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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_METRICS_HISTOGRAM_BASE_H_
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#define BASE_METRICS_HISTOGRAM_BASE_H_
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#include "base/atomicops.h"
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#include "base/base_export.h"
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#include "base/basictypes.h"
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#include "base/memory/scoped_ptr.h"
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#include "base/strings/string_piece.h"
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#include "base/time/time.h"
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class DictionaryValue;
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class HistogramSamples;
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////////////////////////////////////////////////////////////////////////////////
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// These enums are used to facilitate deserialization of histograms from other
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// processes into the browser. If you create another class that inherits from
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// HistogramBase, add new histogram types and names below.
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enum BASE_EXPORT HistogramType {
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std::string HistogramTypeToString(HistogramType type);
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// Create or find existing histogram that matches the pickled info.
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// Returns NULL if the pickled data has problems.
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BASE_EXPORT_PRIVATE HistogramBase* DeserializeHistogramInfo(
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PickleIterator* iter);
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////////////////////////////////////////////////////////////////////////////////
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class BASE_EXPORT HistogramBase {
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typedef int Sample; // Used for samples.
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typedef subtle::Atomic32 AtomicCount; // Used to count samples.
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typedef int32 Count; // Used to manipulate counts in temporaries.
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static const Sample kSampleType_MAX; // INT_MAX
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// Histogram should be UMA uploaded.
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kUmaTargetedHistogramFlag = 0x1,
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// Indicates that this is a stability histogram. This flag exists to specify
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// which histograms should be included in the initial stability log. Please
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// refer to |MetricsService::PrepareInitialStabilityLog|.
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kUmaStabilityHistogramFlag = kUmaTargetedHistogramFlag | 0x2,
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// Indicates that the histogram was pickled to be sent across an IPC
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// Channel. If we observe this flag on a histogram being aggregated into
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// after IPC, then we are running in a single process mode, and the
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// aggregation should not take place (as we would be aggregating back into
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// the source histogram!).
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kIPCSerializationSourceFlag = 0x10,
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// Only for Histogram and its sub classes: fancy bucket-naming support.
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kHexRangePrintingFlag = 0x8000,
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// Histogram data inconsistency types.
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NO_INCONSISTENCIES = 0x0,
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RANGE_CHECKSUM_ERROR = 0x1,
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BUCKET_ORDER_ERROR = 0x2,
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COUNT_HIGH_ERROR = 0x4,
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COUNT_LOW_ERROR = 0x8,
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NEVER_EXCEEDED_VALUE = 0x10
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explicit HistogramBase(const std::string& name);
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virtual ~HistogramBase();
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std::string histogram_name() const { return histogram_name_; }
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// Comapres |name| to the histogram name and triggers a DCHECK if they do not
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// match. This is a helper function used by histogram macros, which results in
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// in more compact machine code being generated by the macros.
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void CheckName(const StringPiece& name) const;
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// Operations with Flags enum.
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int32 flags() const { return flags_; }
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void SetFlags(int32 flags);
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void ClearFlags(int32 flags);
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virtual HistogramType GetHistogramType() const = 0;
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// Whether the histogram has construction arguments as parameters specified.
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// For histograms that don't have the concept of minimum, maximum or
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// bucket_count, this function always returns false.
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virtual bool HasConstructionArguments(Sample expected_minimum,
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Sample expected_maximum,
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size_t expected_bucket_count) const = 0;
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virtual void Add(Sample value) = 0;
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// 2 convenient functions that call Add(Sample).
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void AddTime(const TimeDelta& time);
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void AddBoolean(bool value);
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virtual void AddSamples(const HistogramSamples& samples) = 0;
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virtual bool AddSamplesFromPickle(PickleIterator* iter) = 0;
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// Serialize the histogram info into |pickle|.
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// Note: This only serializes the construction arguments of the histogram, but
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// does not serialize the samples.
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bool SerializeInfo(Pickle* pickle) const;
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// Try to find out data corruption from histogram and the samples.
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// The returned value is a combination of Inconsistency enum.
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virtual int FindCorruption(const HistogramSamples& samples) const;
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// Snapshot the current complete set of sample data.
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// Override with atomic/locked snapshot if needed.
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virtual scoped_ptr<HistogramSamples> SnapshotSamples() const = 0;
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// The following methods provide graphical histogram displays.
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virtual void WriteHTMLGraph(std::string* output) const = 0;
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virtual void WriteAscii(std::string* output) const = 0;
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// Produce a JSON representation of the histogram. This is implemented with
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// the help of GetParameters and GetCountAndBucketData; overwrite them to
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// customize the output.
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void WriteJSON(std::string* output) const;
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// Subclasses should implement this function to make SerializeInfo work.
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virtual bool SerializeInfoImpl(Pickle* pickle) const = 0;
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// Writes information about the construction parameters in |params|.
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virtual void GetParameters(DictionaryValue* params) const = 0;
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// Writes information about the current (non-empty) buckets and their sample
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// counts to |buckets|, the total sample count to |count| and the total sum
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virtual void GetCountAndBucketData(Count* count,
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ListValue* buckets) const = 0;
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//// Produce actual graph (set of blank vs non blank char's) for a bucket.
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void WriteAsciiBucketGraph(double current_size,
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std::string* output) const;
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// Return a string description of what goes in a given bucket.
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const std::string GetSimpleAsciiBucketRange(Sample sample) const;
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// Write textual description of the bucket contents (relative to histogram).
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// Output is the count in the buckets, as well as the percentage.
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void WriteAsciiBucketValue(Count current,
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std::string* output) const;
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const std::string histogram_name_;
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DISALLOW_COPY_AND_ASSIGN(HistogramBase);
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#endif // BASE_METRICS_HISTOGRAM_BASE_H_