今天本地使用Knife4j调用后端接口时，报出如下图的错误：
于是，查看后端控制台的输出结果，如下所示：
org.springframework.transaction.UnexpectedRollbackException: Transaction silently rolled back because it has been marked as rollback-only
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:752)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:711)
at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:654)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:407)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:750)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:692)
at com.test.cloud.service.ModelService$$EnhancerBySpringCGLIB$$a05f18b.generatePage(<generated>)
at com.test.cloud.controller.ModelController.generatePage(ModelController.java:169)
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:197)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:894)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1063)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
......
即Transaction silently rolled back because it has been marked as rollback-only
之前也遇到这个错误，但由于不太懂事务的嵌套，且总不能重现这个错误。
趁着此次的错误，彻底研究该错误形成的原因。
将Transaction silently rolled back because it has been marked as rollback-only翻译成中文，即事务以静默方式回滚，因为它已被标记为仅回滚。
那么，这句话是什么意思呢？通过对以下代码的分析，来了解它的含义。
因为公司代码不能泄露，特写如下三个测试类:
CommonApplicationTests：spring boot自带的测试类@SpringBootTest
class CommonApplicationTests {
@Autowired
TestRollbackService testRollbackService;
public void testRollback(){
try{
testRollbackService.functionOne();
}catch(Exception e){
e.printStackTrace();
}
}
}
TestRollbackService：事务回滚类@Autowired
private UserMapper userMapper;
@Autowired
private TestTransactionService testTransactionService;
@Transactional(rollbackFor = BizException.class)
public void functionOne(){
try{
User updateUser = new User();
updateUser.setId(new Long(19));
updateUser.setName("super先生");
userMapper.updateByPrimaryKey(updateUser);
testTransactionService.functionTwo();
}catch(Exception e){
e.printStackTrace();
}
}
TestTransactionService：事务执行类@Autowired
private AddressMapper addressMapper;
@Transactional(rollbackFor = BizException.class)
public void functionTwo(){
Address addressUpdate=new Address();
addressUpdate.setId(1L);
addressUpdate.setDetail("无锡市经开区")
addressMapper.updateByPrimaryKey(addressUpdate);
System.out.println(1/0);
}
如上两个方法，分别为functionOne和functionTwo。
functionOne加上了 @Transactional(rollbackFor = BizException.class)。
与此同时，functionTwo也加上了 @Transactional(rollbackFor = BizException.class)。
你在functionOne中调用了functionTwo，而functionTwo报出了错误信息，即可触发回滚异常的报错。
两个方法都加了事务注解，它们都会受到到事务管理的拦截器增强，并且事务传播的方式都是默认的，也就是REQUIRED，当已经存在事务的时候就加入事务，没有就创建事务。
这里functionOne和functionTwo都受事务控制，并且是处于同一个事务的。
functionOne调用了functionTwo，functionOne中抓了functionTwo的异常。当functionTwo发生异常时，functionTwo的操作应该回滚。
但functionOne吃了异常，functionOne方法中没有产生异常，所以functionOne的操作又应该提交，二者是相互矛盾的。
spring的事务关联拦截器在抓到functionTwo的异常后，就会标记rollback-only为true。当functionOne执行完准备提交后，发现rollback-only为true，也会回滚，并抛出异常告诉调用者。
程序时序图如下:
程序入口走cglib的代理类(CglibAopProxy)。
找到CglibAopProxy的DynamicAdvisedInterceptor.class内部类，可以看到入口方法(intercept)如下：
@Nullable
public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
Object oldProxy = null;
boolean setProxyContext = false;
Object target = null;
TargetSource targetSource = this.advised.getTargetSource();
Object var16;
.....
