分布式事务-TCC（Hmily）[通俗易懂]

大家好，又见面了，我是你们的朋友全栈君。

TCC是什么：
TCC是Try、Confirm、Cancel三个词语的缩写，TCC要求每个分支事务实现三个操作：预处理Try、确认 Confirm、撤销Cancel。Try操作做业务检查及资源预留，Confirm做业务确认操作，Cancel实现一个与Try相反的操作即回滚操作。TM首先发起所有的分支事务的try操作，任何一个分支事务的try操作执行失败，TM将会发起所有分支事务的Cancel操作，若try操作全部成功，TM将会发起所有分支事务的Confirm操作，其中Confirm/Cancel 操作若执行失败，TM会进行重试。
分布式事务执行成功:
在这里插入图片描述
这边try执行成功后，没有异常会直接进入Confirm确认提交阶段。

分布式执行失败：
在这里插入图片描述
这边try执行失败后，执行成功一方的资源会进行事务回滚。

TCC分为三个阶段：
1：Try 阶段是做业务检查(一致性)及资源预留(隔离)，此阶段仅是一个初步操作，它和后续的Confirm 一起才能真正构成一个完整的业务逻辑。
2. Confirm 阶段是做确认提交，Try阶段所有分支事务执行成功后开始执行 Confirm。通常情况下，采用TCC则认为 Confirm阶段是不会出错的。即：只要Try成功，Confirm一定成功。若Confirm阶段真的出错了，需引入重试机制或人工处理。
3. Cancel 阶段是在业务执行错误需要回滚的状态下执行分支事务的业务取消，预留资源释放。通常情况下，采用TCC则认为Cancel阶段也是一定成功的。若Cancel阶段真的出错了，需引入重试机制或人工处理。
4. TM事务管理器 TM事务管理器可以实现为独立的服务，也可以让全局事务发起方充当TM的角色，TM独立出来是为了成为公用组件，是为了考虑系统结构和软件复用。TM在发起全局事务时生成全局事务记录，全局事务ID贯穿整个分布式事务调用链条，用来记录事务上下文，追踪和记录状态，由于Confirm 和cancel失败需进行重试，因此需要实现为幂等，幂等性是指同一个操作无论请求多少次，其结果都相同。

Hmily：
Hmily是一个高性能分布式事务TCC开源框架。基于Java语言来开发（JDK1.8），支持Dubbo，Spring Cloud等 RPC框架进行分布式事务。Hmily实现的TCC服务与普通的服务一样，只需要暴露一个接口，也就是它的Try业务。Confirm/Cancel业务逻辑，只是因为全局事务提交/回滚的需要才提供的，因此Confirm/Cancel业务只需要被Hmily TCC事务框架发现即可，不需要被调用它的其他业务服务所感知。
官网介绍：https://dromara.org/website/zh-cn/docs/hmily/index.html

Hmily环境构建：
首先导入hmily：

  <dependency>
            <groupId>org.dromara</groupId>
            <artifactId>hmily-springcloud</artifactId>
            <version>2.0.4-RELEASE</version>
        </dependency>

添加hmily数据库日志:

package com.study1.conf;

import com.alibaba.druid.pool.DruidDataSource;
import org.dromara.hmily.common.config.HmilyConfig;
import org.dromara.hmily.common.config.HmilyDbConfig;
import org.dromara.hmily.core.bootstrap.HmilyTransactionBootstrap;
import org.dromara.hmily.core.service.HmilyInitService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.core.env.Environment;

@Configuration
@EnableAspectJAutoProxy(proxyTargetClass=true)
public class DatabaseHmliyConfiguration { 
   

    private final ApplicationContext applicationContext;

    @Autowired
    private Environment env;

    public DatabaseHmliyConfiguration(ApplicationContext applicationContext) { 
   
        this.applicationContext = applicationContext;
    }

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource")
    public DruidDataSource ds0() { 
   
        DruidDataSource druidDataSource = new DruidDataSource();
        return druidDataSource;
    }

    @Bean
    public HmilyTransactionBootstrap hmilyTransactionBootstrap(HmilyInitService hmilyInitService){ 
   
