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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_RENDERER_DOM_STORAGE_DOM_STORAGE_CACHED_AREA_H_
      6 #define CONTENT_RENDERER_DOM_STORAGE_DOM_STORAGE_CACHED_AREA_H_
      7 
      8 #include <map>
      9 
     10 #include "base/memory/ref_counted.h"
     11 #include "base/memory/weak_ptr.h"
     12 #include "base/strings/nullable_string16.h"
     13 #include "content/common/content_export.h"
     14 #include "url/gurl.h"
     15 
     16 namespace content {
     17 
     18 class DOMStorageMap;
     19 class DOMStorageProxy;
     20 
     21 // Unlike the other classes in the dom_storage library, this one is intended
     22 // for use in renderer processes. It maintains a complete cache of the
     23 // origin's Map of key/value pairs for fast access. The cache is primed on
     24 // first access and changes are written to the backend thru the |proxy|.
     25 // Mutations originating in other processes are applied to the cache via
     26 // the ApplyMutation method.
     27 class CONTENT_EXPORT DOMStorageCachedArea
     28     : public base::RefCounted<DOMStorageCachedArea> {
     29  public:
     30   DOMStorageCachedArea(int64 namespace_id,
     31                        const GURL& origin,
     32                        DOMStorageProxy* proxy);
     33 
     34   int64 namespace_id() const { return namespace_id_; }
     35   const GURL& origin() const { return origin_; }
     36 
     37   unsigned GetLength(int connection_id);
     38   base::NullableString16 GetKey(int connection_id, unsigned index);
     39   base::NullableString16 GetItem(int connection_id, const base::string16& key);
     40   bool SetItem(int connection_id,
     41                const base::string16& key,
     42                const base::string16& value,
     43                const GURL& page_url);
     44   void RemoveItem(int connection_id,
     45                   const base::string16& key,
     46                   const GURL& page_url);
     47   void Clear(int connection_id, const GURL& page_url);
     48 
     49   void ApplyMutation(const base::NullableString16& key,
     50                      const base::NullableString16& new_value);
     51 
     52   size_t MemoryBytesUsedByCache() const;
     53 
     54   // Resets the object back to its newly constructed state.
     55   void Reset();
     56 
     57  private:
     58   friend class DOMStorageCachedAreaTest;
     59   friend class base::RefCounted<DOMStorageCachedArea>;
     60   ~DOMStorageCachedArea();
     61 
     62   // Primes the cache, loading all values for the area.
     63   void Prime(int connection_id);
     64   void PrimeIfNeeded(int connection_id) {
     65     if (!map_.get())
     66       Prime(connection_id);
     67   }
     68 
     69   // Async completion callbacks for proxied operations.
     70   // These are used to maintain cache consistency by preventing
     71   // mutation events from other processes from overwriting local
     72   // changes made after the mutation.
     73   void OnLoadComplete(bool success);
     74   void OnSetItemComplete(const base::string16& key, bool success);
     75   void OnClearComplete(bool success);
     76   void OnRemoveItemComplete(const base::string16& key, bool success);
     77 
     78   bool should_ignore_key_mutation(const base::string16& key) const {
     79     return ignore_key_mutations_.find(key) != ignore_key_mutations_.end();
     80   }
     81 
     82   bool ignore_all_mutations_;
     83   std::map<base::string16, int> ignore_key_mutations_;
     84 
     85   int64 namespace_id_;
     86   GURL origin_;
     87   scoped_refptr<DOMStorageMap> map_;
     88   scoped_refptr<DOMStorageProxy> proxy_;
     89   // Sometimes, we need to send  messages to the browser for each get access,
     90   // for logging purposes. However, we only do this for a fixed maximum number
     91   // of gets. Here, we keep track of how many remaining get log messages we
     92   // need to send.
     93   int remaining_log_get_messages_;
     94   base::WeakPtrFactory<DOMStorageCachedArea> weak_factory_;
     95 };
     96 
     97 }  // namespace content
     98 
     99 #endif  // CONTENT_RENDERER_DOM_STORAGE_DOM_STORAGE_CACHED_AREA_H_
    100