[Sensors] Improvements in fetching reading for sensors with continuous reporting mode

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/SensorPollingStrategy.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(ScriptState* scriptState,
                const SensorOptions& sensorOptions,
                ExceptionState& exceptionState,
                SensorType type)
     : ActiveScriptWrappable(this),
       ContextLifecycleObserver(scriptState->getExecutionContext()),
-      PageVisibilityObserver(
-          toDocument(scriptState->getExecutionContext())->page()),
       m_sensorOptions(sensorOptions),
       m_type(type),
       m_state(Sensor::SensorState::Idle) {
   // Check secure context.
   String errorMessage;
   if (!scriptState->getExecutionContext()->isSecureContext(errorMessage)) {
     exceptionState.throwDOMException(SecurityError, errorMessage);
     return;
   }
 
@@ skipping 81 matching lines @@
   if (m_state != Sensor::SensorState::Active)
     return nullptr;
   DCHECK(m_sensorProxy);
   return m_sensorProxy->sensorReading();
 }
 
 DEFINE_TRACE(Sensor) {
   visitor->trace(m_sensorProxy);
   ActiveScriptWrappable::trace(visitor);
   ContextLifecycleObserver::trace(visitor);
-  PageVisibilityObserver::trace(visitor);
   EventTargetWithInlineData::trace(visitor);
 }
 
 bool Sensor::hasPendingActivity() const {
   if (m_state == Sensor::SensorState::Idle ||
       m_state == Sensor::SensorState::Errored)
     return false;
   return hasEventListeners();
 }
 
@@ skipping 16 matching lines @@
 
 void Sensor::initSensorProxyIfNeeded() {
   if (m_sensorProxy)
     return;
 
   Document* document = toDocument(getExecutionContext());
   if (!document || !document->frame())
     return;
 
   auto provider = SensorProviderProxy::from(document->frame());
-  m_sensorProxy = provider->getSensor(m_type);
+  m_sensorProxy = provider->getSensorProxy(m_type);
 
   if (!m_sensorProxy) {
-    m_sensorProxy =
-        provider->createSensor(m_type, createSensorReadingFactory());
+    m_sensorProxy = provider->createSensorProxy(m_type, document->page(),
+                                                createSensorReadingFactory());
   }
 }
 
 void Sensor::contextDestroyed() {
   if (m_state == Sensor::SensorState::Active ||
       m_state == Sensor::SensorState::Activating)
     stopListening();
 }
 
 void Sensor::onSensorInitialized() {
   if (m_state != Sensor::SensorState::Activating)
     return;
 
   startListening();
 }
 
 void Sensor::onSensorReadingChanged() {
-  if (m_polling)
-    m_polling->onSensorReadingChanged();
+  if (m_state == Sensor::SensorState::Active) {
+    DCHECK(m_sensorUpdateNotifier);
+    m_sensorUpdateNotifier->onSensorReadingChanged();
+  }
 }
 
 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 pollCallback = WTF::bind(&Sensor::pollForData, wrapWeakPersistent(this));
+  auto updateCallback =
+      WTF::bind(&Sensor::onSensorUpdateNotification, wrapWeakPersistent(this));
   DCHECK_GT(m_configuration->frequency, 0);
-  m_polling = SensorPollingStrategy::create(1 / m_configuration->frequency,
-                                            std::move(pollCallback),
-                                            m_sensorProxy->reportingMode());
+  m_sensorUpdateNotifier = SensorUpdateNotificationStrategy::create(
+      m_configuration->frequency, std::move(updateCallback));
   updateState(Sensor::SensorState::Active);
 }
 
-void Sensor::onStopRequestCompleted(bool result) {
-  if (m_state == Sensor::SensorState::Idle)
-    return;
-
-  if (!result)
-    reportError(OperationError);
-
-  DCHECK(m_sensorProxy);
-  m_sensorProxy->removeObserver(this);
-}
-
-void Sensor::pageVisibilityChanged() {
-  updatePollingStatus();
-
-  if (!m_sensorProxy || !m_sensorProxy->isInitialized())
-    return;
-
-  if (page()->visibilityState() != PageVisibilityStateVisible) {
-    m_sensorProxy->suspend();
-  } else {
-    m_sensorProxy->resume();
-  }
-}
-
 void Sensor::startListening() {
   DCHECK(m_sensorProxy);
   updateState(Sensor::SensorState::Activating);
 
   m_sensorProxy->addObserver(this);
   if (!m_sensorProxy->isInitialized()) {
     m_sensorProxy->initialize();
     return;
   }
 
   if (!m_configuration) {
     m_configuration = createSensorConfig();
     DCHECK(m_configuration);
     DCHECK(m_configuration->frequency > 0 &&
            m_configuration->frequency <= m_sensorProxy->maximumFrequency());
   }
 
   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()) {
-    auto callback =
-        WTF::bind(&Sensor::onStopRequestCompleted, wrapWeakPersistent(this));
     DCHECK(m_configuration);
-    m_sensorProxy->removeConfiguration(m_configuration->Clone(),
-                                       std::move(callback));
-  } else {
-    m_sensorProxy->removeObserver(this);
+    m_sensorProxy->removeConfiguration(m_configuration->Clone());
   }
+  m_sensorProxy->removeObserver(this);
 }
 
-void Sensor::pollForData() {
-  if (m_state != Sensor::SensorState::Active) {
-    DCHECK(m_polling);
-    m_polling->stopPolling();
+void Sensor::onSensorUpdateNotification() {
+  if (m_state != Sensor::SensorState::Active)
     return;
-  }
 
   DCHECK(m_sensorProxy);
   DCHECK(m_sensorProxy->isInitialized());
-  m_sensorProxy->updateSensorReading();
+  DCHECK(m_sensorProxy->sensorReading());
 
-  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::Active && getExecutionContext()) {
     DCHECK_EQ(SensorState::Activating, m_state);
     getExecutionContext()->postTask(
         BLINK_FROM_HERE, createSameThreadTask(&Sensor::notifyOnActivate,
                                               wrapWeakPersistent(this)));
   }
 
   m_state = newState;
-  updatePollingStatus();
 }
 
 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::updatePollingStatus() {
-  if (!m_polling)
-    return;
-
-  if (m_state != Sensor::SensorState::Active ||
-      page()->visibilityState() != PageVisibilityStateVisible) {
-    m_polling->stopPolling();
-  } else {
-    m_polling->startPolling();
-  }
+void Sensor::onSuspended() {
+  if (m_sensorUpdateNotifier)
+    m_sensorUpdateNotifier->cancelPendingNotifications();
 }
 
 void Sensor::notifySensorReadingChanged() {
   dispatchEvent(Event::create(EventTypeNames::change));
 }
 
 void Sensor::notifyOnActivate() {
   dispatchEvent(Event::create(EventTypeNames::activate));
 }
 
 void Sensor::notifyError(DOMException* error) {
   dispatchEvent(
       SensorErrorEvent::create(EventTypeNames::error, std::move(error)));
 }
 
 }  // namespace blink