Resource: helper class to prohibit {add,remove}Client() calls in scope

third_party/WebKit/Source/core/fetch/Resource.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
     rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
@@ skipping 295 matching lines @@
       m_preloadCount(0),
       m_preloadDiscoveryTime(0.0),
       m_cacheIdentifier(MemoryCache::defaultCacheIdentifier()),
       m_preloadResult(PreloadNotReferenced),
       m_type(type),
       m_status(NotStarted),
       m_needsSynchronousCacheHit(false),
       m_linkPreload(false),
       m_isRevalidating(false),
       m_isAlive(false),
+      m_isAddRemoveClientProhibited(false),
       m_options(options),
       m_responseTimestamp(currentTime()),
       m_cancelTimer(this, &Resource::cancelTimerFired),
       m_resourceRequest(request) {
   // m_type is a bitfield, so this tests careless updates of the enum.
   DCHECK_EQ(m_type, unsigned(type));
   InstanceCounters::incrementCounter(InstanceCounters::ResourceCounter);
 
   // Currently we support the metadata caching only for HTTP family.
   if (m_resourceRequest.url().protocolIsInHTTPFamily())
@@ skipping 354 matching lines @@
     }
   }
   if (!hasClientsOrObservers()) {
     m_isAlive = true;
     memoryCache()->makeLive(this);
   }
 }
 
 void Resource::addClient(ResourceClient* client,
                          PreloadReferencePolicy policy) {
+  CHECK(!m_isAddRemoveClientProhibited);
+
   willAddClientOrObserver(policy);
 
   if (m_isRevalidating) {
     m_clients.add(client);
     return;
   }
 
   // If we have existing data to send to the new client and the resource type
   // supprts it, send it asynchronously.
   if (!m_response.isNull() &&
       !shouldSendCachedDataSynchronouslyForType(getType()) &&
       !m_needsSynchronousCacheHit) {
     m_clientsAwaitingCallback.add(client);
     ResourceCallback::callbackHandler().schedule(this);
     return;
   }
 
   m_clients.add(client);
   didAddClient(client);
   return;
 }
 
 void Resource::removeClient(ResourceClient* client) {
+  CHECK(!m_isAddRemoveClientProhibited);
+
   // This code may be called in a pre-finalizer, where weak members in the
   // HashCountedSet are already swept out.
 
   if (m_finishedClients.contains(client))
     m_finishedClients.remove(client);
   else if (m_clientsAwaitingCallback.contains(client))
     m_clientsAwaitingCallback.remove(client);
   else
     m_clients.remove(client);
 
@@ skipping 351 matching lines @@
     case Resource::TextTrack:
     case Resource::Media:
     case Resource::Manifest:
       return false;
   }
   NOTREACHED();
   return false;
 }
 
 }  // namespace blink