事务简单介绍
- 本文源码基于spring-framework-5.3.10。
- 事务是基于AOP的机制进行实现的！
Spring事务基本执行原理
- 一个Bean在执行Bean的创建生命周期时，会经过InfrastructureAdvisorAutoProxyCreator的初始化后的方法，会判断当前当前Bean对象是否和BeanFactoryTransactionAttributeSourceAdvisor匹配，匹配逻辑为判断该Bean的类上是否存在@Transactional注解，或者类中的某个方法上是否存在@Transactional注解，如果存在则表示该Bean需要进行动态代理产生一个代理对象作为Bean对象。
Spring事务基本执行流程
- 利用所配置的PlatformTransactionManager事务管理器新建一个数据库连接。
- 修改数据库连接的autocommit为false。
- 执行MethodInvocation.proceed()方法，简单理解就是执行业务方法，其中就会执行sql。
- 如果没有抛异常，则提交。
- 如果抛了异常，则回滚。
源码执行流程
- 加了@Transactional注解的类，或者类中拥有@Transactional注解的方法，都会生成代理对象作为bean。
- 代理对象执行方法时。
- 获取当前正在执行的方法上的@Transactional注解的信息TransactionAttribute。
- 查看@Transactional注解上是否指定了TransactionManager，如果没有指定，则默认获取TransactionManager类型的bean作为TransactionManager。
- 对于TransactionManager有一个限制，必须是PlatformTransactionManager。
- 生成一个joinpointIdentification，作为事务的名字。
- 开始创建事务。
- 创建事务成功后执行业务方法。
- 如果执行业务方法出现异常，则会进行回滚，然后执行完finally中的方法后再将异常抛出。
- 如果执行业务方法没有出现异常，那么则会执行完finally中的方法后再进行提交。
创建事务源码流程
- 得到一个TransactionStatus对象、
- 将PlatformTransactionManager、TransactionAttribute、TransactionStatus构造成为一个TransactionInfo对象，并返回TransactionInfo对象。
回滚事务源码流程
- 判断当前异常是否需要回滚。不需要回滚直接走提价的流程。
- 触发同步器的beforeCompletion()。
- 调用数据库连接对象的rollback()。
- 触发同步器的afterCompletion()。
- 判断是否有事务挂起。
- 如果有则把挂起的事务重新设置到TransactionSynchronizationManager中去，并执行同步器的resume()方法。
提交事务源码流程
- 触发同步器的beforeCommit。
- 触发同步器的beforeCompletion()。
- 调用数据库连接对象的commit()。
- 触发同步器的afterCommit。
- 触发同步器的afterCompletion()。
- 判断是否有事务挂起。
- 如果有则把挂起的事务重新设置到TransactionSynchronizationManager中去，并执行同步器的resume()方法。
创建TransactionStatus的源码流程
- 调用AbstractPlatformTransactionManager类中的getTransaction(txAttr)方法，实际上这个方法就是真正去开启事务的方法。
- 调用DataSourceTransactionManager中的doGetTransaction()得到一个事务对象，得到的事务对象中可能持有也可能没有持有数据库连接对象。不同船舶机制下，是否持有事务，逻辑不同！
| 传播机制 |
含义 |
之前方法持有事务的逻辑 |
之前方法未持有事务的逻辑 |
| REQUIRED(TransactionDefinition.PROPAGATION_REQUIRED) |
支持当前事务，如果没有事务会创建一个新的事务 |
在当前事务运行 |
创建一个新的事务 |
| SUPPORTS(TransactionDefinition.PROPAGATION_SUPPORTS) |
支持当前事务，如果没有事务的话以非事务方式执行 |
在当前事务运行 |
使用非事务的方式运行 |
| MANDATORY(TransactionDefinition.PROPAGATION_MANDATORY) |
支持当前事务，如果没有事务抛出异常 |
在当前事务运行 |
抛异常 |
| REQUIRES_NEW(TransactionDefinition.PROPAGATION_REQUIRES_NEW) |
创建一个新的事务并挂起当前事务 |
创建一个新的事务并挂起当前事务 |
创建一个新的事务 |
| NOT_SUPPORTED(TransactionDefinition.PROPAGATION_NOT_SUPPORTED) |
以非事务方式执行，如果当前存在事务则将当前事务挂起 |
挂起当前事务 |
使用非事务的方式运行 |
| NEVER(TransactionDefinition.PROPAGATION_NEVER) |
以非事务方式进行，如果存在事务则抛出异常 |
抛异常 |
使用非事务的方式运行 |
| NESTED(TransactionDefinition.PROPAGATION_NESTED) |
如果当前存在事务，则在嵌套事务内执行。如果当前没有事务，则创建一个新事务 |
利用数据库连接对象，设置一个savepoint，比如mysql就支持，在一个事务中，可以在某个位置设置一个savepoint，后续可以只回滚到某个savepoint |
创建一个新的事务 |
doBegin源码流程
- 如果事务对象中没有持有数据库连接对象，那么则调用DataSource获取一个数据库连接对象，并设置到事务对象中去
- 设置当前数据库连接的隔离级别。
- 设置数据库连接的autoCommit为false。
- 设置数据库连接的timeout。
- 把获得的数据库连接对象通过TransactionSynchronizationManager设置到当前线程的ThreadLocal中。
同步器使用方式
TransactionSynchronizationManager.registerSynchronization(new TransactionSynchronizationAdapter() {
@Override
public void afterCommit() {
System.out.println("after commit...");
}
}
开启事务的注解@EnableTransactionManagement源码分析
/**
* 这个注解导入了TransactionManagementConfigurationSelector类
*/
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(TransactionManagementConfigurationSelector.class)
public @interface EnableTransactionManagement {
boolean proxyTargetClass() default false;
AdviceMode mode() default AdviceMode.PROXY;
int order() default Ordered.LOWEST_PRECEDENCE;
}
导入的TransactionManagementConfigurationSelector源码分析
/**
* 在调用process方法的时候会调用到这里
*/
protected String[] selectImports(AdviceMode adviceMode) {
switch (adviceMode) {
case PROXY:
// 默认是PROXY。往Spring容器中添加了两个Bean：AutoProxyRegistrar、ProxyTransactionManagementConfiguration
return new String[] {AutoProxyRegistrar.class.getName(),
ProxyTransactionManagementConfiguration.class.getName()};
case ASPECTJ:
// 表示不用动态代理技术，用ASPECTJ技术，比较麻烦了
return new String[] {determineTransactionAspectClass()};
default:
return null;
}
}
AutoProxyRegistrar的Bean源码分析
/**
* 这个类实现了ImportBeanDefinitionRegistrar，他在启动的时候会调用registerBeanDefinitions方法。
* 最核心的逻辑是往Spring容器中注册了一个InfrastructureAdvisorAutoProxyCreator的Bean。
* InfrastructureAdvisorAutoProxyCreator继承了AbstractAdvisorAutoProxyCreator，所以这个类的主要作用就是开启自动代理的作用，也就是一个BeanPostProcessor，会在初始化后步骤中去寻找Advisor类型的Bean，并判断当前某个Bean是否有匹配的Advisor，是否需要利用动态代理产生一个代理对象。
*/
public class AutoProxyRegistrar implements ImportBeanDefinitionRegistrar {
