- 事务的特性（ACID）：
- 原子性（atomicity）：事务是一个原子操作，是有一系类的动作组成，事务的原子性是确保这一系列动作要么全部完成，要么全部不起作用。
- 一致性（consistency）：一旦事务完成（不管是成功还是失败），系统必须确保他所建模的业务处于一致的状态，在现实的数据中不应该被破坏。
- 隔离性（isolation）：在多事务的操作相同的数据时每个事物都应该与其他事物隔离开来，防止数据破坏。
- 持久性（durability）： 一旦事务完成。无论系统发生什么错误，他的结果都不应该收到影响，这样就能从任何系统崩溃中回复过来，通常情况下，事物的结果被持久化存储。
- 核心接口
Spring事务管理的实现有许多细节，如果对整个接口框架有个大体了解会非常有利于我们理解事务，下面通过讲解Spring的事务接口来了解Spring实现事务的具体策略。 Spring事务管理涉及的接口的联系如下： - 事物管理器
spring并不是直接管理事务，而是提供事务管理器给第三方去实现。spring提供的事务管理接口为org.springframework.transaction.PlatformTransactionManager，此接口的具体内容为：
public interface PlatformTransactionManager { /** * Return a currently active transaction or create a new one, according to * the specified propagation behavior. * <p>Note that parameters like isolation level or timeout will only be applied * to new transactions, and thus be ignored when participating in active ones. * <p>Furthermore, not all transaction definition settings will be supported * by every transaction manager: A proper transaction manager implementation * should throw an exception when unsupported settings are encountered. * <p>An exception to the above rule is the read-only flag, which should be * ignored if no explicit read-only mode is supported. Essentially, the * read-only flag is just a hint for potential optimization. * @param definition TransactionDefinition instance (can be {@code null} for defaults), * describing propagation behavior, isolation level, timeout etc. * @return transaction status object representing the new or current transaction * @throws TransactionException in case of lookup, creation, or system errors * @throws IllegalTransactionStateException if the given transaction definition * cannot be executed (for example, if a currently active transaction is in * conflict with the specified propagation behavior) * @see TransactionDefinition#getPropagationBehavior * @see TransactionDefinition#getIsolationLevel * @see TransactionDefinition#getTimeout * @see TransactionDefinition#isReadOnly */ TransactionStatus getTransaction(TransactionDefinition definition) throws TransactionException; /** * Commit the given transaction, with regard to its status. If the transaction * has been marked rollback-only programmatically, perform a rollback. * <p>If the transaction wasn't a new one, omit the commit for proper * participation in the surrounding transaction. If a previous transaction * has been suspended to be able to create a new one, resume the previous * transaction after committing the new one. * <p>Note that when the commit call completes, no matter if normally or * throwing an exception, the transaction must be fully completed and * cleaned up. No rollback call should be expected in such a case. * <p>If this method throws an exception other than a TransactionException, * then some before-commit error caused the commit attempt to fail. For * example, an O/R Mapping tool might have tried to flush changes to the * database right before commit, with the resulting DataAccessException * causing the transaction to fail. The original exception will be * propagated to the caller of this commit method in such a case. * @param status object returned by the {@code getTransaction} method * @throws UnexpectedRollbackException in case of an unexpected rollback * that the transaction coordinator initiated * @throws HeuristicCompletionException in case of a transaction failure * caused by a heuristic decision on the side of the transaction coordinator * @throws TransactionSystemException in case of commit or system errors * (typically caused by fundamental resource failures) * @throws IllegalTransactionStateException if the given transaction * is already completed (that is, committed or rolled back) * @see TransactionStatus#setRollbackOnly */ void commit(TransactionStatus status) throws TransactionException; /** * Perform a rollback of the given transaction. * <p>If the transaction wasn't a new one, just set it rollback-only for proper * participation in the surrounding transaction. If a previous transaction * has been suspended to be able to create a new one, resume the previous * transaction after rolling back the new one. * <p><b>Do not call rollback on a transaction if commit threw an exception.</b> * The transaction will already have been completed and cleaned up when commit * returns, even in case of a commit exception. Consequently, a rollback call * after commit failure will lead to an IllegalTransactionStateException. * @param status object returned by the {@code getTransaction} method * @throws TransactionSystemException in case of rollback or system errors * (typically caused by fundamental resource failures) * @throws IllegalTransactionStateException if the given transaction * is already completed (that is, committed or rolled back) */ void rollback(TransactionStatus status) throws TransactionException; }
从这里可知具体的具体的事务管理机制对Spring来说是透明的，它并不关心那些，那些是对应各个平台需要关心的，所以Spring事务管理的一个优点就是为不同的事务API提供一致的编程模型，如JTA、JDBC、Hibernate、JPA。下面分别介绍各个平台框架实现事务管理的机制。
一下是一些实现的事务管理类：
- jdbc事务管理
