Refactor histogram_persistence to be a class.

base/metrics/histogram.h

 // Copyright (c) 2012 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.
 
 // Histogram is an object that aggregates statistics, and can summarize them in
 // various forms, including ASCII graphical, HTML, and numerically (as a
 // vector of numbers corresponding to each of the aggregating buckets).
 
 // It supports calls to accumulate either time intervals (which are processed
 // as integral number of milliseconds), or arbitrary integral units.
@@ skipping 86 matching lines @@
 class PickleIterator;
 class SampleVector;
 
 class BASE_EXPORT Histogram : public HistogramBase {
  public:
   // Initialize maximum number of buckets in histograms as 16,384.
   static const uint32_t kBucketCount_MAX;
 
   typedef std::vector<Count> Counts;
 
+  ~Histogram() override;
+
   //----------------------------------------------------------------------------
   // For a valid histogram, input should follow these restrictions:
   // minimum > 0 (if a minimum below 1 is specified, it will implicitly be
   //              normalized up to 1)
   // maximum > minimum
   // buckets > 2 [minimum buckets needed: underflow, overflow and the range]
   // Additionally,
   // buckets <= (maximum - minimum + 2) - this is to ensure that we don't have
   // more buckets than the range of numbers; having more buckets than 1 per
   // value in the range would be nonsensical.
@@ skipping 15 matching lines @@
                                    Sample minimum,
                                    Sample maximum,
                                    uint32_t bucket_count,
                                    int32_t flags);
   static HistogramBase* FactoryTimeGet(const char* name,
                                        base::TimeDelta minimum,
                                        base::TimeDelta maximum,
                                        uint32_t bucket_count,
                                        int32_t flags);
 
-  // Get a histogram using data in persistent storage.
-  static HistogramBase* PersistentGet(const std::string& name,
-                                      Sample minimum,
-                                      Sample maximum,
-                                      const BucketRanges* ranges,
-                                      HistogramBase::AtomicCount* counts,
-                                      HistogramBase::AtomicCount* logged_counts,
-                                      uint32_t counts_size,
-                                      HistogramSamples::Metadata* meta,
-                                      HistogramSamples::Metadata* logged_meta);
+  // Create a histogram using data in persistent storage.
+  static scoped_ptr<HistogramBase> PersistentCreate(
+      const std::string& name,
+      Sample minimum,
+      Sample maximum,
+      const BucketRanges* ranges,
+      HistogramBase::AtomicCount* counts,
+      HistogramBase::AtomicCount* logged_counts,
+      uint32_t counts_size,
+      HistogramSamples::Metadata* meta,
+      HistogramSamples::Metadata* logged_meta);
 
   static void InitializeBucketRanges(Sample minimum,
                                      Sample maximum,
                                      BucketRanges* ranges);
 
   // This constant if for FindCorruption. Since snapshots of histograms are
   // taken asynchronously relative to sampling, and our counting code currently
   // does not prevent race conditions, it is pretty likely that we'll catch a
   // redundant count that doesn't match the sample count.  We allow for a
   // certain amount of slop before flagging this as an inconsistency. Even with
@@ skipping 68 matching lines @@
   Histogram(const std::string& name,
             Sample minimum,
             Sample maximum,
             const BucketRanges* ranges,
             HistogramBase::AtomicCount* counts,
             HistogramBase::AtomicCount* logged_counts,
             uint32_t counts_size,
             HistogramSamples::Metadata* meta,
             HistogramSamples::Metadata* logged_meta);
 
-  ~Histogram() override;
-
   // HistogramBase implementation:
   bool SerializeInfoImpl(base::Pickle* pickle) const override;
 
   // Method to override to skip the display of the i'th bucket if it's empty.
   virtual bool PrintEmptyBucket(uint32_t index) const;
 
   // Get normalized size, relative to the ranges(i).
   virtual double GetBucketSize(Count current, uint32_t i) const;
 
   // Return a string description of what goes in a given bucket.
@@ skipping 91 matching lines @@
                                    Sample minimum,
                                    Sample maximum,
                                    uint32_t bucket_count,
                                    int32_t flags);
   static HistogramBase* FactoryTimeGet(const char* name,
                                        TimeDelta minimum,
                                        TimeDelta maximum,
                                        uint32_t bucket_count,
                                        int32_t flags);
 
