Purge browser cache for dom storage in a smarter way

content/browser/dom_storage/dom_storage_namespace.h

 // Copyright 2013 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.
 
 #ifndef CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_NAMESPACE_H_
 #define CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_NAMESPACE_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 14 matching lines @@
 
 class DOMStorageArea;
 class DOMStorageTaskRunner;
 class SessionStorageDatabase;
 
 // Container for the set of per-origin Areas.
 // See class comments for DOMStorageContextImpl for a larger overview.
 class CONTENT_EXPORT DOMStorageNamespace
     : public base::RefCountedThreadSafe<DOMStorageNamespace> {
  public:
-  // Option for PurgeMemory.
-  enum PurgeOption {
-    // Purge unopened areas only.
-    PURGE_UNOPENED,
-
-    // Purge aggressively, i.e. discard cache even for areas that have
-    // non-zero open count.
-    PURGE_AGGRESSIVE,
+  // Struct to hold statistics about the areas in the namespace.
+  struct UsageStatistics {
+    size_t total_cache_size;
+    unsigned total_area_count;
+    unsigned inactive_area_count;  // areas with open count 0.
   };
 
   // Constructor for a LocalStorage namespace with id of 0
   // and an optional backing directory on disk.
   DOMStorageNamespace(const base::FilePath& directory,  // may be empty
                       DOMStorageTaskRunner* task_runner);
 
   // Constructor for a SessionStorage namespace with a non-zero id and an
   // optional backing on disk via |session_storage_database| (may be NULL).
   DOMStorageNamespace(int64_t namespace_id,
@@ skipping 16 matching lines @@
   DOMStorageArea* GetOpenStorageArea(const GURL& origin);
 
   // Creates a clone of |this| namespace including
   // shallow copies of all contained areas.
   // Should only be called for session storage namespaces.
   DOMStorageNamespace* Clone(int64_t clone_namespace_id,
                              const std::string& clone_persistent_namespace_id);
 
   void DeleteLocalStorageOrigin(const GURL& origin);
   void DeleteSessionStorageOrigin(const GURL& origin);
-  void PurgeMemory(PurgeOption purge);
+  void PurgeMemory(bool aggressively);
   void Shutdown();
   void Flush();
 
-  unsigned int CountInMemoryAreas() const;
+  // Returns statistics about the areas in the namespace.
+  UsageStatistics GetUsageStatistics() const;
 
   // Adds memory statistics to |pmd| for chrome://tracing.
   void OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd);
 
   void GetOriginsWithAreas(std::vector<GURL>* origins) const;
 
  private:
   friend class base::RefCountedThreadSafe<DOMStorageNamespace>;
 
   // Struct to hold references to our contained areas and
@@ skipping 18 matching lines @@
   base::FilePath directory_;
   AreaMap areas_;
   scoped_refptr<DOMStorageTaskRunner> task_runner_;
   scoped_refptr<SessionStorageDatabase> session_storage_database_;
 };
 
 }  // namespace content
 
 
 #endif  // CONTENT_BROWSER_DOM_STORAGE_DOM_STORAGE_NAMESPACE_H_