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
boolean candidateFound = false;
Set<String> annTypes = importingClassMetadata.getAnnotationTypes();
for (String annType : annTypes) {
AnnotationAttributes candidate = AnnotationConfigUtils.attributesFor(importingClassMetadata, annType);
if (candidate == null) {
continue;
}
Object mode = candidate.get("mode");
Object proxyTargetClass = candidate.get("proxyTargetClass");
if (mode != null && proxyTargetClass != null && AdviceMode.class == mode.getClass() &&
Boolean.class == proxyTargetClass.getClass()) {
candidateFound = true;
if (mode == AdviceMode.PROXY) {
// 注册InfrastructureAdvisorAutoProxyCreator，才可以Bean进行AOP
AopConfigUtils.registerAutoProxyCreatorIfNecessary(registry);
if ((Boolean) proxyTargetClass) {
// 设置InfrastructureAdvisorAutoProxyCreator的proxyTargetClass为true
AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry);
return;
}
}
}
}
if (!candidateFound && logger.isInfoEnabled()) {
String name = getClass().getSimpleName();
logger.info(String.format("%s was imported but no annotations were found " +
"having both 'mode' and 'proxyTargetClass' attributes of type " +
"AdviceMode and boolean respectively. This means that auto proxy " +
"creator registration and configuration may not have occurred as " +
"intended, and components may not be proxied as expected. Check to " +
"ensure that %s has been @Import'ed on the same class where these " +
"annotations are declared; otherwise remove the import of %s " +
"altogether.", name, name, name));
}
}
}
导入的ProxyTransactionManagementConfiguration源码分析
/**
* ProxyTransactionManagementConfiguration是一个配置类，它又定义了另外三个bean：
* BeanFactoryTransactionAttributeSourceAdvisor：一个Advisor
* AnnotationTransactionAttributeSource：相当于BeanFactoryTransactionAttributeSourceAdvisor中的Pointcut
* TransactionInterceptor：相当于BeanFactoryTransactionAttributeSourceAdvisor中的Advice
*/
@Configuration(proxyBeanMethods = false)
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public class ProxyTransactionManagementConfiguration extends AbstractTransactionManagementConfiguration {
// 定义一个Advisor的Bean
@Bean(name = TransactionManagementConfigUtils.TRANSACTION_ADVISOR_BEAN_NAME)
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public BeanFactoryTransactionAttributeSourceAdvisor transactionAdvisor(
TransactionAttributeSource transactionAttributeSource, TransactionInterceptor transactionInterceptor) {
BeanFactoryTransactionAttributeSourceAdvisor advisor = new BeanFactoryTransactionAttributeSourceAdvisor();
advisor.setTransactionAttributeSource(transactionAttributeSource);
advisor.setAdvice(transactionInterceptor);
if (this.enableTx != null) {
advisor.setOrder(this.enableTx.<Integer>getNumber("order"));
}
return advisor;
}
// 定义Advisor的Pointcut
@Bean
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public TransactionAttributeSource transactionAttributeSource() {
// AnnotationTransactionAttributeSource中定义了一个Pointcut
// 并且AnnotationTransactionAttributeSource可以用来解析@Transactional注解，并得到一个RuleBasedTransactionAttribute对象
return new AnnotationTransactionAttributeSource();
}
// 定义Advisor的Advice
// 开启事务、回滚、提交都在这个TransactionInterceptor中
@Bean
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
public TransactionInterceptor transactionInterceptor(TransactionAttributeSource transactionAttributeSource) {
TransactionInterceptor interceptor = new TransactionInterceptor();
interceptor.setTransactionAttributeSource(transactionAttributeSource);
if (this.txManager != null) {
interceptor.setTransactionManager(this.txManager);
}
return interceptor;
}
}
使用用到的Pointcut源码分析
public class BeanFactoryTransactionAttributeSourceAdvisor extends AbstractBeanFactoryPointcutAdvisor {
/**
* pointcut就是一个new TransactionAttributeSourcePointcut对象
*/
private final TransactionAttributeSourcePointcut pointcut = new TransactionAttributeSourcePointcut() {
@Override
@Nullable
protected TransactionAttributeSource getTransactionAttributeSource() {
return transactionAttributeSource;
}
};
/**
* 获取pointcut采用的是内部类的方式构建
*/
@Override
public Pointcut getPointcut() {
return this.pointcut;
}
}
/**
* 构建Pointcut用到的类
*/
abstract class TransactionAttributeSourcePointcut extends StaticMethodMatcherPointcut implements Serializable {
// 外部构造方法调用到这里，其实就是设置new TransactionAttributeSourceClassFilter()
// 这里面主要进行类的判断
