[JDBC 라이브러리 구현하기 - 4단계] 다즐(최우창) 미션 제출합니다. (#566)

* feat: 트랜잭션 서비스 추상화

* feat: TransactionSynchronizationManager 적용

* feat: TransactionSynchronizationManager 사용하도록 수정

* test: UserService 트랜잭션 테스트

app/src/main/java/com/techcourse/service/AppUserService.java

@@ -0,0 +1,35 @@
+package com.techcourse.service;
+
+import com.techcourse.dao.UserDao;
+import com.techcourse.dao.UserHistoryDao;
+import com.techcourse.domain.User;
+import com.techcourse.domain.UserHistory;
+
+public class AppUserService implements UserService {
+
+    private final UserDao userDao;
+    private final UserHistoryDao userHistoryDao;
+
+    public AppUserService(UserDao userDao, UserHistoryDao userHistoryDao) {
+        this.userDao = userDao;
+        this.userHistoryDao = userHistoryDao;
+    }
+
+    @Override
+    public User findById(long id) {
+        return userDao.findById(id);
+    }
+
+    @Override
+    public void insert(User user) {
+        userDao.insert(user);
+    }
+
+    @Override
+    public void changePassword(long id, String newPassword, String createBy) {
+        var user = findById(id);
+        user.changePassword(newPassword);
+        userDao.update(user);
+        userHistoryDao.log(new UserHistory(user, createBy));
+    }
+}

app/src/main/java/com/techcourse/service/TxUserService.java

@@ -0,0 +1,36 @@
+package com.techcourse.service;
+
+import com.techcourse.domain.User;
+import org.springframework.transaction.support.TransactionTemplate;
+
+public class TxUserService implements UserService {
+
+    private final UserService userService;
+    private final TransactionTemplate transactionTemplate;
+
+    public TxUserService(UserService userService, TransactionTemplate transactionTemplate) {
+        this.userService = userService;
+        this.transactionTemplate = transactionTemplate;
+    }
+
+    @Override
+    public User findById(long id) {
+        return transactionTemplate.execute(() -> userService.findById(id));
+    }
+
+    @Override
+    public void insert(User user) {
+        transactionTemplate.execute(() -> {
+            userService.insert(user);
+            return null;
+        });
+    }
+
+    @Override
+    public void changePassword(long id, String newPassword, String createBy) {
+        transactionTemplate.execute(() -> {
+            userService.changePassword(id, newPassword, createBy);
+            return null;
+        });
+    }
+}

app/src/main/java/com/techcourse/service/UserService.java

@@ -1,38 +1,12 @@
 package com.techcourse.service;
 
-import com.techcourse.dao.UserDao;
-import com.techcourse.dao.UserHistoryDao;
 import com.techcourse.domain.User;
-import com.techcourse.domain.UserHistory;
-import org.springframework.transaction.support.TransactionTemplate;
 
-public class UserService {
+public interface UserService {
 
-    private final UserDao userDao;
-    private final UserHistoryDao userHistoryDao;
-    private final TransactionTemplate transactionTemplate;
+    User findById(long id);
 
-    public UserService(UserDao userDao, UserHistoryDao userHistoryDao, TransactionTemplate transactionTemplate) {
-        this.userDao = userDao;
-        this.userHistoryDao = userHistoryDao;
-        this.transactionTemplate = transactionTemplate;
-    }
+    void insert(User user);
 
-    public User findById(long id) {
-        return userDao.findById(id);
-    }
-
-    public void insert(User user) {
-        userDao.insert(user);
-    }
-
-    public void changePassword(long id, String newPassword, String createBy) {
-        transactionTemplate.execute(() -> {
-            var user = findById(id);
-            user.changePassword(newPassword);
-            userDao.update(user);
-            userHistoryDao.log(new UserHistory(user, createBy));
-            return null;
-        });
-    }
+    void changePassword(long id, String newPassword, String createBy);
 }

app/src/test/java/com/techcourse/service/UserServiceTest.java → app/src/test/java/com/techcourse/service/AppUserServiceTest.java

@@ -14,7 +14,7 @@
 import org.springframework.jdbc.core.JdbcTemplate;
 import org.springframework.transaction.support.TransactionTemplate;
 
