Cache-aware Resource loading

third_party/WebKit/Source/core/fetch/Resource.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
     rights reserved.
 
     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 292 matching lines @@
 
   void addToEncodedBodyLength(int value) {
     m_response.addToEncodedBodyLength(value);
   }
   void addToDecodedBodyLength(int value) {
     m_response.addToDecodedBodyLength(value);
   }
 
   virtual bool canReuse(const ResourceRequest&) const { return true; }
 
+  // If cache-aware loading is activated, this callback is called when the first
+  // disk-cache-only request failed due to cache miss.
+  virtual void willReloadAfterDiskCacheMiss() {}

[kinuko, 2016/11/08 06:10:18]

nit/optional:

This method naming feels a little weird to me, because 1) the willDoFoo() naming
pattern is often used to notify observers right before doFoo() is called while
we're not in that pattern in this change, and 2) the method name seems to imply
very specific action (i.e. reload) to be taken while the default impl does
nothing. 

I slightly prefer having a more generic name in the base class like:
didDetectCacheMiss()

and have a comment to note, say, 'subclasses (e.g. FontResource) may trigger
reloading to actually fetch the resource from network'.  Wdyt..?

[Shao-Chuan Lee, 2016/11/08 06:28:01]

SGTM, but I wonder if it's better to mention "disk" cache miss to distinguish
from memory cache miss? Naming is hard...

The reload is actually triggered by ResourceLoader, but it's indeed nice to have
comments here.

[kinuko, 2016/11/08 06:42:15]

Oh that's true, so maybe the current name is just ok.  Could we still slightly
improve the comment to note that reload is triggered right after this method by
ResourceLoader then?

[Shao-Chuan Lee, 2016/11/08 07:19:06]

Done, PTAL

+
+  // TODO(shaochuan): This is for saving back the actual ResourceRequest sent
+  // in ResourceFetcher::startLoad() for retry in cache-aware loading, remove
+  // once ResourceRequest is not modified in startLoad(). crbug.com/632580
+  void setResourceRequest(const ResourceRequest& resourceRequest) {
+    m_resourceRequest = resourceRequest;
+  }
+
   // Used by the MemoryCache to reduce the memory consumption of the entry.
   void prune();
 
   virtual void onMemoryDump(WebMemoryDumpLevelOfDetail,
                             WebProcessMemoryDump*) const;
 
   static const char* resourceTypeToString(Type, const FetchInitiatorInfo&);
 
  protected:
   Resource(const ResourceRequest&, Type, const ResourceLoaderOptions&);
@@ skipping 158 matching lines @@
 };
 
 #define DEFINE_RESOURCE_TYPE_CASTS(typeName)                   \
   DEFINE_TYPE_CASTS(typeName##Resource, Resource, resource,    \
                     resource->getType() == Resource::typeName, \
                     resource.getType() == Resource::typeName);
 
 }  // namespace blink
 
 #endif