tcc框架用于解决分布式场景多服务间的事务问题，该框架不建立在dubbo、http 、grpc等基础协议上层，服务可以任意选择暴露的协议，
只要遵循Try 、Commit、 Cancel规范即可。已解决悬挂、幂等、空回滚、事务嵌套问题，业务层面无需关注这部分处理。
tcc分为以下几个阶段：
- 执行前置动作 (业务资源的初始化，例如: 创建一个初始化的订单)
- Try (调用外部服务，进行资源的预留)
- 执行本地事务 (需要保证业务是在一个事务内完成)
- Commit\Cancel (根据本地事务的执行的成功与否，进行commit || cancel)
该示例主要用于用户下单的同时，需要扣减用户积分的场景，订单服务和积分服务分别是独立服务部署，它们之间存在分布式事务的问题， 我们通过当前框架展示是如何解决以上问题的。
https://github.com/654894017/tcc/tree/master/src/test/java/com/damon/sample
步骤1.初始化订单服务数据库表
-- 创建事务表
CREATE TABLE `tcc_main_log_order` (
`biz_id` bigint NOT NULL COMMENT '业务id',
`status` int NOT NULL DEFAULT '0' COMMENT '状态: 1 创建事务成功 2 回滚成功 3 完成本地事务成功 4 提交事务成功',
`version` int NOT NULL DEFAULT '0' COMMENT '版本号',
`last_update_time` bigint NOT NULL DEFAULT '0' COMMENT '最后更新时间',
`create_time` bigint NOT NULL DEFAULT '0' COMMENT '创建时间',
`checked_times` int NOT NULL DEFAULT '0' COMMENT '失败检查次数',
PRIMARY KEY (`biz_id`),
KEY `idx_status_checked_times_create_time` (`status`,`checked_times`,`create_time`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin COMMENT='主事务日志表';
-- 创建订单表
CREATE TABLE `tcc_demo_order` (
`order_id` bigint NOT NULL,
`status` int NOT NULL,
`user_id` bigint NOT NULL,
`deduction_points` bigint DEFAULT NULL,
PRIMARY KEY (`order_id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
步骤2.积分服务创建子事务表
-- 创建子事务表
CREATE TABLE `tcc_sub_log_order` (
`biz_id` bigint NOT NULL COMMENT '业务id',
`sub_biz_id` bigint NOT NULL DEFAULT '0' COMMENT '子业务id',
`status` int NOT NULL DEFAULT '0' COMMENT '状态: 1 创建事务成功 2 提交事务成功 3 回滚事务成功',
`version` int NOT NULL DEFAULT '0' COMMENT '版本号',
`last_update_time` bigint NOT NULL DEFAULT '0' COMMENT '最后更新时间',
`create_time` bigint NOT NULL DEFAULT '0' COMMENT '创建时间',
PRIMARY KEY (`biz_id`,`sub_biz_id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin COMMENT='子事务日志表';
-- 创建积分变动日志表
CREATE TABLE `tcc_demo_points_changing_log` (
`biz_id` bigint NOT NULL,
`user_id` bigint NOT NULL,
`change_points` bigint NOT NULL,
`change_type` int NOT NULL,
`status` int NOT NULL,
PRIMARY KEY (`biz_id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
-- 创建用户积分表
CREATE TABLE `tcc_demo_user_points` (
`user_id` bigint NOT NULL,
`points` bigint NOT NULL,
PRIMARY KEY (`user_id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
-- 初始化用户积分
INSERT INTO `tcc_demo_user_points` (`user_id`, `points`) VALUES (12345678, 999999999989989999);
事务表都是以tcc_main_log_xxxx 命名,子事务表都是以tcc_sub_log_xxxx命名,xxxx为业务分类,例如订单下单的业务,事务表命名为tcc_main_log_order, 子事务表命名为tcc_sub_log_order.
