Verify the order of RawResourceClient callbacks in DocumentThreadableLoader

third_party/WebKit/Source/core/fetch/RawResource.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007 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
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later version.
@@ skipping 93 matching lines @@
 
 class CORE_EXPORT RawResourceClient : public ResourceClient {
 public:
     RawResourceClient()
         : m_weakFactory(this) { }
     WeakPtr<RawResourceClient> createWeakPtr() { return m_weakFactory.createWeakPtr(); }
     ~RawResourceClient() override {}
     static bool isExpectedType(ResourceClient* client) { return client->getResourceClientType() == RawResourceType; }
     ResourceClientType getResourceClientType() const final { return RawResourceType; }
 
+    // The order of the callbacks is as follows:
+    // [Case 1] A successful load:
+    // 0+  redirectReceived() and/or dataSent()
+    // 1   responseReceived()
+    // 0-1 setSerializedCachedMetadata()
+    // 0+  dataReceived() or dataDownloaded(), but never both
+    // 1   notifyFinished() with errorOccurred() = false
+    // [Case 2] When redirect is blocked:
+    // 0+  redirectReceived() and/or dataSent()
+    // 1   redirectBlocked()
+    // 1   notifyFinished() with errorOccurred() = true
+    // [Case 3] Other failures:
+    //     notifyFinished() with errorOccurred() = true is called at any time
+    //     (unless notifyFinished() is already called).
+    // In all cases:
+    //     No callbacks are made after notifyFinished() or
+    //     removeClient() is called.
     virtual void dataSent(Resource*, unsigned long long /* bytesSent */, unsigned long long /* totalBytesToBeSent */) { }
     virtual void responseReceived(Resource*, const ResourceResponse&, PassOwnPtr<WebDataConsumerHandle>) { }
     virtual void setSerializedCachedMetadata(Resource*, const char*, size_t) { }
     virtual void dataReceived(Resource*, const char* /* data */, size_t /* length */) { }
     virtual void redirectReceived(Resource*, ResourceRequest&, const ResourceResponse&) { }
     virtual void redirectBlocked() {}
     virtual void dataDownloaded(Resource*, int) { }
     virtual void didReceiveResourceTiming(Resource*, const ResourceTimingInfo&) { }
 
 private:
     WeakPtrFactory<RawResourceClient> m_weakFactory;
 };
 
+// Checks the sequence of callbacks of RawResourceClient.
+// This can be used only when a RawResourceClient is added as a client to
+// at most one RawResource.
+class CORE_EXPORT RawResourceClientStateChecker {

[yhirano, 2016/06/03 07:25:13]

+final

[hiroshige, 2016/08/03 11:50:34]

Done.

+public:
+    RawResourceClientStateChecker();
+    ~RawResourceClientStateChecker();
+
+    // Call before addClient()/removeClient() is called.
+    void willAddClient();

[yhirano, 2016/06/03 07:25:13]

I'm a bit concerned about the case when DocumentThreadableLoader is a subclass
of ResourceOwner<RawResource>. In that case ResourceOwner::setResource adds the
client to a Resource without notifying DocumentThreadableLoader (Currently no
one outside of the class calls setResource but we will not be able to forbid
it).

Does that mean DocumentThreadableLoader will never be able to be a subclass of
ResourceOwner?

[hiroshige, 2016/06/03 09:58:38]

ResourceOwner::setResource() is |protected|.
Doesn't it prevent setResource() calls from outside DocumentThreadableLoader?

[yhirano, 2016/06/07 05:18:25]

I didn't notice that, thank you.
But ResourceOwner may call removeClient(self) in the prefinalizer step, so can
you remove the assertion from the destructor?

[hiroshige, 2016/08/03 11:50:34]

Done.

+    void willRemoveClient();
+
+    // Call RawResourceClientStateChecker::f() at the beginning of
+    // RawResourceClient::f().
+    void redirectReceived();
+    void redirectBlocked();
+    void dataSent();
+    void responseReceived();
+    void setSerializedCachedMetadata();
+    void dataReceived();
+    void dataDownloaded();
+    void notifyFinished(Resource*);
+
+private:
+    enum State {
+        NotAddedAsClient,
+        Started,
+        RedirectBlocked,
+        ResponseReceived,
+        SetSerializedCachedMetadata,
+        DataReceived,
+        DataDownloaded,
+        NotifyFinished
+    };
+    State m_state;
+};
+
 } // namespace blink
 
 #endif // RawResource_h