cogl: Store latest GPU work completed sync fd

This keeps an internal sync_fd for the latest work submitted to
the GPU. This can then be fetched with cogl_context_get_latest_sync_fd
for use. This is intended for use with linux-drm-syncobj-v1

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3300>

cogl/cogl/cogl-context-private.h

@@ -311,3 +311,6 @@ _cogl_context_set_current_projection_entry (CoglContext *context,
 void
 _cogl_context_set_current_modelview_entry (CoglContext *context,
                                            CoglMatrixEntry *entry);
+
+void
+_cogl_context_update_sync (CoglContext *context);

cogl/cogl/cogl-context.c

@@ -463,6 +463,28 @@ _cogl_context_set_current_modelview_entry (CoglContext *context,
   context->current_modelview_entry = entry;
 }
 
+void
+_cogl_context_update_sync (CoglContext *context)
+{
+  const CoglWinsysVtable *winsys = _cogl_context_get_winsys (context);
+
+  if (!winsys->update_sync)
+    return;
+
+  winsys->update_sync (context);
+}
+
+int
+cogl_context_get_latest_sync_fd (CoglContext *context)
+{
+  const CoglWinsysVtable *winsys = _cogl_context_get_winsys (context);
+
+  if (!winsys->get_sync_fd)
+    return -1;
+
+  return winsys->get_sync_fd (context);
+}
+
 CoglGraphicsResetStatus
 cogl_get_graphics_reset_status (CoglContext *context)
 {

cogl/cogl/cogl-context.h

@@ -367,4 +367,18 @@ cogl_context_timestamp_query_get_time_ns (CoglContext        *context,
 COGL_EXPORT int64_t
 cogl_context_get_gpu_time_ns (CoglContext *context);
 
+/**
+ * cogl_context_get_latest_sync_fd
+ * @context: a #CoglContext pointer
+ *
+ * This function is used to get support for waiting on previous
+ * GPU work through sync fds. It will return a sync fd which will
+ * signal when the previous work has completed.
+ *
+ * Return value: sync fd for latest GPU submission if available,
+ * returns -1 if not.
+ */
+COGL_EXPORT int
+cogl_context_get_latest_sync_fd (CoglContext *context);
+
 G_END_DECLS

cogl/cogl/winsys/cogl-onscreen-egl.c

@@ -309,6 +309,9 @@ cogl_onscreen_egl_swap_buffers_with_damage (CoglOnscreen  *onscreen,
                                         COGL_FRAMEBUFFER (onscreen),
                                         COGL_FRAMEBUFFER_STATE_BIND);
 
+  /* Update our "latest" sync fd to contain all previous work */
+  _cogl_context_update_sync (context);
+
   if (cogl_has_feature (context, COGL_FEATURE_ID_TIMESTAMP_QUERY))
     {
       info->gpu_time_before_buffer_swap_ns =

cogl/cogl/winsys/cogl-winsys-egl-feature-functions.h

@@ -162,6 +162,15 @@ COGL_WINSYS_FEATURE_FUNCTION (EGLBoolean, eglDestroySync,
                               (EGLDisplay dpy,
                                EGLSyncKHR sync))
 COGL_WINSYS_FEATURE_END ()
+
+COGL_WINSYS_FEATURE_BEGIN (native_fence_sync,
+                           "ANDROID\0",
+                           "native_fence_sync\0",
+                           COGL_EGL_WINSYS_FEATURE_NATIVE_FENCE_SYNC)
+COGL_WINSYS_FEATURE_FUNCTION (EGLint, eglDupNativeFenceFD,
+                              (EGLDisplay dpy,
+                               EGLSyncKHR sync))
+COGL_WINSYS_FEATURE_END ()
 #endif
 
