Bug 1031407 - DataStoreService doesn't need to use IDBCursor to know if a revision exists., r=janv

dom/datastore/DataStoreCallbacks.h

@@ -20,7 +20,13 @@ public:
   NS_IMETHOD_(MozExternalRefCountType) AddRef(void) = 0;
   NS_IMETHOD_(MozExternalRefCountType) Release(void) = 0;
 
-  virtual void Run(DataStoreDB* aDb, bool aSuccess) = 0;
+  enum RunStatus {
+    Success,
+    CreatedSchema,
+    Error
+  };
+
+  virtual void Run(DataStoreDB* aDb, RunStatus aStatus) = 0;
 
 protected:
   virtual ~DataStoreDBCallback()

dom/datastore/DataStoreDB.cpp

@@ -78,6 +78,7 @@ NS_IMPL_ISUPPORTS(DataStoreDB, nsIDOMEventListener)
 
 DataStoreDB::DataStoreDB(const nsAString& aManifestURL, const nsAString& aName)
   : mState(Inactive)
+  , mCreatedSchema(false)
 {
   mDatabaseName.Assign(aName);
   mDatabaseName.Append('|');
@@ -145,9 +146,11 @@ DataStoreDB::HandleEvent(nsIDOMEvent* aEvent)
 
     rv = DatabaseOpened();
     if (NS_WARN_IF(NS_FAILED(rv))) {
-      mCallback->Run(this, false);
+      mCallback->Run(this, DataStoreDBCallback::Error);
     } else {
-      mCallback->Run(this, true);
+      mCallback->Run(this, mCreatedSchema
+                      ? DataStoreDBCallback::CreatedSchema :
+                        DataStoreDBCallback::Success);
     }
 
     mRequest = nullptr;
@@ -155,13 +158,13 @@ DataStoreDB::HandleEvent(nsIDOMEvent* aEvent)
   }
 
   if (type.EqualsASCII("upgradeneeded")) {
-    return UpgradeSchema();
+    return UpgradeSchema(aEvent);
   }
 
   if (type.EqualsASCII("error") || type.EqualsASCII("blocked")) {
     RemoveEventListeners();
     mState = Inactive;
-    mCallback->Run(this, false);
+    mCallback->Run(this, DataStoreDBCallback::Error);
     mRequest = nullptr;
     return NS_OK;
   }
@@ -170,10 +173,23 @@ DataStoreDB::HandleEvent(nsIDOMEvent* aEvent)
 }
 
 nsresult
-DataStoreDB::UpgradeSchema()
+DataStoreDB::UpgradeSchema(nsIDOMEvent* aEvent)
 {
   MOZ_ASSERT(NS_IsMainThread());
 
+  // This DB has been just created and we have to inform the callback about
+  // this.
+  mCreatedSchema = true;
+
+#ifdef DEBUG
+  nsCOMPtr<IDBVersionChangeEvent> event = do_QueryInterface(aEvent);
+  MOZ_ASSERT(event);
+
+  Nullable<uint64_t> version = event->GetNewVersion();
+  MOZ_ASSERT(!version.IsNull());
+  MOZ_ASSERT(version.Value() == DATASTOREDB_VERSION);
+#endif
+
   AutoSafeJSContext cx;
 
   ErrorResult error;

dom/datastore/DataStoreDB.h

@@ -50,7 +50,7 @@ private:
 
   nsresult CreateFactoryIfNeeded();
 
-  nsresult UpgradeSchema();
+  nsresult UpgradeSchema(nsIDOMEvent* aEvent);
 
   nsresult DatabaseOpened();
 
@@ -75,6 +75,7 @@ private:
 
   IDBTransactionMode mTransactionMode;
   Sequence<nsString> mObjectStores;
+  bool mCreatedSchema;
 };
 
 } // namespace dom

dom/datastore/DataStoreService.cpp

@@ -518,12 +518,11 @@ private:
 };
 
 // This DataStoreDBCallback is called when DataStoreDB opens the DataStore DB.
-// Then the first revision will be created if it doesn't exist yet.
+// Then the first revision will be created if it's needed.
 class FirstRevisionIdCallback MOZ_FINAL : public DataStoreDBCallback
-                                        , public nsIDOMEventListener
 {
 public:
-  NS_DECL_ISUPPORTS
+  NS_INLINE_DECL_REFCOUNTING(FirstRevisionIdCallback)
 
   FirstRevisionIdCallback(uint32_t aAppId, const nsAString& aName,
                           const nsAString& aManifestURL)
@@ -536,113 +535,66 @@ public:
   }
 
   void
-  Run(DataStoreDB* aDb, bool aSuccess)
+  Run(DataStoreDB* aDb, RunStatus aStatus)
   {
     AssertIsInMainProcess();
     MOZ_ASSERT(NS_IsMainThread());
     MOZ_ASSERT(aDb);
 
