- 处理回滚流程图
- 传播机制图
- AbstractPlatformTransactionManager的processRollback处理回滚
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- AbstractTransactionStatus的rollbackToHeldSavepoint回滚到保存点
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- JdbcTransactionObjectSupport的rollbackToSavepoint回滚到保存点
- DataSourceTransactionManager的doRollback回滚
- DataSourceTransactionManager的doSetRollbackOnly设置回滚标记
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- DataSourceTransactionObject 的setRollbackOnly设置回滚标记
处理回滚流程图
传播机制图
AbstractPlatformTransactionManager的processRollback处理回滚
unexpectedRollback这个一般是false，除非是设置rollback-only=true，才是true，表示是全局的回滚标记。首先会进行回滚前回调，然后判断是否设置了保存点，比如NESTED会设置，要先回滚到保存点。如果状态是新的事务，那就进行回滚，如果不是新的，就设置一个回滚标记，内部是设置连接持有器回滚标记。然后回滚完成回调，根据事务状态信息，完成后数据清除,和线程的私有资源解绑，重置连接自动提交，隔离级别，是否只读，释放连接，恢复挂起事务等
private void processRollback(DefaultTransactionStatus status, boolean unexpected) {
try {
boolean unexpectedRollback = unexpected;//意外的回滚
try {
triggerBeforeCompletion(status);//回滚完成前回调
//有保存点回滚到保存点
if (status.hasSavepoint()) {
if (status.isDebug()) {
logger.debug("Rolling back transaction to savepoint");
}
status.rollbackToHeldSavepoint();
}
else if (status.isNewTransaction()) {
//当前状态是一个新事务
if (status.isDebug()) {
logger.debug("Initiating transaction rollback");
}
doRollback(status);//进行回滚
}
else {
// Participating in larger transaction
if (status.hasTransaction()) {
if (status.isLocalRollbackOnly() || isGlobalRollbackOnParticipationFailure()) {
if (status.isDebug()) {
logger.debug("Participating transaction failed - marking existing transaction as rollback-only");
}
doSetRollbackOnly(status);//设置连接要回滚标记，也就是全局回滚
}
else {
if (status.isDebug()) {
logger.debug("Participating transaction failed - letting transaction originator decide on rollback");
}
}
}
else {
logger.debug("Should roll back transaction but cannot - no transaction available");
}
// Unexpected rollback only matters here if we're asked to fail early
if (!isFailEarlyOnGlobalRollbackOnly()) {
unexpectedRollback = false;
}
}
}
catch (RuntimeException | Error ex) {
triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN);
throw ex;
}
//回滚完成后回调
triggerAfterCompletion(status, TransactionSynchronization.STATUS_ROLLED_BACK);
// Raise UnexpectedRollbackException if we had a global rollback-only marker
if (unexpectedRollback) {
throw new UnexpectedRollbackException(
"Transaction rolled back because it has been marked as rollback-only");
}
}
finally {
//根据事务状态信息，完成后数据清除,和线程的私有资源解绑，重置连接自动提交，隔离级别，是否只读，释放连接，恢复挂起事务等
cleanupAfterCompletion(status);
}
}
AbstractTransactionStatus的rollbackToHeldSavepoint回滚到保存点
如果设置了保存点的话，会进行处理，回滚到保存点，内部就是调用JDBC的连接回滚，释放保存点，其实没做什么，空的，最后清除保存点：
public void rollbackToHeldSavepoint() throws TransactionException {
Object savepoint = getSavepoint();
if (savepoint == null) {
throw new TransactionUsageException(
"Cannot roll back to savepoint - no savepoint associated with current transaction");
}
getSavepointManager().rollbackToSavepoint(savepoint);//回滚到保存点
getSavepointManager().releaseSavepoint(savepoint);//释放保存点，其实啥都没做
setSavepoint(null);//清除保存点
}
JdbcTransactionObjectSupport的rollbackToSavepoint回滚到保存点
内部就是获取连接对象，然后调用rollback回滚到保存点，然后重置连接持有器的回滚标记为false。所以这里不会影响外层的提交，否则外层提交的时候发现有回滚标记，会进行回滚的，这个在讲提交的时候会说到。
@Override
public void rollbackToSavepoint(Object savepoint) throws TransactionException {
ConnectionHolder conHolder = getConnectionHolderForSavepoint();
try {
conHolder.getConnection().rollback((Savepoint) savepoint);//回滚到保存点
conHolder.resetRollbackOnly();//重置回滚标记,不需要回滚
}
catch (Throwable ex) {
throw new TransactionSystemException("Could not roll back to JDBC savepoint", ex);
}
}
重置回滚标记：
DataSourceTransactionManager的doRollback回滚
真正的回滚就是这里啦，也是获取到JDBC的连接，然后回滚。
@Override
protected void doRollback(DefaultTransactionStatus status) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) status.getTransaction();
Connection con = txObject.getConnectionHolder().getConnection();
if (status.isDebug()) {
logger.debug("Rolling back JDBC transaction on Connection [" + con + "]");
}
try {
con.rollback();//jdbc的回滚
}
catch (SQLException ex) {
throw new TransactionSystemException("Could not roll back JDBC transaction", ex);
}
}
DataSourceTransactionManager的doSetRollbackOnly设置回滚标记
如果既没有保存点，又不是新的事务，如果可以设置全局的回滚标记的话，就会设置。
@Override
protected void doSetRollbackOnly(DefaultTransactionStatus status) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) status.getTransaction();
if (status.isDebug()) {
logger.debug("Setting JDBC transaction [" + txObject.getConnectionHolder().getConnection() +
"] rollback-only");
}
txObject.setRollbackOnly();
}
DataSourceTransactionObject 的setRollbackOnly设置回滚标记
最终就是设置了连接持有器的回滚标记啦。
public void setRollbackOnly() {
getConnectionHolder().setRollbackOnly();
}
最后再进行cleanupAfterCompletion的清除处理，里面也涉及到很多东西，后面说。
好了，今天就到这里了，希望对学习理解有帮助，大神看见勿喷，仅为自己的学习理解，能力有限，请多包涵。