[IndexedDB] Propogating changes to observers : Renderer

third_party/WebKit/Source/modules/indexeddb/IDBObserver.h

 // 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.
 
 #ifndef IDBObserver_h
 #define IDBObserver_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "modules/ModulesExport.h"
 #include "platform/heap/Handle.h"
+#include "public/platform/modules/indexeddb/WebIDBTypes.h"
 #include <set>
 
 namespace blink {
 
 class ExceptionState;
 class IDBDatabase;
 class IDBObserverCallback;
 class IDBObserverInit;
 class IDBTransaction;
+struct WebIDBObservation;
 
 class MODULES_EXPORT IDBObserver final : public GarbageCollectedFinalized<IDBObserver>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 
 public:
     static IDBObserver* create(IDBObserverCallback&, const IDBObserverInit&);
 
     ~IDBObserver();
+
     // API methods

[Marijn Kruisselbrink, 2016/07/11 23:10:40]

I'm not sure what the "API methods" and "API Attributes" comments are supposed
to say? Generally classes implementing IDL interfaces have some block of methods
to implement that IDL interface, with some comment saying so. But these "API
foo" comments don't seem to refer to that, as most of these methods don't
correspond to anything in IDL.

[palakj1, 2016/07/13 00:43:51]

Removed. Not aware of the right comments to put here.

     void observe(IDBDatabase*, IDBTransaction*, ExceptionState&);
     void unobserve(IDBDatabase*, ExceptionState&);
     void removeObserver(int32_t id);
+    void onChange(int32_t id, const std::vector<WebIDBObservation>&, const std::vector<int32_t>& observation_index);
+
+    // API Attributes
+    bool transaction() const { return m_transaction; }
+    bool noRecords() const { return m_noRecords; }
+    bool values() const { return m_values; }
 
     DECLARE_TRACE();
 
 private:
     IDBObserver(IDBObserverCallback&, const IDBObserverInit&);
 
     Member<IDBObserverCallback> m_callback;
     bool m_transaction;
     bool m_values;
     bool m_noRecords;
-    std::set<int32_t> m_observerIds;
+    std::map<int32_t, WeakMember<IDBDatabase>> m_observerIds;

[Marijn Kruisselbrink, 2016/07/11 23:10:40]

You should not use stl containers to hold references to garbage collected object
(for one the WeakMember won't be properly zeroed out without tracing). You
probably want to use a HeapHashMap<int32_t, WeakMember<IDBDatabase>> here, and
trace it in your trace method.

Also, should this really be a WeakMember? I'm afraid I'm not entirely familiar
with the exact lifetime guarantees of IDBDatabase instances and IDBObserver
instances (does anything observable happens if an IDBDatabase instance is
garbage collected?)

[palakj1, 2016/07/13 00:43:51]

Changed stl container to heaphashmap. As discussed with you, we ensure that if
IDBDatabase is getting deleted, our reference is removed prior to it being
garbage collected. So, keeping a weakptr reference to IDBDatabase.

 };
 
 } // namespace blink
 
 #endif // IDBObserver_h