Count exact cache size for time ranges

components/browsing_data/content/conditional_cache_counting_helper.h

 // Copyright 2016 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 COMPONENTS_BROWSING_DATA_CONTENT_CONDITIONAL_CACHE_COUNTING_HELPER_H_
 #define COMPONENTS_BROWSING_DATA_CONTENT_CONDITIONAL_CACHE_COUNTING_HELPER_H_
 
 #include <memory>
 
 #include "base/callback_forward.h"
@@ skipping 16 matching lines @@
   // Returns the number bytes in the selected range.
   typedef base::Callback<void(int64_t)> CacheCountCallback;
 
   static ConditionalCacheCountingHelper* CreateForRange(
       content::StoragePartition* storage_partition,
       base::Time begin_time,
       base::Time end_time);
 
   // Count the cache entries according to the specified time range. Destroys
   // this instance of ConditionalCacheCountingHelper when finished.
+  // The returned WeakPtr can be used to cancel the operation if necessary.
   // Must be called on the UI thread!
   //
   // The |completion_callback| will be invoked when the operation completes.
   base::WeakPtr<ConditionalCacheCountingHelper> CountAndDestroySelfWhenFinished(
       const CacheCountCallback& result_callback);
 
+  // Cancel the currently counting process. The task on the IO thread will stop
+  // and the callback will return net::ERR_ABORTED.
+  void CancelCounting();
+
   bool IsFinished();
 
  private:
   enum class CacheState {
     NONE,
     CREATE_MAIN,
     CREATE_MEDIA,
     COUNT_MAIN,
     COUNT_MEDIA,
     DONE
   };
 
   friend class base::DeleteHelper<ConditionalCacheCountingHelper>;
 
   ConditionalCacheCountingHelper(
       base::Time begin_time,
       base::Time end_time,
       net::URLRequestContextGetter* main_context_getter,
       net::URLRequestContextGetter* media_context_getter);
   ~ConditionalCacheCountingHelper();
 
   void Finished();
 
   void CountHttpCacheOnIOThread();
   void DoCountCache(int rv);
 
+  int CountEntries(disk_cache::Backend* backend);
+  void IterateOverEntries(int error);
+
   // Stores the cache size computation result before it can be returned
   // via a callback. This is either the sum of size of the the two cache
   // backends, or an error code if the calculation failed.
   int64_t calculation_result_;
 
   CacheCountCallback result_callback_;
   const base::Time begin_time_;
   const base::Time end_time_;
 
+  // This flag is used to tell the IO thread to stop counting if the user
+  // called CancelCounting().
+  volatile bool is_cancelled_;
   bool is_finished_;
 
   const scoped_refptr<net::URLRequestContextGetter> main_context_getter_;
   const scoped_refptr<net::URLRequestContextGetter> media_context_getter_;
 
   CacheState next_cache_state_;
   disk_cache::Backend* cache_;
 
   std::unique_ptr<disk_cache::Backend::Iterator> iterator_;
+  disk_cache::Entry* current_entry_;
 
   base::WeakPtrFactory<ConditionalCacheCountingHelper> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ConditionalCacheCountingHelper);
 };
 
 }  // namespace browsing_data
 
 #endif  // COMPONENTS_BROWSING_DATA_CONTENT_CONDITIONAL_CACHE_COUNTING_HELPER_H_