log_entry.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 "storage/clog/log_module.h"
#include "common/lang/vector.h"
#include "common/lang/string.h"
#include "common/lang/memory.h"
 
struct LogHeader final
{
  LSN     lsn;        
  int32_t size;       
  int32_t module_id;  
 
  static const int32_t SIZE;  
 
  string to_string() const;
};
 
class LogEntry
{
public:
  LogEntry();
  ~LogEntry() = default;
 
  LogEntry(LogEntry &&other);
 
  LogEntry &operator=(LogEntry &&other);
 
  LogEntry(const LogEntry &)            = delete;
  LogEntry &operator=(const LogEntry &) = delete;
 
public:
  static int32_t max_size() { return 4 * 1024 * 1024; }
  static int32_t max_payload_size() { return max_size() - LogHeader::SIZE; }
 
public:
  RC init(LSN lsn, LogModule::Id module_id, vector<char> &&data);
  RC init(LSN lsn, LogModule module, vector<char> &&data);
 
  const LogHeader &header() const { return header_; }
  const char      *data() const { return data_.data(); }
  int32_t          payload_size() const { return header_.size; }
  int32_t          total_size() const { return LogHeader::SIZE + header_.size; }
 
  void set_lsn(LSN lsn) { header_.lsn = lsn; }
 
  LSN       lsn() const { return header_.lsn; }
  LogModule module() const { return LogModule(header_.module_id); }
 
public:
  string to_string() const;
 
private:
  LogHeader    header_;  
  vector<char> data_;    
};