// Copyright (c) 2011 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.
// The default layout of buckets is exponential. For example, buckets might
// contain (sequentially) the count of values in the following intervals:
// [0,1), [1,2), [2,4), [4,8), [8,16), [16,32), [32,64), [64,infinity)
// That bucket allocation would actually result from construction of a histogram
// for values between 1 and 64, with 8 buckets, such as:
// Histogram count(L"some name", 1, 64, 8);
// Note that the underflow bucket [0,1) and the overflow bucket [64,infinity)
// are not counted by the constructor in the user supplied "bucket_count"
// argument.
// The above example has an exponential ratio of 2 (doubling the bucket width
// in each consecutive bucket. The Histogram class automatically calculates
// the smallest ratio that it can use to construct the number of buckets
// selected in the constructor. An another example, if you had 50 buckets,
// and millisecond time values from 1 to 10000, then the ratio between
// consecutive bucket widths will be approximately somewhere around the 50th
// root of 10000. This approach provides very fine grain (narrow) buckets
// at the low end of the histogram scale, but allows the histogram to cover a
// gigantic range with the addition of very few buckets.
// Histograms use a pattern involving a function static variable, that is a
// pointer to a histogram. This static is explicitly initialized on any thread
// that detects a uninitialized (NULL) pointer. The potentially racy
// initialization is not a problem as it is always set to point to the same
// value (i.e., the FactoryGet always returns the same value). FactoryGet
// is also completely thread safe, which results in a completely thread safe,
// and relatively fast, set of counters. To avoid races at shutdown, the static
// pointer is NOT deleted, and we leak the histograms at process termination.
#ifndef BASE_METRICS_HISTOGRAM_H_
#define BASE_METRICS_HISTOGRAM_H_
#pragma once
#include <map>
#include <string>
#include <vector>
#include "base/base_api.h"
#include "base/gtest_prod_util.h"
#include "base/logging.h"
#include "base/time.h"
class Pickle;
namespace base {
class Lock;
//------------------------------------------------------------------------------
// Provide easy general purpose histogram in a macro, just like stats counters.
// The first four macros use 50 buckets.
#define HISTOGRAM_TIMES(name, sample) HISTOGRAM_CUSTOM_TIMES( \
name, sample, base::TimeDelta::FromMilliseconds(1), \
base::TimeDelta::FromSeconds(10), 50)
#define HISTOGRAM_COUNTS(name, sample) HISTOGRAM_CUSTOM_COUNTS( \
name, sample, 1, 1000000, 50)
#define HISTOGRAM_COUNTS_100(name, sample) HISTOGRAM_CUSTOM_COUNTS( \
name, sample, 1, 100, 50)
#define HISTOGRAM_COUNTS_10000(name, sample) HISTOGRAM_CUSTOM_COUNTS( \
name, sample, 1, 10000, 50)
#define HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::Histogram::FactoryGet(name, min, max, bucket_count, \
base::Histogram::kNoFlags); \
DCHECK_EQ(name, counter->histogram_name()); \
counter->Add(sample); \
} while (0)
#define HISTOGRAM_PERCENTAGE(name, under_one_hundred) \
HISTOGRAM_ENUMERATION(name, under_one_hundred, 101)
// For folks that need real specific times, use this to select a precise range
// of times you want plotted, and the number of buckets you want used.
#define HISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::Histogram::FactoryTimeGet(name, min, max, bucket_count, \
base::Histogram::kNoFlags); \
DCHECK_EQ(name, counter->histogram_name()); \
counter->AddTime(sample); \
} while (0)
// DO NOT USE THIS. It is being phased out, in favor of HISTOGRAM_CUSTOM_TIMES.
#define HISTOGRAM_CLIPPED_TIMES(name, sample, min, max, bucket_count) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::Histogram::FactoryTimeGet(name, min, max, bucket_count, \
base::Histogram::kNoFlags); \
DCHECK_EQ(name, counter->histogram_name()); \
if ((sample) < (max)) counter->AddTime(sample); \
} while (0)
// Support histograming of an enumerated value. The samples should always be
// less than boundary_value.
#define HISTOGRAM_ENUMERATION(name, sample, boundary_value) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::LinearHistogram::FactoryGet(name, 1, boundary_value, \
boundary_value + 1, base::Histogram::kNoFlags); \
DCHECK_EQ(name, counter->histogram_name()); \
counter->Add(sample); \
} while (0)
#define HISTOGRAM_CUSTOM_ENUMERATION(name, sample, custom_ranges) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::CustomHistogram::FactoryGet(name, custom_ranges, \
base::Histogram::kNoFlags); \
DCHECK_EQ(name, counter->histogram_name()); \
counter->Add(sample); \
} while (0)
//------------------------------------------------------------------------------
// Define Debug vs non-debug flavors of macros.