        HmilyTransactionBootstrap hmilyTransactionBootstrap = new HmilyTransactionBootstrap(hmilyInitService);
        hmilyTransactionBootstrap.setSerializer(env.getProperty("org.dromara.hmily.serializer"));
        hmilyTransactionBootstrap.setRecoverDelayTime(Integer.parseInt(env.getProperty("org.dromara.hmily.recoverDelayTime")));
        hmilyTransactionBootstrap.setRetryMax(Integer.parseInt(env.getProperty("org.dromara.hmily.retryMax")));
        hmilyTransactionBootstrap.setScheduledDelay(Integer.parseInt(env.getProperty("org.dromara.hmily.scheduledDelay")));
        hmilyTransactionBootstrap.setScheduledThreadMax(Integer.parseInt(env.getProperty("org.dromara.hmily.scheduledThreadMax")));
        hmilyTransactionBootstrap.setRepositorySupport(env.getProperty("org.dromara.hmily.repositorySupport"));
        hmilyTransactionBootstrap.setStarted(Boolean.parseBoolean(env.getProperty("org.dromara.hmily.started")));
        HmilyDbConfig hmilyDbConfig = new HmilyDbConfig();
        hmilyDbConfig.setDriverClassName(env.getProperty("org.dromara.hmily.hmilyDbConfig.driverClassName"));
        hmilyDbConfig.setUrl(env.getProperty("org.dromara.hmily.hmilyDbConfig.url"));
        hmilyDbConfig.setUsername(env.getProperty("org.dromara.hmily.hmilyDbConfig.username"));
        hmilyDbConfig.setPassword(env.getProperty("org.dromara.hmily.hmilyDbConfig.password"));
        hmilyTransactionBootstrap.setHmilyDbConfig(hmilyDbConfig);
        return hmilyTransactionBootstrap;
    }

}

添加yml配置：

org:
  dromara:
    hmily:
      serializer: kryo
      recoverDelayTime: 30
      retryMax: 30
      scheduledDelay: 30
      scheduledThreadMax:  10
      repositorySupport: db
      started: true
      hmilyDbConfig:
        driverClassName: com.mysql.jdbc.Driver
        url:  jdbc:mysql://localhost:3306/bank1?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
        username: root
        password: 123

添加扫描:

@EnableEurekaClient
@SpringBootApplication
@EnableFeignClients //使用@feign
//@EnableHystrix //使用hystrix
@ComponentScan({ 
   "com.study1","org.dromara.hmily"})
@MapperScan("com.study1.mapper")
public class ServceBank1Application { 
   
    public static void main(String[] args) { 
   
        SpringApplication.run(ServceBank1Application.class, args);
    }
}

第二个服务同上
这边数据库采用bank1,bank2
bank1实现用户扣款功能：

 //--------------Hmily------------------
    //只要标记@Hmily就是try方法，在注解中指定confirm、cancel两个方法的名字
    @Override
    @Transactional
    @Hmily(confirmMethod = "commit", cancelMethod = "rollback")
    public boolean reduceHmilyAmount(int amount) { 
   
        //预处理->扣款 张三扣款成功
        if (bankMapper.reduceAmount(amount) > 0) { 
   
            System.out.println("开始调用远程服务");
            //李四添加金额
            bankFeignService.addAmount(amount);
            return true;
        } else { 
   
            return false;
        }
    }

    @Transactional
    public void commit(int amount) { 
   
        System.out.println("成功处理事务");
    }

    @Transactional
    public void rollback(int amount) { 
   
        System.out.println("失败处理事务");
    }

bank2实现用户添加余额的功能:

//--------------Hmily------------------
    //只要标记@Hmily就是try方法，在注解中指定confirm、cancel两个方法的名字
    @Override
    @Transactional
    @Hmily(confirmMethod = "commit", cancelMethod = "rollback")
    public void addAmount(Integer amount) { 
   
        //预处理->扣款 张三扣款成功
        bankMapper.addAmount(amount);
        System.out.println("调用完成");
        int y = 3 / 0;
        System.out.println("执行其他业务");
    }

