record.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. */
 
//
// Created by Wangyunlai on 2022/5/4.
//
 
#pragma once
 
#include <stddef.h>
 
#include "common/log/log.h"
#include "common/sys/rc.h"
#include "common/types.h"
#include "common/lang/vector.h"
#include "common/lang/sstream.h"
#include "common/lang/limits.h"
#include "storage/field/field_meta.h"
#include "storage/index/index_meta.h"
 
class Field;
 
struct RID
{
  PageNum page_num;  // record's page number
  SlotNum slot_num;  // record's slot number
 
  RID() = default;
  RID(const PageNum _page_num, const SlotNum _slot_num) : page_num(_page_num), slot_num(_slot_num) {}
 
  const string to_string() const
  {
    stringstream ss;
    ss << "PageNum:" << page_num << ", SlotNum:" << slot_num;
    return ss.str();
  }
 
  bool operator==(const RID &other) const { return page_num == other.page_num && slot_num == other.slot_num; }
 
  bool operator!=(const RID &other) const { return !(*this == other); }
 
  static int compare(const RID *rid1, const RID *rid2)
  {
    int page_diff = rid1->page_num - rid2->page_num;
    if (page_diff != 0) {
      return page_diff;
    } else {
      return rid1->slot_num - rid2->slot_num;
    }
  }
 
  static RID *min()
  {
    static RID rid{0, 0};
    return &rid;
  }
 
  static RID *max()
  {
    static RID rid{numeric_limits<PageNum>::max(), numeric_limits<SlotNum>::max()};
    return &rid;
  }
};
 
struct RIDHash
{
  size_t operator()(const RID &rid) const noexcept
  {
    return hash<PageNum>()(rid.page_num) ^ hash<SlotNum>()(rid.slot_num);
  }
};
 
class Record
{
public:
  Record() = default;
  ~Record()
  {
    if (owner_ && data_ != nullptr) {
      free(data_);
      data_ = nullptr;
    }
  }
 
  Record(const Record &other)
  {
    rid_   = other.rid_;
    data_  = other.data_;
    len_   = other.len_;
    owner_ = other.owner_;
 
    if (other.owner_) {
      char *tmp = (char *)malloc(other.len_);
      ASSERT(nullptr != tmp, "failed to allocate memory. size=%d", other.len_);
      memcpy(tmp, other.data_, other.len_);
      data_ = tmp;
    }
  }
 
  Record &operator=(const Record &other)
  {
    if (this == &other) {
      return *this;
    }
 
    if (!owner_ || len_ != other.len_) {
      this->~Record();
      new (this) Record(other);
      return *this;
    }
    this->rid_ = other.rid_;
    memcpy(data_, other.data_, other.len_);
    return *this;
  }
 
  Record(Record &&other)
  {
    rid_ = other.rid_;
 
    if (!other.owner_) {
      data_        = other.data_;
      len_         = other.len_;
      other.data_  = nullptr;
      other.len_   = 0;
      this->owner_ = false;
    } else {
      data_        = other.data_;
      len_         = other.len_;
      other.data_  = nullptr;
      other.len_   = 0;
      this->owner_ = true;
    }
  }
 
  Record &operator=(Record &&other)
  {
    if (this == &other) {
      return *this;
    }
 
    this->~Record();
    new (this) Record(std::move(other));
    return *this;
  }
 
  void set_data(char *data, int len = 0)
  {
    this->data_ = data;
    this->len_  = len;
  }
  void set_data_owner(char *data, int len)
  {
    ASSERT(len != 0, "the len of data should not be 0");
    this->~Record();
 
    this->data_  = data;
    this->len_   = len;
    this->owner_ = true;
  }
 
  RC copy_data(const char *data, int len)
  {
    ASSERT(len!= 0, "the len of data should not be 0");
    char *tmp = (char *)malloc(len);
    if (nullptr == tmp) {
      LOG_WARN("failed to allocate memory. size=%d", len);
      return RC::NOMEM;
    }
 
    memcpy(tmp, data, len);
    set_data_owner(tmp, len);
    return RC::SUCCESS;
  }
 
  RC new_record(int len)
  {
    ASSERT(len!= 0, "the len of data should not be 0");
    char *tmp = (char *)malloc(len);
    if (nullptr == tmp) {
      LOG_WARN("failed to allocate memory. size=%d", len);
      return RC::NOMEM;
    }
    set_data_owner(tmp, len);
    return RC::SUCCESS;
  }
 
  RC set_field(int field_offset, int field_len, char *data)
  {
    if (!owner_) {
      LOG_ERROR("cannot set field when record does not own the memory");
      return RC::INTERNAL;
    }
    if (field_offset + field_len > len_) {
      LOG_ERROR("invalid offset or length. offset=%d, length=%d, total length=%d", field_offset, field_len, len_);
      return RC::INVALID_ARGUMENT;
    }
 
    memcpy(data_ + field_offset, data, field_len);
    return RC::SUCCESS;
  }
 
  char       *data() { return this->data_; }
  const char *data() const { return this->data_; }
  int         len() const { return this->len_; }
 
  void set_rid(const RID &rid) { this->rid_ = rid; }
  void set_rid(const PageNum page_num, const SlotNum slot_num)
  {
    this->rid_.page_num = page_num;
    this->rid_.slot_num = slot_num;
  }
  RID       &rid() { return rid_; }
  const RID &rid() const { return rid_; }
 
private:
  RID rid_;
 
  char *data_  = nullptr;
  int   len_   = 0;      
  bool  owner_ = false;  
};