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 #include "base/time/default_tick_clock.h"
   8
   9 namespace scheduler {
  10
  11 TaskCostEstimator::TaskCostEstimator(int sample_count,
  12                                      double estimation_percentile)
  13     : rolling_time_delta_history_(sample_count),
  14       time_source_(new base::DefaultTickClock),
  15       outstanding_task_count_(0),
  16       estimation_percentile_(estimation_percentile) {}
  17
  18 TaskCostEstimator::~TaskCostEstimator() {}
  19
  20 void TaskCostEstimator::WillProcessTask(const base::PendingTask& pending_task) {
  21   // Avoid measuring the duration in nested run loops.
  22   if (++outstanding_task_count_ == 1)
  23     task_start_time_ = time_source_->NowTicks();
  24 }
  25
  26 void TaskCostEstimator::DidProcessTask(const base::PendingTask& pending_task) {
  27   if (--outstanding_task_count_ == 0) {
  28     base::TimeDelta duration = time_source_->NowTicks() - task_start_time_;
  29     rolling_time_delta_history_.InsertSample(duration);
  30
  31     // TODO(skyostil): Should we do this less often?
  32     expected_task_duration_ =
  33         rolling_time_delta_history_.Percentile(estimation_percentile_);
  34   }
  35 }
  36
  37 void TaskCostEstimator::Clear() {
  38   rolling_time_delta_history_.Clear();
  39   expected_task_duration_ = base::TimeDelta();
  40 }
  41
  42 void TaskCostEstimator::SetTimeSourceForTesting(
  43     scoped_ptr<base::TickClock> time_source) {
  44   time_source_ = time_source.Pass();
  45 }
  46
  47 }  // namespace scheduler