-    if (!aSuccess) {
+    if (aStatus == Error) {
       NS_WARNING("Failed to create the first revision.");
       return;
     }
 
-    mTxn = aDb->Transaction();
-
-    ErrorResult rv;
-    nsRefPtr<IDBObjectStore> store =
-      mTxn->ObjectStore(NS_LITERAL_STRING(DATASTOREDB_REVISION), rv);
-    if (NS_WARN_IF(rv.Failed())) {
-      return;
-    }
-
-    // a Null JSContext is ok because OpenCursor ignores it if the range is
-    // undefined.
-    mRequest = store->OpenCursor(nullptr, JS::UndefinedHandleValue,
-                                 IDBCursorDirection::Prev, rv);
-    if (NS_WARN_IF(rv.Failed())) {
-      return;
-    }
-
-    nsresult res;
-    res = mRequest->EventTarget::AddEventListener(NS_LITERAL_STRING("success"),
-                                                  this, false);
-    if (NS_WARN_IF(NS_FAILED(res))) {
-      return;
-    }
-  }
-
-  // nsIDOMEventListener
-  NS_IMETHOD
-  HandleEvent(nsIDOMEvent* aEvent)
-  {
-    AssertIsInMainProcess();
-    MOZ_ASSERT(NS_IsMainThread());
-
-    nsString type;
-    nsresult rv = aEvent->GetType(type);
-    if (NS_WARN_IF(NS_FAILED(rv))) {
-      return rv;
-    }
-
-    if (!type.EqualsASCII("success")) {
-      return NS_ERROR_FAILURE;
-    }
-
-    mRequest->RemoveEventListener(NS_LITERAL_STRING("success"), this, false);
-
-    // Note: this cx is only used for rooting and AddRevision, neither of which
-    // actually care which compartment we're in.
-    AutoSafeJSContext cx;
-
-    ErrorResult error;
-    JS::Rooted<JS::Value> result(cx);
-    mRequest->GetResult(cx, &result, error);
-    if (NS_WARN_IF(error.Failed())) {
-      return error.ErrorCode();
-    }
-
-    // This means that the content is a IDBCursor, so the first revision already
-    // exists.
-    if (result.isObject()) {
+    if (aStatus == Success) {
       nsRefPtr<DataStoreService> service = DataStoreService::Get();
       MOZ_ASSERT(service);
 
-      return service->EnableDataStore(mAppId, mName, mManifestURL);
+      nsresult rv = service->EnableDataStore(mAppId, mName, mManifestURL);
+      if (NS_FAILED(rv)) {
+        NS_WARNING("Failed to enable a DataStore.");
+      }
+
+      return;
     }
 
-    MOZ_ASSERT(mTxn);
+    // The DB has just been created.
+
+    ErrorResult error;
     nsRefPtr<IDBObjectStore> store =
-      mTxn->ObjectStore(NS_LITERAL_STRING(DATASTOREDB_REVISION), error);
-    if (NS_WARN_IF(error.Failed())) {
-      return error.ErrorCode();
+      aDb->Transaction()->ObjectStore(NS_LITERAL_STRING(DATASTOREDB_REVISION),
+                                      error);
+    if (error.Failed()) {
+      NS_WARNING("Failed to get an ObjectStore object.");
+      return;
     }
     MOZ_ASSERT(store);
 
     nsRefPtr<RevisionAddedEnableStoreCallback> callback =
       new RevisionAddedEnableStoreCallback(mAppId, mName, mManifestURL);
 
+    // Note: this cx is only used for rooting and AddRevision, neither of which
+    // actually care which compartment we're in.
+    AutoSafeJSContext cx;
+
     // If the revision doesn't exist, let's create it.
     nsRefPtr<DataStoreRevision> revision = new DataStoreRevision();
-    return revision->AddRevision(cx, store, 0, DataStoreRevision::RevisionVoid,
-                                 callback);
+    nsresult rv = revision->AddRevision(cx, store, 0,
+                                        DataStoreRevision::RevisionVoid,
+                                        callback);
+    if (NS_FAILED(rv)) {
+      NS_WARNING("Failed to add a revision to a DataStore.");
+    }
   }
 
 private:
   ~FirstRevisionIdCallback() {}
 
-  nsRefPtr<IDBRequest> mRequest;
-
-  nsRefPtr<IDBTransaction> mTxn;
-  nsRefPtr<DataStoreRevision> mRevision;
-
   uint32_t mAppId;
   nsString mName;
   nsString mManifestURL;
 };
 
-NS_IMPL_ISUPPORTS(FirstRevisionIdCallback, nsIDOMEventListener)
-
 // This class calls the 'retrieveRevisionId' method of the DataStore object for
 // any DataStore in the 'mResults' array. When all of them are called, the
 // promise is resolved with 'mResults'.