Make "Table" pluggable

Summary: This patch makes Table and TableBuilder a abstract class and make all the implementation of the current table into BlockedBasedTable and BlockedBasedTable Builder.

Test Plan: Make db_test.cc to work with block based table. Add a new test simple_table_db_test.cc where a different simple table format is implemented.

Reviewers: dhruba, haobo, kailiu, emayanke, vamsi

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D13521

table/block_based_table_factory.cc

@@ -0,0 +1,36 @@
+//  Copyright (c) 2013, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+
+#include "table/block_based_table_factory.h"
+
+#include <memory>
+#include <stdint.h>
+#include "table/block_based_table_builder.h"
+#include "table/block_based_table.h"
+#include "port/port.h"
+
+namespace rocksdb {
+
+Status BlockBasedTableFactory::OpenTable(const Options& options,
+                                         const EnvOptions& soptions,
+                                         unique_ptr<RandomAccessFile> && file,
+                                         uint64_t file_size,
+                                         unique_ptr<Table>* table) const {
+
+  return BlockBasedTable::Open(options, soptions, std::move(file), file_size,
+                            table);
+}
+
+TableBuilder* BlockBasedTableFactory::GetTableBuilder(
+    const Options& options, WritableFile* file, int level,
+    const bool enable_compression) const {
+  return new BlockBasedTableBuilder(options, file, level, enable_compression);
+}
+}  // namespace rocksdb