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

components/data_reduction_proxy/core/browser/data_usage_storage_helper.h

Index: components/data_reduction_proxy/core/browser/data_usage_storage_helper.h
diff --git a/components/data_reduction_proxy/core/browser/data_usage_storage_helper.h b/components/data_reduction_proxy/core/browser/data_usage_storage_helper.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_STORAGE_HELPER_H_
+#define COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_USAGE_STORAGE_HELPER_H_
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "base/time/time.h"
+
+namespace data_reduction_proxy {
+class DataReductionProxyStore;
+class DataUsageBucket;
+
+// Refcounted wrapper around DataUsageBucket. Using ref counting allows us to
+// pass DataUsageBucket across threads.
+class DataUsageBucketWrapper
+    : base::RefCountedThreadSafe<DataUsageBucketWrapper> {
+ public:
+  DataUsageBucketWrapper(DataUsageBucket* bucket);
+
+  inline DataUsageBucket* bucket() { return bucket_.get(); }
+
+  inline void set_bucket(DataUsageBucket* bucket) {
+    DCHECK(bucket_.get() == nullptr);
+    bucket_.reset(bucket);
+  }
+
+ private:
+  ~DataUsageBucketWrapper();
+
+  scoped_ptr<DataUsageBucket> bucket_;
+};
+
+// Store for detailed data usage stats. Data usage from every
+// |kDataUsageBucketLengthMins| interval is stored in a DataUsageBucket.
+class DataUsageStorageHelper
+    : public base::SupportsWeakPtr<DataUsageStorageHelper> {
+ public:
+  DataUsageStorageHelper(scoped_refptr<DataReductionProxyStore> db);
+  ~DataUsageStorageHelper();
+
+  // Loads the data usage bucket for the current interval. This method must be
+  // called atleast once before any calls to |StoreCurrentDataUsageBucket|.
+  void LoadCurrentDataUsageBucket(
+      scoped_refptr<DataUsageBucketWrapper> current_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(
+      scoped_refptr<DataUsageBucketWrapper> current_bucket);
+
+ private:
+  // Converts the given |bucket| into a string format for persistance to
+  // |DataReductionProxyStore| and add to the map.
+  void AddBucketToMap(std::map<std::string, std::string>* map,
+                      DataUsageBucket* bucket);
+
+  // 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);
+
+  // The store to persist data usage information.
+  scoped_refptr<DataReductionProxyStore> 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::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(DataUsageStorageHelper);
+};
+
+}  // namespace data_reduction_proxy
+#endif  // COMPONENTS_DATA_REDUCTION_PROXY_CORE_BROWSER_DATA_USAGE_STORAGE_HELPER_H_