-class UserServiceTest {
+class AppUserServiceTest {
 
     private JdbcTemplate jdbcTemplate;
     private TransactionTemplate transactionTemplate;
@@ -34,7 +34,7 @@ void setUp() {
     @Test
     void testChangePassword() {
         var userHistoryDao = new UserHistoryDao(jdbcTemplate);
-        var userService = new UserService(userDao, userHistoryDao, transactionTemplate);
+        var userService = new AppUserService(userDao, userHistoryDao);
 
         var newPassword = "qqqqq";
         var createBy = "gugu";
@@ -49,7 +49,8 @@ void testChangePassword() {
     void testTransactionRollback() {
         // 트랜잭션 롤백 테스트를 위해 mock으로 교체
         var userHistoryDao = new MockUserHistoryDao(jdbcTemplate);
-        var userService = new UserService(userDao, userHistoryDao, transactionTemplate);
+        var appUserService = new AppUserService(userDao, userHistoryDao);
+        var userService = new TxUserService(appUserService, transactionTemplate);
 
         var newPassword = "newPassword";
         var createBy = "gugu";

jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java

@@ -9,27 +9,27 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.dao.DataAccessException;
-import org.springframework.transaction.support.DataSourceTransactionManager;
+import org.springframework.jdbc.datasource.DataSourceUtils;
 
 public class JdbcTemplate {
 
     private static final Logger log = LoggerFactory.getLogger(JdbcTemplate.class);
 
-    private final DataSourceTransactionManager transactionManager;
+    private final DataSource dataSource;
 
     public JdbcTemplate(DataSource dataSource) {
-        this.transactionManager = new DataSourceTransactionManager(dataSource);
+        this.dataSource = dataSource;
     }
 
     private <T> T execute(PreparedStatementCreator psc, PreparedStatementCallback<T> action) {
-        var con = transactionManager.getConnection();
+        var con = DataSourceUtils.getConnection(dataSource);
         try (var ps = psc.createPreparedStatement(con)) {
             return action.doInPreparedStatement(ps);
         } catch (SQLException e) {
             log.error(e.getMessage(), e);
             throw new DataAccessException(e);
         } finally {
-            transactionManager.release(con);
+            DataSourceUtils.releaseConnection(con, dataSource);
         }
     }
 

jdbc/src/main/java/org/springframework/jdbc/datasource/DataSourceUtils.java

@@ -1,19 +1,19 @@
 package org.springframework.jdbc.datasource;
 
-import org.springframework.jdbc.CannotGetJdbcConnectionException;
-import org.springframework.transaction.support.TransactionSynchronizationManager;
-
-import javax.sql.DataSource;
 import java.sql.Connection;
 import java.sql.SQLException;
+import javax.sql.DataSource;
+import org.springframework.jdbc.CannotGetJdbcConnectionException;
+import org.springframework.transaction.support.TransactionSynchronizationManager;
 
 // 4단계 미션에서 사용할 것
 public abstract class DataSourceUtils {
 
-    private DataSourceUtils() {}
+    private DataSourceUtils() {
+    }
 
     public static Connection getConnection(DataSource dataSource) throws CannotGetJdbcConnectionException {
-        Connection connection = TransactionSynchronizationManager.getResource(dataSource);
+        var connection = TransactionSynchronizationManager.getResource(dataSource);
         if (connection != null) {
             return connection;
         }
@@ -28,8 +28,13 @@ public static Connection getConnection(DataSource dataSource) throws CannotGetJd
     }
 
     public static void releaseConnection(Connection connection, DataSource dataSource) {
+        if (TransactionSynchronizationManager.isActualTransactionActive()) {
+            return;
+        }
+
         try {
             connection.close();
+            TransactionSynchronizationManager.unbindResource(dataSource);
         } catch (SQLException ex) {
             throw new CannotGetJdbcConnectionException("Failed to close JDBC Connection");
         }

jdbc/src/main/java/org/springframework/transaction/support/DataSourceTransactionManager.java

@@ -3,75 +3,48 @@
 import java.sql.Connection;
 import java.sql.SQLException;
 import javax.sql.DataSource;
+import org.springframework.jdbc.datasource.DataSourceUtils;
 
 public class DataSourceTransactionManager {
 
-    private static final ThreadLocal<Connection> connectionHolder = new ThreadLocal<>();
-
     private final DataSource dataSource;
 
     public DataSourceTransactionManager(DataSource dataSource) {
         this.dataSource = dataSource;
     }
 
