Align IndexedDB metadata rollback on transaction abort to spec.

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

 /*
  * Copyright (C) 2010 Google 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
@@ skipping 22 matching lines @@
 #include "core/events/EventListener.h"
 #include "modules/EventModules.h"
 #include "modules/EventTargetModules.h"
 #include "modules/ModulesExport.h"
 #include "modules/indexeddb/IDBMetadata.h"
 #include "modules/indexeddb/IndexedDB.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/modules/indexeddb/WebIDBDatabase.h"
 #include "public/platform/modules/indexeddb/WebIDBTypes.h"
 #include "wtf/HashSet.h"
+#include "wtf/Vector.h"
 
 namespace blink {
 
 class DOMException;
 class ExceptionState;
 class IDBDatabase;
+class IDBIndex;
 class IDBObjectStore;
 class IDBOpenDBRequest;
-struct IDBObjectStoreMetadata;
 
 class MODULES_EXPORT IDBTransaction final
     : public EventTargetWithInlineData
     , public ActiveScriptWrappable
     , public ActiveDOMObject {
     USING_GARBAGE_COLLECTED_MIXIN(IDBTransaction);
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static IDBTransaction* create(ScriptState*, int64_t, const HashSet<String>& objectStoreNames, WebIDBTransactionMode, IDBDatabase*);
-    static IDBTransaction* create(ScriptState*, int64_t, IDBDatabase*, IDBOpenDBRequest*, const IDBDatabaseMetadata& previousMetadata);
+    static IDBTransaction* createNonVersionChange(ScriptState*, int64_t, const HashSet<String>& objectStoreNames, WebIDBTransactionMode, IDBDatabase*);

[jsbell, 2016/09/16 18:17:29]

Why these renames?

If it's just to avoid the overload, I'd keep this one just "create".

[pwnall, 2016/09/17 01:34:22]

The renames document when each create version gets called.

If you don't like the "createNonVersionChange" name, I can move that information
into a comment with an accompanying DCHECK. Does this seem reasoanble?

+    static IDBTransaction* createVersionChange(ScriptState*, int64_t, IDBDatabase*, IDBOpenDBRequest*, const IDBDatabaseOwnMetadata& oldMetadata);
     ~IDBTransaction() override;
     DECLARE_VIRTUAL_TRACE();
 
     static WebIDBTransactionMode stringToMode(const String&);
 
     // When the connection is closed backend will be 0.
     WebIDBDatabase* backendDB() const;
 
     int64_t id() const { return m_id; }
     bool isActive() const { return m_state == Active; }
     bool isFinished() const { return m_state == Finished; }
     bool isFinishing() const { return m_state == Finishing; }
     bool isReadOnly() const { return m_mode == WebIDBTransactionModeReadOnly; }
     bool isVersionChange() const { return m_mode == WebIDBTransactionModeVersionChange; }
 
     // Implement the IDBTransaction IDL
     const String& mode() const;
     DOMStringList* objectStoreNames() const;
     IDBDatabase* db() const { return m_database.get(); }
     DOMException* error() const { return m_error; }
     IDBObjectStore* objectStore(const String& name, ExceptionState&);
     void abort(ExceptionState&);
 
     void registerRequest(IDBRequest*);
     void unregisterRequest(IDBRequest*);
-    void objectStoreCreated(const String&, IDBObjectStore*);
-    void objectStoreDeleted(const String&);
+
+    // The methods below are called before the changes are applied to the
+    // database's metadata.

[jsbell, 2016/09/16 18:17:29]

Can you expand this comment to answer "why?"

[pwnall, 2016/09/17 01:34:22]

Done.

Can you please see if my revision makes sense?

+    void objectStoreCreated(const String& name, IDBObjectStore*);
+    void objectStoreDeleted(const int64_t objectStoreId, const String& name);
     void objectStoreRenamed(const String& oldName, const String& newName);
+    void indexDeleted(IDBIndex*); // only called when the index's IDBIndex had been created
+
     void setActive(bool);
     void setError(DOMException*);
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(abort);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(complete);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(error);
 
     void onAbort(DOMException*);
     void onComplete();
 
     // EventTarget
     const AtomicString& interfaceName() const override;
     ExecutionContext* getExecutionContext() const override;
 
     // ScriptWrappable
     bool hasPendingActivity() const final;
 