}
在该方法(intercept)中的找到如下语句：
即语句retVal = (new CglibAopProxy.CglibMethodInvocation(proxy, target, method, args, targetClass, chain, methodProxy)).proceed();
点击上图中CglibMethodInvocation类，即可到CglibAopProxy的CglibMethodInvocation内部类的如下方法：
然后找到TransactionInterceptor类，即到了事务管理的拦截器，如下图所示：
invokeWithinTransaction是事务管理的主方法。
@Nullable
protected Object invokeWithinTransaction(Method method, @Nullable Class<?> targetClass, TransactionAspectSupport.InvocationCallback invocation) throws Throwable {
TransactionAttributeSource tas = this.getTransactionAttributeSource();
TransactionAttribute txAttr = tas != null ? tas.getTransactionAttribute(method, targetClass) : null;
TransactionManager tm = this.determineTransactionManager(txAttr);
if (this.reactiveAdapterRegistry != null && tm instanceof ReactiveTransactionManager) {
boolean isSuspendingFunction = KotlinDetector.isSuspendingFunction(method);
boolean hasSuspendingFlowReturnType = isSuspendingFunction && "kotlinx.coroutines.flow.Flow".equals((new MethodParameter(method, -1)).getParameterType().getName());
if (isSuspendingFunction && !(invocation instanceof TransactionAspectSupport.CoroutinesInvocationCallback)) {
throw new IllegalStateException("Coroutines invocation not supported: " + method);
} else {
TransactionAspectSupport.CoroutinesInvocationCallback corInv = isSuspendingFunction ? (TransactionAspectSupport.CoroutinesInvocationCallback)invocation : null;
TransactionAspectSupport.ReactiveTransactionSupport txSupport = (TransactionAspectSupport.ReactiveTransactionSupport)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());
} else {
return new TransactionAspectSupport.ReactiveTransactionSupport(adapter);
}
});
TransactionAspectSupport.InvocationCallback callback = invocation;
if (corInv != null) {
callback = () -> {
return 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 ? TransactionAspectSupport.KotlinDelegate.asFlow(pr) : TransactionAspectSupport.KotlinDelegate.awaitSingleOrNull(pr, corInv.getContinuation());
} else {
return result;
}
}
} else {
PlatformTransactionManager ptm = this.asPlatformTransactionManager(tm);
String joinpointIdentification = this.methodIdentification(method, targetClass, txAttr);
if (txAttr != null && ptm instanceof CallbackPreferringPlatformTransactionManager) {
TransactionAspectSupport.ThrowableHolder throwableHolder = new TransactionAspectSupport.ThrowableHolder();
Object result;
try {
result = ((CallbackPreferringPlatformTransactionManager)ptm).execute(txAttr, (statusx) -> {
TransactionAspectSupport.TransactionInfo txInfo = this.prepareTransactionInfo(ptm, txAttr, joinpointIdentification, statusx);
Object var9;
try {
Object retVal = invocation.proceedWithInvocation();
if (retVal != null && vavrPresent && TransactionAspectSupport.VavrDelegate.isVavrTry(retVal)) {
retVal = TransactionAspectSupport.VavrDelegate.evaluateTryFailure(retVal, txAttr, statusx);
}
var9 = retVal;
return var9;
} catch (Throwable var13) {
if (txAttr.rollbackOn(var13)) {
if (var13 instanceof RuntimeException) {
throw (RuntimeException)var13;
}
throw new TransactionAspectSupport.ThrowableHolderException(var13);
}
throwableHolder.throwable = var13;
var9 = null;
} finally {
this.cleanupTransactionInfo(txInfo);
}
return var9;
});
} catch (TransactionAspectSupport.ThrowableHolderException var22) {
throw var22.getCause();
} catch (TransactionSystemException var23) {
if (throwableHolder.throwable != null) {
this.logger.error("Application exception overridden by commit exception", throwableHolder.throwable);
var23.initApplicationException(throwableHolder.throwable);
}
throw var23;
} catch (Throwable var24) {
if (throwableHolder.throwable != null) {