#ifndef NDEBUG
#define DHISTOGRAM_TIMES(name, sample) HISTOGRAM_TIMES(name, sample)
#define DHISTOGRAM_COUNTS(name, sample) HISTOGRAM_COUNTS(name, sample)
#define DHISTOGRAM_PERCENTAGE(name, under_one_hundred) HISTOGRAM_PERCENTAGE(\
name, under_one_hundred)
#define DHISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) \
HISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count)
#define DHISTOGRAM_CLIPPED_TIMES(name, sample, min, max, bucket_count) \
HISTOGRAM_CLIPPED_TIMES(name, sample, min, max, bucket_count)
#define DHISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) \
HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count)
#define DHISTOGRAM_ENUMERATION(name, sample, boundary_value) \
HISTOGRAM_ENUMERATION(name, sample, boundary_value)
#define DHISTOGRAM_CUSTOM_ENUMERATION(name, sample, custom_ranges) \
HISTOGRAM_CUSTOM_ENUMERATION(name, sample, custom_ranges)
#else // NDEBUG
#define DHISTOGRAM_TIMES(name, sample) do {} while (0)
#define DHISTOGRAM_COUNTS(name, sample) do {} while (0)
#define DHISTOGRAM_PERCENTAGE(name, under_one_hundred) do {} while (0)
#define DHISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) \
do {} while (0)
#define DHISTOGRAM_CLIPPED_TIMES(name, sample, min, max, bucket_count) \
do {} while (0)
#define DHISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) \
do {} while (0)
#define DHISTOGRAM_ENUMERATION(name, sample, boundary_value) do {} while (0)
#define DHISTOGRAM_CUSTOM_ENUMERATION(name, sample, custom_ranges) \
do {} while (0)
#endif // NDEBUG
//------------------------------------------------------------------------------
// The following macros provide typical usage scenarios for callers that wish
// to record histogram data, and have the data submitted/uploaded via UMA.
// Not all systems support such UMA, but if they do, the following macros
// should work with the service.
#define UMA_HISTOGRAM_TIMES(name, sample) UMA_HISTOGRAM_CUSTOM_TIMES( \
name, sample, base::TimeDelta::FromMilliseconds(1), \
base::TimeDelta::FromSeconds(10), 50)
#define UMA_HISTOGRAM_MEDIUM_TIMES(name, sample) UMA_HISTOGRAM_CUSTOM_TIMES( \
name, sample, base::TimeDelta::FromMilliseconds(10), \
base::TimeDelta::FromMinutes(3), 50)
// Use this macro when times can routinely be much longer than 10 seconds.
#define UMA_HISTOGRAM_LONG_TIMES(name, sample) UMA_HISTOGRAM_CUSTOM_TIMES( \
name, sample, base::TimeDelta::FromMilliseconds(1), \
base::TimeDelta::FromHours(1), 50)
#define UMA_HISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::Histogram::FactoryTimeGet(name, min, max, bucket_count, \
base::Histogram::kUmaTargetedHistogramFlag); \
DCHECK_EQ(name, counter->histogram_name()); \
counter->AddTime(sample); \
} while (0)
// DO NOT USE THIS. It is being phased out, in favor of HISTOGRAM_CUSTOM_TIMES.
