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// 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.
#include <string>
#include <vector>
#include "base/atomicops.h"
#include "base/base_export.h"
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "base/strings/string_piece.h"
#include "base/time/time.h"
class Pickle;
class PickleIterator;
namespace base {
class DictionaryValue;
class HistogramBase;
class HistogramSamples;
class ListValue;
// These enums are used to facilitate deserialization of histograms from other
// processes into the browser. If you create another class that inherits from
// HistogramBase, add new histogram types and names below.
enum BASE_EXPORT HistogramType {
std::string HistogramTypeToString(HistogramType type);
// Create or find existing histogram that matches the pickled info.
// Returns NULL if the pickled data has problems.
BASE_EXPORT_PRIVATE HistogramBase* DeserializeHistogramInfo(
PickleIterator* iter);
class BASE_EXPORT HistogramBase {
typedef int Sample; // Used for samples.
typedef subtle::Atomic32 AtomicCount; // Used to count samples.
typedef int32 Count; // Used to manipulate counts in temporaries.
static const Sample kSampleType_MAX; // INT_MAX
enum Flags {
kNoFlags = 0,
// Histogram should be UMA uploaded.
kUmaTargetedHistogramFlag = 0x1,
// Indicates that this is a stability histogram. This flag exists to specify
// which histograms should be included in the initial stability log. Please
// refer to |MetricsService::PrepareInitialStabilityLog|.
kUmaStabilityHistogramFlag = kUmaTargetedHistogramFlag | 0x2,
// Indicates 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,
// Only for Histogram and its sub classes: fancy bucket-naming support.
kHexRangePrintingFlag = 0x8000,
// Histogram data inconsistency types.
enum Inconsistency {
explicit HistogramBase(const std::string& name);
virtual ~HistogramBase();
std::string histogram_name() const { return histogram_name_; }
// Comapres |name| to the histogram name and triggers a DCHECK if they do not
// match. This is a helper function used by histogram macros, which results in
// in more compact machine code being generated by the macros.
void CheckName(const StringPiece& name) const;
// Operations with Flags enum.
int32 flags() const { return flags_; }
void SetFlags(int32 flags);
void ClearFlags(int32 flags);
virtual HistogramType GetHistogramType() const = 0;
// Whether the histogram has construction arguments as parameters specified.
// For histograms that don't have the concept of minimum, maximum or
// bucket_count, this function always returns false.
virtual bool HasConstructionArguments(Sample expected_minimum,
Sample expected_maximum,
size_t expected_bucket_count) const = 0;
virtual void Add(Sample value) = 0;
// 2 convenient functions that call Add(Sample).
void AddTime(const TimeDelta& time);
void AddBoolean(bool value);
virtual void AddSamples(const HistogramSamples& samples) = 0;
virtual bool AddSamplesFromPickle(PickleIterator* iter) = 0;
// Serialize the histogram info into |pickle|.
// Note: This only serializes the construction arguments of the histogram, but
// does not serialize the samples.
bool SerializeInfo(Pickle* pickle) const;
// Try to find out data corruption from histogram and the samples.
// The returned value is a combination of Inconsistency enum.
virtual int FindCorruption(const HistogramSamples& samples) const;
// Snapshot the current complete set of sample data.
// Override with atomic/locked snapshot if needed.
virtual scoped_ptr<HistogramSamples> SnapshotSamples() const = 0;
// The following methods provide graphical histogram displays.
virtual void WriteHTMLGraph(std::string* output) const = 0;
virtual void WriteAscii(std::string* output) const = 0;
// Produce a JSON representation of the histogram. This is implemented with
// the help of GetParameters and GetCountAndBucketData; overwrite them to
// customize the output.
void WriteJSON(std::string* output) const;
// Subclasses should implement this function to make SerializeInfo work.
virtual bool SerializeInfoImpl(Pickle* pickle) const = 0;
// Writes information about the construction parameters in |params|.
virtual void GetParameters(DictionaryValue* params) const = 0;
// Writes information about the current (non-empty) buckets and their sample
// counts to |buckets|, the total sample count to |count| and the total sum
// to |sum|.
virtual void GetCountAndBucketData(Count* count,
int64* sum,
ListValue* buckets) const = 0;
//// 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;
// Return a string description of what goes in a given bucket.
const std::string GetSimpleAsciiBucketRange(Sample sample) 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;
const std::string histogram_name_;
int32 flags_;
} // namespace base