트랜잭션 적용
트랜잭션 없는 단순한 로직
@RequiredArgsConstructor
public class MemberServiceV1 {
private final MemberRepositoryV1 memberRepository;
public void accountTransfer(String fromId, String toId, int money) throws SQLException {
Member fromMember = memberRepository.findById(fromId);
Member toMember = memberRepository.findById(toId);
memberRepository.update(fromId, fromMember.getMoney() - money);
validation(toMember);
memberRepository.update(toId, toMember.getMoney() + money);
}
private void validation(Member toMember) {
if (toMember.getMemberId().equals("ex")) {
throw new IllegalStateException("이체중 예외 발생");
}
}
}테스트 코드
/**
* 기본 동작, 트랜잭션이 없어서 문제 발생
*/
class MemberServiceV1Test {
static final String MEMBER_A = "memberA";
static final String MEMBER_B = "memberB";
static final String MEMBER_EX = "ex";
private MemberRepositoryV1 memberRepository;
private MemberServiceV1 memberService;
@BeforeEach
void beforeEach() {
DriverManagerDataSource dataSource = new DriverManagerDataSource(URL, USERNAME, PASSWORD);
memberRepository = new MemberRepositoryV1(dataSource);
memberService = new MemberServiceV1(memberRepository);
}
@AfterEach
void afterEach() throws SQLException {
memberRepository.delete(MEMBER_A);
memberRepository.delete(MEMBER_B);
memberRepository.delete(MEMBER_EX);
}
@Test
@DisplayName("정상 이체")
void accountTransfer() throws SQLException {
//given
Member memberA = new Member(MEMBER_A, 10000);
Member memberB = new Member(MEMBER_B, 10000);
memberRepository.save(memberA);
memberRepository.save(memberB);
//when
memberService.accountTransfer(memberA.getMemberId(), memberB.getMemberId(), 2000);
//then
Member findMemberA = memberRepository.findById(memberA.getMemberId());
Member findMemberB = memberRepository.findById(memberB.getMemberId());
assertThat(findMemberA.getMoney()).isEqualTo(8000);
assertThat(findMemberB.getMoney()).isEqualTo(12000);
}
@Test
@DisplayName("이체 중 예외 발생")
void accountTransferEx() throws SQLException {
//given
Member memberA = new Member(MEMBER_A, 10000);
Member memberEx = new Member(MEMBER_EX, 10000);
memberRepository.save(memberA);
memberRepository.save(memberEx);
//when
assertThatThrownBy(() -> memberService.accountTransfer(memberA.getMemberId(), memberEx.getMemberId(), 2000))
.isInstanceOf(IllegalStateException.class);
//then
Member findMemberA = memberRepository.findById(memberA.getMemberId());
Member findMemberB = memberRepository.findById(memberEx.getMemberId());
assertThat(findMemberA.getMoney()).isEqualTo(8000);
assertThat(findMemberB.getMoney()).isEqualTo(10000);
}
}트랜잭션 활용
트랜잭션은 비즈니스 로직이 있는 서비스 계층에서 시작해야 한다. 비즈니스 로직이 잘못 되면 해당 비즈니스 로직으로 인해 문제가 되는 부분을 함께 롤백해야 하기 때문이다.
그런데 트랜잭션을 시작하려면 커넥션이 필요하다. 서비스 계층에서 커넥션을 만들고 트랜잭션 커밋 이후에 커넥션을 종료해야 한다.
애플리케이션에서 DB 트랜잭션을 사용하려면 트랜잭션을 사용하는 동안 같은 커넥션을 유지해야 한다. 그래야 같은 세션을 사용할 수 있다.
같은 커넥션을 유지하는 가장 단순한 방법은 커넥션을 파라미터로 전달해서 같은 커넥션이 사용되도록 유지하는 것이다.