#define UMA_HISTOGRAM_CLIPPED_TIMES(name, sample, min, max, bucket_count) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::Histogram::FactoryTimeGet(name, min, max, bucket_count, \
base::Histogram::kUmaTargetedHistogramFlag); \
DCHECK_EQ(name, counter->histogram_name()); \
if ((sample) < (max)) counter->AddTime(sample); \
} while (0)
#define UMA_HISTOGRAM_COUNTS(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
name, sample, 1, 1000000, 50)
#define UMA_HISTOGRAM_COUNTS_100(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
name, sample, 1, 100, 50)
#define UMA_HISTOGRAM_COUNTS_10000(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
name, sample, 1, 10000, 50)
#define UMA_HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::Histogram::FactoryGet(name, min, max, bucket_count, \
base::Histogram::kUmaTargetedHistogramFlag); \
DCHECK_EQ(name, counter->histogram_name()); \
counter->Add(sample); \
} while (0)
#define UMA_HISTOGRAM_MEMORY_KB(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
name, sample, 1000, 500000, 50)
#define UMA_HISTOGRAM_MEMORY_MB(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
name, sample, 1, 1000, 50)
#define UMA_HISTOGRAM_PERCENTAGE(name, under_one_hundred) \
UMA_HISTOGRAM_ENUMERATION(name, under_one_hundred, 101)
#define UMA_HISTOGRAM_BOOLEAN(name, sample) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::BooleanHistogram::FactoryGet(name, \
base::Histogram::kUmaTargetedHistogramFlag); \
DCHECK_EQ(name, counter->histogram_name()); \
counter->AddBoolean(sample); \
} while (0)
#define UMA_HISTOGRAM_ENUMERATION(name, sample, boundary_value) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::LinearHistogram::FactoryGet(name, 1, boundary_value, \
boundary_value + 1, base::Histogram::kUmaTargetedHistogramFlag); \
DCHECK_EQ(name, counter->histogram_name()); \
counter->Add(sample); \
} while (0)
#define UMA_HISTOGRAM_CUSTOM_ENUMERATION(name, sample, custom_ranges) do { \
static base::Histogram* counter(NULL); \
if (!counter) \
counter = base::CustomHistogram::FactoryGet(name, custom_ranges, \
base::Histogram::kUmaTargetedHistogramFlag); \
DCHECK_EQ(name, counter->histogram_name()); \
counter->Add(sample); \
} while (0)
//------------------------------------------------------------------------------
class BooleanHistogram;
class CustomHistogram;
class Histogram;
class LinearHistogram;
class BASE_API Histogram {
public:
typedef int Sample; // Used for samples (and ranges of samples).
typedef int Count; // Used to count samples in a bucket.
static const Sample kSampleType_MAX = INT_MAX;
// Initialize maximum number of buckets in histograms as 16,384.
static const size_t kBucketCount_MAX;
typedef std::vector<Count> Counts;
typedef std::vector<Sample> Ranges;
// These enums are used to facilitate deserialization of renderer histograms
// into the browser.
enum ClassType {
HISTOGRAM,
LINEAR_HISTOGRAM,
BOOLEAN_HISTOGRAM,
CUSTOM_HISTOGRAM,
NOT_VALID_IN_RENDERER
};
enum BucketLayout {
EXPONENTIAL,
LINEAR,
CUSTOM
};
enum Flags {
kNoFlags = 0,
kUmaTargetedHistogramFlag = 0x1, // Histogram should be UMA uploaded.
// Indicate that the histogram was pickled to be sent across an IPC Channel.
// If we observe this flag on a histogram being aggregated into after IPC,
// then we are running in a single process mode, and the aggregation should
// not take place (as we would be aggregating back into the source
// histogram!).
kIPCSerializationSourceFlag = 0x10,
kHexRangePrintingFlag = 0x8000, // Fancy bucket-naming supported.
};
enum Inconsistencies {
NO_INCONSISTENCIES = 0x0,
RANGE_CHECKSUM_ERROR = 0x1,
BUCKET_ORDER_ERROR = 0x2,
COUNT_HIGH_ERROR = 0x4,
COUNT_LOW_ERROR = 0x8,
NEVER_EXCEEDED_VALUE = 0x10
};
struct DescriptionPair {
Sample sample;
const char* description; // Null means end of a list of pairs.
};
//----------------------------------------------------------------------------
// Statistic values, developed over the life of the histogram.
class BASE_API SampleSet {
public:
explicit SampleSet();
~SampleSet();
// Adjust size of counts_ for use with given histogram.
void Resize(const Histogram& histogram);
void CheckSize(const Histogram& histogram) const;
// Accessor for histogram to make routine additions.
void Accumulate(Sample value, Count count, size_t index);
// Accessor methods.
Count counts(size_t i) const { return counts_[i]; }
Count TotalCount() const;
int64 sum() const { return sum_; }
int64 redundant_count() const { return redundant_count_; }
// Arithmetic manipulation of corresponding elements of the set.
void Add(const SampleSet& other);
void Subtract(const SampleSet& other);
bool Serialize(Pickle* pickle) const;
bool Deserialize(void** iter, const Pickle& pickle);
protected:
// Actual histogram data is stored in buckets, showing the count of values
// that fit into each bucket.
Counts counts_;
// Save simple stats locally. Note that this MIGHT get done in base class
// without shared memory at some point.
int64 sum_; // sum of samples.
private:
// Allow tests to corrupt our innards for testing purposes.
