Implement BroadcastChannel

third_party/WebKit/Source/modules/broadcastchannel/BroadcastChannelConnection.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/BroadcastChannelConnection.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(Platform::current()->mainThread()->isCurrentThread());
+    Platform::current()->serviceRegistry()->connectToRemoteService(std::move(request));
+}
+
+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))));
+    }
+    return *service;
+}
+
+using ConnectionKey = std::pair<RefPtr<SecurityOrigin>, String>;
+using ConnectionMap = HashMap<ConnectionKey, BroadcastChannelConnection*>;
+
+ConnectionMap* getConnectionMap()
+{
+    DEFINE_THREAD_SAFE_STATIC_LOCAL(ThreadSpecific<ConnectionMap>, connectionMap, new ThreadSpecific<ConnectionMap>);
+    return connectionMap;
+}
+
+} // namespace
+
+// static
+BroadcastChannelConnection* BroadcastChannelConnection::getForChannel(const RefPtr<SecurityOrigin>& origin, const String& name)
+{
+    ConnectionMap* connectionMap = getConnectionMap();
+    auto it = connectionMap->find(ConnectionKey(origin, name));
+    if (it != connectionMap->end())
+        return it->value;
+
+    webmessaging::mojom::blink::BroadcastChannelServicePtr& service = getThreadSpecificService();
+    webmessaging::mojom::blink::BroadcastChannelClientAssociatedPtrInfo localClientInfo;
+    BroadcastChannelConnection* connection = new BroadcastChannelConnection(name, origin, &localClientInfo, service.associated_group());
+    service->Subscribe(origin, name, std::move(localClientInfo));
+    return connection;
+}
+
+BroadcastChannelConnection::~BroadcastChannelConnection()
+{
+    getConnectionMap()->remove(ConnectionKey(m_origin, m_name));
+    for (Client* client : m_clients)
+        client->onError();
+}
+
+void BroadcastChannelConnection::registerClient(Client* client)
+{
+    m_clients.add(client);
+}
+
+void BroadcastChannelConnection::unregisterClient(Client* client)
+{
+    m_clients.remove(client);
+    if (m_clients.isEmpty())
+        onError();
+}
+
+void BroadcastChannelConnection::broadcast(Client* from, const String& message)
+{
+    for (Client* client : m_clients) {
+        if (client != from)
+            client->onMessage(message);
+    }
+    getThreadSpecificService()->Broadcast(from->origin(), from->name(), message);
+}
+
+BroadcastChannelConnection::BroadcastChannelConnection(const String& name, const RefPtr<SecurityOrigin>& origin, webmessaging::mojom::blink::BroadcastChannelClientAssociatedPtrInfo* clientInfo, mojo::AssociatedGroup* associatedGroup)
+    : m_name(name)
+    , m_origin(origin)
+    , m_binding(this, clientInfo, associatedGroup)
+{
+    m_binding.set_connection_error_handler(createBaseCallback(bind(&BroadcastChannelConnection::onError, this)));

[Marijn Kruisselbrink, 2016/05/31 23:57:08]

Oh, one more mojo specific question: since my error callback is pretty much just
"delete this", would it make sense to have something like a
mojo::StrongAssociatedBinding that would just do that for me? Since regular
interfaces already have Binding and StrongBinding it might make sense to have
both for associated interfaces as well.

+    auto result = getConnectionMap()->set(ConnectionKey(m_origin, m_name), this);
+    DCHECK(result.isNewEntry) << "There should only be one connection per channel per thread.";
+    ALLOW_UNUSED_LOCAL(result);
+}
+
+void BroadcastChannelConnection::OnMessage(const String& message)
+{
+    for (Client* client : m_clients)
+        client->onMessage(message);
+}
+
+void BroadcastChannelConnection::onError()
+{
+    // Destructor will call onError of clients and unregister the connection.
+    delete this;
+}
+
+} // namespace blink