components/scheduling_metrics/task_duration_metric_reporter.h

   1 // Copyright 2018 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COMPONENTS_SCHEDULING_METRICS_TASK_DURATION_METRIC_REPORTER_H_
   6 #define COMPONENTS_SCHEDULING_METRICS_TASK_DURATION_METRIC_REPORTER_H_
   7
   8 #include <memory>
   9
  10 #include "base/component_export.h"
  11 #include "base/macros.h"
  12 #include "base/metrics/histogram.h"
  13 #include "base/time/time.h"
  14
  15 namespace base {
  16 class HistogramBase;
  17 }
  18
  19 namespace scheduling_metrics {
  20
  21 // A helper class to report total task runtime split by the different types of
  22 // |TypeClass|. Only full seconds are reported. Note that partial seconds are
  23 // rounded up/down, so that on average the correct value is reported when many
  24 // reports are added.
  25 //
  26 // |TaskClass| is an enum which should have kClass field.
  27 template <class TaskClass>
  28 class TaskDurationMetricReporter {
  29  public:
  30   // Note that 1000*1000 is used to get microseconds precision.
  31   explicit TaskDurationMetricReporter(const char* metric_name)
  32       : value_per_type_histogram_(new base::ScaledLinearHistogram(
  33             metric_name,
  34             1,
  35             static_cast<int>(TaskClass::kCount),
  36             static_cast<int>(TaskClass::kCount) + 1,
  37             1000 * 1000,
  38             base::HistogramBase::kUmaTargetedHistogramFlag)){};
  39
  40   void RecordTask(TaskClass task_class, base::TimeDelta duration) {
  41     DCHECK_LT(static_cast<int>(task_class),
  42               static_cast<int>(TaskClass::kCount));
  43
  44     // To get mircoseconds precision, duration is converted to microseconds
  45     // since |value_per_type_histogram_| is constructed with a scale of
  46     // 1000*1000.
  47     if (!duration.is_zero()) {
  48       value_per_type_histogram_->AddScaledCount(
  49           static_cast<int>(task_class),
  50           base::saturated_cast<int>(duration.InMicroseconds()));
  51     }
  52   }
  53
  54  private:
  55   std::unique_ptr<base::ScaledLinearHistogram> value_per_type_histogram_;
  56
  57   DISALLOW_COPY_AND_ASSIGN(TaskDurationMetricReporter);
  58 };
  59
  60 }  // namespace scheduling_metrics
  61
  62 #endif  // COMPONENTS_SCHEDULING_METRICS_TASK_DURATION_METRIC_REPORTER_H_