this.logger.error("Application exception overridden by commit exception", throwableHolder.throwable);
}
throw var24;
}
if (throwableHolder.throwable != null) {
throw throwableHolder.throwable;
} else {
return result;
}
} else {
TransactionAspectSupport.TransactionInfo txInfo = this.createTransactionIfNecessary(ptm, txAttr, joinpointIdentification);
Object retVal;
try {
retVal = invocation.proceedWithInvocation();
} catch (Throwable var20) {
this.completeTransactionAfterThrowing(txInfo, var20);
throw var20;
} finally {
this.cleanupTransactionInfo(txInfo);
}
if (retVal != null && vavrPresent && TransactionAspectSupport.VavrDelegate.isVavrTry(retVal)) {
TransactionStatus status = txInfo.getTransactionStatus();
if (status != null && txAttr != null) {
retVal = TransactionAspectSupport.VavrDelegate.evaluateTryFailure(retVal, txAttr, status);
}
}
this.commitTransactionAfterReturning(txInfo);
return retVal;
}
}
}
程序执行的是else分支，步骤很清晰
获取TransactionAttribute
基于TransactionAttribute获取TransactionManager
基于TransactionAttribute获取joinpointIdentification(没研究什么作用)
基于1,2,3创建的对象获取 TransactionAspectSupport.TransactionInfo。transactionInfo是TransactionAspectSupport的一个内部类
执行业务方法
抓到异常就回滚，并清除事务，然后向上抛异常；没有异常就清除事务，然后提交。
对象之间的关联关系如下图所示：
TransactionManager的获取比较简单，程序里获取到的其实就是自己配置的bean。
创建TransactionInfo的过程中要先获取TransactionStatus。
TransactionStatus又需要拿到ConnectionHolder。
createTransactionIfNecessary方法在类TransactionAspectSupport中。
protected TransactionAspectSupport.TransactionInfo createTransactionIfNecessary(@Nullable PlatformTransactionManager tm, @Nullable TransactionAttribute txAttr, final String joinpointIdentification) {
if (txAttr != null && ((TransactionAttribute)txAttr).getName() == null) {
txAttr = new DelegatingTransactionAttribute((TransactionAttribute)txAttr) {
public String getName() {
return joinpointIdentification;
}
};
}
TransactionStatus status = null;
if (txAttr != null) {
if (tm != null) {
status = tm.getTransaction((TransactionDefinition)txAttr);
} else if (this.logger.isDebugEnabled()) {
this.logger.debug("Skipping transactional joinpoint [" + joinpointIdentification + "] because no transaction manager has been configured");
}
}
return this.prepareTransactionInfo(tm, (TransactionAttribute)txAttr, joinpointIdentification, status);
}
这里通过status = tm.getTransaction((TransactionDefinition)txAttr)语句来创建TransactionStatus。
接着看语句中的getTransaction方法，它在在类AbstractPlatformTransactionManager中，如下所示：
public final TransactionStatus getTransaction(@Nullable TransactionDefinition definition) throws TransactionException {
Object transaction = this.doGetTransaction();
boolean debugEnabled = this.logger.isDebugEnabled();
if (definition == null) {
definition = new DefaultTransactionDefinition();
}
if (this.isExistingTransaction(transaction)) {
return this.handleExistingTransaction((TransactionDefinition)definition, transaction, debugEnabled);
} else if (((TransactionDefinition)definition).getTimeout() < -1) {
throw new InvalidTimeoutException("Invalid transaction timeout", ((TransactionDefinition)definition).getTimeout());
} else if (((TransactionDefinition)definition).getPropagationBehavior() == 2) {
throw new IllegalTransactionStateException("No existing transaction found for transaction marked with propagation 'mandatory'");
} else if (((TransactionDefinition)definition).getPropagationBehavior() != 0 && ((TransactionDefinition)definition).getPropagationBehavior() != 3 && ((TransactionDefinition)definition).getPropagationBehavior() != 6) {
if (((TransactionDefinition)definition).getIsolationLevel() != -1 && this.logger.isWarnEnabled()) {
this.logger.warn("Custom isolation level specified but no actual transaction initiated; isolation level will effectively be ignored: " + definition);
}
