Preparation for enabling slimming paint synchronized painting

third_party/WebKit/Source/platform/graphics/paint/PaintController.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "platform/graphics/paint/PaintController.h"
 
 #include "platform/NotImplemented.h"
 #include "platform/TraceEvent.h"
 #include "platform/graphics/GraphicsLayer.h"
@@ skipping 106 matching lines @@
     invalidateClient(client);
 
     if (visualRect) {
         // TODO(wkorman): cache visualRect for the client.
     }
 }
 
 void PaintController::invalidateClient(const DisplayItemClientWrapper& client)
 {
 #if ENABLE(ASSERT)
-    m_invalidations.append(client.debugName());
+    // Slimming paint v1 CompositedLayerMapping may invalidate client on extra layers.

[chrishtr, 2015/10/28 21:12:58]

v2 or v1?

[Xianzhu, 2015/10/29 04:22:01]

v1. For example, in invalidatePaintIncludingNonCompoisitingDescendants(), we may
invalidate a fixed-pos object on a paint invalidation container which the
fixed-pos object doesn't belong to. Here we add into m_invalidations only if the
object has previously cached to avoid ASSERT(m_invalidations.isEmpty()) failure
when a whole GraphicsLayer is cached but something unrelated was invalidated on
the layer.

[chrishtr, 2015/10/29 20:22:45]

Yikes. How does this situation avoid causing the whole GraphicsLayer caching to
fail?

[Xianzhu, 2015/10/30 00:03:57]

Sometimes somehow we also invalidate the object in other paths on the correct
paint invalidation container, so here we ignore the extra one.

Sometimes it's a bug (crbug.com/548495 -- to be fixed by
https://codereview.chromium.org/1413823005/ (WIP)).

[Xianzhu, 2015/10/30 18:05:51]

Also crbug.com/416535.

+    if (RuntimeEnabledFeatures::slimmingPaintV2Enabled() || clientCacheIsValid(client.displayItemClient()))
+        m_invalidations.append(client.debugName());
 #endif
 
     invalidateUntracked(client.displayItemClient());
     if (RuntimeEnabledFeatures::slimmingPaintV2Enabled() && m_trackedPaintInvalidationObjects)
         m_trackedPaintInvalidationObjects->append(client.debugName());
 }
 
 void PaintController::invalidateUntracked(DisplayItemClient client)
 {
     // This can be called during painting, but we can't invalidate already painted clients.
@@ skipping 133 matching lines @@
 {
     TRACE_EVENT2("blink,benchmark", "PaintController::commitNewDisplayItems",
         "current_display_list_size", (int)m_currentPaintArtifact.displayItemList().size(),
         "num_non_cached_new_items", (int)m_newDisplayItemList.size() - m_numCachedItems);
 
     if (RuntimeEnabledFeatures::slimmingPaintSynchronizedPaintingEnabled()
         && !m_newDisplayItemList.isEmpty()
         && m_newDisplayItemList.last().type() == DisplayItem::CachedDisplayItemList) {
         // The whole display item list is cached.
         ASSERT(m_newDisplayItemList.size() == 1
-            || (m_newDisplayItemList.size() == 2 && m_newDisplayItemList[0].type() == DisplayItem::DebugRedFill));
+            || (m_newDisplayItemList.size() == 2 && DisplayItem::nonCachedType(m_newDisplayItemList[0].type()) == DisplayItem::DebugRedFill));

[pdr., 2015/10/29 04:06:10]

Why does synchronous painting cause us to hit this codepath with cached debug
red fills whereas we didn't before?

[Xianzhu, 2015/10/29 04:22:01]

This assert is only for CachedDisplayItemList which is a sync painting feature.

         ASSERT(m_invalidations.isEmpty());
         ASSERT(m_clientsCheckedPaintInvalidation.isEmpty());
         m_newDisplayItemList.clear();
         m_newPaintChunks.clear();
         return;
     }
     if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
         m_clientsCheckedPaintInvalidation.clear();
 
     // These data structures are used during painting only.
@@ skipping 270 matching lines @@
 
 void PaintController::showDebugData() const
 {
     WTFLogAlways("current display item list: [%s]\n", displayItemListAsDebugString(m_currentPaintArtifact.displayItemList()).utf8().data());
     WTFLogAlways("new display item list: [%s]\n", displayItemListAsDebugString(m_newDisplayItemList).utf8().data());
 }
 
 #endif // ifndef NDEBUG
 
 } // namespace blink