Implementation of OnDiskAttachmentStore.

sync/internal_api/public/attachments/on_disk_attachment_store.h

 // Copyright 2014 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 SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_IN_MEMORY_ATTACHMENT_STORE_H_
-#define SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_IN_MEMORY_ATTACHMENT_STORE_H_
+#ifndef SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_ON_DISK_ATTACHMENT_STORE_H_
+#define SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_ON_DISK_ATTACHMENT_STORE_H_
 
+#include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
-#include "base/single_thread_task_runner.h"
 #include "base/threading/non_thread_safe.h"
 #include "sync/api/attachments/attachment.h"
 #include "sync/api/attachments/attachment_id.h"
 #include "sync/api/attachments/attachment_store.h"
 #include "sync/base/sync_export.h"
 
+namespace base {
+class SequencedTaskRunner;
+}  // namespace base
+
+namespace leveldb {
+class DB;
+}  // namespace leveldb
+
 namespace syncer {
 
-// An in-memory implementation of AttachmentStore used for testing.
-// InMemoryAttachmentStore is not threadsafe, it lives on backend thread and
-// posts callbacks with results on |callback_task_runner|.
-class SYNC_EXPORT InMemoryAttachmentStore : public AttachmentStoreBase,
-                                            public base::NonThreadSafe {
+// On-disk implementation of AttachmentStore. Stores attachments in leveldb
+// database in |path| directory.
+class SYNC_EXPORT OnDiskAttachmentStore : public AttachmentStoreBase,
+                                          public base::NonThreadSafe {
  public:
-  InMemoryAttachmentStore(
-      const scoped_refptr<base::SingleThreadTaskRunner>& callback_task_runner);
-  virtual ~InMemoryAttachmentStore();
+  // Constructs attachment store.
+  OnDiskAttachmentStore(
+      const scoped_refptr<base::SequencedTaskRunner>& callback_task_runner);
+  virtual ~OnDiskAttachmentStore();
 
   // AttachmentStoreBase implementation.
+  // Load opens database, creating it if needed. In the future upgrade code will
+  // be invoked from Load as well. If loading fails it posts |callback| with
+  // UNSPECIFIED_ERROR.
   virtual void Read(const AttachmentIdList& ids,
                     const ReadCallback& callback) override;
   virtual void Write(const AttachmentList& attachments,
                      const WriteCallback& callback) override;
   virtual void Drop(const AttachmentIdList& ids,
                     const DropCallback& callback) override;
 
+  // Opens leveldb database at |path|. It will create directory and database if
+  // it doesn't exist.
+  Result OpenOrCreate(const base::FilePath& path);
+
  private:
-  scoped_refptr<base::SingleThreadTaskRunner> callback_task_runner_;
-  AttachmentMap attachments_;
+  std::string CreateDataKeyFromAttachmentId(const AttachmentId& attachment_id);
+
+  scoped_refptr<base::SequencedTaskRunner> callback_task_runner_;
+  scoped_ptr<leveldb::DB> db_;
 };
 
 }  // namespace syncer
 
-#endif  // SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_IN_MEMORY_ATTACHMENT_STORE_H_
+#endif  // SYNC_INTERNAL_API_PUBLIC_ATTACHMENTS_ON_DISK_ATTACHMENT_STORE_H_