FRIEND_TEST(HistogramTest, CorruptSampleCounts);
// To help identify memory corruption, we reduntantly save the number of
// samples we've accumulated into all of our buckets. We can compare this
// count to the sum of the counts in all buckets, and detect problems. Note
// that due to races in histogram accumulation (if a histogram is indeed
// updated on several threads simultaneously), the tallies might mismatch,
// and also the snapshotting code may asynchronously get a mismatch (though
// generally either race based mismatch cause is VERY rare).
int64 redundant_count_;
};
//----------------------------------------------------------------------------
// minimum should start from 1. 0 is invalid as a minimum. 0 is an implicit
// default underflow bucket.
static Histogram* FactoryGet(const std::string& name,
Sample minimum,
Sample maximum,
size_t bucket_count,
Flags flags);
static Histogram* FactoryTimeGet(const std::string& name,
base::TimeDelta minimum,
base::TimeDelta maximum,
size_t bucket_count,
Flags flags);
void Add(int value);
// This method is an interface, used only by BooleanHistogram.
virtual void AddBoolean(bool value);
// Accept a TimeDelta to increment.
void AddTime(TimeDelta time) {
Add(static_cast<int>(time.InMilliseconds()));
}
void AddSampleSet(const SampleSet& sample);
// This method is an interface, used only by LinearHistogram.
virtual void SetRangeDescriptions(const DescriptionPair descriptions[]);
// The following methods provide graphical histogram displays.
void WriteHTMLGraph(std::string* output) const;
void WriteAscii(bool graph_it, const std::string& newline,
std::string* output) const;
// Support generic flagging of Histograms.
// 0x1 Currently used to mark this histogram to be recorded by UMA..
// 0x8000 means print ranges in hex.
void SetFlags(Flags flags) { flags_ = static_cast<Flags> (flags_ | flags); }
void ClearFlags(Flags flags) { flags_ = static_cast<Flags>(flags_ & ~flags); }
int flags() const { return flags_; }
// Convenience methods for serializing/deserializing the histograms.
// Histograms from Renderer process are serialized and sent to the browser.
// Browser process reconstructs the histogram from the pickled version
// accumulates the browser-side shadow copy of histograms (that mirror
// histograms created in the renderer).
// Serialize the given snapshot of a Histogram into a String. Uses
// Pickle class to flatten the object.
static std::string SerializeHistogramInfo(const Histogram& histogram,
const SampleSet& snapshot);
// The following method accepts a list of pickled histograms and
// builds a histogram and updates shadow copy of histogram data in the
// browser process.
static bool DeserializeHistogramInfo(const std::string& histogram_info);
// Check to see if bucket ranges, counts and tallies in the snapshot are
// consistent with the bucket ranges and checksums in our histogram. This can
// produce a false-alarm if a race occurred in the reading of the data during
// a SnapShot process, but should otherwise be false at all times (unless we
// have memory over-writes, or DRAM failures).
virtual Inconsistencies FindCorruption(const SampleSet& snapshot) const;
//----------------------------------------------------------------------------
// Accessors for factory constuction, serialization and testing.
//----------------------------------------------------------------------------
virtual ClassType histogram_type() const;
const std::string& histogram_name() const { return histogram_name_; }
Sample declared_min() const { return declared_min_; }
Sample declared_max() const { return declared_max_; }
virtual Sample ranges(size_t i) const;
uint32 range_checksum() const { return range_checksum_; }
virtual size_t bucket_count() const;
// Snapshot the current complete set of sample data.
// Override with atomic/locked snapshot if needed.
virtual void SnapshotSample(SampleSet* sample) const;
virtual bool HasConstructorArguments(Sample minimum, Sample maximum,
size_t bucket_count);
virtual bool HasConstructorTimeDeltaArguments(TimeDelta minimum,
TimeDelta maximum,
size_t bucket_count);
// Return true iff the range_checksum_ matches current ranges_ vector.
bool HasValidRangeChecksum() const;
protected:
Histogram(const std::string& name, Sample minimum,
Sample maximum, size_t bucket_count);
Histogram(const std::string& name, TimeDelta minimum,
TimeDelta maximum, size_t bucket_count);
virtual ~Histogram();
// Initialize ranges_ mapping.
void InitializeBucketRange();
// Method to override to skip the display of the i'th bucket if it's empty.
virtual bool PrintEmptyBucket(size_t index) const;
//----------------------------------------------------------------------------
// Methods to override to create histogram with different bucket widths.