 COGL_WINSYS_FEATURE_BEGIN (surfaceless_context,

cogl/cogl/winsys/cogl-winsys-egl-private.h

@@ -101,6 +101,7 @@ typedef enum _CoglEGLWinsysFeature
   COGL_EGL_WINSYS_FEATURE_SURFACELESS_CONTEXT           = 1L << 6,
   COGL_EGL_WINSYS_FEATURE_CONTEXT_PRIORITY              = 1L << 7,
   COGL_EGL_WINSYS_FEATURE_NO_CONFIG_CONTEXT             = 1L << 8,
+  COGL_EGL_WINSYS_FEATURE_NATIVE_FENCE_SYNC             = 1L << 9,
 } CoglEGLWinsysFeature;
 
 typedef struct _CoglRendererEGL
@@ -119,6 +120,9 @@ typedef struct _CoglRendererEGL
   /* vtable for platform specific parts */
   const CoglWinsysEGLVtable *platform_vtable;
 
+  /* Sync for latest submitted work */
+  EGLSyncKHR sync;
+
   /* Function pointers for EGL specific extensions */
 #define COGL_WINSYS_FEATURE_BEGIN(a, b, c, d)
 

cogl/cogl/winsys/cogl-winsys-egl-x11.c

@@ -243,6 +243,7 @@ _cogl_winsys_renderer_connect (CoglRenderer *renderer,
   xlib_renderer = _cogl_xlib_renderer_get_data (renderer);
 
   egl_renderer->platform_vtable = &_cogl_winsys_egl_vtable;
+  egl_renderer->sync = EGL_NO_SYNC_KHR;
 
   if (!_cogl_xlib_renderer_connect (renderer, error))
     goto error;

cogl/cogl/winsys/cogl-winsys-egl.c

@@ -441,6 +441,9 @@ _cogl_winsys_display_destroy (CoglDisplay *display)
 
   g_return_if_fail (egl_display != NULL);
 
+  if (egl_renderer->sync != EGL_NO_SYNC_KHR)
+    egl_renderer->pf_eglDestroySync (egl_renderer->edpy, egl_renderer->sync);
+
   cleanup_context (display);
 
   if (egl_renderer->platform_vtable->display_destroy)
@@ -573,6 +576,37 @@ _cogl_winsys_fence_destroy (CoglContext *context, void *fence)
 
   renderer->pf_eglDestroySync (renderer->edpy, fence);
 }
+
+static int
+_cogl_winsys_get_sync_fd (CoglContext *context)
+{
+  CoglRendererEGL *renderer = context->display->renderer->winsys;
+  int fd;
+
+  if (!renderer->pf_eglDupNativeFenceFD)
+    return -1;
+
+  fd = renderer->pf_eglDupNativeFenceFD (renderer->edpy, renderer->sync);
+  if (fd == EGL_NO_NATIVE_FENCE_FD_ANDROID)
+    return -1;
+
+  return fd;
+}
+
+static void
+_cogl_winsys_update_sync (CoglContext *context)
+{
+  CoglRendererEGL *renderer = context->display->renderer->winsys;
+
+  if (!renderer->pf_eglDestroySync || !renderer->pf_eglCreateSync)
+    return;
+
+  if (renderer->sync != EGL_NO_SYNC_KHR)
+    renderer->pf_eglDestroySync (renderer->edpy, renderer->sync);
+
+  renderer->sync = renderer->pf_eglCreateSync (renderer->edpy,
+        EGL_SYNC_NATIVE_FENCE_ANDROID, NULL);
+}
 #endif
 
 static CoglWinsysVtable _cogl_winsys_vtable =
@@ -595,6 +629,8 @@ static CoglWinsysVtable _cogl_winsys_vtable =
     .fence_add = _cogl_winsys_fence_add,
     .fence_is_complete = _cogl_winsys_fence_is_complete,
     .fence_destroy = _cogl_winsys_fence_destroy,
+    .get_sync_fd = _cogl_winsys_get_sync_fd,
+    .update_sync = _cogl_winsys_update_sync,
 #endif
   };
 

cogl/cogl/winsys/cogl-winsys-private.h

@@ -141,6 +141,12 @@ typedef struct _CoglWinsysVtable
   (*fence_destroy) (CoglContext *ctx,
                     void        *fence);
 
+  void
+  (*update_sync) (CoglContext *ctx);
+
+  int
+  (*get_sync_fd) (CoglContext *ctx);
+
 } CoglWinsysVtable;
 
 typedef const CoglWinsysVtable *(*CoglWinsysVtableGetter) (void);