bluetooth: Update BluetoothCharacteristic.value on readValue

third_party/WebKit/Source/modules/bluetooth/BluetoothGATTCharacteristic.cpp

 // 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 "modules/bluetooth/BluetoothGATTCharacteristic.h"
 
 #include "bindings/core/v8/CallbackPromiseAdapter.h"
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMException.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/events/Event.h"
 #include "modules/bluetooth/BluetoothCharacteristicProperties.h"
 #include "modules/bluetooth/BluetoothError.h"
 #include "modules/bluetooth/BluetoothSupplement.h"
-#include "modules/bluetooth/ConvertWebVectorToArrayBuffer.h"
 #include "public/platform/modules/bluetooth/WebBluetooth.h"
 
 namespace blink {
 
 BluetoothGATTCharacteristic::BluetoothGATTCharacteristic(ExecutionContext* context, PassOwnPtr<WebBluetoothGATTCharacteristicInit> webCharacteristic)
     : ActiveDOMObject(context)
     , m_webCharacteristic(webCharacteristic)
     , m_stopped(false)
 {
     m_properties = BluetoothCharacteristicProperties::create(m_webCharacteristic->characteristicProperties);
     // See example in Source/platform/heap/ThreadState.h
     ThreadState::current()->registerPreFinalizer(this);
 }
 
 BluetoothGATTCharacteristic* BluetoothGATTCharacteristic::take(ScriptPromiseResolver* resolver, PassOwnPtr<WebBluetoothGATTCharacteristicInit> webCharacteristic)
 {
     if (!webCharacteristic) {
         return nullptr;
     }
     BluetoothGATTCharacteristic* characteristic = new BluetoothGATTCharacteristic(resolver->executionContext(), webCharacteristic);
     // See note in ActiveDOMObject about suspendIfNeeded.
     characteristic->suspendIfNeeded();
     return characteristic;
 }
 
+void BluetoothGATTCharacteristic::setValue(
+    const WebVector<uint8_t>& value)
+{
+    static_assert(sizeof(*value.data()) == 1, "uint8_t should be a single byte");
+
+    m_value = DOMArrayBuffer::create(value.data(), value.size());
+}
+
 void BluetoothGATTCharacteristic::dispatchCharacteristicValueChanged(
     const WebVector<uint8_t>& value)
 {
-    static_assert(sizeof(*value.data()) == 1, "uint8_t should be a single byte");
-
-    m_value = DOMArrayBuffer::create(value.data(), value.size());
+    setValue(value);
 
     dispatchEvent(Event::create(EventTypeNames::characteristicvaluechanged));
 }
 
 void BluetoothGATTCharacteristic::stop()
 {
     notifyCharacteristicObjectRemoved();
 }
 
 void BluetoothGATTCharacteristic::dispose()
@@ skipping 24 matching lines @@
 {
     // We will also need to unregister a characteristic once all the event
     // listeners have been removed. See http://crbug.com/541390
     if (eventType == EventTypeNames::characteristicvaluechanged) {
         WebBluetooth* webbluetooth = BluetoothSupplement::fromExecutionContext(executionContext());
         webbluetooth->registerCharacteristicObject(m_webCharacteristic->characteristicInstanceID, this);
     }
     return EventTarget::addEventListenerInternal(eventType, listener, options);
 }
 
+
+class ReadValueCallback : public WebBluetoothReadValueCallbacks {
+public:
+    ReadValueCallback(BluetoothGATTCharacteristic* characteristic, ScriptPromiseResolver* resolver) : m_webCharacteristic(characteristic), m_resolver(resolver) {}
+
+    void onSuccess(const WebVector<uint8_t>& value) override
+    {
+        if (!m_resolver->executionContext() || m_resolver->executionContext()->activeDOMObjectsAreStopped())
+            return;
+
+        m_webCharacteristic->setValue(value);
+        m_resolver->resolve(m_webCharacteristic->value());
+    }
+
+    void onError(const WebBluetoothError& e) override
+    {
+        if (!m_resolver->executionContext() || m_resolver->executionContext()->activeDOMObjectsAreStopped())
+            return;
+        m_resolver->reject(BluetoothError::take(m_resolver, e));
+    }
+
+private:
+    Persistent<BluetoothGATTCharacteristic> m_webCharacteristic;

[ortuno, 2016/01/13 21:14:09]

Talked to jyasskin about this. We don't need to keep an object alive longer than
necessary so we should use WeakPersistent instead. That would mean you need to
add a null check before resolving the promise:

RefPtr<DOMArrayBuffer> domBuffer = ConvertWebVectorToArrayBuffer(value);
if (m_webCharacteristic != nullptr) {
    m_webCharacteristic->setValue(domBuffer);
}
m_resolver->resolve(domBuffer);

+    Persistent<ScriptPromiseResolver> m_resolver;
+};
+
 ScriptPromise BluetoothGATTCharacteristic::readValue(ScriptState* scriptState)
 {
     WebBluetooth* webbluetooth = BluetoothSupplement::fromScriptState(scriptState);
 
     ScriptPromiseResolver* resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
-    webbluetooth->readValue(m_webCharacteristic->characteristicInstanceID, new CallbackPromiseAdapter<ConvertWebVectorToArrayBuffer, BluetoothError>(resolver));
+    webbluetooth->readValue(m_webCharacteristic->characteristicInstanceID, new ReadValueCallback(this, resolver));
 
     return promise;
 }
 
 ScriptPromise BluetoothGATTCharacteristic::writeValue(ScriptState* scriptState, const DOMArrayPiece& value)
 {
     WebBluetooth* webbluetooth = BluetoothSupplement::fromScriptState(scriptState);
     // Partial implementation of writeValue algorithm:
     // https://webbluetoothchrome.github.io/web-bluetooth/#dom-bluetoothgattcharacteristic-writevalue
 
@@ skipping 33 matching lines @@
 }
 
 DEFINE_TRACE(BluetoothGATTCharacteristic)
 {
     RefCountedGarbageCollectedEventTargetWithInlineData<BluetoothGATTCharacteristic>::trace(visitor);
     ActiveDOMObject::trace(visitor);
     visitor->trace(m_properties);
 }
 
 } // namespace blink