레포지토리
/**
* JDBC - ConnectionParam
*/
@Slf4j
public class MemberRepositoryV2 {
private final DataSource dataSource;
public MemberRepositoryV2(DataSource dataSource) {
this.dataSource = dataSource;
}
public Member save(Member member) throws SQLException {
String sql = "insert into member(member_id, money) values(?, ?)";
Connection con = null;
PreparedStatement pstmt = null;
try {
con = getConnection();
pstmt = con.prepareStatement(sql);
pstmt.setString(1, member.getMemberId());
pstmt.setInt(2, member.getMoney());
pstmt.executeUpdate();
return member;
} catch (SQLException e) {
log.error("db error", e);
throw e;
} finally {
close(con, pstmt, null);
}
}
public Member findById(String memberId) throws SQLException {
String sql = "select * from member where member_Id = ?";
Connection con = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
try {
con = getConnection();
pstmt = con.prepareStatement(sql);
pstmt.setString(1, memberId);
rs = pstmt.executeQuery();
if (rs.next()) {
Member member = new Member();
member.setMemberId(rs.getString("member_id"));
member.setMoney(rs.getInt("money"));
return member;
} else {
throw new NoSuchElementException("member not found memberId=" + memberId);
}
} catch (SQLException e) {
log.error("db error", e);
throw e;
} finally {
close(con, pstmt, rs);
}
}
public Member findById(Connection con, String memberId) throws SQLException {
String sql = "select * from member where member_Id = ?";
PreparedStatement pstmt = null;
ResultSet rs = null;
try {
pstmt = con.prepareStatement(sql);
pstmt.setString(1, memberId);
rs = pstmt.executeQuery();
if (rs.next()) {
Member member = new Member();
member.setMemberId(rs.getString("member_id"));
member.setMoney(rs.getInt("money"));
return member;
} else {
throw new NoSuchElementException("member not found memberId=" + memberId);
}
} catch (SQLException e) {
log.error("db error", e);
throw e;
} finally {
//connection은 여기서 닫지 않는다.
JdbcUtils.closeResultSet(rs);
JdbcUtils.closeStatement(pstmt);
}
}
public void update(String memberId, int money) throws SQLException {
String sql = "update member set money = ? where member_id = ?";
Connection con = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
try {
con = getConnection();
pstmt = con.prepareStatement(sql);
pstmt.setInt(1,money);
pstmt.setString(2, memberId);
int resultSize = pstmt.executeUpdate();
log.info("resultSize={}", resultSize);
} catch (SQLException e) {
log.error("db error", e);
throw e;
} finally {
close(con, pstmt, rs);
}
}
public void update(Connection con, String memberId, int money) throws SQLException {
String sql = "update member set money = ? where member_id = ?";
PreparedStatement pstmt = null;
try {
pstmt = con.prepareStatement(sql);
pstmt.setInt(1,money);
pstmt.setString(2, memberId);
int resultSize = pstmt.executeUpdate();
log.info("resultSize={}", resultSize);
} catch (SQLException e) {
log.error("db error", e);
throw e;
} finally {
JdbcUtils.closeStatement(pstmt);
}
}
public void delete(String memberId) throws SQLException {
String sql = "delete from member where member_id = ?";
Connection con = null;
PreparedStatement pstmt = null;
try {
con = getConnection();
pstmt = con.prepareStatement(sql);
pstmt.setString(1, memberId);
pstmt.executeUpdate();
} catch (SQLException e) {
log.error("db error", e);
throw e;
} finally {
close(con, pstmt, null);
}
}
private void close(Connection con, Statement stmt, ResultSet rs) {
JdbcUtils.closeResultSet(rs);
JdbcUtils.closeStatement(stmt);
JdbcUtils.closeConnection(con);
}
private Connection getConnection() throws SQLException {
Connection con = dataSource.getConnection();
log.info("get connection={}, class={}", con, con.getClass());
return con;
}
}커넥션 유지가 필요한 두 메서드가 추가되었다. 계좌이체 서비스 로직에서 호출하는 메서드이다.
findById(Connection con, String memberId)update(Connection con, String memberId, int money)
커넥션 유지가 필요한 두 메서드는 파라미터로 넘어온 커넥션을 사용해야 하기에
getConnection()코드가 있으면 안 된다.그리고 레포지토리에서 커넥션을 닫으면 안 된다. 커넥션을 전달 받은 레포지토리 뿐만 아니라 이후에도 커넥션을 계속 이어서 사용하기 때문에 이후 서비스 로직이 끝날 때 트랜잭션을 종료하고 닫아야 한다.