boolean newSynchronization = this.getTransactionSynchronization() == 0;
return this.prepareTransactionStatus((TransactionDefinition)definition, (Object)null, true, newSynchronization, debugEnabled, (Object)null);
} else {
AbstractPlatformTransactionManager.SuspendedResourcesHolder suspendedResources = this.suspend((Object)null);
if (debugEnabled) {
this.logger.debug("Creating new transaction with name [" + ((TransactionDefinition)definition).getName() + "]: " + definition);
}
try {
boolean newSynchronization = this.getTransactionSynchronization() != 2;
DefaultTransactionStatus status = this.newTransactionStatus((TransactionDefinition)definition, transaction, true, newSynchronization, debugEnabled, suspendedResources);
this.doBegin(transaction, (TransactionDefinition)definition);
this.prepareSynchronization(status, (TransactionDefinition)definition);
return status;
} catch (Error | RuntimeException var7) {
this.resume((Object)null, suspendedResources);
throw var7;
}
}
}
通过程序最上面的语句 Object transaction = this.doGetTransaction();来创建DataSourceTransactionObject对象，这是DataSourceTransactionManager的内部类
我们来看语句中的doGetTransaction方法，它在类DataSourceTransactionManager中，如下代码所示：
protected Object doGetTransaction() {
DataSourceTransactionManager.DataSourceTransactionObject txObject = new DataSourceTransactionManager.DataSourceTransactionObject();
txObject.setSavepointAllowed(this.isNestedTransactionAllowed());
ConnectionHolder conHolder = (ConnectionHolder)TransactionSynchronizationManager.getResource(this.obtainDataSource());
txObject.setConnectionHolder(conHolder, false);
return txObject;
}
同时，这里获取了ConnectionHolder对象，此处的newConnectionHolder为false
接着看doGetTransaction方法中的TransactionSynchronizationManager.getResource方法，如下代码所示：
@Nullable
public static Object getResource(Object key) {
Object actualKey = TransactionSynchronizationUtils.unwrapResourceIfNecessary(key);
Object value = doGetResource(actualKey);
if (value != null && logger.isTraceEnabled()) {
logger.trace("Retrieved value [" + value + "] for key [" + actualKey + "] bound to thread [" + Thread.currentThread().getName() + "]");
}
return value;
}
通过一个key获取的，类似于从一个池子里面拿东西一样。
其实当functionOne方法执行时，并没有获取到ConnectionHolder，拿到的是null。
我们继续看getResource方法中的doGetResource方法。
doGetResource方法是在类TransactionSynchronizationManager中。
private static Object doGetResource(Object actualKey) {
Map<Object, Object> map = (Map)resources.get();
if (map == null) {
return null;
} else {
Object value = map.get(actualKey);
if (value instanceof ResourceHolder && ((ResourceHolder)value).isVoid()) {
map.remove(actualKey);
if (map.isEmpty()) {
resources.remove();
}
value = null;
}
return value;
}
}
resources对象其实是一个ThreadLocal，意思是同一个线程中拿到的ConnectionHolder是相同的。
doBegin方法是在类DataSourceTransactionManager中。
protected void doBegin(Object transaction, TransactionDefinition definition) {
DataSourceTransactionManager.DataSourceTransactionObject txObject = (DataSourceTransactionManager.DataSourceTransactionObject)transaction;
Connection con = null;
try {
if (!txObject.hasConnectionHolder() || txObject.getConnectionHolder().isSynchronizedWithTransaction()) {
Connection newCon = this.obtainDataSource().getConnection();
if (this.logger.isDebugEnabled()) {
this.logger.debug("Acquired Connection [" + newCon + "] for JDBC transaction");
}
txObject.setConnectionHolder(new ConnectionHolder(newCon), true);
}
txObject.getConnectionHolder().setSynchronizedWithTransaction(true);
con = txObject.getConnectionHolder().getConnection();
Integer previousIsolationLevel = DataSourceUtils.prepareConnectionForTransaction(con, definition);
txObject.setPreviousIsolationLevel(previousIsolationLevel);
if (con.getAutoCommit()) {
txObject.setMustRestoreAutoCommit(true);
