SpringBoot中事务执行原理分析（二）

// CglibAopProxy.DynamicAdvisedInterceptor#intercept
List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);

public Object proceed() throws Throwable {
// We start with an index of -1 and increment early.
  if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
    return invokeJoinpoint();
  }
  Object interceptorOrInterceptionAdvice =
      this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
  if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {
    // Evaluate dynamic method matcher here: static part will already have
    // been evaluated and found to match.
    InterceptorAndDynamicMethodMatcher dm =
        (InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice;
    Class<?> targetClass = (this.targetClass != null ? this.targetClass : this.method.getDeclaringClass());
    if (dm.methodMatcher.matches(this.method, targetClass, this.arguments)) {
      return dm.interceptor.invoke(this);
    }
    else {
      // Dynamic matching failed.
      // Skip this interceptor and invoke the next in the chain.
      return proceed();
    }
  }
  else {
    // It's an interceptor, so we just invoke it: The pointcut will have
    // been evaluated statically before this object was constructed.
    return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
  }
}

// TransactionAspectSupport#invokeWithinTransaction
@Nullable
protected Object invokeWithinTransaction(Method method, @Nullable Class<?> targetClass,
    final InvocationCallback invocation) throws Throwable {
  // If the transaction attribute is null, the method is non-transactional.
// 获取TransactionAttributeSource ，用于解析事务注解属性，其维护了annotationParsers
  TransactionAttributeSource tas = getTransactionAttributeSource();
//获取事务注解的属性
  final TransactionAttribute txAttr = (tas != null ? tas.getTransactionAttribute(method, targetClass) : null);
//根据事务注解属性信息获取事务管理器TransactionManager，本文获取的是DataSourceTransactionManager
  final TransactionManager tm = determineTransactionManager(txAttr);
//响应式事务管理，本文跳过这个
//...
//转换为为PlatformTransactionManager
  PlatformTransactionManager ptm = asPlatformTransactionManager(tm);
//获取方法的描述信息 com.recommend.service.impl.SysAdviceServiceImpl.testSave
  final String joinpointIdentification = methodIdentification(method, targetClass, txAttr);
//这里是事务处理逻辑
  if (txAttr == null || !(ptm instanceof CallbackPreferringPlatformTransactionManager)) {
    // Standard transaction demarcation with getTransaction and commit/rollback calls.
    //获取事务对象，这里将会触发事务的创建
    TransactionInfo txInfo = createTransactionIfNecessary(ptm, txAttr, joinpointIdentification);
    Object retVal;
    try {
      // This is an around advice: Invoke the next interceptor in the chain.
      // This will normally result in a target object being invoked.
  //触发CglibMethodInvocation的proceed方法,
  //其又会走到父类ReflectiveMethodInvocation的proceed方法
      retVal = invocation.proceedWithInvocation();
    }
    catch (Throwable ex) {
      // target invocation exception 触发事务回滚
      completeTransactionAfterThrowing(txInfo, ex);
      throw ex;
    }
    finally {
    // 清理事务信息
      cleanupTransactionInfo(txInfo);
    }
    if (vavrPresent && VavrDelegate.isVavrTry(retVal)) {
      // Set rollback-only in case of Vavr failure matching our rollback rules...
      TransactionStatus status = txInfo.getTransactionStatus();
      if (status != null && txAttr != null) {
        retVal = VavrDelegate.evaluateTryFailure(retVal, txAttr, status);
      }
    }
  //提交事务 
    commitTransactionAfterReturning(txInfo);
    return retVal;
  }
//下面是处理CallbackPreferringPlatformTransactionManager类型，我们可以忽略
  //...
}

protected void cleanupTransactionInfo(@Nullable TransactionInfo txInfo) {
  if (txInfo != null) {
    txInfo.restoreThreadLocalStatus();
  }
}
private void restoreThreadLocalStatus() {
  // Use stack to restore old transaction TransactionInfo.
  // Will be null if none was set.
  transactionInfoHolder.set(this.oldTransactionInfo);
}
private static final ThreadLocal<TransactionInfo> transactionInfoHolder =
    new NamedThreadLocal<>("Current aspect-driven transaction");