chromium/base/metrics/statistics_recorder.h

// Copyright 2012 The Chromium Authors
// 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 <stdint.h>

#include <atomic>  // For std::memory_order_*.
#include <memory>
#include <string>
#include <string_view>
#include <unordered_map>
#include <vector>

#include "base/base_export.h"
#include "base/functional/callback.h"
#include "base/gtest_prod_util.h"
#include "base/lazy_instance.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/metrics/histogram_base.h"
#include "base/metrics/ranges_manager.h"
#include "base/metrics/record_histogram_checker.h"
#include "base/observer_list_threadsafe.h"
#include "base/synchronization/lock.h"
#include "base/thread_annotations.h"
#include "base/types/pass_key.h"

namespace base {

class BucketRanges;
class HistogramSnapshotManager;

// In-memory recorder of usage statistics (aka metrics, aka histograms).
//
// All the public methods are static and act on a global recorder. This global
// recorder is internally synchronized and all the static methods are thread
// safe. This is intended to only be run/used in the browser process.
//
// StatisticsRecorder doesn't have any public constructor. For testing purpose,
// you can create a temporary recorder using the factory method
// CreateTemporaryForTesting(). This temporary recorder becomes the global one
// until deleted. When this temporary recorder is deleted, it restores the
// previous global one.
class BASE_EXPORT StatisticsRecorder { … };

}  // namespace base

#endif  // BASE_METRICS_STATISTICS_RECORDER_H_