-    public void startTransaction() {
+    public void doGetTransaction() {
         try {
-            var connection = getConnection();
+            var connection = DataSourceUtils.getConnection(dataSource);
             connection.setAutoCommit(false);
-            connectionHolder.set(connection);
+            TransactionSynchronizationManager.setActualTransactionActive(true);
         } catch (SQLException e) {
             throw new RuntimeException("트랜잭션 시작 실패", e);
         }
     }
 
-    public Connection getConnection() {
-        var connection = connectionHolder.get();
-        if (connection != null) {
-            return connection;
-        }
-
-        try {
-            return dataSource.getConnection();
-        } catch (SQLException e) {
-            throw new RuntimeException("커넥션 획득 실패", e);
-        }
-    }
-
-    public void commit() {
+    public void doCommit() {
         try {
-            var connection = getConnection();
+            var connection = DataSourceUtils.getConnection(dataSource);
             connection.commit();
-            close(connection, true);
+            release(connection);
         } catch (SQLException e) {
             throw new RuntimeException("커밋 실패", e);
         }
     }
 
-    public void rollback() {
+    public void doRollback() {
         try {
-            var connection = getConnection();
+            var connection = DataSourceUtils.getConnection(dataSource);
             connection.rollback();
-            close(connection, true);
+            release(connection);
         } catch (SQLException e) {
             throw new RuntimeException("롤백 실패", e);
         }
     }
 
-    public void release(Connection connection) {
-        if (connectionHolder.get() != connection) {
-            close(connection, false);
-        }
-    }
-
-    private void close(Connection connection, boolean clear) {
-        if (clear) {
-            connectionHolder.remove();
-        }
-
-        try {
-            connection.close();
-        } catch (SQLException e) {
-            throw new RuntimeException("커넥션 종료 실패", e);
-        }
+    private void release(Connection connection) {
+        TransactionSynchronizationManager.setActualTransactionActive(false);
+        DataSourceUtils.releaseConnection(connection, dataSource);
     }
 }

jdbc/src/main/java/org/springframework/transaction/support/TransactionSynchronizationManager.java

@@ -1,23 +1,41 @@
 package org.springframework.transaction.support;
 
-import javax.sql.DataSource;
+import static java.lang.ThreadLocal.withInitial;
+
 import java.sql.Connection;
+import java.util.HashMap;
 import java.util.Map;
+import javax.sql.DataSource;
 
 public abstract class TransactionSynchronizationManager {
 
-    private static final ThreadLocal<Map<DataSource, Connection>> resources = new ThreadLocal<>();
+    private static final ThreadLocal<Map<DataSource, Connection>> resources = withInitial(HashMap::new);
+    private static final ThreadLocal<Boolean> actualTransactionActive = withInitial(() -> false);
 
-    private TransactionSynchronizationManager() {}
+    private TransactionSynchronizationManager() {
+    }
 
     public static Connection getResource(DataSource key) {
-        return null;
+        return getResources().get(key);
     }
 
     public static void bindResource(DataSource key, Connection value) {
+        getResources().put(key, value);
     }
 
     public static Connection unbindResource(DataSource key) {
-        return null;
+        return getResources().remove(key);
+    }
+
+    private static Map<DataSource, Connection> getResources() {
+        return resources.get();
+    }
+
+    public static boolean isActualTransactionActive() {
+        return actualTransactionActive.get();
+    }
+
+    public static void setActualTransactionActive(boolean active) {
+        actualTransactionActive.set(active);
     }
 }

jdbc/src/main/java/org/springframework/transaction/support/TransactionTemplate.java

@@ -12,12 +12,12 @@ public TransactionTemplate(DataSource dataSource) {
 
     public <T> T execute(TransactionCallBack<T> action) {
         try {
-            transactionManager.startTransaction();
+            transactionManager.doGetTransaction();
             T result = action.doInTransaction();
-            transactionManager.commit();
+            transactionManager.doCommit();
             return result;
         } catch (RuntimeException | Error e) {
-            transactionManager.rollback();
+            transactionManager.doRollback();
             throw e;
         }
     }