protected TransactionAttributeSourcePointcut() {
setClassFilter(new TransactionAttributeSourceClassFilter());
}
// 判断方法是否匹配
@Override
public boolean matches(Method method, Class<?> targetClass) {
// 调用外部重写的方法
TransactionAttributeSource tas = getTransactionAttributeSource();
return (tas == null || tas.getTransactionAttribute(method, targetClass) != null);
}
// 具体的匹配逻辑
private class TransactionAttributeSourceClassFilter implements ClassFilter {
@Override
public boolean matches(Class<?> clazz) {
// 事务内部的一些类，直接返回false
if (TransactionalProxy.class.isAssignableFrom(clazz) ||
TransactionManager.class.isAssignableFrom(clazz) ||
PersistenceExceptionTranslator.class.isAssignableFrom(clazz)) {
return false;
}
// 调用外部重写的方法
TransactionAttributeSource tas = getTransactionAttributeSource();
// 判断有没有@Transaction注解
return (tas == null || tas.isCandidateClass(clazz));
}
}
}
/**
* 源码位置：org.springframework.transaction.annotation.AnnotationTransactionAttributeSource.isCandidateClass(Class<?>)
* 判断是否能成为候选者
*/
public boolean isCandidateClass(Class<?> targetClass) {
for (TransactionAnnotationParser parser : this.annotationParsers) {
if (parser.isCandidateClass(targetClass)) {
return true;
}
}
return false;
}
/**
* 源码位置：org.springframework.transaction.interceptor.AbstractFallbackTransactionAttributeSource.getTransactionAttribute(Method, Class<?>)
* 判断当前类上面是否有@Transactional注解
*/
public boolean isCandidateClass(Class<?> targetClass) {
return AnnotationUtils.isCandidateClass(targetClass, Transactional.class);
}
/**
* 源码位置：org.springframework.transaction.annotation.SpringTransactionAnnotationParser.isCandidateClass(Class<?>)
* 获取方法上或者类上是否有@Transaction注解
*/
public TransactionAttribute getTransactionAttribute(Method method, @Nullable Class<?> targetClass) {
// Object类直接返回null
if (method.getDeclaringClass() == Object.class) {
return null;
}
// First, see if we have a cached value.
// 检查缓存里的结果，缓存里存了当前类和方法是否存在Transactional注解
Object cacheKey = getCacheKey(method, targetClass);
TransactionAttribute cached = this.attributeCache.get(cacheKey);
if (cached != null) {
// Value will either be canonical value indicating there is no transaction attribute,
// or an actual transaction attribute.
// 缓存中没有，直接返回null
if (cached == NULL_TRANSACTION_ATTRIBUTE) {
return null;
}
else {
return cached;
}
}
else {
// We need to work it out.
// 解析。实际对象为RuleBasedTransactionAttribute
TransactionAttribute txAttr = computeTransactionAttribute(method, targetClass);
// Put it in the cache.
// 为空，缓存一个空的
if (txAttr == null) {
this.attributeCache.put(cacheKey, NULL_TRANSACTION_ATTRIBUTE);
}
else {
String methodIdentification = ClassUtils.getQualifiedMethodName(method, targetClass);
if (txAttr instanceof DefaultTransactionAttribute) {
DefaultTransactionAttribute dta = (DefaultTransactionAttribute) txAttr;
dta.setDescriptor(methodIdentification);
dta.resolveAttributeStrings(this.embeddedValueResolver);
}
if (logger.isTraceEnabled()) {
logger.trace("Adding transactional method '" + methodIdentification + "' with attribute: " + txAttr);
}
// 不为空，缓存结果
this.attributeCache.put(cacheKey, txAttr);
}
return txAttr;
}
}
最终执行的Advisor:TransactionInterceptor源码分析
/**
* 源码位置：org.springframework.transaction.interceptor.TransactionInterceptor.invoke(MethodInvocation)
*/
public Object invoke(MethodInvocation invocation) throws Throwable {
// Work out the target class: may be {@code null}.
// The TransactionAttributeSource should be passed the target class
// as well as the method, which may be from an interface.
// 获取代理类
Class<?> targetClass = (invocation.getThis() != null ? AopUtils.getTargetClass(invocation.getThis()) : null);
// Adapt to TransactionAspectSupport's invokeWithinTransaction...
return invokeWithinTransaction(invocation.getMethod(), targetClass, new CoroutinesInvocationCallback() {
@Override
@Nullable
public Object proceedWithInvocation() throws Throwable {
// 执行后续的Interceptor，以及被代理的方法
return invocation.proceed(); // test() sql
}
@Override
public Object getTarget() {
return invocation.getThis();
}
@Override
public Object[] getArguments() {
return invocation.getArguments();
}
});
}
/**
* 具体的执行代码
*/
protected Object invokeWithinTransaction(Method method, @Nullable Class<?> targetClass,
final InvocationCallback invocation) throws Throwable {
// If the transaction attribute is null, the method is non-transactional.
