Stop double counting link rel preload preloads for metrics tracking

third_party/WebKit/Source/core/fetch/ResourceFetcher.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
     rights reserved.
     Copyright (C) 2009 Torch Mobile Inc. http://www.torchmobile.com/
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
@@ skipping 1055 matching lines @@
 
 bool ResourceFetcher::isPreloadedForTest(const KURL& url) const {
   DCHECK(m_preloadedURLsForTest);
   return m_preloadedURLsForTest->contains(url.getString());
 }
 
 void ResourceFetcher::clearPreloads(ClearPreloadsPolicy policy) {
   if (!m_preloads)
     return;
 
-  logPreloadStats();
+  logPreloadStats(policy);
 
   for (const auto& resource : *m_preloads) {
     if (policy == ClearAllPreloads || !resource->isLinkPreload()) {
       resource->decreasePreloadCount();
       if (resource->getPreloadResult() == Resource::PreloadNotReferenced)
         memoryCache()->remove(resource.get());
       m_preloads->remove(resource);
     }
   }
   if (!m_preloads->size())
@@ skipping 341 matching lines @@
 void ResourceFetcher::reloadLoFiImages() {
   for (const auto& documentResource : m_documentResources) {
     Resource* resource = documentResource.value.get();
     if (resource && resource->isImage()) {
       ImageResource* imageResource = toImageResource(resource);
       imageResource->reloadIfLoFiOrPlaceholder(this);
     }
   }
 }
 
-void ResourceFetcher::logPreloadStats() {
+void ResourceFetcher::logPreloadStats(ClearPreloadsPolicy policy) {
   if (!m_preloads)
     return;
   unsigned scripts = 0;
   unsigned scriptMisses = 0;
   unsigned stylesheets = 0;
   unsigned stylesheetMisses = 0;
   unsigned images = 0;
   unsigned imageMisses = 0;
   unsigned fonts = 0;
   unsigned fontMisses = 0;
   unsigned medias = 0;
   unsigned mediaMisses = 0;
   unsigned textTracks = 0;
   unsigned textTrackMisses = 0;
   unsigned imports = 0;
   unsigned importMisses = 0;
   unsigned raws = 0;
   unsigned rawMisses = 0;
   for (const auto& resource : *m_preloads) {
+    // Do not double count link rel preloads. These do not get cleared if the
+    // ClearPreloadsPolicy is only clearing speculative markup preloads.
+    if (resource->isLinkPreload() && policy == ClearSpeculativeMarkupPreloads) {
+      continue;
+    }
     int missCount =
         resource->getPreloadResult() == Resource::PreloadNotReferenced ? 1 : 0;
     switch (resource->getType()) {
       case Resource::Image:
         images++;
         imageMisses += missCount;
         break;
       case Resource::Script:
         scripts++;
         scriptMisses += missCount;
@@ skipping 19 matching lines @@
         importMisses += missCount;
         break;
       case Resource::Raw:
         raws++;
         rawMisses += missCount;
         break;
       default:
         NOTREACHED();
     }
   }
-  // TODO(csharrison): These can falsely attribute link rel="preload" requests
-  // as misses if they are referenced after parsing completes. Migrate this
-  // logic to the memory cache / individual resources to prevent this.
   DEFINE_STATIC_LOCAL(CustomCountHistogram, imagePreloads,
                       ("PreloadScanner.Counts2.Image", 0, 100, 25));
   DEFINE_STATIC_LOCAL(CustomCountHistogram, imagePreloadMisses,
                       ("PreloadScanner.Counts2.Miss.Image", 0, 100, 25));
   DEFINE_STATIC_LOCAL(CustomCountHistogram, scriptPreloads,
                       ("PreloadScanner.Counts2.Script", 0, 100, 25));
   DEFINE_STATIC_LOCAL(CustomCountHistogram, scriptPreloadMisses,
                       ("PreloadScanner.Counts2.Miss.Script", 0, 100, 25));
   DEFINE_STATIC_LOCAL(CustomCountHistogram, stylesheetPreloads,
                       ("PreloadScanner.Counts2.CSSStyleSheet", 0, 100, 25));
@@ skipping 109 matching lines @@
   visitor->trace(m_context);
   visitor->trace(m_archive);
   visitor->trace(m_loaders);
   visitor->trace(m_nonBlockingLoaders);
   visitor->trace(m_documentResources);
   visitor->trace(m_preloads);
   visitor->trace(m_resourceTimingInfoMap);
 }
 
 }  // namespace blink