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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.
// StatisticsRecorder holds all Histograms and BucketRanges that are used by
// Histograms in the system. It provides a general place for
// Histograms/BucketRanges to register, and supports a global API for accessing
// (i.e., dumping, or graphing) the data.
#ifndef BASE_METRICS_STATISTICS_RECORDER_H_
#define BASE_METRICS_STATISTICS_RECORDER_H_
#include <list>
#include <map>
#include <string>
#include <vector>
#include "base/base_export.h"
#include "base/basictypes.h"
#include "base/gtest_prod_util.h"
#include "base/lazy_instance.h"
namespace base {
class BucketRanges;
class HistogramBase;
class Lock;
class BASE_EXPORT StatisticsRecorder {
public:
typedef std::vector<HistogramBase*> Histograms;
// Initializes the StatisticsRecorder system.
static void Initialize();
// 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 HistogramBase* RegisterOrDeleteDuplicate(HistogramBase* histogram);
// Register, or add a new BucketRanges. If an identically BucketRanges is
// already registered, then the argument |ranges| will deleted. The returned
// value is always the registered BucketRanges (either the argument, or the
// pre-existing one).
static const BucketRanges* RegisterOrDeleteDuplicateRanges(
const BucketRanges* ranges);
// Methods for appending histogram data to a string. 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);
// Returns the histograms with |query| as a substring as JSON text (an empty
// |query| will process all registered histograms).
static std::string ToJSON(const std::string& query);
// Method for extracting histograms which were marked for use by UMA.
static void GetHistograms(Histograms* output);
// Method for extracting BucketRanges used by all histograms registered.
static void GetBucketRanges(std::vector<const BucketRanges*>* output);
// Find a histogram by name. It matches the exact name. This method is thread
// safe. It returns NULL if a matching histogram is not found.
static HistogramBase* FindHistogram(const std::string& name);
// 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, HistogramBase*> HistogramMap;
// We keep all |bucket_ranges_| in a map, from checksum to a list of
// |bucket_ranges_|. Checksum is calculated from the |ranges_| in
// |bucket_ranges_|.
typedef std::map<uint32, std::list<const BucketRanges*>*> RangesMap;
friend struct DefaultLazyInstanceTraits<StatisticsRecorder>;
friend class HistogramBaseTest;
friend class HistogramTest;
friend class SparseHistogramTest;
friend class StatisticsRecorderTest;
FRIEND_TEST_ALL_PREFIXES(HistogramDeltaSerializationTest,
DeserializeHistogramAndAddSamples);
// The constructor just initializes static members. Usually client code should
// use Initialize to do this. But in test code, you can friend this class and
// call destructor/constructor to get a clean StatisticsRecorder.
StatisticsRecorder();
~StatisticsRecorder();
static void DumpHistogramsToVlog(void* instance);
static HistogramMap* histograms_;
static RangesMap* ranges_;
// Lock protects access to above maps.
static base::Lock* lock_;
DISALLOW_COPY_AND_ASSIGN(StatisticsRecorder);
};
} // namespace base
#endif // BASE_METRICS_STATISTICS_RECORDER_H_
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