
     }
@@ -1169,10 +1173,20 @@ WriteRedirectProperty (XdgRole *role)
 		   (unsigned char *) &bypass_compositor, 1);
 }
 
+static Bool
+WasFrameQueued (XdgRole *role)
+{
+  /* Return whether or not the translator slept before displaying this
+     frame in response to a frame drawn event.  */
+
+  return (role->state & StateLateFrame) != 0;
+}
+
 static void
 NoteFrame (FrameMode mode, uint64_t id, void *data)
 {
   XdgRole *role;
+  Bool predict_refresh, urgent;
 
   role = data;
 
@@ -1186,9 +1200,28 @@ NoteFrame (FrameMode mode, uint64_t id, void *data)
 	{
 	  /* Update whether or not frame refresh prediction is to be
 	     used.  */
-	  UpdateFrameRefreshPrediction (role);
+	  predict_refresh = UpdateFrameRefreshPrediction (role);
 
-	  if (XLFrameClockStartFrame (role->clock, False))
+	  /* A rule of thumb is to never let the compositing manager
+	     read or try to scan out incomplete buffer contents.
+	     Thus, if the client asked for async presentation, Commit
+	     will still wait for the compositor to finish drawing the
+	     last frame.
+
+	     In addition, how subsurfaces fit into all of this is
+	     unclear.  At present, the presentation hint of
+	     subsurfaces is simply discarded, and the hint of the
+	     topmost surface used instead.  In addition, asynchronous
+	     subsurfaces will prevent async presentation from taking
+	     place at all.  */
+
+	  urgent = (WasFrameQueued (role)
+		    && !predict_refresh
+		    && role->role.surface
+		    && (role->role.surface->current_state.presentation_hint
+			== PresentationHintAsync));
+
+	  if (XLFrameClockStartFrame (role->clock, urgent))
 	    role->state |= StateFrameStarted;
 	}