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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 // The common code for different SparseHistogram macros.
     23 #define HISTOGRAM_SPARSE_COMMON(name, sample, flag) \
     24     do { \
     25       base::HistogramBase* histogram( \
     26           base::SparseHistogram::FactoryGet(name, flag)); \
     27       DCHECK_EQ(histogram->histogram_name(), name); \
     28       histogram->Add(sample); \
     29     } while (0)
     30 
     31 #define HISTOGRAM_SPARSE_SLOWLY(name, sample) \
     32     HISTOGRAM_SPARSE_COMMON(name, sample, base::HistogramBase::kNoFlags)
     33 
     34 #define UMA_HISTOGRAM_SPARSE_SLOWLY(name, sample) \
     35     HISTOGRAM_SPARSE_COMMON(name, sample, \
     36                             base::HistogramBase::kUmaTargetedHistogramFlag)
     37 
     38 //------------------------------------------------------------------------------
     39 // Define debug only version of macros.
     40 #ifndef NDEBUG
     41 
     42 #define DHISTOGRAM_SPARSE_SLOWLY(name, sample) \
     43     HISTOGRAM_SPARSE_SLOWLY(name, sample)
     44 
     45 #else  // NDEBUG
     46 
     47 #define DHISTOGRAM_SPARSE_SLOWLY(name, sample) \
     48     while (0) { \
     49       static_cast<void>(name); \
     50       static_cast<void>(sample); \
     51     }
     52 
     53 #endif  // NDEBUG
     54 
     55 class HistogramSamples;
     56 
     57 class BASE_EXPORT_PRIVATE SparseHistogram : public HistogramBase {
     58  public:
     59   // If there's one with same name, return the existing one. If not, create a
     60   // new one.
     61   static HistogramBase* FactoryGet(const std::string& name, int32 flags);
     62 
     63   virtual ~SparseHistogram();
     64 
     65   // HistogramBase implementation:
     66   virtual HistogramType GetHistogramType() const OVERRIDE;
     67   virtual bool HasConstructionArguments(
     68       Sample expected_minimum,
     69       Sample expected_maximum,
     70       size_t expected_bucket_count) const OVERRIDE;
     71   virtual void Add(Sample value) OVERRIDE;
     72   virtual void AddSamples(const HistogramSamples& samples) OVERRIDE;
     73   virtual bool AddSamplesFromPickle(PickleIterator* iter) OVERRIDE;
     74   virtual scoped_ptr<HistogramSamples> SnapshotSamples() const OVERRIDE;
     75   virtual void WriteHTMLGraph(std::string* output) const OVERRIDE;
     76   virtual void WriteAscii(std::string* output) const OVERRIDE;
     77 
     78  protected:
     79   // HistogramBase implementation:
     80   virtual bool SerializeInfoImpl(Pickle* pickle) const OVERRIDE;
     81 
     82  private:
     83   // Clients should always use FactoryGet to create SparseHistogram.
     84   explicit SparseHistogram(const std::string& name);
     85 
     86   friend BASE_EXPORT_PRIVATE HistogramBase* DeserializeHistogramInfo(
     87       PickleIterator* iter);
     88   static HistogramBase* DeserializeInfoImpl(PickleIterator* iter);
     89 
     90   virtual void GetParameters(DictionaryValue* params) const OVERRIDE;
     91   virtual void GetCountAndBucketData(Count* count,
     92                                      int64* sum,
     93                                      ListValue* buckets) const OVERRIDE;
     94 
     95   // Helpers for emitting Ascii graphic.  Each method appends data to output.
     96   void WriteAsciiImpl(bool graph_it,
     97                       const std::string& newline,
     98                       std::string* output) const;
     99 
    100   // Write a common header message describing this histogram.
    101   void WriteAsciiHeader(const Count total_count,
    102                         std::string* output) const;
    103 
    104   // For constuctor calling.
    105   friend class SparseHistogramTest;
    106 
    107   // Protects access to |samples_|.
    108   mutable base::Lock lock_;
    109 
    110   SampleMap samples_;
    111 
    112   DISALLOW_COPY_AND_ASSIGN(SparseHistogram);
    113 };
    114 
    115 }  // namespace base
    116 
    117 #endif  // BASE_METRICS_SPARSE_HISTOGRAM_H_
    118