public abstract class AbstractPlatformTransactionManager implements PlatformTransactionManager, Serializable { public static final int SYNCHRONIZATION_ALWAYS = 0; public static final int SYNCHRONIZATION_ON_ACTUAL_TRANSACTION = 1; /** * Never active transaction synchronization, not even for actual transactions. */ public static final int SYNCHRONIZATION_NEVER = 2; /** * Constants instance for AbstractPlatformTransactionManager */ private static final Constants constants = new Constants(AbstractPlatformTransactionManager.class); protected transient Log logger = LogFactory.getLog(getClass()); private int transactionSynchronization = SYNCHRONIZATION_ALWAYS; private int defaultTimeout = TransactionDefinition.TIMEOUT_DEFAULT; private boolean nestedTransactionAllowed = false; private boolean validateExistingTransaction = false; private boolean globalRollbackOnParticipationFailure = true; private boolean failEarlyOnGlobalRollbackOnly = false; private boolean rollbackOnCommitFailure = false; public final void setTransactionSynchronizationName(String constantName) { setTransactionSynchronization(constants.asNumber(constantName).intValue()); } public final void setTransactionSynchronization(int transactionSynchronization) { this.transactionSynchronization = transactionSynchronization; } public final int getTransactionSynchronization() { return this.transactionSynchronization; } public final void setDefaultTimeout(int defaultTimeout) { if (defaultTimeout < TransactionDefinition.TIMEOUT_DEFAULT) { throw new InvalidTimeoutException("Invalid default timeout", defaultTimeout); } this.defaultTimeout = defaultTimeout; } public final int getDefaultTimeout() { return this.defaultTimeout; } public final void setNestedTransactionAllowed(boolean nestedTransactionAllowed) { this.nestedTransactionAllowed = nestedTransactionAllowed; } /** * Return whether nested transactions are allowed. */ public final boolean isNestedTransactionAllowed() { return this.nestedTransactionAllowed; } public final void setValidateExistingTransaction(boolean validateExistingTransaction) { this.validateExistingTransaction = validateExistingTransaction; } /** * Return whether existing transactions should be validated before participating * in them. */ public final boolean isValidateExistingTransaction() { return this.validateExistingTransaction; } public final void setGlobalRollbackOnParticipationFailure(boolean globalRollbackOnParticipationFailure) { this.globalRollbackOnParticipationFailure = globalRollbackOnParticipationFailure; } /** * Return whether to globally mark an existing transaction as rollback-only * after a participating transaction failed. */ public final boolean isGlobalRollbackOnParticipationFailure() { return this.globalRollbackOnParticipationFailure; } public final void setFailEarlyOnGlobalRollbackOnly(boolean failEarlyOnGlobalRollbackOnly) { this.failEarlyOnGlobalRollbackOnly = failEarlyOnGlobalRollbackOnly; } /** * Return whether to fail early in case of the transaction being globally marked * as rollback-only. */ public final boolean isFailEarlyOnGlobalRollbackOnly() { return this.failEarlyOnGlobalRollbackOnly; } public final void setRollbackOnCommitFailure(boolean rollbackOnCommitFailure) { this.rollbackOnCommitFailure = rollbackOnCommitFailure; } /** * Return whether {@code doRollback} should be performed on failure of the * {@code doCommit} call. */ public final boolean isRollbackOnCommitFailure() { return this.rollbackOnCommitFailure; } //--------------------------------------------------------------------- // Implementation of PlatformTransactionManager //--------------------------------------------------------------------- public final TransactionStatus getTransaction(TransactionDefinition definition) throws TransactionException { Object transaction = doGetTransaction(); // Cache debug flag to avoid repeated checks. boolean debugEnabled = logger.isDebugEnabled(); if (definition == null) { // Use defaults if no transaction definition given. definition = new DefaultTransactionDefinition(); } if (isExistingTransaction(transaction)) { // Existing transaction found -> check propagation behavior to find out how to behave. return handleExistingTransaction(definition, transaction, debugEnabled); } // Check definition settings for new transaction. if (definition.getTimeout() < TransactionDefinition.TIMEOUT_DEFAULT) { throw new InvalidTimeoutException("Invalid transaction timeout", definition.getTimeout()); } // No existing transaction found -> check propagation behavior to find out how to proceed. if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_MANDATORY) { throw new IllegalTransactionStateException( "No existing transaction found for transaction marked with propagation 'mandatory'"); } else if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRED || definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW || definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NESTED) { SuspendedResourcesHolder suspendedResources = suspend(null); if (debugEnabled) { logger.debug("Creating new transaction with name [" + definition.getName() + "]: " + definition); } try { boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER); DefaultTransactionStatus status = newTransactionStatus( definition, transaction, true, newSynchronization, debugEnabled, suspendedResources); doBegin(transaction, definition); prepareSynchronization(status, definition); return status; } catch (RuntimeException ex) { resume(null, suspendedResources); throw ex; } catch (Error err) { resume(null, suspendedResources); throw err; } } else { // Create "empty" transaction: no actual transaction, but potentially synchronization. boolean newSynchronization = (getTransactionSynchronization() == SYNCHRONIZATION_ALWAYS); return prepareTransactionStatus(definition, null, true, newSynchronization, debugEnabled, null); } } private TransactionStatus handleExistingTransaction( TransactionDefinition definition, Object transaction, boolean debugEnabled) throws TransactionException { if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NEVER) { throw new IllegalTransactionStateException( "Existing transaction found for transaction marked with propagation 'never'"); } if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NOT_SUPPORTED) { if (debugEnabled) { logger.debug("Suspending current transaction"); } Object suspendedResources = suspend(transaction); boolean newSynchronization = (getTransactionSynchronization() == SYNCHRONIZATION_ALWAYS); return prepareTransactionStatus( definition, null, false, newSynchronization, debugEnabled, suspendedResources); } if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW) { if (debugEnabled) { logger.debug("Suspending current transaction, creating new transaction with name [" + definition.getName() + "]"); } SuspendedResourcesHolder suspendedResources = suspend(transaction); try { boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER); DefaultTransactionStatus status = newTransactionStatus( definition, transaction, true, newSynchronization, debugEnabled, suspendedResources); doBegin(transaction, definition); prepareSynchronization(status, definition); return status; } catch (RuntimeException beginEx) { resumeAfterBeginException(transaction, suspendedResources, beginEx); throw beginEx; } catch (Error beginErr) { resumeAfterBeginException(transaction, suspendedResources, beginErr); throw beginErr; } } 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); 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. boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER); DefaultTransactionStatus status = newTransactionStatus( definition, transaction, true, newSynchronization, debugEnabled, null); doBegin(transaction, definition); prepareSynchronization(status, definition); return status; } } // 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"); } } } boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER); return prepareTransactionStatus(definition, transaction, false, newSynchronization, debugEnabled, null); } protected final DefaultTransactionStatus prepareTransactionStatus( TransactionDefinition definition, Object transaction, boolean newTransaction, boolean newSynchronization, boolean debug, Object suspendedResources) { DefaultTransactionStatus status = newTransactionStatus( definition, transaction, newTransaction, newSynchronization, debug, suspendedResources); prepareSynchronization(status, definition); return status; } protected DefaultTransactionStatus newTransactionStatus( TransactionDefinition definition, Object transaction, boolean newTransaction, boolean newSynchronization, boolean debug, Object suspendedResources) { boolean actualNewSynchronization = newSynchronization && !TransactionSynchronizationManager.isSynchronizationActive(); return new DefaultTransactionStatus( transaction, newTransaction, actualNewSynchronization, definition.isReadOnly(), debug, suspendedResources); } protected void prepareSynchronization(DefaultTransactionStatus status, TransactionDefinition definition) { if (status.isNewSynchronization()) { TransactionSynchronizationManager.setActualTransactionActive(status.hasTransaction()); TransactionSynchronizationManager.setCurrentTransactionIsolationLevel( (definition.getIsolationLevel() != TransactionDefinition.ISOLATION_DEFAULT) ? definition.getIsolationLevel() : null); TransactionSynchronizationManager.setCurrentTransactionReadOnly(definition.isReadOnly()); TransactionSynchronizationManager.setCurrentTransactionName(definition.getName()); TransactionSynchronizationManager.initSynchronization(); } } protected int determineTimeout(TransactionDefinition definition) { if (definition.getTimeout() != TransactionDefinition.TIMEOUT_DEFAULT) { return definition.getTimeout(); } return this.defaultTimeout; } protected final SuspendedResourcesHolder suspend(Object transaction) throws TransactionException { if (TransactionSynchronizationManager.isSynchronizationActive()) { List<TransactionSynchronization> suspendedSynchronizations = doSuspendSynchronization(); try { Object suspendedResources = null; if (transaction != null) { suspendedResources = doSuspend(transaction); } 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); return new SuspendedResourcesHolder( suspendedResources, suspendedSynchronizations, name, readOnly, isolationLevel, wasActive); } catch (RuntimeException ex) { // doSuspend failed - original transaction is still active... doResumeSynchronization(suspendedSynchronizations); throw ex; } catch (Error err) { // doSuspend failed - original transaction is still active... doResumeSynchronization(suspendedSynchronizations); throw err; } } 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; } } protected final void resume(Object transaction, SuspendedResourcesHolder resourcesHolder) throws TransactionException { if (resourcesHolder != null) { Object suspendedResources = resourcesHolder.suspendedResources; if (suspendedResources != null) { doResume(transaction, suspendedResources); } List<TransactionSynchronization> suspendedSynchronizations = resourcesHolder.suspendedSynchronizations; if (suspendedSynchronizations != null) { TransactionSynchronizationManager.setActualTransactionActive(resourcesHolder.wasActive); TransactionSynchronizationManager.setCurrentTransactionIsolationLevel(resourcesHolder.isolationLevel); TransactionSynchronizationManager.setCurrentTransactionReadOnly(resourcesHolder.readOnly); TransactionSynchronizationManager.setCurrentTransactionName(resourcesHolder.name); doResumeSynchronization(suspendedSynchronizations); } } } private void resumeAfterBeginException( Object transaction, SuspendedResourcesHolder suspendedResources, Throwable beginEx) { String exMessage = "Inner transaction begin exception overridden by outer transaction resume exception"; try { resume(transaction, suspendedResources); } catch (RuntimeException resumeEx) { logger.error(exMessage, beginEx); throw resumeEx; } catch (Error resumeErr) { logger.error(exMessage, beginEx); throw resumeErr; } } private List<TransactionSynchronization> doSuspendSynchronization() { List<TransactionSynchronization> suspendedSynchronizations = TransactionSynchronizationManager.getSynchronizations(); for (TransactionSynchronization synchronization : suspendedSynchronizations) { synchronization.suspend(); } TransactionSynchronizationManager.clearSynchronization(); return suspendedSynchronizations; } private void doResumeSynchronization(List<TransactionSynchronization> suspendedSynchronizations) { TransactionSynchronizationManager.initSynchronization(); for (TransactionSynchronization synchronization : suspendedSynchronizations) { synchronization.resume(); TransactionSynchronizationManager.registerSynchronization(synchronization); } } 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; if (defStatus.isLocalRollbackOnly()) { if (defStatus.isDebug()) { logger.debug("Transactional code has requested rollback"); } processRollback(defStatus); return; } if (!shouldCommitOnGlobalRollbackOnly() && defStatus.isGlobalRollbackOnly()) { if (defStatus.isDebug()) { logger.debug("Global transaction is marked as rollback-only but transactional code requested commit"); } processRollback(defStatus); // Throw UnexpectedRollbackException only at outermost transaction boundary // or if explicitly asked to. if (status.isNewTransaction() || isFailEarlyOnGlobalRollbackOnly()) { throw new UnexpectedRollbackException( "Transaction rolled back because it has been marked as rollback-only"); } return; } processCommit(defStatus); } private void processCommit(DefaultTransactionStatus status) throws TransactionException { try { boolean beforeCompletionInvoked = false; try { prepareForCommit(status); triggerBeforeCommit(status); triggerBeforeCompletion(status); beforeCompletionInvoked = true; boolean globalRollbackOnly = false; if (status.isNewTransaction() || isFailEarlyOnGlobalRollbackOnly()) { globalRollbackOnly = status.isGlobalRollbackOnly(); } if (status.hasSavepoint()) { if (status.isDebug()) { logger.debug("Releasing transaction savepoint"); } status.releaseHeldSavepoint(); } else if (status.isNewTransaction()) { if (status.isDebug()) { logger.debug("Initiating transaction commit"); } doCommit(status); } // Throw UnexpectedRollbackException if we have a global rollback-only // marker but still didn't get a corresponding exception from commit. if (globalRollbackOnly) { 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 ex) { if (!beforeCompletionInvoked) { triggerBeforeCompletion(status); } doRollbackOnCommitException(status, ex); throw ex; } catch (Error err) { if (!beforeCompletionInvoked) { triggerBeforeCompletion(status); } doRollbackOnCommitException(status, err); throw err; } // Trigger afterCommit callbacks, with an exception thrown there // propagated to callers but the transaction still considered as committed. try { triggerAfterCommit(status); } finally { triggerAfterCompletion(status, TransactionSynchronization.STATUS_COMMITTED); } } finally { cleanupAfterCompletion(status); } } 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"); } DefaultTransactionStatus defStatus = (DefaultTransactionStatus) status; processRollback(defStatus); } private void processRollback(DefaultTransactionStatus status) { try { try { triggerBeforeCompletion(status); if (status.hasSavepoint()) { if (status.isDebug()) { logger.debug("Rolling back transaction to savepoint"); } status.rollbackToHeldSavepoint(); } else if (status.isNewTransaction()) { if (status.isDebug()) { logger.debug("Initiating transaction rollback"); } doRollback(status); } else if (status.hasTransaction()) { if (status.isLocalRollbackOnly() || isGlobalRollbackOnParticipationFailure()) { if (status.isDebug()) { logger.debug("Participating transaction failed - marking existing transaction as rollback-only"); } 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"); } } catch (RuntimeException ex) { triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN); throw ex; } catch (Error err) { triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN); throw err; } triggerAfterCompletion(status, TransactionSynchronization.STATUS_ROLLED_BACK); } finally { cleanupAfterCompletion(status); } } private void doRollbackOnCommitException(DefaultTransactionStatus status, Throwable ex) throws TransactionException { try { if (status.isNewTransaction()) { if (status.isDebug()) { logger.debug("Initiating transaction rollback after commit exception", ex); } doRollback(status); } else if (status.hasTransaction() && isGlobalRollbackOnParticipationFailure()) { if (status.isDebug()) { logger.debug("Marking existing transaction as rollback-only after commit exception", ex); } doSetRollbackOnly(status); } } catch (RuntimeException rbex) { logger.error("Commit exception overridden by rollback exception", ex); triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN); throw rbex; } catch (Error rberr) { logger.error("Commit exception overridden by rollback exception", ex); triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN); throw rberr; } triggerAfterCompletion(status, TransactionSynchronization.STATUS_ROLLED_BACK); } protected final void triggerBeforeCommit(DefaultTransactionStatus status) { if (status.isNewSynchronization()) { if (status.isDebug()) { logger.trace("Triggering beforeCommit synchronization"); } TransactionSynchronizationUtils.triggerBeforeCommit(status.isReadOnly()); } } protected final void triggerBeforeCompletion(DefaultTransactionStatus status) { if (status.isNewSynchronization()) { if (status.isDebug()) { logger.trace("Triggering beforeCompletion synchronization"); } TransactionSynchronizationUtils.triggerBeforeCompletion(); } } private void triggerAfterCommit(DefaultTransactionStatus status) { if (status.isNewSynchronization()) { if (status.isDebug()) { logger.trace("Triggering afterCommit synchronization"); } TransactionSynchronizationUtils.triggerAfterCommit(); } } private