ob_lsm_iterator.h

/* Copyright (c) 2021 OceanBase and/or its affiliates. All rights reserved.
miniob is licensed under Mulan PSL v2.
You can use this software according to the terms and conditions of the Mulan PSL v2.
You may obtain a copy of Mulan PSL v2 at:
         http://license.coscl.org.cn/MulanPSL2
THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
See the Mulan PSL v2 for more details. */
 
// 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.
//
// An iterator yields a sequence of key/value pairs from a source.
// The following class defines the interface.  Multiple implementations
// are provided by this library.  In particular, iterators are provided
// to access the contents of a Table or a DB.
//
// Multiple threads can invoke const methods on an ObLsmIterator without
// external synchronization, but if any of the threads may call a
// non-const method, all threads accessing the same ObLsmIterator must use
// external synchronization.
 
#pragma once
 
#include "common/lang/string_view.h"
#include "common/sys/rc.h"
 
namespace oceanbase {
 
class ObLsmIterator
{
public:
  ObLsmIterator(){};
 
  ObLsmIterator(const ObLsmIterator &) = delete;
 
  ObLsmIterator &operator=(const ObLsmIterator &) = delete;
 
  virtual ~ObLsmIterator(){};
 
  virtual bool valid() const = 0;
 
  virtual void next() = 0;
 
  virtual string_view key() const = 0;
 
  virtual string_view value() const = 0;
 
  virtual void seek(const string_view &k) = 0;
 
  virtual void seek_to_first() = 0;
 
  virtual void seek_to_last() = 0;
};
 
}  // namespace oceanbase