//----------------------------------------------------------------------------
// Find bucket to increment for sample value.
virtual size_t BucketIndex(Sample value) const;
// Get normalized size, relative to the ranges_[i].
virtual double GetBucketSize(Count current, size_t i) const;
// Recalculate range_checksum_.
void ResetRangeChecksum();
// Return a string description of what goes in a given bucket.
// Most commonly this is the numeric value, but in derived classes it may
// be a name (or string description) given to the bucket.
virtual const std::string GetAsciiBucketRange(size_t it) const;
//----------------------------------------------------------------------------
// Methods to override to create thread safe histogram.
//----------------------------------------------------------------------------
// Update all our internal data, including histogram
virtual void Accumulate(Sample value, Count count, size_t index);
//----------------------------------------------------------------------------
// Accessors for derived classes.
//----------------------------------------------------------------------------
void SetBucketRange(size_t i, Sample value);
// Validate that ranges_ was created sensibly (top and bottom range
// values relate properly to the declared_min_ and declared_max_)..
bool ValidateBucketRanges() const;
virtual uint32 CalculateRangeChecksum() const;
private:
// Allow tests to corrupt our innards for testing purposes.
FRIEND_TEST(HistogramTest, CorruptBucketBounds);
FRIEND_TEST(HistogramTest, CorruptSampleCounts);
FRIEND_TEST(HistogramTest, Crc32SampleHash);
FRIEND_TEST(HistogramTest, Crc32TableTest);
friend class StatisticsRecorder; // To allow it to delete duplicates.
// Post constructor initialization.
void Initialize();
// Checksum function for accumulating range values into a checksum.
static uint32 Crc32(uint32 sum, Sample range);
//----------------------------------------------------------------------------
// Helpers for emitting Ascii graphic. Each method appends data to output.
// Find out how large the (graphically) the largest bucket will appear to be.
double GetPeakBucketSize(const SampleSet& snapshot) const;
// Write a common header message describing this histogram.
void WriteAsciiHeader(const SampleSet& snapshot,
Count sample_count, std::string* output) const;
// Write information about previous, current, and next buckets.
// Information such as cumulative percentage, etc.
void WriteAsciiBucketContext(const int64 past, const Count current,
const int64 remaining, const size_t i,
std::string* output) const;
// Write textual description of the bucket contents (relative to histogram).
// Output is the count in the buckets, as well as the percentage.
void WriteAsciiBucketValue(Count current, double scaled_sum,
std::string* output) const;
// Produce actual graph (set of blank vs non blank char's) for a bucket.
void WriteAsciiBucketGraph(double current_size, double max_size,
std::string* output) const;
//----------------------------------------------------------------------------
// Table for generating Crc32 values.
static const uint32 kCrcTable[256];
//----------------------------------------------------------------------------
// Invariant values set at/near construction time
// ASCII version of original name given to the constructor. All identically
// named instances will be coalesced cross-project.
const std::string histogram_name_;
Sample declared_min_; // Less than this goes into counts_[0]
Sample declared_max_; // Over this goes into counts_[bucket_count_ - 1].
size_t bucket_count_; // Dimension of counts_[].
// Flag the histogram for recording by UMA via metric_services.h.
Flags flags_;
// For each index, show the least value that can be stored in the
// corresponding bucket. We also append one extra element in this array,
// containing kSampleType_MAX, to make calculations easy.
// The dimension of ranges_ is bucket_count + 1.
Ranges ranges_;
// For redundancy, we store a checksum of all the sample ranges when ranges
// are generated. If ever there is ever a difference, then the histogram must
// have been corrupted.
uint32 range_checksum_;
// Finally, provide the state that changes with the addition of each new
// sample.
SampleSet sample_;
DISALLOW_COPY_AND_ASSIGN(Histogram);
};
//------------------------------------------------------------------------------
// LinearHistogram is a more traditional histogram, with evenly spaced
// buckets.
class BASE_API LinearHistogram : public Histogram {
public:
virtual ~LinearHistogram();
/* minimum should start from 1. 0 is as minimum is invalid. 0 is an implicit
default underflow bucket. */
static Histogram* FactoryGet(const std::string& name,
Sample minimum,
Sample maximum,
size_t bucket_count,
Flags flags);
static Histogram* FactoryTimeGet(const std::string& name,
TimeDelta minimum,
TimeDelta maximum,
size_t bucket_count,
Flags flags);
// Overridden from Histogram:
virtual ClassType histogram_type() const;
// Store a list of number/text values for use in rendering the histogram.