// TransactionAttribute就是@Transactional中的配置
TransactionAttributeSource tas = getTransactionAttributeSource();
// 获取@Transactional注解中的属性值
final TransactionAttribute txAttr = (tas != null ? tas.getTransactionAttribute(method, targetClass) : null);
// 返回Spring容器中类型为TransactionManager的Bean对象。事务的开启，提交，回滚都会用到TransactionManager对象。
final TransactionManager tm = determineTransactionManager(txAttr);
// ReactiveTransactionManager用得少，并且它只是执行方式是响应式的，原理流程和普通的是一样的
if (this.reactiveAdapterRegistry != null && tm instanceof ReactiveTransactionManager) {
boolean isSuspendingFunction = KotlinDetector.isSuspendingFunction(method);
boolean hasSuspendingFlowReturnType = isSuspendingFunction &&
COROUTINES_FLOW_CLASS_NAME.equals(new MethodParameter(method, -1).getParameterType().getName());
if (isSuspendingFunction && !(invocation instanceof CoroutinesInvocationCallback)) {
throw new IllegalStateException("Coroutines invocation not supported: " + method);
}
CoroutinesInvocationCallback corInv = (isSuspendingFunction ? (CoroutinesInvocationCallback) invocation : null);
ReactiveTransactionSupport txSupport = this.transactionSupportCache.computeIfAbsent(method, key -> {
Class<?> reactiveType =
(isSuspendingFunction ? (hasSuspendingFlowReturnType ? Flux.class : Mono.class) : method.getReturnType());
ReactiveAdapter adapter = this.reactiveAdapterRegistry.getAdapter(reactiveType);
if (adapter == null) {
throw new IllegalStateException("Cannot apply reactive transaction to non-reactive return type: " +
method.getReturnType());
}
return new ReactiveTransactionSupport(adapter);
});
InvocationCallback callback = invocation;
if (corInv != null) {
callback = () -> CoroutinesUtils.invokeSuspendingFunction(method, corInv.getTarget(), corInv.getArguments());
}
Object result = txSupport.invokeWithinTransaction(method, targetClass, callback, txAttr, (ReactiveTransactionManager) tm);
if (corInv != null) {
Publisher<?> pr = (Publisher<?>) result;
return (hasSuspendingFlowReturnType ? KotlinDelegate.asFlow(pr) :
KotlinDelegate.awaitSingleOrNull(pr, corInv.getContinuation()));
}
return result;
}
// 把tm强制转换为PlatformTransactionManager，所以我们在定义时得定义PlatformTransactionManager类型
PlatformTransactionManager ptm = asPlatformTransactionManager(tm);
// joinpoint的唯一标识，就是当前在执行的方法名字
final String joinpointIdentification = methodIdentification(method, targetClass, txAttr);
// CallbackPreferringPlatformTransactionManager表示拥有回调功能的PlatformTransactionManager，也不常用
if (txAttr == null || !(ptm instanceof CallbackPreferringPlatformTransactionManager)) {
// Standard transaction demarcation with getTransaction and commit/rollback calls.
// 如果有必要就创建事务，这里就涉及到事务传播机制的实现了
// TransactionInfo表示一个逻辑事务，比如两个逻辑事务属于同一个物理事务
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.
// 执行下一个Interceptor或被代理对象中的方法
retVal = invocation.proceedWithInvocation(); //test
}
catch (Throwable ex) {
// target invocation exception
// 抛异常了，则回滚事务
completeTransactionAfterThrowing(txInfo, ex);
throw ex;
}
finally {
cleanupTransactionInfo(txInfo);
}
if (retVal != null && 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;
}
else {
Object result;
final ThrowableHolder throwableHolder = new ThrowableHolder();
// It's a CallbackPreferringPlatformTransactionManager: pass a TransactionCallback in.
try {
result = ((CallbackPreferringPlatformTransactionManager) ptm).execute(txAttr, status -> {
TransactionInfo txInfo = prepareTransactionInfo(ptm, txAttr, joinpointIdentification, status);
try {
Object retVal = invocation.proceedWithInvocation();
if (retVal != null && vavrPresent && VavrDelegate.isVavrTry(retVal)) {
// Set rollback-only in case of Vavr failure matching our rollback rules...
retVal = VavrDelegate.evaluateTryFailure(retVal, txAttr, status);
}
return retVal;
}
catch (Throwable ex) {
if (txAttr.rollbackOn(ex)) {
// A RuntimeException: will lead to a rollback.
if (ex instanceof RuntimeException) {
throw (RuntimeException) ex;
}
else {
throw new ThrowableHolderException(ex);
}
}
else {
// A normal return value: will lead to a commit.
throwableHolder.throwable = ex;
return null;
}
}
finally {
cleanupTransactionInfo(txInfo);
}
});
}
catch (ThrowableHolderException ex) {
throw ex.getCause();
}
catch (TransactionSystemException ex2) {
if (throwableHolder.throwable != null) {
logger.error("Application exception overridden by commit exception", throwableHolder.throwable);
ex2.initApplicationException(throwableHolder.throwable);
}
throw ex2;
}
catch (Throwable ex2) {
if (throwableHolder.throwable != null) {
logger.error("Application exception overridden by commit exception", throwableHolder.throwable);
}
throw ex2;
}
// Check result state: It might indicate a Throwable to rethrow.
if (throwableHolder.throwable != null) {
throw throwableHolder.throwable;
}
return result;
}
}
/**
* 创建事务的逻辑
*/
protected TransactionInfo createTransactionIfNecessary(@Nullable PlatformTransactionManager tm,
@Nullable TransactionAttribute txAttr, final String joinpointIdentification) {
// If no name specified, apply method identification as transaction name.
// name为空，取方法名字
if (txAttr != null && txAttr.getName() == null) {
txAttr = new DelegatingTransactionAttribute(txAttr) {
@Override
public String getName() {
return joinpointIdentification;
}
};
}
// 每个逻辑事务都会创建一个TransactionStatus，但是TransactionStatus中有一个属性代表当前逻辑事务底层的物理事务是不是新的
TransactionStatus status = null;
if (txAttr != null) {
if (tm != null) {
// 开启事务！
status = tm.getTransaction(txAttr);
}
else {
if (logger.isDebugEnabled()) {
logger.debug("Skipping transactional joinpoint [" + joinpointIdentification +
"] because no transaction manager has been configured");
}
}
}
// 返回一个TransactionInfo对象，表示得到了一个事务，可能是新创建的一个事务，也可能是拿到的已有的事务
return prepareTransactionInfo(tm, txAttr, joinpointIdentification, status);
}
获取（开启）事务的逻辑
/**
* 获取事务的逻辑
* 源码位置：org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(TransactionDefinition)
* definition：Transaction注解的信息的对象
*/
public final TransactionStatus getTransaction(@Nullable TransactionDefinition definition)
throws TransactionException {
// Use defaults if no transaction definition given.
TransactionDefinition def = (definition != null ? definition : TransactionDefinition.withDefaults());
// 从ThreadLocal中拿到txObject对象
Object transaction = doGetTransaction();
boolean debugEnabled = logger.isDebugEnabled();
// transaction.getConnectionHolder().isTransactionActive()
// 判断是不是存在一个事务
if (isExistingTransaction(transaction)) {
// Existing transaction found -> check propagation behavior to find out how to behave.
return handleExistingTransaction(def, transaction, debugEnabled);
}
// Check definition settings for new transaction.
