LevelDB storage for data reduction proxy to store data usage stats.

components/data_reduction_proxy/core/browser/data_usage_store.h

Index: components/data_reduction_proxy/core/browser/data_usage_store.h
diff --git a/components/data_reduction_proxy/core/browser/data_usage_store.h b/components/data_reduction_proxy/core/browser/data_usage_store.h
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+// Copyright 2015 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_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_USAGE_STORE_H_
+#define COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_USAGE_STORE_H_
+
+#include <map>
+#include <string>
+
+#include "base/macros.h"
+#include "base/sequence_checker.h"
+#include "base/time/time.h"
+
+namespace data_reduction_proxy {
+class DataStore;
+class DataUsageBucket;
+
+// Store for detailed data usage stats. Data usage from every
+// |kDataUsageBucketLengthMins| interval is stored in a DataUsageBucket.
+class DataUsageStore {
+ public:
+  explicit DataUsageStore(DataStore* db);
+
+  ~DataUsageStore();
+
+  // Loads the data usage bucket for the current interval into |current_bucket|.
+  // This method must be called at least once before any calls to
+  // |StoreCurrentDataUsageBucket|.
+  void LoadCurrentDataUsageBucket(DataUsageBucket* bucket);
+
+  // Stores the data usage bucket for the current interval. This will overwrite
+  // the current data usage bucket in the |db_| if they are for the same
+  // interval. It will also backfill any missed intervals with empty data.
+  // Intervals might be missed because Chrome was not running, or there was no
+  // network activity during an interval.
+  void StoreCurrentDataUsageBucket(const DataUsageBucket& current_bucket);
+
+ private:
+  friend class DataUsageStoreTest;
+
+  // Converts the given |bucket| into a string format for persistance to
+  // |DataReductionProxyStore| and add to the map.
+  void AddBucketToMap(const DataUsageBucket& bucket,
+                      std::map<std::string, std::string>* map);
+
+  // Returns the number of buckets between the current interval bucket and the
+  // last bucket that was persisted to the store.
+  int NumBucketsSinceLastSaved(base::Time current) const;
+
+  // The store to persist data usage information.
+  DataStore* db_;
+
+  // The index of the last bucket persisted in the |db_|. |DataUsageBucket| is
+  // stored in the |db_| as a circular array. This index points to the array
+  // position corresponding to the current bucket.
+  int current_bucket_index_;
+
+  // The time when the current bucket was last written to |db_|. This field is
+  // used to determine if a DataUsageBucket to be saved belongs to the same
+  // interval, or a more recent interval.
+  base::Time current_bucket_last_updated_;
+
+  base::SequenceChecker sequence_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(DataUsageStore);
+};
+
+}  // namespace data_reduction_proxy
+#endif  // COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_USAGE_STORE_H_