서비스 로직
/**
* 트랜잭션 - 파라미터를 연동, 풀을 고려한 종료
*/
@Slf4j
@RequiredArgsConstructor
public class MemberServiceV2 {
private final DataSource dataSource;
private final MemberRepositoryV2 memberRepository;
public void accountTransfer(String fromId, String toId, int money) throws SQLException {
//서비스 계층에서 커넥션 획득
Connection con = dataSource.getConnection();
try {
// 수동 커밋 모드 변경 = 트랜잭션 시작
con.setAutoCommit(false);
// 비즈니스 로직 시작 (커넥션 전달)
bisLogic(con, fromId, toId, money);
// 성공 시 커밋
con.commit();
}
catch (Exception e) {
con.rollback(); // 실패 시 롤백
throw new IllegalStateException(e);
} finally {
release(con);
}
}
private void bisLogic(Connection con, String fromId, String toId, int money) throws SQLException {
Member fromMember = memberRepository.findById(con, fromId);
Member toMember = memberRepository.findById(con, toId);
memberRepository.update(con, fromId, fromMember.getMoney() - money);
validation(toMember);
memberRepository.update(con, toId, toMember.getMoney() + money);
}
private void validation(Member toMember) {
if (toMember.getMemberId().equals("ex")) {
throw new IllegalStateException("이체중 예외 발생");
}
}
private void release(Connection con) {
if (con != null) {
try {
con.setAutoCommit(true); // 커넥션 풀 고려, 풀에 반납하기 전에 기본 값인 자동 커밋 모드로 변경해주는 것이 안전하다.
con.close();
} catch (Exception e) {
log.info("error", e);
}
}
}
}테스트 코드
/**
* 트랜잭션 - 커넥션 파라미터 전달 방식 동기화
*/
@Slf4j
class MemberServiceV2Test {
public static final String MEMBER_A = "memberA";
public static final String MEMBER_B = "memberB";
public static final String MEMBER_EX = "ex";
private MemberRepositoryV2 memberRepository;
private MemberServiceV2 memberService;
@BeforeEach
void beforeEach() {
DriverManagerDataSource dataSource = new DriverManagerDataSource(URL, USERNAME, PASSWORD);
memberRepository = new MemberRepositoryV2(dataSource);
memberService = new MemberServiceV2(dataSource , memberRepository);
}
@AfterEach
void afterEach() throws SQLException {
memberRepository.delete(MEMBER_A);
memberRepository.delete(MEMBER_B);
memberRepository.delete(MEMBER_EX);
}
@Test
@DisplayName("정상 이체")
void accountTransfer() throws SQLException {
//given
Member memberA = new Member(MEMBER_A, 10000);
Member memberB = new Member(MEMBER_B, 10000);
memberRepository.save(memberA);
memberRepository.save(memberB);
//when
log.info("START TX");
memberService.accountTransfer(memberA.getMemberId(), memberB.getMemberId(), 2000);
log.info("END TX");
//then
Member findMemberA = memberRepository.findById(memberA.getMemberId());
Member findMemberB = memberRepository.findById(memberB.getMemberId());
assertThat(findMemberA.getMoney()).isEqualTo(8000);
assertThat(findMemberB.getMoney()).isEqualTo(12000);
}
@Test
@DisplayName("이체 중 예외 발생")
void accountTransferEx() throws SQLException {
//given
Member memberA = new Member(MEMBER_A, 10000);
Member memberEx = new Member(MEMBER_EX, 10000);
memberRepository.save(memberA);
memberRepository.save(memberEx);
//when
assertThatThrownBy(() -> memberService.accountTransfer(memberA.getMemberId(), memberEx.getMemberId(), 2000))
.isInstanceOf(IllegalStateException.class);
//then
Member findMemberA = memberRepository.findById(memberA.getMemberId());
Member findMemberB = memberRepository.findById(memberEx.getMemberId());
assertThat(findMemberA.getMoney()).isEqualTo(10000);
assertThat(findMemberB.getMoney()).isEqualTo(10000);
}
}Last updated