// The last element in the array has a null in its "description" slot.
virtual void SetRangeDescriptions(const DescriptionPair descriptions[]);
protected:
LinearHistogram(const std::string& name, Sample minimum,
Sample maximum, size_t bucket_count);
LinearHistogram(const std::string& name, TimeDelta minimum,
TimeDelta maximum, size_t bucket_count);
// Initialize ranges_ mapping.
void InitializeBucketRange();
virtual double GetBucketSize(Count current, size_t i) const;
// If we have a description for a bucket, then return that. Otherwise
// let parent class provide a (numeric) description.
virtual const std::string GetAsciiBucketRange(size_t i) const;
// Skip printing of name for numeric range if we have a name (and if this is
// an empty bucket).
virtual bool PrintEmptyBucket(size_t index) const;
private:
// For some ranges, we store a printable description of a bucket range.
// If there is no desciption, then GetAsciiBucketRange() uses parent class
// to provide a description.
typedef std::map<Sample, std::string> BucketDescriptionMap;
BucketDescriptionMap bucket_description_;
DISALLOW_COPY_AND_ASSIGN(LinearHistogram);
};
//------------------------------------------------------------------------------
// BooleanHistogram is a histogram for booleans.
class BASE_API BooleanHistogram : public LinearHistogram {
public:
static Histogram* FactoryGet(const std::string& name, Flags flags);
virtual ClassType histogram_type() const;
virtual void AddBoolean(bool value);
private:
explicit BooleanHistogram(const std::string& name);
DISALLOW_COPY_AND_ASSIGN(BooleanHistogram);
};
//------------------------------------------------------------------------------
// CustomHistogram is a histogram for a set of custom integers.
class BASE_API CustomHistogram : public Histogram {
public:
static Histogram* FactoryGet(const std::string& name,
const std::vector<Sample>& custom_ranges,
Flags flags);
// Overridden from Histogram:
virtual ClassType histogram_type() const;
protected:
CustomHistogram(const std::string& name,
const std::vector<Sample>& custom_ranges);
// Initialize ranges_ mapping.
void InitializedCustomBucketRange(const std::vector<Sample>& custom_ranges);
virtual double GetBucketSize(Count current, size_t i) const;
DISALLOW_COPY_AND_ASSIGN(CustomHistogram);
};
//------------------------------------------------------------------------------
// StatisticsRecorder handles all histograms in the system. It provides a
// general place for histograms to register, and supports a global API for
// accessing (i.e., dumping, or graphing) the data in all the histograms.
class BASE_API StatisticsRecorder {
public:
typedef std::vector<Histogram*> Histograms;
StatisticsRecorder();
~StatisticsRecorder();
// Find out if histograms can now be registered into our list.
static bool IsActive();
// Register, or add a new histogram to the collection of statistics. If an
// identically named histogram is already registered, then the argument
// |histogram| will deleted. The returned value is always the registered
// histogram (either the argument, or the pre-existing registered histogram).
static Histogram* RegisterOrDeleteDuplicate(Histogram* histogram);
// Methods for printing histograms. Only histograms which have query as
// a substring are written to output (an empty string will process all
// registered histograms).
static void WriteHTMLGraph(const std::string& query, std::string* output);
static void WriteGraph(const std::string& query, std::string* output);
// Method for extracting histograms which were marked for use by UMA.
static void GetHistograms(Histograms* output);
// Find a histogram by name. It matches the exact name. This method is thread
// safe. If a matching histogram is not found, then the |histogram| is
// not changed.
static bool FindHistogram(const std::string& query, Histogram** histogram);
static bool dump_on_exit() { return dump_on_exit_; }
static void set_dump_on_exit(bool enable) { dump_on_exit_ = enable; }
// GetSnapshot copies some of the pointers to registered histograms into the
// caller supplied vector (Histograms). Only histograms with names matching
// query are returned. The query must be a substring of histogram name for its
// pointer to be copied.
static void GetSnapshot(const std::string& query, Histograms* snapshot);
private:
// We keep all registered histograms in a map, from name to histogram.
typedef std::map<std::string, Histogram*> HistogramMap;
static HistogramMap* histograms_;
// lock protects access to the above map.
static base::Lock* lock_;
// Dump all known histograms to log.
static bool dump_on_exit_;
DISALLOW_COPY_AND_ASSIGN(StatisticsRecorder);
};
} // namespace base
#endif // BASE_METRICS_HISTOGRAM_H_