record_manager.h

 
/* Copyright (c) 2021 Xie Meiyi(xiemeiyi@hust.edu.cn) and 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 Meiyi & Longda on 2021/4/13.
//
#pragma once
 
#include <sstream>
#include <limits>
#include "storage/buffer/disk_buffer_pool.h"
#include "storage/trx/latch_memo.h"
#include "storage/record/record.h"
#include "common/lang/bitmap.h"
 
class ConditionFilter;
class RecordPageHandler;
class Trx;
class Table;
 
struct PageHeader
{
  int32_t record_num;           
  int32_t record_real_size;     
  int32_t record_size;          
  int32_t record_capacity;      
  int32_t first_record_offset;  
};
 
class RecordPageIterator
{
public:
  RecordPageIterator();
  ~RecordPageIterator();
 
  void init(RecordPageHandler &record_page_handler, SlotNum start_slot_num = 0);
 
  bool has_next();
 
  RC   next(Record &record);
 
  bool is_valid() const { return record_page_handler_ != nullptr; }
 
private:
  RecordPageHandler *record_page_handler_ = nullptr;
  PageNum            page_num_            = BP_INVALID_PAGE_NUM;
  common::Bitmap     bitmap_;             
  SlotNum            next_slot_num_ = 0;  
};
 
class RecordPageHandler
{
public:
  RecordPageHandler() = default;
  ~RecordPageHandler();
 
  RC init(DiskBufferPool &buffer_pool, PageNum page_num, bool readonly);
 
  RC recover_init(DiskBufferPool &buffer_pool, PageNum page_num);
 
  RC init_empty_page(DiskBufferPool &buffer_pool, PageNum page_num, int record_size);
 
  RC cleanup();
 
  RC insert_record(const char *data, RID *rid);
 
  RC recover_insert_record(const char *data, const RID &rid);
 
  RC delete_record(const RID *rid);
 
  RC get_record(const RID *rid, Record *rec);
 
  PageNum get_page_num() const;
 
  bool is_full() const;
 
protected:
  void fix_record_capacity() {
    int32_t last_record_offset = page_header_->first_record_offset + 
                                 page_header_->record_capacity * page_header_->record_size;
    while(last_record_offset > BP_PAGE_DATA_SIZE) {
      page_header_->record_capacity -= 1;
      last_record_offset -= page_header_->record_size;
    }
  }
 
  char *get_record_data(SlotNum slot_num)
  {
    return frame_->data() + page_header_->first_record_offset + (page_header_->record_size * slot_num);
  }
 
protected:
  DiskBufferPool *disk_buffer_pool_ = nullptr;  
  Frame          *frame_            = nullptr;  
  bool            readonly_         = false;    
  PageHeader     *page_header_      = nullptr;  
  char           *bitmap_           = nullptr;  
 
private:
  friend class RecordPageIterator;
};
 
class RecordFileHandler
{
public:
  RecordFileHandler() = default;
  ~RecordFileHandler();
 
  RC init(DiskBufferPool *buffer_pool);
 
  void close();
 
  RC delete_record(const RID *rid);
 
  RC insert_record(const char *data, int record_size, RID *rid);
 
  RC recover_insert_record(const char *data, int record_size, const RID &rid);
 
  RC get_record(RecordPageHandler &page_handler, const RID *rid, bool readonly, Record *rec);
 
  RC visit_record(const RID &rid, bool readonly, std::function<void(Record &)> visitor);
 
private:
  RC init_free_pages();
 
private:
  DiskBufferPool             *disk_buffer_pool_ = nullptr;
  std::unordered_set<PageNum> free_pages_;  
  common::Mutex               lock_;        
};
 
class RecordFileScanner
{
public:
  RecordFileScanner() = default;
  ~RecordFileScanner();
 
  RC open_scan(Table *table, DiskBufferPool &buffer_pool, Trx *trx, bool readonly, ConditionFilter *condition_filter);
 
  RC close_scan();
 
  bool has_next();
 
  RC   next(Record &record);
 
private:
  RC fetch_next_record();
 
  RC fetch_next_record_in_page();
 
private:
  // TODO 对于一个纯粹的record遍历器来说，不应该关心表和事务
  Table             *table_            = nullptr;  
  DiskBufferPool    *disk_buffer_pool_ = nullptr;  
  Trx               *trx_              = nullptr;  
  bool               readonly_         = false;    
 
  BufferPoolIterator bp_iterator_;                 
  ConditionFilter   *condition_filter_ = nullptr;  
  RecordPageHandler  record_page_handler_;         
  RecordPageIterator record_page_iterator_;        
  Record             next_record_;                 
};