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      1 // Copyright (c) 2012 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 BASE_METRICS_SPARSE_HISTOGRAM_H_
      6 #define BASE_METRICS_SPARSE_HISTOGRAM_H_
      7 
      8 #include <map>
      9 #include <string>
     10 
     11 #include "base/base_export.h"
     12 #include "base/basictypes.h"
     13 #include "base/compiler_specific.h"
     14 #include "base/logging.h"
     15 #include "base/memory/scoped_ptr.h"
     16 #include "base/metrics/histogram_base.h"
     17 #include "base/metrics/sample_map.h"
     18 #include "base/synchronization/lock.h"
     19 
     20 namespace base {
     21 
     22 #define UMA_HISTOGRAM_SPARSE_SLOWLY(name, sample) \
     23     do { \
     24       base::HistogramBase* histogram = base::SparseHistogram::FactoryGet( \
     25           name, base::HistogramBase::kUmaTargetedHistogramFlag); \
     26       histogram->Add(sample); \
     27     } while (0)
     28 
     29 class HistogramSamples;
     30 
     31 class BASE_EXPORT_PRIVATE SparseHistogram : public HistogramBase {
     32  public:
     33   // If there's one with same name, return the existing one. If not, create a
     34   // new one.
     35   static HistogramBase* FactoryGet(const std::string& name, int32 flags);
     36 
     37   virtual ~SparseHistogram();
     38 
     39   // HistogramBase implementation:
     40   virtual HistogramType GetHistogramType() const OVERRIDE;
     41   virtual bool HasConstructionArguments(
     42       Sample expected_minimum,
     43       Sample expected_maximum,
     44       size_t expected_bucket_count) const OVERRIDE;
     45   virtual void Add(Sample value) OVERRIDE;
     46   virtual void AddSamples(const HistogramSamples& samples) OVERRIDE;
     47   virtual bool AddSamplesFromPickle(PickleIterator* iter) OVERRIDE;
     48   virtual scoped_ptr<HistogramSamples> SnapshotSamples() const OVERRIDE;
     49   virtual void WriteHTMLGraph(std::string* output) const OVERRIDE;
     50   virtual void WriteAscii(std::string* output) const OVERRIDE;
     51 
     52  protected:
     53   // HistogramBase implementation:
     54   virtual bool SerializeInfoImpl(Pickle* pickle) const OVERRIDE;
     55 
     56  private:
     57   // Clients should always use FactoryGet to create SparseHistogram.
     58   explicit SparseHistogram(const std::string& name);
     59 
     60   friend BASE_EXPORT_PRIVATE HistogramBase* DeserializeHistogramInfo(
     61       PickleIterator* iter);
     62   static HistogramBase* DeserializeInfoImpl(PickleIterator* iter);
     63 
     64   virtual void GetParameters(DictionaryValue* params) const OVERRIDE;
     65   virtual void GetCountAndBucketData(Count* count,
     66                                      int64* sum,
     67                                      ListValue* buckets) const OVERRIDE;
     68 
     69   // Helpers for emitting Ascii graphic.  Each method appends data to output.
     70   void WriteAsciiImpl(bool graph_it,
     71                       const std::string& newline,
     72                       std::string* output) const;
     73 
     74   // Write a common header message describing this histogram.
     75   void WriteAsciiHeader(const Count total_count,
     76                         std::string* output) const;
     77 
     78   // For constuctor calling.
     79   friend class SparseHistogramTest;
     80 
     81   // Protects access to |samples_|.
     82   mutable base::Lock lock_;
     83 
     84   SampleMap samples_;
     85 
     86   DISALLOW_COPY_AND_ASSIGN(SparseHistogram);
     87 };
     88 
     89 }  // namespace base
     90 
     91 #endif  // BASE_METRICS_SPARSE_HISTOGRAM_H_
     92