-  // Get a histogram using data in persistent storage.
-  static HistogramBase* PersistentGet(const std::string& name,
-                                      Sample minimum,
-                                      Sample maximum,
-                                      const BucketRanges* ranges,
-                                      HistogramBase::AtomicCount* counts,
-                                      HistogramBase::AtomicCount* logged_counts,
-                                      uint32_t counts_size,
-                                      HistogramSamples::Metadata* meta,
-                                      HistogramSamples::Metadata* logged_meta);
+  // Create a histogram using data in persistent storage.
+  static scoped_ptr<HistogramBase> PersistentCreate(
+      const std::string& name,
+      Sample minimum,
+      Sample maximum,
+      const BucketRanges* ranges,
+      HistogramBase::AtomicCount* counts,
+      HistogramBase::AtomicCount* logged_counts,
+      uint32_t counts_size,
+      HistogramSamples::Metadata* meta,
+      HistogramSamples::Metadata* logged_meta);
 
   struct DescriptionPair {
     Sample sample;
     const char* description;  // Null means end of a list of pairs.
   };
 
   // Create a LinearHistogram and store a list of number/text values for use in
   // writing the histogram graph.
   // |descriptions| can be NULL, which means no special descriptions to set. If
   // it's not NULL, the last element in the array must has a NULL in its
@@ skipping 60 matching lines @@
 // BooleanHistogram is a histogram for booleans.
 class BASE_EXPORT BooleanHistogram : public LinearHistogram {
  public:
   static HistogramBase* FactoryGet(const std::string& name, int32_t flags);
 
   // Overload of the above function that takes a const char* |name| param,
   // to avoid code bloat from the std::string constructor being inlined into
   // call sites.
   static HistogramBase* FactoryGet(const char* name, int32_t flags);
 
-  // Get a histogram using data in persistent storage.
-  static HistogramBase* PersistentGet(const std::string& name,
-                                      const BucketRanges* ranges,
-                                      HistogramBase::AtomicCount* counts,
-                                      HistogramBase::AtomicCount* logged_counts,
-                                      HistogramSamples::Metadata* meta,
-                                      HistogramSamples::Metadata* logged_meta);
+  // Create a histogram using data in persistent storage.
+  static scoped_ptr<HistogramBase> PersistentCreate(
+      const std::string& name,
+      const BucketRanges* ranges,
+      HistogramBase::AtomicCount* counts,
+      HistogramBase::AtomicCount* logged_counts,
+      HistogramSamples::Metadata* meta,
+      HistogramSamples::Metadata* logged_meta);
 
   HistogramType GetHistogramType() const override;
 
  protected:
   class Factory;
 
  private:
   BooleanHistogram(const std::string& name, const BucketRanges* ranges);
   BooleanHistogram(const std::string& name,
                    const BucketRanges* ranges,
@@ skipping 22 matching lines @@
                                    const std::vector<Sample>& custom_ranges,
                                    int32_t flags);
 
   // Overload of the above function that takes a const char* |name| param,
   // to avoid code bloat from the std::string constructor being inlined into
   // call sites.
   static HistogramBase* FactoryGet(const char* name,
                                    const std::vector<Sample>& custom_ranges,
                                    int32_t flags);
 
-  // Get a histogram using data in persistent storage.
-  static HistogramBase* PersistentGet(const std::string& name,
-                                      const BucketRanges* ranges,
-                                      HistogramBase::AtomicCount* counts,
-                                      HistogramBase::AtomicCount* logged_counts,
-                                      uint32_t counts_size,
-                                      HistogramSamples::Metadata* meta,
-                                      HistogramSamples::Metadata* logged_meta);
+  // Create a histogram using data in persistent storage.
+  static scoped_ptr<HistogramBase> PersistentCreate(
+      const std::string& name,
+      const BucketRanges* ranges,
+      HistogramBase::AtomicCount* counts,
+      HistogramBase::AtomicCount* logged_counts,
+      uint32_t counts_size,
+      HistogramSamples::Metadata* meta,
+      HistogramSamples::Metadata* logged_meta);
 
   // Overridden from Histogram:
   HistogramType GetHistogramType() const override;
 
   // Helper method for transforming an array of valid enumeration values
   // to the std::vector<int> expected by UMA_HISTOGRAM_CUSTOM_ENUMERATION.
   // This function ensures that a guard bucket exists right after any
   // valid sample value (unless the next higher sample is also a valid value),
   // so that invalid samples never fall into the same bucket as valid samples.
   // TODO(kaiwang): Change name to ArrayToCustomEnumRanges.
@@ skipping 24 matching lines @@
   static HistogramBase* DeserializeInfoImpl(base::PickleIterator* iter);
 
   static bool ValidateCustomRanges(const std::vector<Sample>& custom_ranges);
 
   DISALLOW_COPY_AND_ASSIGN(CustomHistogram);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_H_