void triggerAfterCompletion(DefaultTransactionStatus status, int completionStatus) { if (status.isNewSynchronization()) { List<TransactionSynchronization> synchronizations = TransactionSynchronizationManager.getSynchronizations(); if (!status.hasTransaction() || status.isNewTransaction()) { if (status.isDebug()) { logger.trace("Triggering afterCompletion synchronization"); } // No transaction or new transaction for the current scope -> // invoke the afterCompletion callbacks immediately invokeAfterCompletion(synchronizations, completionStatus); } else if (!synchronizations.isEmpty()) { // Existing transaction that we participate in, controlled outside // of the scope of this Spring transaction manager -> try to register // an afterCompletion callback with the existing (JTA) transaction. registerAfterCompletionWithExistingTransaction(status.getTransaction(), synchronizations); } } } protected final void invokeAfterCompletion(List<TransactionSynchronization> synchronizations, int completionStatus) { TransactionSynchronizationUtils.invokeAfterCompletion(synchronizations, completionStatus); } private void cleanupAfterCompletion(DefaultTransactionStatus status) { status.setCompleted(); if (status.isNewSynchronization()) { TransactionSynchronizationManager.clear(); } if (status.isNewTransaction()) { doCleanupAfterCompletion(status.getTransaction()); } if (status.getSuspendedResources() != null) { if (status.isDebug()) { logger.debug("Resuming suspended transaction after completion of inner transaction"); } resume(status.getTransaction(), (SuspendedResourcesHolder) status.getSuspendedResources()); } } //--------------------------------------------------------------------- // Template methods to be implemented in subclasses //--------------------------------------------------------------------- protected abstract Object doGetTransaction() throws TransactionException; protected boolean isExistingTransaction(Object transaction) throws TransactionException { return false; } protected boolean useSavepointForNestedTransaction() { return true; } protected abstract void doBegin(Object transaction, TransactionDefinition definition) throws TransactionException; protected Object doSuspend(Object transaction) throws TransactionException { throw new TransactionSuspensionNotSupportedException( "Transaction manager [" + getClass().getName() + "] does not support transaction suspension"); } protected void doResume(Object transaction, Object suspendedResources) throws TransactionException { throw new TransactionSuspensionNotSupportedException( "Transaction manager [" + getClass().getName() + "] does not support transaction suspension"); } protected boolean shouldCommitOnGlobalRollbackOnly() { return false; } protected void prepareForCommit(DefaultTransactionStatus status) { } protected abstract void doCommit(DefaultTransactionStatus status) throws TransactionException; protected abstract void doRollback(DefaultTransactionStatus status) throws TransactionException; protected void doSetRollbackOnly(DefaultTransactionStatus status) throws TransactionException { throw new IllegalTransactionStateException( "Participating in existing transactions is not supported - when 'isExistingTransaction' " + "returns true, appropriate 'doSetRollbackOnly' behavior must be provided"); } protected void registerAfterCompletionWithExistingTransaction( Object transaction, List<TransactionSynchronization> synchronizations) throws TransactionException { logger.debug("Cannot register Spring after-completion synchronization with existing transaction - " + "processing Spring after-completion callbacks immediately, with outcome status 'unknown'"); invokeAfterCompletion(synchronizations, TransactionSynchronization.STATUS_UNKNOWN); } protected void doCleanupAfterCompletion(Object transaction) { } //--------------------------------------------------------------------- // Serialization support //--------------------------------------------------------------------- private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException { // Rely on default serialization; just initialize state after deserialization. ois.defaultReadObject(); // Initialize transient fields. this.logger = LogFactory.getLog(getClass()); } /** * Holder for suspended resources. * Used internally by {@code suspend} and {@code resume}. */ protected static class SuspendedResourcesHolder { private final Object suspendedResources; private List<TransactionSynchronization> suspendedSynchronizations; private String name; private boolean readOnly; private Integer isolationLevel; private boolean wasActive; private SuspendedResourcesHolder(Object suspendedResources) { this.suspendedResources = suspendedResources; } private SuspendedResourcesHolder( Object suspendedResources, List<TransactionSynchronization> suspendedSynchronizations, String name, boolean readOnly, Integer isolationLevel, boolean wasActive) { this.suspendedResources = suspendedResources; this.suspendedSynchronizations = suspendedSynchronizations; this.name = name; this.readOnly = readOnly; this.isolationLevel = isolationLevel; this.wasActive = wasActive; } } }
