[Sensors] Align sensor reading updates and 'onchange' notification with rAF.

third_party/WebKit/Source/modules/sensor/Sensor.cpp

 // 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 "modules/sensor/Sensor.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ExecutionContextTask.h"
 #include "core/inspector/ConsoleMessage.h"
 #include "device/generic_sensor/public/interfaces/sensor.mojom-blink.h"
 #include "modules/sensor/SensorErrorEvent.h"
 #include "modules/sensor/SensorProviderProxy.h"
 #include "modules/sensor/SensorReading.h"
-#include "modules/sensor/SensorUpdateNotificationStrategy.h"
 
 using namespace device::mojom::blink;
 
 namespace blink {
 
 Sensor::Sensor(ExecutionContext* executionContext,
                const SensorOptions& sensorOptions,
                ExceptionState& exceptionState,
                SensorType type)
     : ActiveScriptWrappable<Sensor>(this),
       ContextLifecycleObserver(executionContext),
       m_sensorOptions(sensorOptions),
       m_type(type),
-      m_state(Sensor::SensorState::Idle) {
+      m_state(Sensor::SensorState::Idle),
+      m_lastUpdateTimestamp(0.0) {
   // Check secure context.
   String errorMessage;
   if (!executionContext->isSecureContext(errorMessage)) {
     exceptionState.throwDOMException(SecurityError, errorMessage);
     return;
   }
 
   // Check top-level browsing context.
   if (!toDocument(executionContext)->domWindow()->frame() ||
       !toDocument(executionContext)->frame()->isMainFrame()) {
@@ skipping 117 matching lines @@
     return;
 
   Document* document = toDocument(getExecutionContext());
   if (!document || !document->frame())
     return;
 
   auto provider = SensorProviderProxy::from(document->frame());
   m_sensorProxy = provider->getSensorProxy(m_type);
 
   if (!m_sensorProxy) {
-    m_sensorProxy = provider->createSensorProxy(m_type, document->page(),
+    m_sensorProxy = provider->createSensorProxy(m_type, document,
                                                 createSensorReadingFactory());
   }
 }
 
 void Sensor::contextDestroyed() {
   if (m_state == Sensor::SensorState::Activated ||
       m_state == Sensor::SensorState::Activating)
     stopListening();
 }
 
 void Sensor::onSensorInitialized() {
   if (m_state != Sensor::SensorState::Activating)
     return;
 
   startListening();
 }
 
-void Sensor::onSensorReadingChanged() {
-  if (m_state == Sensor::SensorState::Activated) {
-    DCHECK(m_sensorUpdateNotifier);
-    m_sensorUpdateNotifier->onSensorReadingChanged();
+void Sensor::onSensorReadingChanged(double timestamp) {
+  if (m_state != Sensor::SensorState::Activated)
+    return;
+
+  DCHECK_GT(m_configuration->frequency, 0.0);
+  double period = 1 / m_configuration->frequency;
+  if (timestamp - m_lastUpdateTimestamp >= period) {
+    m_lastUpdateTimestamp = timestamp;
+    notifySensorReadingChanged();
   }
 }
 
 void Sensor::onSensorError(ExceptionCode code,
                            const String& sanitizedMessage,
                            const String& unsanitizedMessage) {
   reportError(code, sanitizedMessage, unsanitizedMessage);
-  if (m_sensorUpdateNotifier)
-    m_sensorUpdateNotifier->cancelPendingNotifications();
 }
 
 void Sensor::onStartRequestCompleted(bool result) {
   if (m_state != Sensor::SensorState::Activating)
     return;
 
   if (!result) {
     reportError(
         OperationError,
         "start() call has failed possibly due to inappropriate options.");
     return;
   }
 
