Implement BroadcastChannel

third_party/WebKit/Source/modules/broadcastchannel/BroadcastChannel.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/broadcastchannel/BroadcastChannel.h"
+
+#include "bindings/core/v8/SerializedScriptValue.h"
+#include "core/dom/ExceptionCode.h"
+#include "core/events/EventQueue.h"
+#include "core/events/MessageEvent.h"
+#include "platform/ThreadSafeFunctional.h"
+#include "platform/mojo/MojoHelper.h"
+#include "public/platform/Platform.h"
+#include "public/platform/ServiceRegistry.h"
+#include "public/platform/WebTaskRunner.h"
+#include "public/platform/WebTraceLocation.h"
+
+namespace blink {
+
+namespace {
+
+void connectToService(webmessaging::mojom::blink::BroadcastChannelServiceRequest request)
+{
+    DCHECK(isMainThread());
+    Platform::current()->serviceRegistry()->connectToRemoteService(std::move(request));
+}
+
+// To ensure proper ordering of messages send to/from multiple BroadcastChannel
+// instances in the same thread this uses one BroadcastChannelService
+// connection as basis for all connections to channels from the same thread. The
+// actual connections used to send/receive messages are then created using
+// associated interfaces, ensuring proper message ordering.
+webmessaging::mojom::blink::BroadcastChannelServicePtr& getThreadSpecificService()
+{
+    DEFINE_THREAD_SAFE_STATIC_LOCAL(ThreadSpecific<webmessaging::mojom::blink::BroadcastChannelServicePtr>, service, new ThreadSpecific<webmessaging::mojom::blink::BroadcastChannelServicePtr>);
+    if (!service.isSet()) {
+        Platform::current()->mainThread()->getWebTaskRunner()->postTask(BLINK_FROM_HERE,
+            threadSafeBind(&connectToService, passed(mojo::GetProxy(&*service))));

[kinuko, 2016/06/23 15:29:57]

I was looking into connectToRemoteService impl and it looks we always post task
to main thread if this is called on non-main thread.  Do we still need this post
task?

[Marijn Kruisselbrink, 2016/06/23 16:32:32]

Ah yes, seems that was changed recently to work from non-main thread. Seems they
forgot to document the new thread safety requirements for blink::ServiceRegistry
implementations though, so I've added that in this CL.

+    }
+    return *service;
+}
+
+} // namespace
+
+// static
+BroadcastChannel* BroadcastChannel::create(ExecutionContext* executionContext, const String& name, ExceptionState& exceptionState)
+{
+    if (executionContext->getSecurityOrigin()->isUnique()) {
+        // TODO(mek): Decide what to do here depending on https://github.com/whatwg/html/issues/1319
+        exceptionState.throwDOMException(NotSupportedError, "Can't create BroadcastChannel in an opaque origin");
+        return nullptr;
+    }
+    return new BroadcastChannel(executionContext, name);
+}
+
+BroadcastChannel::~BroadcastChannel()
+{
+}
+
+void BroadcastChannel::dispose()
+{
+    close();
+}
+
+void BroadcastChannel::postMessage(const ScriptValue& message, ExceptionState& exceptionState)
+{
+    if (!m_binding.is_bound()) {
+        exceptionState.throwDOMException(InvalidStateError, "Channel is closed");
+        return;
+    }
+    RefPtr<SerializedScriptValue> value = SerializedScriptValue::serialize(message.isolate(), message.v8Value(), nullptr, nullptr, exceptionState);
+    if (exceptionState.hadException())
+        return;
+
+    String data = value->toWireString();
+    m_remoteClient->OnMessage(data);
+}
+
+void BroadcastChannel::close()
+{
+    m_remoteClient.reset();
+    if (m_binding.is_bound())
+        m_binding.Close();
+}
+
+const AtomicString& BroadcastChannel::interfaceName() const
+{
+    return EventTargetNames::BroadcastChannel;
+}
+
+bool BroadcastChannel::hasPendingActivity() const
+{
+    return m_binding.is_bound() && hasEventListeners(EventTypeNames::message);
+}
+
+void BroadcastChannel::contextDestroyed()
+{
+    close();
+}
+
+DEFINE_TRACE(BroadcastChannel)
+{
+    ContextLifecycleObserver::trace(visitor);
+    EventTargetWithInlineData::trace(visitor);
+}
+
+void BroadcastChannel::OnMessage(const String& message)
+{
+    // Queue a task to dispatch the event.
+    RefPtr<SerializedScriptValue> value = SerializedScriptValue::create(message);
+    MessageEvent* event = MessageEvent::create(nullptr, value.release(), getExecutionContext()->getSecurityOrigin()->toString());
+    event->setTarget(this);
+    bool success = getExecutionContext()->getEventQueue()->enqueueEvent(event);
+    DCHECK(success);
+    ALLOW_UNUSED_LOCAL(success);
+}
+
+void BroadcastChannel::onError()
+{
+    close();
+}
+
+BroadcastChannel::BroadcastChannel(ExecutionContext* executionContext, const String& name)
+    : ActiveScriptWrappable(this)
+    , ContextLifecycleObserver(executionContext)
+    , m_origin(executionContext->getSecurityOrigin())
+    , m_name(name)
+    , m_binding(this)
+{
+    webmessaging::mojom::blink::BroadcastChannelServicePtr& service = getThreadSpecificService();
+
+    // Local BroadcastChannelClient for messages send from the browser to this channel.
+    webmessaging::mojom::blink::BroadcastChannelClientAssociatedPtrInfo localClientInfo;
+    m_binding.Bind(&localClientInfo, service.associated_group());
+    m_binding.set_connection_error_handler(createBaseCallback(bind(&BroadcastChannel::onError, WeakPersistentThisPointer<BroadcastChannel>(this))));
+
+    // Remote BroadcastChannelClient for messages send from this channel to the browser.
+    webmessaging::mojom::blink::BroadcastChannelClientAssociatedPtrInfo remoteClientInfo;
+    mojo::AssociatedInterfaceRequest<webmessaging::mojom::blink::BroadcastChannelClient> remoteCientRequest;
+    service.associated_group()->CreateAssociatedInterface(mojo::AssociatedGroup::WILL_PASS_REQUEST, &remoteClientInfo, &remoteCientRequest);
+    m_remoteClient.Bind(std::move(remoteClientInfo));
+    m_remoteClient.set_connection_error_handler(createBaseCallback(bind(&BroadcastChannel::onError, WeakPersistentThisPointer<BroadcastChannel>(this))));
+
+    service->ConnectToChannel(m_origin, m_name, std::move(localClientInfo), std::move(remoteCientRequest));
+}
+
+} // namespace blink