// 配置的数据库返回的超时时间小于-1，抛异常。
if (def.getTimeout() < TransactionDefinition.TIMEOUT_DEFAULT) {
throw new InvalidTimeoutException("Invalid transaction timeout", def.getTimeout());
}
// No existing transaction found -> check propagation behavior to find out how to proceed.
// 当前不存在事务，并且配置的传播机制为PROPAGATION_MANDATORY（支持当前事务，如果没有事务抛出异常），抛异常
if (def.getPropagationBehavior() == TransactionDefinition.PROPAGATION_MANDATORY) {
throw new IllegalTransactionStateException(
"No existing transaction found for transaction marked with propagation 'mandatory'");
}
// 在当前Thread中没有事务的前提下，以下三个是等价的。
// PROPAGATION_REQUIRED :支持当前事务，如果没有事务会创建一个新的事务
// PROPAGATION_REQUIRES_NEW ：创建一个新的事务并挂起当前事务
// PROPAGATION_NESTED： 如果当前存在事务，则在嵌套事务内执行。如果当前没有事务，则创建一个事务。
else if (def.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRED ||
def.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW ||
def.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NESTED) {
// 没有事务需要挂起，不过TransactionSynchronization有可能需要挂起。直接调用TransactionSynchronizationManager.initSynchronization方法会有需要被挂起的。
// suspendedResources表示当前线程被挂起的资源持有对象（数据库连接、TransactionSynchronization）
SuspendedResourcesHolder suspendedResources = suspend(null);
if (debugEnabled) {
logger.debug("Creating new transaction with name [" + def.getName() + "]: " + def);
}
try {
// 开启事务方法
// 开启事务后，transaction中就会有数据库连接了，并且isTransactionActive为true
// 并返回TransactionStatus对象，该对象保存了很多信息，包括被挂起的资源
return startTransaction(def, transaction, debugEnabled, suspendedResources);
}
catch (RuntimeException | Error ex) {
resume(null, suspendedResources);
throw ex;
}
}
else {
// Create "empty" transaction: no actual transaction, but potentially synchronization.
if (def.getIsolationLevel() != TransactionDefinition.ISOLATION_DEFAULT && logger.isWarnEnabled()) {
logger.warn("Custom isolation level specified but no actual transaction initiated; " +
"isolation level will effectively be ignored: " + def);
}
boolean newSynchronization = (getTransactionSynchronization() == SYNCHRONIZATION_ALWAYS);
return prepareTransactionStatus(def, null, true, newSynchronization, debugEnabled, null);
}
}
/**
* 开启Transaction事务
*/
private TransactionStatus startTransaction(TransactionDefinition definition, Object transaction,
boolean debugEnabled, @Nullable SuspendedResourcesHolder suspendedResources) {
// 是否开启一个新的TransactionSynchronization
boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER);
// 开启的这个事务的状态信息：
// 事务的定义、用来保存数据库连接的对象、是否是新事务，是否是新的TransactionSynchronization
DefaultTransactionStatus status = newTransactionStatus(
definition, transaction, true, newSynchronization, debugEnabled, suspendedResources);
// 开启事务
doBegin(transaction, definition);
// 如果需要新开一个TransactionSynchronization，就把新创建的事务的一些状态信息设置到TransactionSynchronizationManager中
prepareSynchronization(status, definition);
return status;
}
/**
* 开启事务！DataSource层面
* 源码位置：org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(Object, TransactionDefinition)
*/
protected void doBegin(Object transaction, TransactionDefinition definition) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) transaction;
Connection con = null;
try {
// 如果当前线程中所使用的DataSource还没有创建过数据库连接，就获取一个新的数据库连接
if (!txObject.hasConnectionHolder() ||
txObject.getConnectionHolder().isSynchronizedWithTransaction()) {
// 得到连接对象
Connection newCon = obtainDataSource().getConnection();
if (logger.isDebugEnabled()) {
logger.debug("Acquired Connection [" + newCon + "] for JDBC transaction");
}
// 设置到DataSourceTransactionObject。注意这里设置的true，表示txObject的链接一个新的
txObject.setConnectionHolder(new ConnectionHolder(newCon), true);
}
txObject.getConnectionHolder().setSynchronizedWithTransaction(true);
// 得到连接对象
con = txObject.getConnectionHolder().getConnection();
// 根据@Transactional注解中的设置，设置Connection的readOnly与隔离级别
Integer previousIsolationLevel = DataSourceUtils.prepareConnectionForTransaction(con, definition);
txObject.setPreviousIsolationLevel(previousIsolationLevel);
txObject.setReadOnly(definition.isReadOnly());
// Switch to manual commit if necessary. This is very expensive in some JDBC drivers,
// so we don't want to do it unnecessarily (for example if we've explicitly
// configured the connection pool to set it already).
// 保证autocommit是false。autocommit为true的时候设置autocommit为false
if (con.getAutoCommit()) {
txObject.setMustRestoreAutoCommit(true);
if (logger.isDebugEnabled()) {
logger.debug("Switching JDBC Connection [" + con + "] to manual commit");
}
con.setAutoCommit(false);
}
prepareTransactionalConnection(con, definition);
txObject.getConnectionHolder().setTransactionActive(true);
// 设置数据库连接的过期时间
int timeout = determineTimeout(definition);
if (timeout != TransactionDefinition.TIMEOUT_DEFAULT) {
txObject.getConnectionHolder().setTimeoutInSeconds(timeout);
}
// Bind the connection holder to the thread.
