微服务学习Day9-分布式事务Seata

分布式事务seata

引入

理论基础

CAP定理

BASE理论

初识Seata

动手实践

XA模式

AT模式

TCC模式

@Service
@Slf4j
public class AccountTCCServiceImpl implements AccountTCCService {@Autowiredprivate AccountMapper accountMapper;@Autowiredprivate AccountFreezeMapper freezeMapper;@Override@Transactionalpublic void deduct(String userId, int money) {// 0.获取事务idString xid = RootContext.getXID();//1.判断freeze中是否有冻结记录，如果有，一定是CANCEL执行过，我要拒绝业务AccountFreeze oldFreeze = freezeMapper.selectById(xid);if (oldFreeze != null){//CANCEL执行过，我要拒绝业务return;}// 1.扣减可用余额accountMapper.deduct(userId, money);// 2.记录冻结金额，事务状态AccountFreeze freeze = new AccountFreeze();freeze.setUserId(userId);freeze.setFreezeMoney(money);freeze.setState(AccountFreeze.State.TRY);freeze.setXid(xid);freezeMapper.insert(freeze);}@Overridepublic boolean confirm(BusinessActionContext ctx) {// 1.获取事务idString xid = ctx.getXid();// 2.根据id删除冻结记录int count = freezeMapper.deleteById(xid);return count == 1;}@Overridepublic boolean cancel(BusinessActionContext ctx) {// 0.查询冻结记录String xid = ctx.getXid();String userId = ctx.getActionContext("userId").toString();AccountFreeze freeze = freezeMapper.selectById(xid);//1.空回滚的判断，判断freeze是否为null，为null证明try没执行，需要空回滚if (freeze == null){freeze = new AccountFreeze();freeze.setUserId(userId);freeze.setFreezeMoney(0);freeze.setState(AccountFreeze.State.CANCEL);freeze.setXid(xid);freezeMapper.insert(freeze);return true;}//2.幂等判断if (freeze.getState() == AccountFreeze.State.CANCEL) {//已经处理过一次CANCEL，无需重复处理return true;}// 1.恢复可用余额accountMapper.refund(freeze.getUserId(), freeze.getFreezeMoney());// 2.将冻结金额清零，状态改为CANCELfreeze.setFreezeMoney(0);freeze.setState(AccountFreeze.State.CANCEL);int count = freezeMapper.updateById(freeze);return count == 1;}
}

SAGA模式

高可用