    @Transactional
    public void commit(int amount) { 
   
        System.out.println("bank2成功处理事务");
    }

    @Transactional
    public void rollback(int amount) { 
   
        System.out.println("---------------------失败处理事务------------------------");
        System.out.println("---------------------失败处理事务------------------------");
        System.out.println("---------------------失败处理事务------------------------");
        System.out.println("---------------------失败处理事务------------------------");
    }

feign服务调用:

//可以捕获错误日志
@FeignClient(value = "bank2", fallback = BankFeignServiceImpl.class)
public interface BankFeignService { 
   

    @GetMapping("/bank2/addAmount")
    @Hmily
    public boolean addAmount(@RequestParam("amount") Integer amount);
}

采用的是feign进行微服务调用，测试调用bank2报错，bank1执行回调方法：
在这里插入图片描述

开始调用远程服务
feign.FeignException: status 500 reading BankFeignService#addAmount(Integer)
	at feign.FeignException.errorStatus(FeignException.java:78)
	at feign.codec.ErrorDecoder$Default.decode(ErrorDecoder.java:93)
	at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:149)
	at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:78)
	at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:103)
	at com.sun.proxy.$Proxy133.addAmount(Unknown Source)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:198)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:88)
	at org.dromara.hmily.core.service.handler.ConsumeHmilyTransactionHandler.handler(ConsumeHmilyTransactionHandler.java:35)
	at org.dromara.hmily.core.service.impl.HmilyTransactionAspectServiceImpl.invoke(HmilyTransactionAspectServiceImpl.java:63)
	at org.dromara.hmily.springcloud.interceptor.SpringCloudHmilyTransactionInterceptor.interceptor(SpringCloudHmilyTransactionInterceptor.java:78)
	at org.dromara.hmily.core.interceptor.AbstractHmilyTransactionAspect.interceptTccMethod(AbstractHmilyTransactionAspect.java:61)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:644)
	at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:633)
	at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:175)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
	at org.dromara.hmily.springcloud.feign.HmilyFeignHandler.invoke(HmilyFeignHandler.java:62)
	at com.sun.proxy.$Proxy134.addAmount(Unknown Source)
	at com.study1.service.impl.BankServiceImpl.reduceHmilyAmount(BankServiceImpl.java:52)
	at com.study1.service.impl.BankServiceImpl$$FastClassBySpringCGLIB$$b1ddc6fd.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
	at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:749)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
	at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294)
	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
	at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:88)
	at org.dromara.hmily.core.service.handler.StarterHmilyTransactionHandler.handler(StarterHmilyTransactionHandler.java:70)
	at org.dromara.hmily.core.service.impl.HmilyTransactionAspectServiceImpl.invoke(HmilyTransactionAspectServiceImpl.java:63)
	at org.dromara.hmily.springcloud.interceptor.SpringCloudHmilyTransactionInterceptor.interceptor(SpringCloudHmilyTransactionInterceptor.java:78)
	at org.dromara.hmily.core.interceptor.AbstractHmilyTransactionAspect.interceptTccMethod(AbstractHmilyTransactionAspect.java:61)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:644)
	at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:633)
	at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:175)
	at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
	at com.study1.service.impl.BankServiceImpl$$EnhancerBySpringCGLIB$$e3476692.reduceHmilyAmount(<generated>)
	at com.study1.controller.BankController.reduceAmount(BankController.java:19)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:892)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:908)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at com.alibaba.druid.support.http.WebStatFilter.doFilter(WebStatFilter.java:123)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.boot.actuate.web.trace.servlet.HttpTraceFilter.doFilterInternal(HttpTraceFilter.java:90)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:117)
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:106)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:200)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:834)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
失败处理事务

使用Hmily注意事项：
在使用Hmliy时候注意里面的try，confirm,cancel等方法都是异步线程调用，注意避免他们进行频繁调用可以在数据库中添加方法调用记录，避免重复调用导致数据不一致的情况。同时当事务处理失败未得到处理时，数据库表中有一个hmily的日志记录表，它会对日志中的记录进行定时重复调用。

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