if (this.logger.isDebugEnabled()) {
this.logger.debug("Switching JDBC Connection [" + con + "] to manual commit");
}
con.setAutoCommit(false);
}
this.prepareTransactionalConnection(con, definition);
txObject.getConnectionHolder().setTransactionActive(true);
int timeout = this.determineTimeout(definition);
if (timeout != -1) {
txObject.getConnectionHolder().setTimeoutInSeconds(timeout);
}
if (txObject.isNewConnectionHolder()) {
TransactionSynchronizationManager.bindResource(this.obtainDataSource(), txObject.getConnectionHolder());
}
} catch (Throwable var7) {
if (txObject.isNewConnectionHolder()) {
DataSourceUtils.releaseConnection(con, this.obtainDataSource());
txObject.setConnectionHolder((ConnectionHolder)null, false);
}
throw new CannotCreateTransactionException("Could not open JDBC Connection for transaction", var7);
}
}
截取该方法的重要几行:
Connection newCon = this.obtainDataSource().getConnection();
if (this.logger.isDebugEnabled()) {
this.logger.debug("Acquired Connection [" + newCon + "] for JDBC transaction");
}
txObject.setConnectionHolder(new ConnectionHolder(newCon), true);
先获取连接(java.sql.Connection)，接着创建ConnectionHolder。
newConnectionHolder设置为true，如果之前不为空，newConnectionHolder则为false。
如果newConnectionHolder为true，还需要将connectionHolder放到threadLocal里面，让后面的方法可以获取到相同的ConnectionHolder，截取的代码如下:
if (txObject.isNewConnectionHolder()) {
TransactionSynchronizationManager.bindResource(this.obtainDataSource(), txObject.getConnectionHolder());
}
到此，TransactionStatus就创建好了。
首先看类TransactionAspectSupport中的prepareTransactionInfo。
protected TransactionAspectSupport.TransactionInfo prepareTransactionInfo(@Nullable PlatformTransactionManager tm, @Nullable TransactionAttribute txAttr, String joinpointIdentification, @Nullable TransactionStatus status) {
TransactionAspectSupport.TransactionInfo txInfo = new TransactionAspectSupport.TransactionInfo(tm, txAttr, joinpointIdentification);
if (txAttr != null) {
if (this.logger.isTraceEnabled()) {
this.logger.trace("Getting transaction for [" + txInfo.getJoinpointIdentification() + "]");
}
txInfo.newTransactionStatus(status);
} else if (this.logger.isTraceEnabled()) {
this.logger.trace("Don't need to create transaction for [" + joinpointIdentification + "]: This method isn't transactional.");
}
txInfo.bindToThread();
return txInfo;
}
我们细看txInfo.bindToThread();方法。
bindToThread方法在类TransactionAspectSupport.TransactionInfo中，如下代码所示：
private void bindToThread() {
this.oldTransactionInfo = (TransactionAspectSupport.TransactionInfo)TransactionAspectSupport.transactionInfoHolder.get();
TransactionAspectSupport.transactionInfoHolder.set(this);
}
java.lang.ThreadLocal#get
java.lang.ThreadLocal类中的get方法如下：
public T get() {
Thread t = Thread.currentThread();
ThreadLocalMap map = getMap(t);
if (map != null) {
ThreadLocalMap.Entry e = map.getEntry(this);
if (e != null) {
@SuppressWarnings("unchecked")
T result = (T)e.value;
return result;
}
}
return setInitialValue();
}
bindToThread()的的作用是获取oldTransactionInfo，还有线程有有关。
我们首先看类TransactionAspectSupport中的completeTransactionAfterThrowing方法，如下所示：
protected void completeTransactionAfterThrowing(@Nullable TransactionAspectSupport.TransactionInfo txInfo, Throwable ex) {
if (txInfo != null && txInfo.getTransactionStatus() != null) {
if (this.logger.isTraceEnabled()) {
this.logger.trace("Completing transaction for [" + txInfo.getJoinpointIdentification() + "] after exception: " + ex);
}
if (txInfo.transactionAttribute != null && txInfo.transactionAttribute.rollbackOn(ex)) {
try {
txInfo.getTransactionManager().rollback(txInfo.getTransactionStatus());
} catch (TransactionSystemException var6) {
this.logger.error("Application exception overridden by rollback exception", ex);