public abstract class AbstractPlatformTransactionManager implements PlatformTransactionManager, Serializable { public static final int SYNCHRONIZATION_ALWAYS = 0; public static final int SYNCHRONIZATION_ON_ACTUAL_TRANSACTION = 1; /** * Never active transaction synchronization, not even for actual transactions. */ public static final int SYNCHRONIZATION_NEVER = 2; /** * Constants instance for AbstractPlatformTransactionManager */ private static final Constants constants = new Constants(AbstractPlatformTransactionManager.class); protected transient Log logger = LogFactory.getLog(getClass()); private int transactionSynchronization = SYNCHRONIZATION_ALWAYS; private int defaultTimeout = TransactionDefinition.TIMEOUT_DEFAULT; private boolean nestedTransactionAllowed = false; private boolean validateExistingTransaction = false; private boolean globalRollbackOnParticipationFailure = true; private boolean failEarlyOnGlobalRollbackOnly = false; private boolean rollbackOnCommitFailure = false; public final void setTransactionSynchronizationName(String constantName) { setTransactionSynchronization(constants.asNumber(constantName).intValue()); } public final void setTransactionSynchronization(int transactionSynchronization) { this.transactionSynchronization = transactionSynchronization; } public final int getTransactionSynchronization() { return this.transactionSynchronization; } public final void setDefaultTimeout(int defaultTimeout) { if (defaultTimeout < TransactionDefinition.TIMEOUT_DEFAULT) { throw new InvalidTimeoutException("Invalid default timeout", defaultTimeout); } this.defaultTimeout = defaultTimeout; } public final int getDefaultTimeout() { return this.defaultTimeout; } public final void setNestedTransactionAllowed(boolean nestedTransactionAllowed) { this.nestedTransactionAllowed = nestedTransactionAllowed; } /** * Return whether nested transactions are allowed. */ public final boolean isNestedTransactionAllowed() { return this.nestedTransactionAllowed; } public final void setValidateExistingTransaction(boolean validateExistingTransaction) { this.validateExistingTransaction = validateExistingTransaction; } /** * Return whether existing transactions should be validated before participating * in them. */ public final boolean isValidateExistingTransaction() { return this.validateExistingTransaction; } public final void setGlobalRollbackOnParticipationFailure(boolean globalRollbackOnParticipationFailure) { this.globalRollbackOnParticipationFailure = globalRollbackOnParticipationFailure; } /** * Return whether to globally mark an existing transaction as rollback-only * after a participating transaction failed. */ public final boolean isGlobalRollbackOnParticipationFailure() { return this.globalRollbackOnParticipationFailure; } public final void setFailEarlyOnGlobalRollbackOnly(boolean failEarlyOnGlobalRollbackOnly) { this.failEarlyOnGlobalRollbackOnly = failEarlyOnGlobalRollbackOnly; } /** * Return whether to fail early in case of the transaction being globally marked * as rollback-only. */ public final boolean isFailEarlyOnGlobalRollbackOnly() { return this.failEarlyOnGlobalRollbackOnly; } public final void setRollbackOnCommitFailure(boolean rollbackOnCommitFailure) { this.rollbackOnCommitFailure = rollbackOnCommitFailure; } /** * Return whether {@code doRollback} should be performed on failure of the * {@code doCommit} call. */ public final boolean isRollbackOnCommitFailure() { return this.rollbackOnCommitFailure; } //--------------------------------------------------------------------- // Implementation of PlatformTransactionManager //--------------------------------------------------------------------- public final TransactionStatus getTransaction(TransactionDefinition definition) throws TransactionException { Object transaction = doGetTransaction(); // Cache debug flag to avoid repeated checks. boolean debugEnabled = logger.isDebugEnabled(); if (definition == null) { // Use defaults if no transaction definition given. definition = new DefaultTransactionDefinition(); } if (isExistingTransaction(transaction)) { // Existing transaction found -> check propagation behavior to find out how to behave. return handleExistingTransaction(definition, transaction, debugEnabled); } // Check definition settings for new transaction. if (definition.getTimeout() < TransactionDefinition.TIMEOUT_DEFAULT) { throw new InvalidTimeoutException("Invalid transaction timeout", definition.getTimeout()); } // No existing transaction found -> check propagation behavior to find out how to proceed. if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_MANDATORY) { throw new IllegalTransactionStateException( "No existing transaction found for transaction marked with propagation 'mandatory'"); } else if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRED || definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW || definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NESTED) { SuspendedResourcesHolder suspendedResources = suspend(null); if (debugEnabled) { logger.debug("Creating new transaction with name [" + definition.getName() + "]: " + definition); } try { boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER); DefaultTransactionStatus status = newTransactionStatus( definition, transaction, true, newSynchronization, debugEnabled, suspendedResources); doBegin(transaction, definition); prepareSynchronization(status, definition); return status; } catch (RuntimeException ex) { resume(null, suspendedResources); throw ex; } catch (Error err) { resume(null, suspendedResources); throw err; } } else { // Create "empty" transaction: no actual transaction, but potentially synchronization. boolean newSynchronization = (getTransactionSynchronization() == SYNCHRONIZATION_ALWAYS); return prepareTransactionStatus(definition, null, true, newSynchronization, debugEnabled, null); } } private TransactionStatus handleExistingTransaction( TransactionDefinition definition, Object transaction, boolean debugEnabled) throws TransactionException { if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NEVER) { throw new IllegalTransactionStateException( "Existing transaction found for transaction marked with propagation 'never'"); } if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NOT_SUPPORTED) { if (debugEnabled) { logger.debug("Suspending