Wrap large IndexedDB values into Blobs before writing to LevelDB.

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

+// Copyright 2017 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 IDBRequestLoader_h
+#define IDBRequestLoader_h
+
+#include "core/fileapi/FileReaderLoaderClient.h"
+#include "platform/heap/Handle.h"
+#include "platform/wtf/PassRefPtr.h"
+#include "platform/wtf/RefPtr.h"
+#include "platform/wtf/Vector.h"
+
+#include <memory>
+
+namespace blink {
+
+class FileReaderLoader;
+class IDBRequestQueueItem;
+class IDBRequest;
+class IDBValue;
+
+// Loads IndexedDB values that have been wrapped in Blobs by IDBValueWrapper.
+class IDBRequestLoader : public GarbageCollectedFinalized<IDBRequestLoader>,
+                         public FileReaderLoaderClient {
+ public:
+  // Creates a loader that will unwrap IDBValues received by a IDBRequest.
+  //
+  // result_values must be kept alive until the loader calls
+  // IDBRequestQueueItem::MarkReady().
+  IDBRequestLoader(IDBRequestQueueItem*,
+                   Vector<RefPtr<IDBValue>>* result_values);
+
+  ~IDBRequestLoader() override;
+
+  static bool NeedsUnwrapping(IDBValue*);
+  static bool NeedUnwrapping(const Vector<RefPtr<IDBValue>>&);
+
+  // Start unwrapping values.
+  //
+  // When the unwrapping completes, the loader will call MarkReady() on the
+  // request queue item.
+  void Start();
+
+  // FileReaderLoaderClient implementaton.
+  void DidStartLoading() override;
+  void DidReceiveDataForClient(const char* data, unsigned data_length) override;
+  void DidFinishLoading() override;
+  void DidFail(FileError::ErrorCode) override;
+
+  DEFINE_INLINE_TRACE() { visitor->Trace(queue_item_); }
+
+ private:
+  // Starts unwrapping the next wrapped IDBValue.
+  //
+  // If no more wrapped IDBValues are found, this calls the IDBRequest
+  // callbacks.
+  void StartNextValue();
+
+  void ReportSuccess();
+  void ReportError();
+
+  std::unique_ptr<FileReaderLoader> loader_;
+
+  // Transaction result queue item for the IDBRequest.
+  Member<IDBRequestQueueItem> queue_item_;
+
+  // All the values that will be passed back to the IDBRequest.
+  Vector<RefPtr<IDBValue>>* const values_;
+
+  // Buffer used to unwrap an IDBValue.
+  Vector<char> wrapped_data_;
+
+  // The value being currently unwrapped.
+  Vector<RefPtr<IDBValue>>::iterator current_value_;
+};
+
+}  // namespace blink
+
+#endif  // IDBRequestLoader_h