步骤3.运行 com.damon.sample.points.PointsApplication
步骤4.运行 com.damon.sample.order.TestRun
下单服务继承TccMainService服务
package com.damon.sample.order.app;
import cn.hutool.core.util.IdUtil;
import com.damon.sample.order.client.IOrderSubmitAppService;
import com.damon.sample.order.domain.IPointsGateway;
import com.damon.sample.order.domain.Order;
import com.damon.tcc.config.TccMainConfig;
import com.damon.tcc.TccMainService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;
import java.util.HashMap;
import java.util.Map;
@Service
public class OrderSubmitAppService extends TccMainService<Long, Map<String, Boolean>, Order> implements IOrderSubmitAppService {
private final JdbcTemplate jdbcTemplate;
private final IPointsGateway pointsGateway;
@Autowired
public OrderSubmitAppService(TccMainConfig config, IPointsGateway pointsGateway) {
super(config);
this.jdbcTemplate = new JdbcTemplate(config.getDataSource());
this.pointsGateway = pointsGateway;
}
/**
* 检查失败的日志，校正事务是否需要回滚还是提交
*/
public void executeFailedLogCheck() {
super.executeFailedLogCheck();
}
/**
* 检查死亡的日志，校正事务是否需要回滚还是提交
*/
public void executeDeadLogCheck() {
super.executeDeadLogCheck();
}
/**
* 执行失败日志检查的时候需要回查请求参数（因为事务日志未记录方法请求参数，所以需要回查一下）
* @param bizId 实体对象id（业务id）
* @return
*/
@Override
protected Order callbackParameter(Long bizId) {
return jdbcTemplate.queryForObject("select * from tcc_demo_order where order_id = ? ", new BeanPropertyRowMapper<>(Order.class), bizId);
}
/**
* 创建订单 （1 预先创建订单 2 执行try动作）
*
* @param userId
* @param points
* @return
*/
@Override
public Long submitOrder(Long userId, Long points) {
Long orderId = IdUtil.getSnowflakeNextId();
jdbcTemplate.update("insert into tcc_demo_order(order_id, user_id, status, deduction_points) values (?, ?, ? ,? )", orderId, userId, 0, points);
Order order = new Order(orderId, 0, userId, points);
try {
return super.process(order);
} catch (RuntimeException e) {
// try localTransaction commit cancel 错误可以通过自定义异常抛出
throw e;
} catch (Exception e) {
throw new RuntimeException("系统异常");
}
}
/**
* try执行用户积分扣除
*
* @param order
* @return
*/
@Override
protected Map<String, Boolean> attempt(Order order) {
Boolean result = pointsGateway.tryDeductionPoints(order.getOrderId(), order.getUserId(), order.getDeductionPoints());
Map<String, Boolean> map = new HashMap<>();
map.put("flag", result);
return map;
}
@Override
protected Long executeLocalTransaction(Order object, Map<String, Boolean> map) {
int result = jdbcTemplate.update("update tcc_demo_order set status = ? where order_id = ? ", 1, object.getOrderId());
if (result == 0) {
throw new RuntimeException("无效的订单id : " + object.getOrderId());
}
return object.getOrderId();
}
/**
* commit积分
*
* @param order
*/
@Override
protected void commit(Order order) {
pointsGateway.commitDeductionPoints(order.getOrderId(), order.getUserId(), order.getDeductionPoints());
}
/**
* cancel回滚积分
*
* @param order
*/
@Override
protected void cancel(Order order) {
pointsGateway.cancelDeductionPoints(order.getOrderId(), order.getUserId(), order.getDeductionPoints());
}
}积分服务继承TccSubService服务
package com.damon.sample.points.app;
import com.damon.sample.points.client.IPointsDeductionAppService;
import com.damon.sample.points.client.PointsDeductCmd;
import com.damon.tcc.config.TccSubConfig;
import com.damon.tcc.TccSubService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.support.TransactionSynchronizationManager;
@Service
public class PointsDeductionAppService extends TccSubService<Boolean, PointsDeductCmd> implements IPointsDeductionAppService {
private final Logger log = LoggerFactory.getLogger(PointsDeductionAppService.class);
private final JdbcTemplate jdbcTemplate;
@Autowired
public PointsDeductionAppService(TccSubConfig config) {
super(config);
this.jdbcTemplate = new JdbcTemplate(config.getDataSource());
}
/**
* try执行积分扣减
* @param parameter
* @return
*/
@Override
public boolean attempt(PointsDeductCmd parameter) {
return super.attempt(parameter, cmd -> {
int result = jdbcTemplate.update("update tcc_demo_user_points set points = points - ? where user_id = ? and points - ? >= 0",
cmd.getDeductionPoints(), cmd.getUserId(), cmd.getDeductionPoints());
boolean transactionActive = TransactionSynchronizationManager.isActualTransactionActive();
if (result == 0) {
throw new RuntimeException("用户积分不足 || 用户不存在");
}
int result2 = jdbcTemplate.update("insert tcc_demo_points_changing_Log (user_id, change_points, change_type, biz_id, status) values(?,?,?,?,?)",
cmd.getUserId(), cmd.getDeductionPoints(), 1, cmd.getOrderId(), 0);
return true;
});
}
/**
* commit提交积分扣减
* @param parameter
*/
@Override
public void commit(PointsDeductCmd parameter) {
super.commit(parameter, cmd -> {
int result = jdbcTemplate.update("update tcc_demo_points_changing_Log set status = 1 where biz_id = ?", cmd.getBizId());
if (result == 0) {
throw new RuntimeException("无效的业务id，无法积分commit");
}
});
}
/**
* cancel回滚积分扣减
* @param parameter
*/
@Override
public void cancel(PointsDeductCmd parameter) {
super.cancel(parameter, cmd -> {
int result = jdbcTemplate.update("update tcc_demo_points_changing_Log set status = 2 where biz_id = ?", cmd.getBizId());
if (result == 0) {
log.error("无效的业务id : {}，无法进行积分cancel", cmd.getBizId());
return;
}
int result2 = jdbcTemplate.update("update tcc_demo_user_points set points = points + ? where user_id = ?",
cmd.getDeductionPoints(), cmd.getUserId()
);
if (result2 == 0) {
throw new RuntimeException("无效的用户id，无法进行积分rollback");
}
});
}
}