MySQL 레플리케이션과 스프링부트 DataSource 라우팅을 통한 쿼리 성능개선

spring:
  datasource:
    master:
      username: haon
      password: password
      driver-class-name: com.mysql.cj.jdbc.Driver
      jdbc-url: jdbc:mysql://111.111.111:.11:3306/replication
    slave:
      username: haon
      password: password
      driver-class-name: com.mysql.cj.jdbc.Driver
      jdbc-url: jdbc:mysql://222.222.222.22:3306/replication

  mvc:
    pathmatch:
      matching-strategy: ant_path_matcher

  jpa:
    database-platform: org.hibernate.dialect.MySQLDialect
    open:
    open-in-view: false
    show-sql: true
  sql:
    init:
      platform: mysql

@Configuration
public class DataSourceConfig {
    private static final String master = "master";
    private static final String slave = "slave";

    @Bean @Qualifier(master)
    @ConfigurationProperties(prefix = "spring.datasource.master")
    public DataSource masterDataSource(){
        return DataSourceBuilder.create().build();
    }

    @Bean @Qualifier(slave)
    @ConfigurationProperties(prefix = "spring.datasource.slave")
    public DataSource slaveDataSource(){
        return DataSourceBuilder.create().build();
    }

    @Bean
    public DataSource routingDataSource(
            @Qualifier(master) DataSource masterDataSource,
            @Qualifier(slave) DataSource slaveDataSource){
        RoutingDataSource routingDataSource = new RoutingDataSource(); // 쿼리 요청을 적절한 서버로 분기할 때 활용됨

        HashMap<Object, Object> targetDataSourceMap = new HashMap<>();

        // targetDataSourceMap 객체에 분기할 서버들의 DataSource 빈을 저장
        targetDataSourceMap.put("master", masterDataSource);
        targetDataSourceMap.put("slave", slaveDataSource);

        routingDataSource.setTargetDataSources(targetDataSourceMap); // DataSource 타깃을 설정한다.
        routingDataSource.setDefaultTargetDataSource(masterDataSource);

        return routingDataSource;
    }

    @Bean
    @Primary
    public DataSource dataSource(){
        DataSource determinedDataSource = routingDataSource(masterDataSource(), slaveDataSource());
        return new LazyConnectionDataSourceProxy(determinedDataSource);
    }
}

private static final String master = "master";
private static final String slave = "slave";

@Bean @Qualifier(master)
@ConfigurationProperties(prefix = "spring.datasource.master")
public DataSource masterDataSource(){
	return DataSourceBuilder.create().build();
}

@Bean @Qualifier(slave)
@ConfigurationProperties(prefix = "spring.datasource.slave")
public DataSource slaveDataSource(){
	return DataSourceBuilder.create().build();
}

//  AbstractRoutingDataSource : Multi DataSource 환경에서 여러 DataSource 를 묶고 분기해줄 때 사용한다.
public class RoutingDataSource extends AbstractRoutingDataSource {
    // determineCurrentLookupKey 메소드 : 여러 datasource 중에서 실제로 사용될 DataSource 를 결정하는 역할
    // 현재 트랜잭션의 속성에 따라 targetDataSourceMap 의 조회 Key 를 결정하기위해 AbstractRoutingDataSource 를 상속받아서 determineCurrentLookupKey 를 구현했다.
    @Override
    protected Object determineCurrentLookupKey() {
        boolean isReadOnly = TransactionSynchronizationManager.isCurrentTransactionReadOnly();
        logger.info("현재 트랜잭션 속성이 ReadOnly인가?:" + isReadOnly);
        return isReadOnly ? "slave" : "master";
    }
}

@Bean
public DataSource routingDataSource(
		@Qualifier(master) DataSource masterDataSource,
		@Qualifier(slave) DataSource slaveDataSource) {

   RoutingDataSource routingDataSource = new RoutingDataSource(); // 쿼리 요청을 적절한 서버로 분기할 때 활용됨
   HashMap<Object, Object> targetDataSourceMap = new HashMap<>();

   // targetDataSourceMap 객체에 분기할 서버들의 DataSource 빈을 저장
   targetDataSourceMap.put("master", masterDataSource);
   targetDataSourceMap.put("slave", slaveDataSource);

   routingDataSource.setTargetDataSources(targetDataSourceMap); // DataSource 타깃을 설정한다.
   routingDataSource.setDefaultTargetDataSource(masterDataSource);

	return routingDataSource;
}

@Bean
@Primary
public DataSource dataSource(){
	DataSource determinedDataSource = routingDataSource(masterDataSource(), slaveDataSource());
	return new LazyConnectionDataSourceProxy(determinedDataSource);
}

@Entity
@AllArgsConstructor @NoArgsConstructor
@Getter @Setter
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private Long age;

    public User(String name, Long age){
        this.name = name;
        this.age = age;
    }
}

@RestController
public class UserController {
    private final UserService userService;

    @Autowired
    public UserController(UserService userService){
        this.userService = userService;
    }

    @GetMapping("/user/{age}")
    public ResponseEntity<List<User>> getUserInfo(@PathVariable("age") Long age){
        return ResponseEntity.ok(userService.getUserInfo(age));
    }

    @PostMapping("/user")
    public ResponseEntity<String> createUser() {
        userService.createUser();
        return ResponseEntity.ok("회원가입에 성공했습니다.");
    }
}

@Service
public class UserService {
    private final UserRepository userRepository;

    @Autowired
    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @Transactional(readOnly = true)
    List<User> getUserInfo(Long age){
        List<User> user_list = userRepository.findAllByAge(age);
        return user_list;
    }

    @Transactional
    public void createUser(){
        String random_name = UUID.randomUUID().toString();
        Random random = new Random();
        Long random_age = Math.abs(random.nextLong()) % 99 + 1;

        User user = new User(random_name, random_age);
        userRepository.save(user);
    }
}

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    List<User> findAllByAge(Long age);
}