current transaction"); } Object suspendedResources = suspend(transaction); boolean newSynchronization = (getTransactionSynchronization() == SYNCHRONIZATION_ALWAYS); return prepareTransactionStatus( definition, null, false, newSynchronization, debugEnabled, suspendedResources); } if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW) { if (debugEnabled) { logger.debug("Suspending current transaction, creating new transaction with name [" + definition.getName() + "]"); } SuspendedResourcesHolder suspendedResources = suspend(transaction); try { boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER); DefaultTransactionStatus status = newTransactionStatus( definition, transaction, true, newSynchronization, debugEnabled, suspendedResources); doBegin(transaction, definition); prepareSynchronization(status, definition); return status; } catch (RuntimeException beginEx) { resumeAfterBeginException(transaction, suspendedResources, beginEx); throw beginEx; } catch (Error beginErr) { resumeAfterBeginException(transaction, suspendedResources, beginErr); throw beginErr; } } 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); 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. boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER); DefaultTransactionStatus status = newTransactionStatus( definition, transaction, true, newSynchronization, debugEnabled, null); doBegin(transaction, definition); prepareSynchronization(status, definition); return status; } } // 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"); } } } boolean newSynchronization = (getTransactionSynchronization() != SYNCHRONIZATION_NEVER); return prepareTransactionStatus(definition, transaction, false, newSynchronization, debugEnabled, null); } protected final DefaultTransactionStatus prepareTransactionStatus( TransactionDefinition definition, Object transaction, boolean newTransaction, boolean newSynchronization, boolean debug, Object suspendedResources) { DefaultTransactionStatus status = newTransactionStatus( definition, transaction, newTransaction, newSynchronization, debug, suspendedResources); prepareSynchronization(status, definition); return status; } protected DefaultTransactionStatus newTransactionStatus( TransactionDefinition definition, Object transaction, boolean newTransaction, boolean newSynchronization, boolean debug, Object suspendedResources) { boolean actualNewSynchronization = newSynchronization && !TransactionSynchronizationManager.isSynchronizationActive(); return new DefaultTransactionStatus( transaction, newTransaction, actualNewSynchronization, definition.isReadOnly(), debug, suspendedResources); } protected void prepareSynchronization(DefaultTransactionStatus status, TransactionDefinition definition) { if (status.isNewSynchronization()) { TransactionSynchronizationManager.setActualTransactionActive(status.hasTransaction()); TransactionSynchronizationManager.setCurrentTransactionIsolationLevel( (definition.getIsolationLevel() != TransactionDefinition.ISOLATION_DEFAULT) ? definition.getIsolationLevel() : null); TransactionSynchronizationManager.setCurrentTransactionReadOnly(definition.isReadOnly()); TransactionSynchronizationManager.setCurrentTransactionName(definition.getName()); TransactionSynchronizationManager.initSynchronization(); } } protected int determineTimeout(TransactionDefinition definition) { if (definition.getTimeout() != TransactionDefinition.TIMEOUT_DEFAULT) { return definition.getTimeout(); } return this.defaultTimeout; } protected final SuspendedResourcesHolder suspend(Object transaction) throws TransactionException { if (TransactionSynchronizationManager.isSynchronizationActive()) { List<TransactionSynchronization> suspendedSynchronizations = doSuspendSynchronization(); try { Object suspendedResources = null; if (transaction != null) { suspendedResources = doSuspend(transaction); } 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); return new SuspendedResourcesHolder( suspendedResources, suspendedSynchronizations, name, readOnly, isolationLevel, wasActive); } catch (RuntimeException ex) { // doSuspend failed - original transaction is still active... doResumeSynchronization(suspendedSynchronizations); throw ex; } catch (Error err) { // doSuspend failed - original transaction is still active... doResumeSynchronization(suspendedSynchronizations); throw err; } } 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; } } protected final void resume(Object transaction, SuspendedResourcesHolder resourcesHolder) throws TransactionException { if (resourcesHolder != null) { Object suspendedResources = resourcesHolder.suspendedResources; if (suspendedResources != null) { doResume(transaction, suspendedResources); } List<TransactionSynchronization> suspendedSynchronizations = resourcesHolder.suspendedSynchronizations; if (suspendedSynchronizations != null) { TransactionSynchronizationManager.setActualTransactionActive(resourcesHolder.wasActive); TransactionSynchronizationManager.setCurrentTransactionIsolationLevel(resourcesHolder.isolationLevel); TransactionSynchronizationManager.setCurrentTransactionReadOnly(resourcesHolder.readOnly); TransactionSynchronizationManager.setCurrentTransactionName(resourcesHolder.name); doResumeSynchronization(suspendedSynchronizations); } } } private void resumeAfterBeginException( Object transaction, SuspendedResourcesHolder suspendedResources, Throwable beginEx) { String exMessage = "Inner transaction begin exception overridden by outer transaction resume exception"; try { resume(transaction, suspendedResources); } catch (RuntimeException resumeEx) { logger.error(exMessage, beginEx); throw resumeEx; } catch (Error resumeErr) { logger.error(exMessage, beginEx); throw resumeErr; } } private