Delay client registration of MessagePort to MessagePortChannel

third_party/WebKit/Source/core/dom/MessagePort.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 44 matching lines @@
 MessagePort::MessagePort(ExecutionContext& executionContext)
     : ActiveScriptWrappable(this)
     , ActiveDOMObject(&executionContext)
     , m_started(false)
     , m_closed(false)
 {
 }
 
 MessagePort::~MessagePort()
 {
     close();

[yhirano, 2016/07/14 04:30:22]

DCHECK(!started() || !isEntangled()) is better than calling close, I think.

[tzik, 2016/07/14 04:59:56]

Done.

     if (m_scriptStateForConversion)
         m_scriptStateForConversion->disposePerContextData();
 }
 
 void MessagePort::postMessage(ExecutionContext* context, PassRefPtr<SerializedScriptValue> message, const MessagePortArray& ports, ExceptionState& exceptionState)
 {
     if (!isEntangled())
         return;
     DCHECK(getExecutionContext());
     DCHECK(m_entangledChannel);
@@ skipping 34 matching lines @@
 {
     std::unique_ptr<MessagePortChannelArray> channels = wrapUnique(new MessagePortChannelArray(webChannels.size()));
     for (size_t i = 0; i < webChannels.size(); ++i)
         (*channels)[i] = WebMessagePortChannelUniquePtr(webChannels[i]);
     return MessagePort::entanglePorts(*context, std::move(channels));
 }
 
 WebMessagePortChannelUniquePtr MessagePort::disentangle()
 {
     DCHECK(m_entangledChannel);
-    m_entangledChannel->setClient(0);
+    m_entangledChannel->setClient(nullptr);
     return std::move(m_entangledChannel);
 }
 
 // Invoked to notify us that there are messages available for this port.
 // This code may be called from another thread, and so should not call any non-threadsafe APIs (i.e. should not call into the entangled channel or access mutable variables).
 void MessagePort::messageAvailable()
 {
     DCHECK(getExecutionContext());
     getExecutionContext()->postTask(BLINK_FROM_HERE, createCrossThreadTask(&MessagePort::dispatchMessages, wrapCrossThreadWeakPersistent(this)));
 }
 
 void MessagePort::start()
 {
     // Do nothing if we've been cloned or closed.
     if (!isEntangled())
         return;
 
     DCHECK(getExecutionContext());
     if (m_started)
         return;
 
+    m_entangledChannel->setClient(this);
     m_started = true;
     messageAvailable();
 }
 
 void MessagePort::close()
 {
     if (isEntangled())
-        m_entangledChannel->setClient(0);
+        m_entangledChannel->setClient(nullptr);
     m_closed = true;
 }
 
 void MessagePort::entangle(WebMessagePortChannelUniquePtr remote)
 {
     // Only invoked to set our initial entanglement.
     DCHECK(!m_entangledChannel);
     DCHECK(getExecutionContext());
 
     m_entangledChannel = std::move(remote);
-    m_entangledChannel->setClient(this);
 }
 
 const AtomicString& MessagePort::interfaceName() const
 {
     return EventTargetNames::MessagePort;
 }
 
 static bool tryGetMessageFrom(WebMessagePortChannel& webChannel, RefPtr<SerializedScriptValue>& message, std::unique_ptr<MessagePortChannelArray>& channels)
 {
     WebString messageString;
@@ skipping 98 matching lines @@
     return portArray;
 }
 
 DEFINE_TRACE(MessagePort)
 {
     ActiveDOMObject::trace(visitor);
     EventTargetWithInlineData::trace(visitor);
 }
 
 } // namespace blink