chromium/base/metrics/single_sample_metrics.h

// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_METRICS_SINGLE_SAMPLE_METRICS_H_
#define BASE_METRICS_SINGLE_SAMPLE_METRICS_H_

#include <memory>
#include <string>

#include "base/base_export.h"
#include "base/memory/raw_ptr.h"
#include "base/metrics/histogram_base.h"

namespace base {

// See base/metrics/histograms.h for parameter definitions. Must only be used
// and destroyed from the same thread as construction.
class BASE_EXPORT SingleSampleMetric { … };

// Factory for creating single sample metrics. A single sample metric only
// reports its sample once at destruction time. The sample may be changed prior
// to destruction using the SetSample() method as many times as desired.
//
// The metric creation methods are safe to call from any thread, however the
// returned class must only be used and destroyed from the same thread as
// construction.
//
// See base/metrics/histogram_macros.h for usage recommendations and
// base/metrics/histogram.h for full parameter definitions.
class BASE_EXPORT SingleSampleMetricsFactory { … };

// Default implementation for when no factory has been provided to the process.
// Samples are only recorded within the current process in this case, so samples
// will be lost in the event of sudden process termination.
class BASE_EXPORT DefaultSingleSampleMetricsFactory
    : public SingleSampleMetricsFactory { … };

class BASE_EXPORT DefaultSingleSampleMetric : public SingleSampleMetric { … };

}  // namespace base

#endif  // BASE_METRICS_SINGLE_SAMPLE_METRICS_H_