MemoryCache: make sure that Resources are evicted only when they can be deleted

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
     version 2 of the License, or (at your option) any later version.
@@ skipping 179 matching lines @@
     void setSerializedCachedMetadata(const char*, size_t);
 
     // Caches the given metadata in association with this resource and suggests
     // that the platform persist it. The dataTypeID is a pseudo-randomly chosen
     // identifier that is used to distinguish data generated by the caller.
     void setCachedMetadata(unsigned dataTypeID, const char*, size_t);
 
     // Returns cached metadata of the given type associated with this resource.
     CachedMetadata* cachedMetadata(unsigned dataTypeID) const;
 
-    bool canDelete() const { return !hasClients() && !m_loader && !m_preloadCount && !m_handleCount && !m_protectorCount && !m_resourceToRevalidate && !m_proxyResource; }
-    bool hasOneHandle() const { return m_handleCount == 1; }
+    bool canDelete() const;
+    bool hasOneHandleApartFromCache() const;
 
     // List of acceptable MIME types separated by ",".
     // A MIME type may contain a wildcard, e.g. "text/*".
     AtomicString accept() const { return m_accept; }
     void setAccept(const AtomicString& accept) { m_accept = accept; }
 
     bool wasCanceled() const { return m_error.isCancellation(); }
     bool errorOccurred() const { return m_status == LoadError || m_status == DecodeError; }
     bool loadFailedOrCanceled() { return !m_error.isNull(); }
 
@@ skipping 123 matching lines @@
 
 private:
     bool addClientToSet(ResourceClient*);
     void cancelTimerFired(Timer<Resource>*);
 
     void revalidationSucceeded(const ResourceResponse&);
     void revalidationFailed();
 
     bool unlock();
 
+    bool hasRightHandleCountApartFromCache(unsigned targetCount) const;
+
     void failBeforeStarting();
 
     String m_fragmentIdentifierForRequest;
 
     RefPtr<CachedMetadata> m_cachedMetadata;
 
     ResourceError m_error;
 
     double m_lastDecodedAccessTime; // Used as a "thrash guard" in the cache
     double m_loadFinishTime;
@@ skipping 46 matching lines @@
 const char* ResourceTypeName(Resource::Type);
 #endif
 
 #define DEFINE_RESOURCE_TYPE_CASTS(typeName) \
     DEFINE_TYPE_CASTS(typeName##Resource, Resource, resource, resource->type() == Resource::typeName, resource.type() == Resource::typeName); \
     inline typeName##Resource* to##typeName##Resource(const ResourcePtr<Resource>& ptr) { return to##typeName##Resource(ptr.get()); }
 
 }
 
 #endif