Index: components/scheduler/renderer/queueing_time_estimator.cc |
diff --git a/components/scheduler/renderer/queueing_time_estimator.cc b/components/scheduler/renderer/queueing_time_estimator.cc |
new file mode 100644 |
index 0000000000000000000000000000000000000000..55c3fee3f4bb43ff0d870e0c7c4e284154f8ebee |
--- /dev/null |
+++ b/components/scheduler/renderer/queueing_time_estimator.cc |
@@ -0,0 +1,108 @@ |
+// Copyright 2016 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#include "components/scheduler/renderer/queueing_time_estimator.h" |
+ |
+#include "components/scheduler/renderer/coarse_duration_timer.h" |
+ |
+namespace scheduler { |
+ |
+namespace { |
+ |
+base::TimeDelta ExpectedQueueingTimeFromTask(base::TimeTicks task_start, |
+ base::TimeTicks task_end, |
+ base::TimeTicks window_start, |
+ base::TimeTicks window_end) { |
+ DCHECK(task_start <= task_end); |
Lei Zhang
2016/06/08 01:05:27
DCHECK_LE() and friends are preferred, BTW. They w
tdresser
2016/06/08 14:25:05
Thanks, I'll clean this up if the overall approach
|
+ DCHECK(task_start <= window_end); |
+ DCHECK(window_start < window_end); |
+ DCHECK(task_end >= window_start); |
+ base::TimeTicks task_in_window_start_time = |
+ std::max(task_start, window_start); |
+ base::TimeTicks task_in_window_end_time = |
+ std::min(task_end, window_end); |
+ DCHECK(task_in_window_end_time <= task_in_window_end_time); |
+ |
+ double probability_of_this_task = |
+ static_cast<double>((task_in_window_end_time - task_in_window_start_time) |
+ .InMicroseconds()) / |
+ (window_end - window_start).InMicroseconds(); |
+ |
+ base::TimeDelta expected_queueing_duration_within_task = |
+ ((task_end - task_in_window_start_time) + |
+ (task_end - task_in_window_end_time)) / |
+ 2; |
+ |
+ return base::TimeDelta::FromMillisecondsD( |
+ probability_of_this_task * |
+ expected_queueing_duration_within_task.InMillisecondsF()); |
+} |
+ |
+} // namespace |
+ |
+QueueingTimeEstimator::QueueingTimeEstimator( |
+ QueueingTimeEstimator::Client* client, |
+ CoarseDurationTimer* timer, |
+ base::TimeDelta window_duration) |
+ : client_(client), |
+ timer_(timer), |
+ outstanding_task_count_(0), |
+ window_duration_(window_duration) {} |
+ |
+QueueingTimeEstimator::~QueueingTimeEstimator() {} |
+ |
+void QueueingTimeEstimator::WillProcessTask( |
+ const base::PendingTask& pending_task) { |
+ // Avoid measuring the duration in nested run loops. |
+ if (++outstanding_task_count_ != 1) |
+ return; |
+ |
+ timer_->BeginInterval(); |
+} |
+ |
+void QueueingTimeEstimator::DidProcessTask( |
+ const base::PendingTask& pending_task) { |
+ if (--outstanding_task_count_ != 0) |
+ return; |
+ |
+ base::TimeDelta duration = timer_->EndInterval(); |
+ if (duration.is_zero()) |
+ return; |
+ |
+ base::TimeTicks task_end_time = timer_->most_recent_time(); |
+ base::TimeTicks task_start_time = task_end_time - duration; |
+ |
+ // If this is the first task, set the window start time such that the window |
+ // and the task end at the same time. |
+ if (window_start_time_.is_null()) |
+ window_start_time_ = task_end_time - window_duration_; |
+ |
+ bool start_past_window = |
+ task_start_time > window_start_time_ + window_duration_; |
+ bool end_past_window = |
+ task_end_time > window_start_time_ + window_duration_; |
+ |
+ while (end_past_window) { |
+ if (!start_past_window) { |
+ // Include the current task in this window. |
+ current_expected_queueing_time_ += ExpectedQueueingTimeFromTask( |
+ task_start_time, task_end_time, window_start_time_, |
+ window_start_time_ + window_duration_); |
+ } |
+ client_->OnQueueingTimeForWindowEstimated(current_expected_queueing_time_); |
+ window_start_time_ += window_duration_; |
+ current_expected_queueing_time_ = base::TimeDelta(); |
+ |
+ start_past_window = |
+ task_start_time > window_start_time_ + window_duration_; |
+ end_past_window = |
+ task_end_time > window_start_time_ + window_duration_; |
+ } |
+ |
+ current_expected_queueing_time_ += ExpectedQueueingTimeFromTask( |
+ task_start_time, task_end_time, window_start_time_, |
+ window_start_time_ + window_duration_); |
+} |
+ |
+} // namespace scheduler |