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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 "base/base_export.h"
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
namespace base {
class DictionaryValue;
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);
class BASE_EXPORT HistogramBase {
typedef int Sample; // Used for samples.
typedef int Count; // Used to count samples.
static const Sample kSampleType_MAX; // INT_MAX
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,
// Only for Histogram and its sub classes: fancy bucket-naming support.
kHexRangePrintingFlag = 0x8000,
HistogramBase(const std::string& name);
virtual ~HistogramBase();
std::string histogram_name() const { return histogram_name_; }
// 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 minimum,
Sample maximum,
size_t bucket_count) const = 0;
virtual void Add(Sample value) = 0;
// 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;
// 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| and the total sample count to |count|.
virtual void GetCountAndBucketData(Count* count,
ListValue* buckets) const = 0;
const std::string histogram_name_;
int32 flags_;
} // namespace base