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      1 // Copyright 2014 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 EXTENSIONS_BROWSER_API_STORAGE_SETTINGS_STORAGE_QUOTA_ENFORCER_H_
      6 #define EXTENSIONS_BROWSER_API_STORAGE_SETTINGS_STORAGE_QUOTA_ENFORCER_H_
      7 
      8 #include "base/compiler_specific.h"
      9 #include "base/memory/weak_ptr.h"
     10 #include "extensions/browser/value_store/value_store.h"
     11 
     12 namespace extensions {
     13 
     14 // Enforces total quota and a per-setting quota in bytes, and a maximum number
     15 // of setting keys, for a delegate storage area.
     16 class SettingsStorageQuotaEnforcer : public ValueStore {
     17  public:
     18   struct Limits {
     19     // The total quota in bytes.
     20     size_t quota_bytes;
     21 
     22     // The quota for each individual item in bytes.
     23     size_t quota_bytes_per_item;
     24 
     25     // The maximum number of items allowed.
     26     size_t max_items;
     27   };
     28 
     29   SettingsStorageQuotaEnforcer(const Limits& limits, ValueStore* delegate);
     30 
     31   virtual ~SettingsStorageQuotaEnforcer();
     32 
     33   // ValueStore implementation.
     34   virtual size_t GetBytesInUse(const std::string& key) OVERRIDE;
     35   virtual size_t GetBytesInUse(const std::vector<std::string>& keys) OVERRIDE;
     36   virtual size_t GetBytesInUse() OVERRIDE;
     37   virtual ReadResult Get(const std::string& key) OVERRIDE;
     38   virtual ReadResult Get(const std::vector<std::string>& keys) OVERRIDE;
     39   virtual ReadResult Get() OVERRIDE;
     40   virtual WriteResult Set(
     41       WriteOptions options,
     42       const std::string& key,
     43       const base::Value& value) OVERRIDE;
     44   virtual WriteResult Set(
     45       WriteOptions options, const base::DictionaryValue& values) OVERRIDE;
     46   virtual WriteResult Remove(const std::string& key) OVERRIDE;
     47   virtual WriteResult Remove(const std::vector<std::string>& keys) OVERRIDE;
     48   virtual WriteResult Clear() OVERRIDE;
     49   virtual bool Restore() OVERRIDE;
     50   virtual bool RestoreKey(const std::string& key) OVERRIDE;
     51 
     52   ValueStore* get_delegate_for_test() { return delegate_.get(); }
     53 
     54  private:
     55   // Calculate the current usage for the database.
     56   void CalculateUsage();
     57 
     58   // Limits configuration.
     59   const Limits limits_;
     60 
     61   // The delegate storage area.
     62   scoped_ptr<ValueStore> const delegate_;
     63 
     64   // Total bytes in used by |delegate_|. Includes both key lengths and
     65   // JSON-encoded values.
     66   size_t used_total_;
     67 
     68   // Map of item key to its size, including the key itself.
     69   std::map<std::string, size_t> used_per_setting_;
     70 
     71   DISALLOW_COPY_AND_ASSIGN(SettingsStorageQuotaEnforcer);
     72 };
     73 
     74 }  // namespace extensions
     75 
     76 #endif  // EXTENSIONS_BROWSER_API_STORAGE_SETTINGS_STORAGE_QUOTA_ENFORCER_H_
     77