var6.initApplicationException(ex);
throw var6;
} catch (Error | RuntimeException var7) {
this.logger.error("Application exception overridden by rollback exception", ex);
throw var7;
}
} else {
try {
txInfo.getTransactionManager().commit(txInfo.getTransactionStatus());
} catch (TransactionSystemException var4) {
this.logger.error("Application exception overridden by commit exception", ex);
var4.initApplicationException(ex);
throw var4;
} catch (Error | RuntimeException var5) {
this.logger.error("Application exception overridden by commit exception", ex);
throw var5;
}
}
}
}
txInfo.getTransactionManager().rollback(txInfo.getTransactionStatus());调用transactionManager进行rollback。
接着看AbstractPlatformTransactionManager类中的rollback方法，如下所示：
public final void rollback(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");
} else {
DefaultTransactionStatus defStatus = (DefaultTransactionStatus)status;
this.processRollback(defStatus, false);
}
}
进一步调自身的processRollback，那就继续看类中AbstractPlatformTransactionManager的processRollback方法，如下所示：
private void processRollback(DefaultTransactionStatus status, boolean unexpected) {
try {
boolean unexpectedRollback = unexpected;
try {
this.triggerBeforeCompletion(status);
if (status.hasSavepoint()) {
if (status.isDebug()) {
this.logger.debug("Rolling back transaction to savepoint");
}
status.rollbackToHeldSavepoint();
} else if (status.isNewTransaction()) {
if (status.isDebug()) {
this.logger.debug("Initiating transaction rollback");
}
this.doRollback(status);
} else {
if (status.hasTransaction()) {
if (!status.isLocalRollbackOnly() && !this.isGlobalRollbackOnParticipationFailure()) {
if (status.isDebug()) {
this.logger.debug("Participating transaction failed - letting transaction originator decide on rollback");
}
} else {
if (status.isDebug()) {
this.logger.debug("Participating transaction failed - marking existing transaction as rollback-only");
}
this.doSetRollbackOnly(status);
}
} else {
this.logger.debug("Should roll back transaction but cannot - no transaction available");
}
if (!this.isFailEarlyOnGlobalRollbackOnly()) {
unexpectedRollback = false;
}
}
} catch (Error | RuntimeException var8) {
this.triggerAfterCompletion(status, 2);
throw var8;
}
this.triggerAfterCompletion(status, 1);
if (unexpectedRollback) {
throw new UnexpectedRollbackException("Transaction rolled back because it has been marked as rollback-only");
}
} finally {
this.cleanupAfterCompletion(status);
}
}
this.triggerBeforeCompletion(status) 方法好像释放了连接。
functionTwo不是新事务，所以最后会执行this.doSetRollbackOnly(status)。
进而看类DataSourceTransactionManager中的doSetRollbackOnly方法，如下所示：
protected void doSetRollbackOnly(DefaultTransactionStatus status) {
DataSourceTransactionManager.DataSourceTransactionObject txObject = (DataSourceTransactionManager.DataSourceTransactionObject)status.getTransaction();
if (status.isDebug()) {
this.logger.debug("Setting JDBC transaction [" + txObject.getConnectionHolder().getConnection() + "] rollback-only");
}
txObject.setRollbackOnly();
}
接着看方法doSetRollbackOnly中的DataSourceTransactionObject.setRollbackOnly()方法，如下所示：
public void setRollbackOnly() {
this.getConnectionHolder().setRollbackOnly();
}
这里，可以看到最终设置的是connectionHolder的rollbackonly属性。
我们首先看TransactionAspectSupport类中的commitTransactionAfterReturning方法，如下所示：
protected void commitTransactionAfterReturning(@Nullable TransactionAspectSupport.TransactionInfo txInfo) {
if (txInfo != null && txInfo.getTransactionStatus() != null) {
if (this.logger.isTraceEnabled()) {
this.logger.trace("Completing transaction for [" + txInfo.getJoinpointIdentification() + "]");
}
txInfo.getTransactionManager().commit(txInfo.getTransactionStatus());
}
}
同样的，这里调用transactionManager进行提交。
