[feat:#18] MySQL user-level 분산락 구현

ticket/src/main/java/comento/backend/ticket/service/LockService.java

@@ -0,0 +1,84 @@
+package comento.backend.ticket.service;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Service;
+
+import javax.sql.DataSource;
+import java.sql.Connection;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.function.Supplier;
+
+@Slf4j
+@Service
+public class LockService {
+    private static final String GET_LOCK = "SELECT GET_LOCK(?, ?)";
+    private static final String RELEASE_LOCK = "SELECT RELEASE_LOCK(?)";
+
+    private final DataSource dataSource;
+
+    public LockService(DataSource dataSource) {
+        this.dataSource = dataSource;
+    }
+
+    public <T> T execute(String lockName, int timeoutSeconds, Supplier<T> supplier) {
+        //@brief : Lock을 획득한 connection으로 Lock 획득, 반납 작업 필요
+        try (Connection connection = dataSource.getConnection()) {
+            try {
+                log.info("lock 획득");
+                getLock(connection, lockName, timeoutSeconds);
+                return supplier.get();
+            } finally {
+                log.info("lock 반납");
+                releaseLock(connection, lockName);
+            }
+        } catch (SQLException e) {
+            log.info("lock 획득 실패");
+            throw new IllegalStateException(e);
+        }
+    }
+
+    //@see : 스레드 당 1개의 lock을 획득하도록
+    public void execute(String lockName, int timeoutSeconds, Runnable runnable) {
+        this.execute(lockName, timeoutSeconds, () -> {
+            runnable.run();
+            return null;
+        });
+    }
+
+    private void getLock(Connection connection, String lockName, int timeoutSeconds) throws SQLException {
+        try (PreparedStatement preparedStatement = connection.prepareStatement(GET_LOCK)) {
+            preparedStatement.setString(1, lockName);
+            preparedStatement.setInt(2, timeoutSeconds);
+
+            try (ResultSet resultSet = preparedStatement.executeQuery()) {
+                if (!resultSet.next()) {
+                    throw new IllegalStateException("[LockFail] RESULT EMPTY");
+                }
+
+                int result = resultSet.getInt(1);
+                if (result != 1) {
+                    throw new IllegalStateException("[LockFail] result : " + result + ", lockName : " + lockName + ", timeoutSeconds : " + timeoutSeconds);
+                }
+            }
+        }
+    }
+
+    private void releaseLock(Connection connection, String lockName) throws SQLException {
+        try (PreparedStatement preparedStatement = connection.prepareStatement(RELEASE_LOCK)) {
+            preparedStatement.setString(1, lockName);
+
+            try (ResultSet resultSet = preparedStatement.executeQuery()) {
+                if (!resultSet.next()) {
+                    throw new IllegalStateException("[UnlockFail] RESULT EMPTY");
+                }
+
+                int result = resultSet.getInt(1);
+                if (result != 1) {
+                    throw new IllegalStateException("[UnlockFail] result : " + result + ", lockName : " + lockName);
+                }
+            }
+        }
+    }
+}