log_file.h

/* Copyright (c) 2021-2022 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. */
 
//
// Created by wangyunlai on 2024/01/30
//
 
#pragma once
 
#include "common/sys/rc.h"
#include "common/types.h"
#include "common/lang/map.h"
#include "common/lang/functional.h"
#include "common/lang/filesystem.h"
#include "common/lang/fstream.h"
#include "common/lang/string.h"
 
class LogEntry;
 
class LogFileReader
{
public:
  LogFileReader()  = default;
  ~LogFileReader() = default;
 
  RC open(const char *filename);
  RC close();
 
  RC iterate(function<RC(LogEntry &)> callback, LSN start_lsn = 0);
 
private:
  RC skip_to(LSN start_lsn);
 
private:
  int    fd_ = -1;
  string filename_;
};
 
class LogFileWriter
{
public:
  LogFileWriter() = default;
  ~LogFileWriter();
 
  RC open(const char *filename, int end_lsn);
 
  RC close();
 
  RC write(LogEntry &entry);
 
  bool valid() const;
 
  bool full() const;
 
  string to_string() const;
 
  const char *filename() const { return filename_.c_str(); }
 
private:
  string filename_;       
  int    fd_       = -1;  
  int    last_lsn_ = 0;   
  int    end_lsn_  = 0;   
};
 
class LogFileManager
{
public:
  LogFileManager()  = default;
  ~LogFileManager() = default;
 
  RC init(const char *directory, int max_entry_number_per_file);
 
  RC list_files(vector<string> &files, LSN start_lsn);
 
  RC last_file(LogFileWriter &file_writer);
 
  RC next_file(LogFileWriter &file_writer);
 
private:
  static RC get_lsn_from_filename(const string &filename, LSN &lsn);
 
private:
  static constexpr const char *file_prefix_ = "clog_";
  static constexpr const char *file_suffix_ = ".log";
 
  filesystem::path directory_;                  
  int              max_entry_number_per_file_;  
 
  map<LSN, filesystem::path> log_files_;  
};