Clear all preloads when document is detached

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
     License as published by the Free Software Foundation; either
@@ skipping 869 matching lines @@
 }
 
 void ResourceFetcher::clearPreloads(ClearPreloadsPolicy policy)
 {
     if (!m_preloads)
         return;
 
     logPreloadStats();
 
     for (auto resource : *m_preloads) {
-        resource->decreasePreloadCount();
-        if (resource->getPreloadResult() == Resource::PreloadNotReferenced && (policy == ClearAllPreloads || !resource->isLinkPreload()))
-            memoryCache()->remove(resource.get());
+        if (policy == ClearAllPreloads || !resource->isLinkPreload()) {
+            resource->decreasePreloadCount();
+            if (resource->getPreloadResult() == Resource::PreloadNotReferenced)
+                memoryCache()->remove(resource.get());
+            m_preloads->remove(resource);
+        }
     }
-    m_preloads.clear();
+    if (!m_preloads->size())

[Charlie Harrison, 2016/08/04 18:10:26]

This is confusing. Clear the preloads only if they are already empty?

[Yoav Weiss, 2016/08/04 20:26:14]

AFAICT the clear here clears the Member (and enables the GC of the HashSet), not
necessarily the resources inside it. Not sure it's absolutely necessary, but I
preferred not to change that, while maintaining correctness (as we don't want
m_preloads to be cleared if there are still preloads in it)

[Charlie Harrison, 2016/08/04 20:59:57]

Ah, makes sense. Thanks for the clarification.

+        m_preloads.clear();
 }
 
 ArchiveResource* ResourceFetcher::createArchive(Resource* resource)
 {
     // Only the top-frame can load MHTML.
     if (!context().isMainFrame())
         return nullptr;
     m_archive = MHTMLArchive::create(resource->url(), resource->resourceBuffer());
     return m_archive ? m_archive->mainResource() : nullptr;
 }
@@ skipping 396 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