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// Copyright 2015 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 "ash/metrics/task_switch_time_tracker.h"
#include "base/metrics/histogram.h"
#include "base/time/default_tick_clock.h"
namespace ash {
namespace {
// The number of buckets in the histogram.
// See IMPORTANT note below if you want to change this value!
const size_t kBucketCount = 50;
// The underflow (aka minimum) bucket size for the histogram.
// See IMPORTANT note below if you want to change this value!
const int kMinBucketSizeInSeconds = 0;
// The overflow (aka maximium) bucket size for the histogram.
// See IMPORTANT note below if you want to change this value!
const int kMaxBucketSizeInSeconds = 60 * 60;
} // namespace
TaskSwitchTimeTracker::TaskSwitchTimeTracker(const std::string& histogram_name)
: histogram_name_(histogram_name),
tick_clock_(new base::DefaultTickClock()) {
}
TaskSwitchTimeTracker::TaskSwitchTimeTracker(
const std::string& histogram_name,
scoped_ptr<base::TickClock> tick_clock)
: histogram_name_(histogram_name), tick_clock_(tick_clock.release()) {
}
TaskSwitchTimeTracker::~TaskSwitchTimeTracker() {
}
void TaskSwitchTimeTracker::OnTaskSwitch() {
if (!HasLastActionTime())
SetLastActionTime();
else
RecordTimeDelta();
}
bool TaskSwitchTimeTracker::HasLastActionTime() const {
return last_action_time_ != base::TimeTicks();
}
base::TimeTicks TaskSwitchTimeTracker::SetLastActionTime() {
base::TimeTicks previous_last_action_time = last_action_time_;
last_action_time_ = tick_clock_->NowTicks();
return previous_last_action_time;
}
void TaskSwitchTimeTracker::RecordTimeDelta() {
base::TimeTicks previous_last_action_time = SetLastActionTime();
base::TimeDelta time_delta = last_action_time_ - previous_last_action_time;
CHECK_GE(time_delta, base::TimeDelta());
GetHistogram()->Add(time_delta.InSeconds());
}
base::HistogramBase* TaskSwitchTimeTracker::GetHistogram() {
if (!histogram_) {
// IMPORTANT: If you change the type of histogram or any values that define
// its bucket construction then you must rename all of the histograms using
// the TaskSwitchTimeTracker mechanism.
histogram_ = base::Histogram::FactoryGet(
histogram_name_,
base::TimeDelta::FromSeconds(kMinBucketSizeInSeconds).InSeconds(),
base::TimeDelta::FromSeconds(kMaxBucketSizeInSeconds).InSeconds(),
kBucketCount, base::HistogramBase::kUmaTargetedHistogramFlag);
}
#if DCHECK_IS_ON()
histogram_->CheckName(histogram_name_);
#endif // DCHECK_IS_ON()
return histogram_;
}
} // namespace ash
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