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 IDBKey;
+class IDBRequest;
+class IDBValue;
+class WebIDBCursor;
+
+// Loads IndexedDB values that have been wrapped in Blobs by IDBValueWrapper.
+class IDBRequestLoader : public GarbageCollectedFinalized<IDBRequestLoader>,
+                         public FileReaderLoaderClient {
+ public:
+  // Creates a reader that will unwrap IDBValues received by a IDBRequest.
+  IDBRequestLoader(IDBRequest*);
+
+  ~IDBRequestLoader() override;
+
+  static bool NeedsUnwrapping(IDBValue*);
+  static bool NeedUnwrapping(const Vector<RefPtr<IDBValue>>&);
+
+  // Start unwrapping values.
+  //
+  // Exactly one of these methods should be called for a reader.
+  void Start(PassRefPtr<IDBValue>);
+  void Start(const Vector<RefPtr<IDBValue>>&);
+  void Start(IDBKey*, IDBKey* primary_key, PassRefPtr<IDBValue>);
+  void Start(std::unique_ptr<WebIDBCursor> backend,
+             IDBKey*,
+             IDBKey* primary_key,
+             PassRefPtr<IDBValue>);
+
+  // 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(request_);
+    visitor->Trace(key_);
+    visitor->Trace(primary_key_);
+  }
+
+ private:
+  // The IDBRequest callback that will be called by this reader.
+  enum Mode {
+    kUninitialized = 0,
+    kValue,
+    kValueArray,
+    kKeyPrimaryKeyValue,
+    kBackendKeyPrimaryKeyValue,
+  };
+
+  // Starts unwrapping the next wrapped IDBValue.
+  //
+  // If no more wrapped IDBValues are found, this calls the IDBRequest
+  // callbacks.
+  void StartNextValue();
+
+  void ReportSuccess();
+  void ReportError();
+
+  // The IDBRequest callback that will be called by this reader.
+  Mode mode_;
+
+  std::unique_ptr<FileReaderLoader> loader_;
+
+  // The IDBRequest whose IDBValues are unwrapped by this reader.
+  Member<IDBRequest> request_;
+
+  // All the values that will be passed back to the IDBRequest.
+  Vector<RefPtr<IDBValue>> values_;
+
+  // The key argument to the IDBRequest callback.
+  //
+  // Only used if mode_ is kKeyPrimaryKeyValue.
+  Member<IDBKey> key_;
+
+  // The primary_key argument to the IDBRequest callback.
+  //
+  // Only used if mode_ is kKeyPrimaryKeyValue.
+  Member<IDBKey> primary_key_;
+
+  // The backend argument to the IDBRequest callback.
+  std::unique_ptr<WebIDBCursor> backend_;
+
+  // Indexes of the IDBValues in values_ that have been wrapped in Blobs.
+  Vector<unsigned> wrapped_value_indexes_;
+
+  // 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