base/metrics/histogram_base.h

   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_HISTOGRAM_BASE_H_
   6 #define BASE_METRICS_HISTOGRAM_BASE_H_
   7
   8 #include <stdint.h>
   9
  10 #include <string>
  11 #include <vector>
  12
  13 #include "base/atomicops.h"
  14 #include "base/base_export.h"
  15 #include "base/basictypes.h"
  16 #include "base/memory/scoped_ptr.h"
  17 #include "base/strings/string_piece.h"
  18 #include "base/time/time.h"
  19
  20 class Pickle;
  21 class PickleIterator;
  22
  23 namespace base {
  24
  25 class DictionaryValue;
  26 class HistogramBase;
  27 class HistogramSamples;
  28 class ListValue;
  29
  30 ////////////////////////////////////////////////////////////////////////////////
  31 // These enums are used to facilitate deserialization of histograms from other
  32 // processes into the browser. If you create another class that inherits from
  33 // HistogramBase, add new histogram types and names below.
  34
  35 enum BASE_EXPORT HistogramType {
  36   HISTOGRAM,
  37   LINEAR_HISTOGRAM,
  38   BOOLEAN_HISTOGRAM,
  39   CUSTOM_HISTOGRAM,
  40   SPARSE_HISTOGRAM,
  41 };
  42
  43 std::string HistogramTypeToString(HistogramType type);
  44
  45 // Create or find existing histogram that matches the pickled info.
  46 // Returns NULL if the pickled data has problems.
  47 BASE_EXPORT_PRIVATE HistogramBase* DeserializeHistogramInfo(
  48     PickleIterator* iter);
  49
  50 ////////////////////////////////////////////////////////////////////////////////
  51
  52 class BASE_EXPORT HistogramBase {
  53  public:
  54   typedef int32_t Sample;                // Used for samples.
  55   typedef subtle::Atomic32 AtomicCount;  // Used to count samples.
  56   typedef int32_t Count;  // Used to manipulate counts in temporaries.
  57
  58   static const Sample kSampleType_MAX;  // INT_MAX
  59
  60   enum Flags {
  61     kNoFlags = 0,
  62
  63     // Histogram should be UMA uploaded.
  64     kUmaTargetedHistogramFlag = 0x1,
  65
  66     // Indicates that this is a stability histogram. This flag exists to specify
  67     // which histograms should be included in the initial stability log. Please
  68     // refer to |MetricsService::PrepareInitialStabilityLog|.
  69     kUmaStabilityHistogramFlag = kUmaTargetedHistogramFlag | 0x2,
  70
  71     // Indicates that the histogram was pickled to be sent across an IPC
  72     // Channel. If we observe this flag on a histogram being aggregated into
  73     // after IPC, then we are running in a single process mode, and the
  74     // aggregation should not take place (as we would be aggregating back into
  75     // the source histogram!).
  76     kIPCSerializationSourceFlag = 0x10,
  77
  78     // Only for Histogram and its sub classes: fancy bucket-naming support.
  79     kHexRangePrintingFlag = 0x8000,
  80   };
  81
  82   // Histogram data inconsistency types.
  83   enum Inconsistency {
  84     NO_INCONSISTENCIES = 0x0,
  85     RANGE_CHECKSUM_ERROR = 0x1,
  86     BUCKET_ORDER_ERROR = 0x2,
  87     COUNT_HIGH_ERROR = 0x4,
  88     COUNT_LOW_ERROR = 0x8,
  89
  90     NEVER_EXCEEDED_VALUE = 0x10
  91   };
  92
  93   explicit HistogramBase(const std::string& name);
  94   virtual ~HistogramBase();
  95
  96   std::string histogram_name() const { return histogram_name_; }
  97
  98   // Comapres |name| to the histogram name and triggers a DCHECK if they do not
  99   // match. This is a helper function used by histogram macros, which results in
 100   // in more compact machine code being generated by the macros.
 101   void CheckName(const StringPiece& name) const;
 102
 103   // Operations with Flags enum.
 104   int32_t flags() const { return flags_; }
 105   void SetFlags(int32_t flags);
 106   void ClearFlags(int32_t flags);
 107
 108   virtual HistogramType GetHistogramType() const = 0;
 109
 110   // Whether the histogram has construction arguments as parameters specified.
 111   // For histograms that don't have the concept of minimum, maximum or
 112   // bucket_count, this function always returns false.
 113   virtual bool HasConstructionArguments(Sample expected_minimum,
 114                                         Sample expected_maximum,
 115                                         size_t expected_bucket_count) const = 0;
 116
 117   virtual void Add(Sample value) = 0;
 118
 119   // 2 convenient functions that call Add(Sample).
 120   void AddTime(const TimeDelta& time);
 121   void AddBoolean(bool value);
 122
 123   virtual void AddSamples(const HistogramSamples& samples) = 0;
 124   virtual bool AddSamplesFromPickle(PickleIterator* iter) = 0;
 125
 126   // Serialize the histogram info into |pickle|.
 127   // Note: This only serializes the construction arguments of the histogram, but
 128   // does not serialize the samples.
 129   bool SerializeInfo(Pickle* pickle) const;
 130
 131   // Try to find out data corruption from histogram and the samples.
 132   // The returned value is a combination of Inconsistency enum.
 133   virtual int FindCorruption(const HistogramSamples& samples) const;
 134
 135   // Snapshot the current complete set of sample data.
 136   // Override with atomic/locked snapshot if needed.
 137   virtual scoped_ptr<HistogramSamples> SnapshotSamples() const = 0;
 138
 139   // The following methods provide graphical histogram displays.
 140   virtual void WriteHTMLGraph(std::string* output) const = 0;
 141   virtual void WriteAscii(std::string* output) const = 0;
 142
 143   // Produce a JSON representation of the histogram. This is implemented with
 144   // the help of GetParameters and GetCountAndBucketData; overwrite them to
 145   // customize the output.
 146   void WriteJSON(std::string* output) const;
 147
 148  protected:
 149   // Subclasses should implement this function to make SerializeInfo work.
 150   virtual bool SerializeInfoImpl(Pickle* pickle) const = 0;
 151
 152   // Writes information about the construction parameters in |params|.
 153   virtual void GetParameters(DictionaryValue* params) const = 0;
 154
 155   // Writes information about the current (non-empty) buckets and their sample
 156   // counts to |buckets|, the total sample count to |count| and the total sum
 157   // to |sum|.
 158   virtual void GetCountAndBucketData(Count* count,
 159                                      int64* sum,
 160                                      ListValue* buckets) const = 0;
 161
 162   //// Produce actual graph (set of blank vs non blank char's) for a bucket.
 163   void WriteAsciiBucketGraph(double current_size,
 164                              double max_size,
 165                              std::string* output) const;
 166
 167   // Return a string description of what goes in a given bucket.
 168   const std::string GetSimpleAsciiBucketRange(Sample sample) const;
 169
 170   // Write textual description of the bucket contents (relative to histogram).
 171   // Output is the count in the buckets, as well as the percentage.
 172   void WriteAsciiBucketValue(Count current,
 173                              double scaled_sum,
 174                              std::string* output) const;
 175
 176  private:
 177   const std::string histogram_name_;
 178   int32_t flags_;
 179
 180   DISALLOW_COPY_AND_ASSIGN(HistogramBase);
 181 };
 182
 183 }  // namespace base
 184
 185 #endif  // BASE_METRICS_HISTOGRAM_BASE_H_