-  DCHECK(m_configuration);
-  DCHECK(m_sensorProxy);
-  auto updateCallback =
-      WTF::bind(&Sensor::onSensorUpdateNotification, wrapWeakPersistent(this));
-  DCHECK_GT(m_configuration->frequency, 0);
-  m_sensorUpdateNotifier = SensorUpdateNotificationStrategy::create(
-      m_configuration->frequency, std::move(updateCallback));
   updateState(Sensor::SensorState::Activated);
 }
 
 void Sensor::startListening() {
   DCHECK(m_sensorProxy);
   updateState(Sensor::SensorState::Activating);
 
   m_sensorProxy->addObserver(this);
   if (!m_sensorProxy->isInitialized()) {
     m_sensorProxy->initialize();
@@ skipping 10 matching lines @@
   auto startCallback =
       WTF::bind(&Sensor::onStartRequestCompleted, wrapWeakPersistent(this));
   m_sensorProxy->addConfiguration(m_configuration->Clone(),
                                   std::move(startCallback));
 }
 
 void Sensor::stopListening() {
   DCHECK(m_sensorProxy);
   updateState(Sensor::SensorState::Idle);
 
-  if (m_sensorUpdateNotifier)
-    m_sensorUpdateNotifier->cancelPendingNotifications();
-
   if (m_sensorProxy->isInitialized()) {
     DCHECK(m_configuration);
     m_sensorProxy->removeConfiguration(m_configuration->Clone());
   }
   m_sensorProxy->removeObserver(this);
 }
 
-void Sensor::onSensorUpdateNotification() {
-  if (m_state != Sensor::SensorState::Activated)
-    return;
-
-  DCHECK(m_sensorProxy);
-  DCHECK(m_sensorProxy->isInitialized());
-  DCHECK(m_sensorProxy->sensorReading());
-
-  if (getExecutionContext() &&
-      m_sensorProxy->sensorReading()->isReadingUpdated(m_storedData)) {
-    getExecutionContext()->postTask(
-        BLINK_FROM_HERE,
-        createSameThreadTask(&Sensor::notifySensorReadingChanged,
-                             wrapWeakPersistent(this)));
-  }
-
-  m_storedData = m_sensorProxy->sensorReading()->data();
-}
-
 void Sensor::updateState(Sensor::SensorState newState) {
   if (newState == m_state)
     return;
 
   if (newState == SensorState::Activated && getExecutionContext()) {
     DCHECK_EQ(SensorState::Activating, m_state);
     getExecutionContext()->postTask(
         BLINK_FROM_HERE, createSameThreadTask(&Sensor::notifyOnActivate,
                                               wrapWeakPersistent(this)));
   }
 
   m_state = newState;
 }
 
 void Sensor::reportError(ExceptionCode code,
                          const String& sanitizedMessage,
                          const String& unsanitizedMessage) {
   updateState(Sensor::SensorState::Errored);
   if (getExecutionContext()) {
     auto error =
         DOMException::create(code, sanitizedMessage, unsanitizedMessage);
     getExecutionContext()->postTask(
         BLINK_FROM_HERE,
         createSameThreadTask(&Sensor::notifyError, wrapWeakPersistent(this),
                              wrapPersistent(error)));
   }
 }
 
-void Sensor::onSuspended() {
-  if (m_sensorUpdateNotifier)
-    m_sensorUpdateNotifier->cancelPendingNotifications();
-}
+void Sensor::notifySensorReadingChanged() {
+  DCHECK(m_sensorProxy);
+  DCHECK(m_sensorProxy->sensorReading());
 
-void Sensor::notifySensorReadingChanged() {
-  dispatchEvent(Event::create(EventTypeNames::change));
+  if (m_sensorProxy->sensorReading()->isReadingUpdated(m_storedData)) {
+    dispatchEvent(Event::create(EventTypeNames::change));

[shalamov, 2016/12/16 17:10:48]

should it be reversed?

m_storedData = m_sensorProxy->sensorReading()->data();
dispatchEvent(Event::create(EventTypeNames::change));

[Reilly Grant (use Gerrit), 2016/12/16 22:09:37]

If this data were used by Sensor::reading() then it would matter. At the moment
I don't think it does but I still would favor the reversed logic.

[Mikhail, 2016/12/19 07:07:56]

Done.

[Mikhail, 2016/12/19 07:07:56]

Done.

+    m_storedData = m_sensorProxy->sensorReading()->data();
+  }
 }
 
 void Sensor::notifyOnActivate() {
   dispatchEvent(Event::create(EventTypeNames::activate));
 }
 
 void Sensor::notifyError(DOMException* error) {
   dispatchEvent(
       SensorErrorEvent::create(EventTypeNames::error, std::move(error)));
 }
 
 }  // namespace blink