MySqlConnectionInterceptor.java

package kr.hconnect.data.jpa.mysql;

import lombok.Getter;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.hibernate.Session;
import org.hibernate.jdbc.Work;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import java.sql.Connection;
import java.sql.SQLException;

/**
 * MySQL Replication 환경 (Master-Slave)에서
 * {@link org.springframework.transaction.annotation.Transactional#readOnly()} 이 true로 정의된 Method에 대해서는
 * Slave 서버로 접속하기 위해, {@link java.sql.Connection#isReadOnly()}의 속성을 true로 변경하여 작업을 수행하도록 합니다.
 *
 * @author 배성혁 [email protected]
 * @since 13. 7. 21. 오후 3:20
 */
@Aspect
@Component
public class MySqlConnectionInterceptor {

    private static final Logger log = LoggerFactory.getLogger(MySqlConnectionInterceptor.class);
    private static final boolean isTraceEnabled = log.isTraceEnabled();

    @PersistenceContext
    EntityManager em;


    /** `@Transactional` 이 있는 메소드를 intercept 해서 readOnly 값에 따라 MySQL의 Master / Slave 서버를 구분합니다. */
    @Around(value = "@annotation(transactional) if transactional.readOnly()", argNames = "pjp, transactional")
    public Object proceed(final ProceedingJoinPoint pjp, final Transactional transactional) throws Throwable {

        if (log.isTraceEnabled())
            log.trace("읽기전용 작업을 수행하기 위해 현 connection를 readonly로 설정합니다...");

        Session session = em.unwrap(Session.class);
        ConnectionReadOnlyWork readOnlyWork = new ConnectionReadOnlyWork();
        try {
            session.doWork(readOnlyWork);
            return pjp.proceed();
        } finally {
            session.doWork(new RestoreConnectionWork(readOnlyWork));
        }

    }

    static class ConnectionReadOnlyWork implements Work {

        @Getter boolean autoCommit;
        @Getter boolean readOnly;

        @Override
        public void execute(Connection connection) throws SQLException {
            this.autoCommit = connection.getAutoCommit();
            this.readOnly = connection.isReadOnly();

            connection.setAutoCommit(false);
            connection.setReadOnly(true);
        }
    }

    static class RestoreConnectionWork implements Work {

        @Getter boolean autoCommit;
        @Getter boolean readOnly;

        public RestoreConnectionWork(ConnectionReadOnlyWork readOnlyWork) {
            this.autoCommit = readOnlyWork.isAutoCommit();
            this.readOnly = readOnlyWork.isReadOnly();
        }

        @Override
        public void execute(Connection connection) throws SQLException {
            connection.setAutoCommit(autoCommit);
            connection.setReadOnly(readOnly);
            if (log.isTraceEnabled())
                log.trace("읽기전용 작업을 수행하고, connection의 원래 설정으로 재설정했습니다.");
        }
    }
}