Track slow paths in DisplayItemList

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 "platform/graphics/paint/PaintController.h"
 
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/graphics/paint/DrawingDisplayItem.h"
 #include "platform/instrumentation/tracing/TraceEvent.h"
 #include "platform/wtf/AutoReset.h"
 #include "platform/wtf/text/StringBuilder.h"
 #include "third_party/skia/include/core/SkPictureAnalyzer.h"
 
 #ifndef NDEBUG
 #include "platform/graphics/LoggingCanvas.h"
 #include <stdio.h>
 #endif
 
-static constexpr int kMaxNumberOfSlowPathsBeforeVeto = 5;
-
 namespace blink {
 
 void PaintController::SetTracksRasterInvalidations(bool value) {
   if (value ||
       RuntimeEnabledFeatures::paintUnderInvalidationCheckingEnabled()) {
     raster_invalidation_tracking_info_ =
         WTF::MakeUnique<RasterInvalidationTrackingInfo>();
 
     // This is called just after a full document cycle update, so all clients in
     // current_paint_artifact_ should be still alive.
@@ skipping 536 matching lines @@
   for (auto& item : current_cached_subsequences_) {
     item.key->SetDisplayItemsCached(current_cache_generation_);
 #if CHECK_DISPLAY_ITEM_CLIENT_ALIVENESS
     DisplayItemClient::EndShouldKeepAliveAllClients(item.key);
     DCHECK(current_subsequence_clients_.IsEmpty());
 #endif
   }
 
   Vector<const DisplayItemClient*> skipped_cache_clients;
   for (const auto& item : new_display_item_list_) {
-    // No reason to continue the analysis once we have a veto.
-    if (num_slow_paths <= kMaxNumberOfSlowPathsBeforeVeto)
-      num_slow_paths += item.NumberOfSlowPaths();
+    num_slow_paths += item.NumberOfSlowPaths();

[chrishtr, 2017/05/13 01:12:04]

Why remove the early-out?

[enne (OOO), 2017/05/13 18:27:40]

Because number of slow paths is a member accessor now and the comment is out of
date.  I didn't want to duplicate kMaxNumberOfSlowPathsBeforeVeto here, and a
conditional to avoid a member access (on an object that is already being used
below) does not seem like it's worth doing even without the code duplication
issue.

 
     // TODO(wkorman): Only compute and append visual rect for drawings.
     new_display_item_list_.AppendVisualRect(
         VisualRectForDisplayItem(item, offset_from_layout_object));
 
     if (item.IsCacheable()) {
       item.Client().SetDisplayItemsCached(current_cache_generation_);
     } else {
       if (item.Client().IsJustCreated())
         item.Client().ClearIsJustCreated();
@@ skipping 20 matching lines @@
   for (auto* client : skipped_cache_clients)
     client->SetDisplayItemsUncached();
 
   // The new list will not be appended to again so we can release unused memory.
   new_display_item_list_.ShrinkToFit();
 
   if (raster_invalidation_tracking_info_) {
     for (const auto& chunk : current_paint_artifact_.PaintChunks())
       raster_invalidation_tracking_info_->map.Remove(&chunk);
   }
-  current_paint_artifact_ = PaintArtifact(
-      std::move(new_display_item_list_), new_paint_chunks_.ReleasePaintChunks(),
-      num_slow_paths <= kMaxNumberOfSlowPathsBeforeVeto);
+  current_paint_artifact_ =
+      PaintArtifact(std::move(new_display_item_list_),
+                    new_paint_chunks_.ReleasePaintChunks(), num_slow_paths);
 
   ResetCurrentListIndices();
   out_of_order_item_indices_.clear();
   out_of_order_chunk_indices_.clear();
   items_moved_into_new_list_.clear();
 
   if (RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
     for (const auto& chunk : current_paint_artifact_.PaintChunks()) {
       if (chunk.id && chunk.id->client.IsJustCreated())
         chunk.id->client.ClearIsJustCreated();
@@ skipping 346 matching lines @@
               show_paint_records
                   ? (DisplayItemList::JsonOptions::kShowPaintRecords |
                      DisplayItemList::JsonOptions::kShowClientDebugName)
                   : DisplayItemList::JsonOptions::kShowClientDebugName)
           ->ToPrettyJSONString()
           .Utf8()
           .data());
 }
 
 }  // namespace blink