components/scheduler/renderer/task_cost_estimator.cc

   1 // Copyright 2015 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 #include "components/scheduler/renderer/task_cost_estimator.h"
   6
   7 namespace scheduler {
   8
   9 TaskCostEstimator::TaskCostEstimator(int sample_count,
  10                                      double estimation_percentile)
  11     : rolling_time_delta_history_(sample_count),
  12       outstanding_task_count_(0),
  13       estimation_percentile_(estimation_percentile) {}
  14
  15 TaskCostEstimator::~TaskCostEstimator() {}
  16
  17 void TaskCostEstimator::WillProcessTask(const base::PendingTask& pending_task) {
  18   // Avoid measuring the duration in nested run loops.
  19   if (++outstanding_task_count_ == 1)
  20     task_start_time_ = Now();
  21 }
  22
  23 void TaskCostEstimator::DidProcessTask(const base::PendingTask& pending_task) {
  24   if (--outstanding_task_count_ == 0) {
  25     base::TimeDelta duration = Now() - task_start_time_;
  26     rolling_time_delta_history_.InsertSample(duration);
  27
  28     // TODO(skyostil): Should we do this less often?
  29     expected_task_duration_ =
  30         rolling_time_delta_history_.Percentile(estimation_percentile_);
  31   }
  32 }
  33
  34 base::TimeTicks TaskCostEstimator::Now() {
  35   return base::TimeTicks::Now();
  36 }
  37
  38 }  // namespace scheduler