// 把新建的数据库连接设置到resources中，resources就是一个ThreadLocal<Map<Object, Object>>，事务管理器中的设置的DataSource对象为key，数据库连接对象为value
if (txObject.isNewConnectionHolder()) {
TransactionSynchronizationManager.bindResource(obtainDataSource(), txObject.getConnectionHolder());
}
}
catch (Throwable ex) {
if (txObject.isNewConnectionHolder()) {
DataSourceUtils.releaseConnection(con, obtainDataSource());
txObject.setConnectionHolder(null, false);
}
throw new CannotCreateTransactionException("Could not open JDBC Connection for transaction", ex);
}
}
挂起相关流程
/**
* 挂起相关流程
* 源码位置：org.springframework.transaction.support.AbstractPlatformTransactionManager.suspend(Object)
*/
protected final SuspendedResourcesHolder suspend(@Nullable Object transaction) throws TransactionException {
// synchronizations是一个ThreadLocal<Set<TransactionSynchronization>>
// 我们可以在任何地方通过TransactionSynchronizationManager给当前线程添加TransactionSynchronization，
// 这里判断有没有开启事务。在prepareSynchronization方法中开启！
if (TransactionSynchronizationManager.isSynchronizationActive()) {
// 调用TransactionSynchronization的suspend方法，并清空和返回当前线程中所有的TransactionSynchronization对象
List<TransactionSynchronization> suspendedSynchronizations = doSuspendSynchronization();
try {
Object suspendedResources = null;
if (transaction != null) {
// 挂起事务，把transaction中的Connection清空，并把resources中的key-value进行移除，并返回数据库连接Connection对象
suspendedResources = doSuspend(transaction);
}
// 获取并清空当前线程中关于TransactionSynchronizationManager的设置
String name = TransactionSynchronizationManager.getCurrentTransactionName();
TransactionSynchronizationManager.setCurrentTransactionName(null);
boolean readOnly = TransactionSynchronizationManager.isCurrentTransactionReadOnly();
TransactionSynchronizationManager.setCurrentTransactionReadOnly(false);
Integer isolationLevel = TransactionSynchronizationManager.getCurrentTransactionIsolationLevel();
TransactionSynchronizationManager.setCurrentTransactionIsolationLevel(null);
boolean wasActive = TransactionSynchronizationManager.isActualTransactionActive();
TransactionSynchronizationManager.setActualTransactionActive(false);
// 将当前线程中的数据库连接对象、TransactionSynchronization对象、TransactionSynchronizationManager中的设置构造成一个对象
// 表示被挂起的资源持有对象，持有了当前线程中的事务对象、TransactionSynchronization对象
// suspendedResources数据库连接、suspendedSynchronizations自己定义的同步器、name事务的名称、readOnly事务是不是只读、isolationLevel事务隔离级别、wasActive切面的Active
return new SuspendedResourcesHolder(
suspendedResources, suspendedSynchronizations, name, readOnly, isolationLevel, wasActive);
}
catch (RuntimeException | Error ex) {
// doSuspend failed - original transaction is still active...
doResumeSynchronization(suspendedSynchronizations);
throw ex;
}
}
else if (transaction != null) {
// Transaction active but no synchronization active.
Object suspendedResources = doSuspend(transaction);
return new SuspendedResourcesHolder(suspendedResources);
}
else {
// Neither transaction nor synchronization active.
return null;
}
}
/**
* 调用TransactionSynchronization的suspend方法，并清空和返回当前线程中所有的TransactionSynchronization对象
*/
private List<TransactionSynchronization> doSuspendSynchronization() {
// 从synchronizations（一个ThreadLocal）中拿到所设置的TransactionSynchronization对象
List<TransactionSynchronization> suspendedSynchronizations =
TransactionSynchronizationManager.getSynchronizations();
// 调用TransactionSynchronization对象的suspend()
for (TransactionSynchronization synchronization : suspendedSynchronizations) {
synchronization.suspend();
}
// 清空synchronizations
TransactionSynchronizationManager.clearSynchronization();
// 把获取到的TransactionSynchronization返回
return suspendedSynchronizations;
}
之前存在事务的执行逻辑
/**
* 之前存在事务的执行逻辑
* 源码位置：org.springframework.transaction.support.AbstractPlatformTransactionManager.handleExistingTransaction(TransactionDefinition, Object, boolean)
*/
private TransactionStatus handleExistingTransaction(
TransactionDefinition definition, Object transaction, boolean debugEnabled)
throws TransactionException {
// PROPAGATION_NEVER：以非事务方式进行，如果存在事务则抛出异常
if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NEVER) {
throw new IllegalTransactionStateException(
"Existing transaction found for transaction marked with propagation 'never'");
}
// PROPAGATION_NOT_SUPPORTED：以非事务方式执行，如果当前存在事务则将当前事务挂起
if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NOT_SUPPORTED) {
if (debugEnabled) {
logger.debug("Suspending current transaction");
}
// 把当前事务挂起，其中就会把数据库连接对象从ThreadLocal中移除
Object suspendedResources = suspend(transaction);
boolean newSynchronization = (getTransactionSynchronization() == SYNCHRONIZATION_ALWAYS);
return prepareTransactionStatus(
definition, null, false, newSynchronization, debugEnabled, suspendedResources);
}
// PROPAGATION_REQUIRES_NEW:创建一个新的事务并挂起当前事务
if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW) {
if (debugEnabled) {
logger.debug("Suspending current transaction, creating new transaction with name [" +
definition.getName() + "]");
}
// 调用挂起的逻辑
SuspendedResourcesHolder suspendedResources = suspend(transaction);
// 开启新事务的逻辑
try {
return startTransaction(definition, transaction, debugEnabled, suspendedResources);
}
catch (RuntimeException | Error beginEx) {
resumeAfterBeginException(transaction, suspendedResources, beginEx);
throw beginEx;
}
}
// PROPAGATION_NESTED：果当前存在事务，则在嵌套事务内执行。如果当前没有事务，则创建一个事务。
if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NESTED) {
if (!isNestedTransactionAllowed()) {
throw new NestedTransactionNotSupportedException(
"Transaction manager does not allow nested transactions by default - " +
"specify 'nestedTransactionAllowed' property with value 'true'");
}
if (debugEnabled) {
logger.debug("Creating nested transaction with name [" + definition.getName() + "]");
}
if (useSavepointForNestedTransaction()) {
// Create savepoint within existing Spring-managed transaction,
// through the SavepointManager API implemented by TransactionStatus.