紧着看AbstractPlatformTransactionManager中的commit方法，如下所示：
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");
} else {
DefaultTransactionStatus defStatus = (DefaultTransactionStatus)status;
if (defStatus.isLocalRollbackOnly()) {
if (defStatus.isDebug()) {
this.logger.debug("Transactional code has requested rollback");
}
this.processRollback(defStatus, false);
} else if (!this.shouldCommitOnGlobalRollbackOnly() && defStatus.isGlobalRollbackOnly()) {
if (defStatus.isDebug()) {
this.logger.debug("Global transaction is marked as rollback-only but transactional code requested commit");
}
this.processRollback(defStatus, true);
} else {
this.processCommit(defStatus);
}
}
}
这个方法判断了一些无法提交的情况，程序这里走第二个分支，部分代码如下:
else if (!this.shouldCommitOnGlobalRollbackOnly() && defStatus.isGlobalRollbackOnly()) {
if (defStatus.isDebug()) {
this.logger.debug("Global transaction is marked as rollback-only but transactional code requested commit");
}
this.processRollback(defStatus, true);
}
判断条件为:
全局不是rollbackonly时，也提交(这个可能是一个配置的参数，配合在rollbackonly的时候也提交，也就是出现现在这种情况后，不用回滚，直接提交)
并且全局是rollbackonly
进而看类DefaultTransactionStatus中的isGlobalRollbackOnly方法，如下所示：
public boolean isGlobalRollbackOnly() {
return this.transaction instanceof SmartTransactionObject && ((SmartTransactionObject)this.transaction).isRollbackOnly();
}
这里又要满足两个条件：
transaction是DataSourceTransactionObject
DataSourceTransaction继承JdbcTransactionObjectSupport
JdbcTransactionObjectSupport又实现SmartTransactionObject，所以第一个条件满足。
DatSourceTransactionObject的RollbackOnly的get和set方法如下：public void setRollbackOnly() {
this.getConnectionHolder().setRollbackOnly();
}
public boolean isRollbackOnly() {
return this.getConnectionHolder().isRollbackOnly();
}
之前functionTwo方法抛出异常时，就是调用的DataSourceTransactionObject的set方法设置rollbackonly为true，现在再用get方法获取，只要是同一个connectionHolder。
functionOne获取到的rollbackOnly就是true，就会触发回滚，执行this.processRollback(defStatus, true)。
最后再次看类AbstractPlatformTransactionManager中的processRollback方法，如下所示：
private void processRollback(DefaultTransactionStatus status, boolean unexpected) {
try {
boolean unexpectedRollback = unexpected;
try {
this.triggerBeforeCompletion(status);
if (status.hasSavepoint()) {
if (status.isDebug()) {
this.logger.debug("Rolling back transaction to savepoint");
}
status.rollbackToHeldSavepoint();
} else if (status.isNewTransaction()) {
if (status.isDebug()) {
this.logger.debug("Initiating transaction rollback");
}
this.doRollback(status);
} else {
if (status.hasTransaction()) {
if (!status.isLocalRollbackOnly() && !this.isGlobalRollbackOnParticipationFailure()) {
if (status.isDebug()) {
this.logger.debug("Participating transaction failed - letting transaction originator decide on rollback");
}
} else {
if (status.isDebug()) {
this.logger.debug("Participating transaction failed - marking existing transaction as rollback-only");
}
this.doSetRollbackOnly(status);
}
} else {
this.logger.debug("Should roll back transaction but cannot - no transaction available");
}
if (!this.isFailEarlyOnGlobalRollbackOnly()) {
unexpectedRollback = false;
}
}
} catch (Error | RuntimeException var8) {
this.triggerAfterCompletion(status, 2);
throw var8;
}
this.triggerAfterCompletion(status, 1);
if (unexpectedRollback) {
throw new UnexpectedRollbackException("Transaction rolled back because it has been marked as rollback-only");
}
} finally {
this.cleanupAfterCompletion(status);
}
}
到这里unexpectedRollback为true，就抛出了Transaction rolled back because it has been marked as rollback-only这个异常了。
以上就是Transaction silently rolled back because it has been marked as rollback-only错误来分析spring boot的事务机制。
如果有不同意见的，可以在评论区中留言，大家共同进步。
如果你对Knife4j感兴趣，可以参考博文：https://blog.csdn.net/lvoelife/article/details/128114264