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| 1 // Copyright 2016 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 "modules/sensor/SensorUpdateNotificationStrategy.h" |
| 6 |
| 7 #include "device/generic_sensor/public/interfaces/sensor.mojom-blink.h" |
| 8 #include "platform/Timer.h" |
| 9 #include "wtf/CurrentTime.h" |
| 10 |
| 11 namespace blink { |
| 12 |
| 13 // Polls the buffer on signal from platform but not more frequently |
| 14 // than the given 'pollingPeriod'. |
| 15 class SensorUpdateNotificationStrategyImpl |
| 16 : public SensorUpdateNotificationStrategy { |
| 17 public: |
| 18 SensorUpdateNotificationStrategyImpl(double frequency, |
| 19 std::unique_ptr<Function<void()>> func) |
| 20 : m_pollingPeriod(1 / frequency), |
| 21 m_func(std::move(func)), |
| 22 m_timer(this, &SensorUpdateNotificationStrategyImpl::onTimer), |
| 23 m_lastPollingTimestamp(0.0) { |
| 24 DCHECK_GT(frequency, 0.0); |
| 25 DCHECK(m_func); |
| 26 } |
| 27 |
| 28 private: |
| 29 // SensorUpdateNotificationStrategy overrides. |
| 30 void onSensorReadingChanged() override; |
| 31 void cancelPendingNotifications() override; |
| 32 |
| 33 void onTimer(TimerBase*); |
| 34 void notifyUpdate(); |
| 35 |
| 36 double m_pollingPeriod; |
| 37 std::unique_ptr<Function<void()>> m_func; |
| 38 Timer<SensorUpdateNotificationStrategyImpl> m_timer; |
| 39 double m_lastPollingTimestamp; |
| 40 }; |
| 41 |
| 42 void SensorUpdateNotificationStrategyImpl::onSensorReadingChanged() { |
| 43 if (m_timer.isActive()) |
| 44 return; // Skipping changes if update notification was already sheduled. |
| 45 |
| 46 double elapsedTime = |
| 47 WTF::monotonicallyIncreasingTime() - m_lastPollingTimestamp; |
| 48 |
| 49 double waitingTime = m_pollingPeriod - elapsedTime; |
| 50 const double minInterval = |
| 51 1 / device::mojom::blink::SensorConfiguration::kMaxAllowedFrequency; |
| 52 |
| 53 // Negative or zero 'waitingTime' means that polling period has elapsed. |
| 54 // We also avoid scheduling if the elapsed time is slightly behind the |
| 55 // polling period. |
| 56 if (waitingTime < minInterval) { |
| 57 notifyUpdate(); |
| 58 } else { |
| 59 m_timer.startOneShot(waitingTime, BLINK_FROM_HERE); |
| 60 } |
| 61 } |
| 62 |
| 63 void SensorUpdateNotificationStrategyImpl::cancelPendingNotifications() { |
| 64 m_timer.stop(); |
| 65 } |
| 66 |
| 67 void SensorUpdateNotificationStrategyImpl::notifyUpdate() { |
| 68 m_lastPollingTimestamp = WTF::monotonicallyIncreasingTime(); |
| 69 (*m_func)(); |
| 70 } |
| 71 |
| 72 void SensorUpdateNotificationStrategyImpl::onTimer(TimerBase*) { |
| 73 notifyUpdate(); |
| 74 } |
| 75 |
| 76 // static |
| 77 std::unique_ptr<SensorUpdateNotificationStrategy> |
| 78 SensorUpdateNotificationStrategy::create( |
| 79 double pollingPeriod, |
| 80 std::unique_ptr<Function<void()>> func) { |
| 81 return std::unique_ptr<SensorUpdateNotificationStrategy>( |
| 82 new SensorUpdateNotificationStrategyImpl(pollingPeriod, std::move(func))); |
| 83 } |
| 84 |
| 85 } // namespace blink |
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