// Usually uses JDBC 3.0 savepoints. Never activates Spring synchronization.
DefaultTransactionStatus status =
prepareTransactionStatus(definition, transaction, false, false, debugEnabled, null);
// 创建一个savepoint
status.createAndHoldSavepoint();
return status;
}
else {
// Nested transaction through nested begin and commit/rollback calls.
// Usually only for JTA: Spring synchronization might get activated here
// in case of a pre-existing JTA transaction.
return startTransaction(definition, transaction, debugEnabled, null);
}
}
// Assumably PROPAGATION_SUPPORTS or PROPAGATION_REQUIRED.
if (debugEnabled) {
logger.debug("Participating in existing transaction");
}
if (isValidateExistingTransaction()) {
if (definition.getIsolationLevel() != TransactionDefinition.ISOLATION_DEFAULT) {
Integer currentIsolationLevel = TransactionSynchronizationManager.getCurrentTransactionIsolationLevel();
if (currentIsolationLevel == null || currentIsolationLevel != definition.getIsolationLevel()) {
Constants isoConstants = DefaultTransactionDefinition.constants;
throw new IllegalTransactionStateException("Participating transaction with definition [" +
definition + "] specifies isolation level which is incompatible with existing transaction: " +
(currentIsolationLevel != null ?
isoConstants.toCode(currentIsolationLevel, DefaultTransactionDefinition.PREFIX_ISOLATION) :
"(unknown)"));
}
}
if (!definition.isReadOnly()) {
if (TransactionSynchronizationManager.isCurrentTransactionReadOnly()) {
throw new IllegalTransactionStateException("Participating transaction with definition [" +
definition + "] is not marked as read-only but existing transaction is");
}
}
}
// 如果依然是Propagation.REQUIRED
boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER);
return prepareTransactionStatus(definition, transaction, false, newSynchronization, debugEnabled, null);
}
事务的提交逻辑
/**
* 事务的提交
*/
protected void commitTransactionAfterReturning(@Nullable TransactionInfo txInfo) {
if (txInfo != null && txInfo.getTransactionStatus() != null) {
if (logger.isTraceEnabled()) {
logger.trace("Completing transaction for [" + txInfo.getJoinpointIdentification() + "]");
}
txInfo.getTransactionManager().commit(txInfo.getTransactionStatus());
}
}
/**
* 事务提交的准备逻辑
*/
public final void commit(TransactionStatus status) throws TransactionException {
if (status.isCompleted()) {
throw new IllegalTransactionStateException(
"Transaction is already completed - do not call commit or rollback more than once per transaction");
}
DefaultTransactionStatus defStatus = (DefaultTransactionStatus) status;
// 可以通过TransactionAspectSupport.currentTransactionStatus().setRollbackOnly();来设置
// 事务本来是可以要提交的，但是可以强制回滚。比如报错后更有好的提示。
if (defStatus.isLocalRollbackOnly()) {
if (defStatus.isDebug()) {
logger.debug("Transactional code has requested rollback");
}
processRollback(defStatus, false);
return;
}
// 判断此事务在之前是否设置了需要回滚，跟globalRollbackOnParticipationFailure有关
if (!shouldCommitOnGlobalRollbackOnly() && defStatus.isGlobalRollbackOnly()) {
if (defStatus.isDebug()) {
logger.debug("Global transaction is marked as rollback-only but transactional code requested commit");
}
processRollback(defStatus, true);
return;
}
// 提交
processCommit(defStatus);
}
/**
* 提交外部逻辑
*/
private void processCommit(DefaultTransactionStatus status) throws TransactionException {
try {
boolean beforeCompletionInvoked = false;
try {
boolean unexpectedRollback = false;
// 空方法，无任何子类的实现
prepareForCommit(status);
// 调用同步器提交前的逻辑（回滚的时候不调用这个）
triggerBeforeCommit(status);
// 调用同步器完成前的逻辑
triggerBeforeCompletion(status);
beforeCompletionInvoked = true;
if (status.hasSavepoint()) {
if (status.isDebug()) {
logger.debug("Releasing transaction savepoint");
}
unexpectedRollback = status.isGlobalRollbackOnly();
status.releaseHeldSavepoint();
}
// 新的事务，直接调用提交
else if (status.isNewTransaction()) {
if (status.isDebug()) {
logger.debug("Initiating transaction commit");
}
unexpectedRollback = status.isGlobalRollbackOnly();
// 调用提交方法
doCommit(status);
}
else if (isFailEarlyOnGlobalRollbackOnly()) {
unexpectedRollback = status.isGlobalRollbackOnly();
}
// Throw UnexpectedRollbackException if we have a global rollback-only
// marker but still didn't get a corresponding exception from commit.
if (unexpectedRollback) {
throw new UnexpectedRollbackException(
"Transaction silently rolled back because it has been marked as rollback-only");
}
}
catch (UnexpectedRollbackException ex) {
// can only be caused by doCommit
triggerAfterCompletion(status, TransactionSynchronization.STATUS_ROLLED_BACK);
throw ex;
}
catch (TransactionException ex) {
// can only be caused by doCommit
if (isRollbackOnCommitFailure()) {
doRollbackOnCommitException(status, ex);
}
else {
triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN);
}
throw ex;
}
catch (RuntimeException | Error ex) {
if (!beforeCompletionInvoked) {
triggerBeforeCompletion(status);
}
doRollbackOnCommitException(status, ex);
throw ex;
}
// Trigger afterCommit callbacks, with an exception thrown there
// propagated to callers but the transaction still considered as committed.
