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// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/timer/hi_res_timer_manager.h"
#include <algorithm>
#include "base/base_switches.h"
#include "base/command_line.h"
#include "base/metrics/histogram_macros.h"
#include "base/power_monitor/power_monitor.h"
#include "base/time/time.h"
namespace base {
namespace {
constexpr TimeDelta kUsageSampleInterval = Minutes(10);
void ReportHighResolutionTimerUsage() {
UMA_HISTOGRAM_PERCENTAGE("Windows.HighResolutionTimerUsage",
Time::GetHighResolutionTimerUsage());
// Reset usage for the next interval.
Time::ResetHighResolutionTimerUsage();
}
bool HighResolutionTimerAllowed() {
return !CommandLine::ForCurrentProcess()->HasSwitch(
switches::kDisableHighResTimer);
}
} // namespace
HighResolutionTimerManager::HighResolutionTimerManager()
: hi_res_clock_available_(false) {
// Register for PowerMonitor callbacks only if high-resolution
// timers are allowed. If high-resolution timers are disabled
// we won't receive power state change callbacks and
// hi_res_clock_available_ will remain at its initial value.
if (HighResolutionTimerAllowed()) {
auto* power_monitor = base::PowerMonitor::GetInstance();
DCHECK(power_monitor->IsInitialized());
power_monitor->AddPowerSuspendObserver(this);
const bool on_battery =
power_monitor->AddPowerStateObserverAndReturnBatteryPowerStatus(this) ==
PowerStateObserver::BatteryPowerStatus::kBatteryPower;
UseHiResClock(!on_battery);
// Start polling the high resolution timer usage.
Time::ResetHighResolutionTimerUsage();
timer_.Start(FROM_HERE, kUsageSampleInterval,
BindRepeating(&ReportHighResolutionTimerUsage));
}
}
HighResolutionTimerManager::~HighResolutionTimerManager() {
if (HighResolutionTimerAllowed()) {
auto* power_monitor = base::PowerMonitor::GetInstance();
power_monitor->RemovePowerSuspendObserver(this);
power_monitor->RemovePowerStateObserver(this);
UseHiResClock(false);
}
}
void HighResolutionTimerManager::OnBatteryPowerStatusChange(
base::PowerStateObserver::BatteryPowerStatus battery_power_status) {
DCHECK(HighResolutionTimerAllowed());
UseHiResClock(battery_power_status !=
PowerStateObserver::BatteryPowerStatus::kBatteryPower);
}
void HighResolutionTimerManager::OnSuspend() {
DCHECK(HighResolutionTimerAllowed());
// Stop polling the usage to avoid including the standby time.
timer_.Stop();
}
void HighResolutionTimerManager::OnResume() {
DCHECK(HighResolutionTimerAllowed());
// Resume polling the usage.
Time::ResetHighResolutionTimerUsage();
timer_.Reset();
}
void HighResolutionTimerManager::UseHiResClock(bool use) {
DCHECK(HighResolutionTimerAllowed());
if (use == hi_res_clock_available_) {
return;
}
hi_res_clock_available_ = use;
Time::EnableHighResolutionTimer(use);
}
} // namespace base
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