     // ActiveDOMObject
     void stop() override;
 
 protected:
     // EventTarget
     DispatchEventResult dispatchEventInternal(Event*) override;
 
 private:
-    IDBTransaction(ScriptState*, int64_t, const HashSet<String>&, WebIDBTransactionMode, IDBDatabase*, IDBOpenDBRequest*, const IDBDatabaseMetadata&);
+    IDBTransaction(ScriptState*, int64_t, const HashSet<String>&, WebIDBTransactionMode, IDBDatabase*, IDBOpenDBRequest*, const IDBDatabaseOwnMetadata&);
 
     void enqueueEvent(Event*);
 
+    // Called when a transaction is aborted.
+    void abortOutstandingRequests();
+    void revertDatabaseMetadata();
+
+    // Called when a transaction is completed (committed or aborted).
+    void finish();
+
     enum State {
         Inactive, // Created or started, but not in an event callback
         Active, // Created or started, in creation scope or an event callback
         Finishing, // In the process of aborting or completing.
         Finished, // No more events will fire and no new requests may be filed.
     };
 
     const int64_t m_id;
     Member<IDBDatabase> m_database;
-    const HashSet<String> m_objectStoreNames;
+    // The name of the object stores that the transaction may operate on.
+    //
+    // The scope is empty for versionchange transactions, which can operate on
+    // the entire database.
+    const HashSet<String> m_scope;
     Member<IDBOpenDBRequest> m_openDBRequest;
     const WebIDBTransactionMode m_mode;
     State m_state = Active;
     bool m_hasPendingActivity = true;
     bool m_contextStopped = false;
     Member<DOMException> m_error;
 
     HeapListHashSet<Member<IDBRequest>> m_requestList;
 
-    typedef HeapHashMap<String, Member<IDBObjectStore>> IDBObjectStoreMap;
+    // Caches the IDBObjectStore instances returned by the objectStore() method.
+    //
+    // The spec requires that a transaction's objectStore() returns the same
+    // IDBObjectStore instance for a specific store, so this cache is necessary
+    // for correctness.
+    //
+    // The cache may be in an inconsistent state after a transaction is aborted.

[jsbell, 2016/09/16 18:17:29]

I think this can be simplified to e.g.:

// objectStore() throws for completed/aborted transactions, 
// so this is not used after that occurs and can be cleared.

[pwnall, 2016/09/17 01:34:22]

Done.

I also revised the comment on IDBIndex.

+    // objectStore() throws for inactive transactions, which makes the cache not
+    // observable, so reverting the cache would be a waste of resources.
+    using IDBObjectStoreMap = HeapHashMap<String, Member<IDBObjectStore>>;
     IDBObjectStoreMap m_objectStoreMap;
 
-    // Used to mark stores created in an aborted upgrade transaction as
-    // deleted.
-    HeapHashSet<Member<IDBObjectStore>> m_createdObjectStores;
+    // The metadata of object stores when they are opened by this transaction.
+    //
+    // Only valid for versionchange transactions.
+    HeapHashMap<Member<IDBObjectStore>, RefPtr<IDBObjectStoreMetadata>> m_oldStoreMetadata;
 
-    // Used to notify object stores (which are no longer in m_objectStoreMap)
-    // when the transaction is finished.
-    HeapHashSet<Member<IDBObjectStore>> m_deletedObjectStores;
+    // The metadata of deleted object stores without IDBObjectStore instaces.

[jsbell, 2016/09/16 18:17:29]

typo: instances

[pwnall, 2016/09/17 01:34:22]

Done.

+    //
+    // Only valid for versionchange transactions.
+    Vector<RefPtr<IDBObjectStoreMetadata>> m_deletedObjectStores;
 
-    // Holds stores created, deleted, or used during upgrade transactions to
-    // reset metadata in case of abort.
-    HeapHashMap<Member<IDBObjectStore>, IDBObjectStoreMetadata> m_objectStoreCleanupMap;
-    IDBDatabaseMetadata m_previousMetadata;
+    // Tracks the indexes deleted by this transaction.
+    //
+    // This set only includes indexes that were created before this transaction,
+    // and were deleted during this transaction. Once marked for deletion, these
+    // indexes are removed from their object stores' index maps, so we need to
+    // stash them somewhere else in case the transaction gets aborted.
+    //
+    // This set does not include indexes created and deleted during this
+    // transaction, because we don't need to change their metadata when the
+    // transaction aborts, as they will still be marked for deletion.
+    HeapVector<Member<IDBIndex>> m_deletedIndexes;
+
+    // Only valid for versionchange transactions.
+    IDBDatabaseOwnMetadata m_oldDatabaseMetadata;
 };
 
 } // namespace blink
 
 #endif // IDBTransaction_h