try {
// 调用同步器提交后的逻辑
triggerAfterCommit(status);
}
finally {
// 调用同步器完成后的逻辑
triggerAfterCompletion(status, TransactionSynchronization.STATUS_COMMITTED);
}
}
finally {
// 恢复被挂起的资源到当前线程中
cleanupAfterCompletion(status);
}
}
/**
* 提交的核心逻辑，直接调用Connection的提交方法
*/
protected void doCommit(DefaultTransactionStatus status) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) status.getTransaction();
Connection con = txObject.getConnectionHolder().getConnection();
if (status.isDebug()) {
logger.debug("Committing JDBC transaction on Connection [" + con + "]");
}
try {
con.commit();
}
catch (SQLException ex) {
throw translateException("JDBC commit", ex);
}
}
/**
* 恢复被挂起的资源到当前线程中
*/
private void cleanupAfterCompletion(DefaultTransactionStatus status) {
status.setCompleted();
if (status.isNewSynchronization()) {
TransactionSynchronizationManager.clear();
}
// 判断当前事务执行的方法，是不是创建这个事务的方法
if (status.isNewTransaction()) {
// 这里会去关闭数据库连接
doCleanupAfterCompletion(status.getTransaction());
}
// 恢复被挂起的资源到当前线程中
if (status.getSuspendedResources() != null) {
if (status.isDebug()) {
logger.debug("Resuming suspended transaction after completion of inner transaction");
}
Object transaction = (status.hasTransaction() ? status.getTransaction() : null);
// 恢复
resume(transaction, (SuspendedResourcesHolder) status.getSuspendedResources());
}
}
回滚事务的逻辑
protected void completeTransactionAfterThrowing(@Nullable TransactionInfo txInfo, Throwable ex) {
if (txInfo != null && txInfo.getTransactionStatus() != null) {
if (logger.isTraceEnabled()) {
logger.trace("Completing transaction for [" + txInfo.getJoinpointIdentification() +
"] after exception: " + ex);
}
// transactionAttribute的实现类为RuleBasedTransactionAttribute，父类为DefaultTransactionAttribute
// 判断配置的rollBackFor的异常信息
if (txInfo.transactionAttribute != null && txInfo.transactionAttribute.rollbackOn(ex)) {
try {
txInfo.getTransactionManager().rollback(txInfo.getTransactionStatus());
}
catch (TransactionSystemException ex2) {
logger.error("Application exception overridden by rollback exception", ex);
ex2.initApplicationException(ex);
throw ex2;
}
catch (RuntimeException | Error ex2) {
logger.error("Application exception overridden by rollback exception", ex);
throw ex2;
}
}
else {
// We don't roll back on this exception.
// Will still roll back if TransactionStatus.isRollbackOnly() is true.
try {
txInfo.getTransactionManager().commit(txInfo.getTransactionStatus());
}
catch (TransactionSystemException ex2) {
logger.error("Application exception overridden by commit exception", ex);
ex2.initApplicationException(ex);
throw ex2;
}
catch (RuntimeException | Error ex2) {
logger.error("Application exception overridden by commit exception", ex);
throw ex2;
}
}
}
}
/**
* 判断回滚条件是否满足
* 源码位置：org.springframework.transaction.interceptor.RuleBasedTransactionAttribute.rollbackOn(Throwable)
*/
public boolean rollbackOn(Throwable ex) {
RollbackRuleAttribute winner = null;
int deepest = Integer.MAX_VALUE;
if (this.rollbackRules != null) {
// 遍历所有的RollbackRuleAttribute，判断现在抛出的异常ex是否匹配RollbackRuleAttribute中指定的异常类型的子类或本身
for (RollbackRuleAttribute rule : this.rollbackRules) {
int depth = rule.getDepth(ex);
if (depth >= 0 && depth < deepest) {
deepest = depth;
winner = rule;
}
}
}
// User superclass behavior (rollback on unchecked) if no rule matches.
// 没有匹配的规则，调用父类判断是不是运行时异常
if (winner == null) {
return super.rollbackOn(ex);
}
// ex所匹配的RollbackRuleAttribute，可能是NoRollbackRuleAttribute，如果是匹配的NoRollbackRuleAttribute，那就表示现在这个异常ex不用回滚
return !(winner instanceof NoRollbackRuleAttribute);
}
/**
* 回滚前的准备逻辑
* 源码位置：org.springframework.transaction.support.AbstractPlatformTransactionManager.rollback(TransactionStatus)
*/
public final void rollback(TransactionStatus status) throws TransactionException {
// 不完整的，没有执行完抛异常
if (status.isCompleted()) {
throw new IllegalTransactionStateException(
"Transaction is already completed - do not call commit or rollback more than once per transaction");
}
DefaultTransactionStatus defStatus = (DefaultTransactionStatus) status;
processRollback(defStatus, false);
}
/**
* 回滚
*/
private void processRollback(DefaultTransactionStatus status, boolean unexpected) {
try {
boolean unexpectedRollback = unexpected;
try {
// 只会触发完成前的同步器逻辑
triggerBeforeCompletion(status);
// 比如mysql中的savepoint
if (status.hasSavepoint()) {
if (status.isDebug()) {
logger.debug("Rolling back transaction to savepoint");
}
// 回滚到上一个savepoint位置
status.rollbackToHeldSavepoint();
}
else if (status.isNewTransaction()) {
if (status.isDebug()) {
logger.debug("Initiating transaction rollback");
}
// 如果当前执行的方法是新开了一个事务，那么就直接回滚
doRollback(status);
}
else {
// Participating in larger transaction
// 如果当前执行的方法，是公用了一个已存在的事务，而当前执行的方法抛了异常，则要判断整个事务到底要不要回滚，看具体配置
if (status.hasTransaction()) {
// 如果一个事务中有两个方法，第二个方法抛异常了，那么第二个方法就相当于执行失败需要回滚，如果globalRollbackOnParticipationFailure为true，那么第一个方法在没有抛异常的情况下也要回滚
if (status.isLocalRollbackOnly() || isGlobalRollbackOnParticipationFailure()) {
if (status.isDebug()) {
logger.debug("Participating transaction failed - marking existing transaction as rollback-only");
}
// 直接将rollbackOnly设置到ConnectionHolder中去，表示整个事务的sql都要回滚
doSetRollbackOnly(status);
}
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;
}
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 {
cleanupAfterCompletion(status);
}
}
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