dri2: Event driven buffer validation.

When a buffer invalidation event is received from the X server, the
"invalidate" hook of the DRI2 flush extension is executed: A generic
implementation (dri2InvalidateDrawable) is provided that just bumps
the "pStamp" sequence number in __DRIdrawableRec.

For old servers not supporting buffer invalidation events, the
invalidate hook will be called before flushing the fake front/back
buffer (that's typically once per frame -- not a lot worse than the
situation we were in before).

No effort has been made on preserving backwards compatibility with
version 2 of the flush extension, but I think it's acceptable because
AFAIK no released stack is making use of it.

Signed-off-by: Kristian Høgsberg <krh@bitplanet.net>

3 files changed, 39 insertions, 15 deletions

diff --git a/src/glx/dri2.c b/src/glx/dri2.c
index 91053d3fb6..a7a8cb50aa 100644
--- a/src/glx/dri2.c
+++ b/src/glx/dri2.c
@@ -81,7 +81,7 @@ static XEXT_GENERATE_FIND_DISPLAY (DRI2FindDisplay,
                                    dri2Info,
                                    dri2ExtensionName,
                                    &dri2ExtensionHooks,
-                                   1, NULL)
+                                   DRI2NumberEvents, NULL)
 
 static Bool
 DRI2WireToEvent(Display *dpy, XEvent *event, xEvent *wire)
@@ -126,7 +126,15 @@ DRI2WireToEvent(Display *dpy, XEvent *event, xEvent *wire)
       return True;
    }
 #endif
+#ifdef DRI2_InvalidateBuffers
+   case DRI2_InvalidateBuffers:
+   {
+      xDRI2InvalidateBuffers *awire = (xDRI2InvalidateBuffers *)wire;
 
+      dri2InvalidateBuffers(dpy, awire->drawable);
+      return False;
+   }
+#endif
    default:
       /* client doesn't support server event */
       break;
diff --git a/src/glx/dri2_glx.c b/src/glx/dri2_glx.c
index 15a3ea5907..29d589cdb9 100644
--- a/src/glx/dri2_glx.c
+++ b/src/glx/dri2_glx.c
@@ -67,6 +67,7 @@ struct __GLXDRIdisplayPrivateRec
    int driMinor;
    int driPatch;
    int swapAvailable;
+   int invalidateAvailable;
 };
 
 struct __GLXDRIcontextPrivateRec
@@ -310,12 +311,18 @@ dri2WaitGL(__GLXDRIdrawable * pdraw)
    XFixesDestroyRegion(pdraw->psc->dpy, region);
 }
 
-
 static void
-dri2FlushFrontBuffer(__DRIdrawable * driDrawable, void *loaderPrivate)
+dri2FlushFrontBuffer(__DRIdrawable *driDrawable, void *loaderPrivate)
 {
-   (void) driDrawable;
-   dri2WaitGL((__GLXDRIdrawable *) loaderPrivate);
+   __GLXDRIdrawablePrivate *pdraw = loaderPrivate;
+   __GLXdisplayPrivate *priv = __glXInitialize(pdraw->base.psc->dpy);
+   __GLXDRIdisplayPrivate *pdp = (__GLXDRIdisplayPrivate *)priv->dri2Display;
+
+   /* Old servers don't send invalidate events */
+   if (!pdp->invalidateAvailable)
+       dri2InvalidateBuffers(priv->dpy, pdraw->base.xDrawable);
+
+   dri2WaitGL(loaderPrivate);
 }
 
 
@@ -375,6 +382,10 @@ dri2SwapBuffers(__GLXDRIdrawable *pdraw, int64_t target_msc, int64_t divisor,
     	(*pdraw->psc->f->flush)(pdraw->driDrawable);
 #endif
 
+    /* Old servers don't send invalidate events */
+    if (!pdp->invalidateAvailable)
+       dri2InvalidateBuffers(dpyPriv->dpy, pdraw->xDrawable);
+
     /* Old servers can't handle swapbuffers */
     if (!pdp->swapAvailable) {
        dri2CopySubBuffer(pdraw, 0, 0, priv->width, priv->height);
@@ -386,11 +397,6 @@ dri2SwapBuffers(__GLXDRIdrawable *pdraw, int64_t target_msc, int64_t divisor,
 		    remainder, &ret);
 #endif
 
-#if __DRI2_FLUSH_VERSION >= 2
-    if (pdraw->psc->f)
-       (*pdraw->psc->f->flushInvalidate)(pdraw->driDrawable);
-#endif
-
     return ret;
 }
 
@@ -485,6 +491,17 @@ static const __DRIextension *loader_extensions_old[] = {
    NULL
 };
 
+_X_HIDDEN void
+dri2InvalidateBuffers(Display *dpy, XID drawable)
+{
+   __GLXDRIdrawable *pdraw = GetGLXDRIDrawable(dpy, drawable, NULL);
+
+#if __DRI2_FLUSH_VERSION >= 3
+   if (pdraw && pdraw->psc->f)
+       pdraw->psc->f->invalidate(pdraw->driDrawable);
+#endif
+}
+
 static __GLXDRIscreen *
 dri2CreateScreen(__GLXscreenConfigs * psc, int screen,
                  __GLXdisplayPrivate * priv)
@@ -651,11 +668,8 @@ dri2CreateDisplay(Display * dpy)
    }
 
    pdp->driPatch = 0;
-   pdp->swapAvailable = 0;
-#ifdef X_DRI2SwapBuffers
-   if (pdp->driMinor >= 2)
-      pdp->swapAvailable = 1;
-#endif
+   pdp->swapAvailable = (pdp->driMinor >= 2);
+   pdp->invalidateAvailable = (pdp->driMinor >= 3);
 
    pdp->base.destroyDisplay = dri2DestroyDisplay;
    pdp->base.createScreen = dri2CreateScreen;
diff --git a/src/glx/glxclient.h b/src/glx/glxclient.h
index f88e9fbcde..04ce781c43 100644
--- a/src/glx/glxclient.h
+++ b/src/glx/glxclient.h
@@ -182,6 +182,8 @@ struct __GLXDRIdrawableRec
 extern __GLXDRIdisplay *driswCreateDisplay(Display * dpy);
 extern __GLXDRIdisplay *driCreateDisplay(Display * dpy);
 extern __GLXDRIdisplay *dri2CreateDisplay(Display * dpy);
+extern void dri2InvalidateBuffers(Display *dpy, XID drawable);
+
 
 extern void DRI_glXUseXFont(Font font, int first, int count, int listbase);