List<TransactionSynchronization> doSuspendSynchronization() { List<TransactionSynchronization> suspendedSynchronizations = TransactionSynchronizationManager.getSynchronizations(); for (TransactionSynchronization synchronization : suspendedSynchronizations) { synchronization.suspend(); } TransactionSynchronizationManager.clearSynchronization(); return suspendedSynchronizations; } private void doResumeSynchronization(List<TransactionSynchronization> suspendedSynchronizations) { TransactionSynchronizationManager.initSynchronization(); for (TransactionSynchronization synchronization : suspendedSynchronizations) { synchronization.resume(); TransactionSynchronizationManager.registerSynchronization(synchronization); } } 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; if (defStatus.isLocalRollbackOnly()) { if (defStatus.isDebug()) { logger.debug("Transactional code has requested rollback"); } processRollback(defStatus); return; } if (!shouldCommitOnGlobalRollbackOnly() && defStatus.isGlobalRollbackOnly()) { if (defStatus.isDebug()) { logger.debug("Global transaction is marked as rollback-only but transactional code requested commit"); } processRollback(defStatus); // Throw UnexpectedRollbackException only at outermost transaction boundary // or if explicitly asked to. if (status.isNewTransaction() || isFailEarlyOnGlobalRollbackOnly()) { throw new UnexpectedRollbackException( "Transaction rolled back because it has been marked as rollback-only"); } return; } processCommit(defStatus); } private void processCommit(DefaultTransactionStatus status) throws TransactionException { try { boolean beforeCompletionInvoked = false; try { prepareForCommit(status); triggerBeforeCommit(status); triggerBeforeCompletion(status); beforeCompletionInvoked = true; boolean globalRollbackOnly = false; if (status.isNewTransaction() || isFailEarlyOnGlobalRollbackOnly()) { globalRollbackOnly = status.isGlobalRollbackOnly(); } if (status.hasSavepoint()) { if (status.isDebug()) { logger.debug("Releasing transaction savepoint"); } status.releaseHeldSavepoint(); } else if (status.isNewTransaction()) { if (status.isDebug()) { logger.debug("Initiating transaction commit"); } doCommit(status); } // Throw UnexpectedRollbackException if we have a global rollback-only // marker but still didn't get a corresponding exception from commit. if (globalRollbackOnly) { 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 ex) { if (!beforeCompletionInvoked) { triggerBeforeCompletion(status); } doRollbackOnCommitException(status, ex); throw ex; } catch (Error err) { if (!beforeCompletionInvoked) { triggerBeforeCompletion(status); } doRollbackOnCommitException(status, err); throw err; } // Trigger afterCommit callbacks, with an exception thrown there // propagated to callers but the transaction still considered as committed. try { triggerAfterCommit(status); } finally { triggerAfterCompletion(status, TransactionSynchronization.STATUS_COMMITTED); } } finally { cleanupAfterCompletion(status); } } 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"); } DefaultTransactionStatus defStatus = (DefaultTransactionStatus) status; processRollback(defStatus); } private void processRollback(DefaultTransactionStatus status) { try { try { triggerBeforeCompletion(status); if (status.hasSavepoint()) { if (status.isDebug()) { logger.debug("Rolling back transaction to savepoint"); } status.rollbackToHeldSavepoint(); } else if (status.isNewTransaction()) { if (status.isDebug()) { logger.debug("Initiating transaction rollback"); } doRollback(status); } else if (status.hasTransaction()) { if (status.isLocalRollbackOnly() || isGlobalRollbackOnParticipationFailure()) { if (status.isDebug()) { logger.debug("Participating transaction failed - marking existing transaction as rollback-only"); } 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"); } } catch (RuntimeException ex) { triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN); throw ex; } catch (Error err) { triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN); throw err; } triggerAfterCompletion(status, TransactionSynchronization.STATUS_ROLLED_BACK); } finally { cleanupAfterCompletion(status); } } private void doRollbackOnCommitException(DefaultTransactionStatus status, Throwable ex) throws TransactionException { try { if (status.isNewTransaction()) { if (status.isDebug()) { logger.debug("Initiating transaction rollback after commit exception", ex); } doRollback(status); } else if (status.hasTransaction() && isGlobalRollbackOnParticipationFailure()) { if (status.isDebug()) { logger.debug("Marking existing transaction as rollback-only after commit exception", ex); } doSetRollbackOnly(status); } } catch (RuntimeException rbex) { logger.error("Commit exception overridden by rollback exception", ex); triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN); throw rbex; } catch (Error rberr) { logger.error("Commit exception overridden by rollback exception", ex); triggerAfterCompletion(status, TransactionSynchronization.STATUS_UNKNOWN); throw rberr; } triggerAfterCompletion(status, TransactionSynchronization.STATUS_ROLLED_BACK); } protected final void triggerBeforeCommit(DefaultTransactionStatus status) { if (status.isNewSynchronization()) { if (status.isDebug()) { logger.trace("Triggering beforeCommit synchronization"); } TransactionSynchronizationUtils.triggerBeforeCommit(status.isReadOnly()); } } protected final void triggerBeforeCompletion(DefaultTransactionStatus status) { if (status.isNewSynchronization()) { if (status.isDebug()) { logger.trace("Triggering beforeCompletion synchronization"); } TransactionSynchronizationUtils.triggerBeforeCompletion(); } } private void triggerAfterCommit(DefaultTransactionStatus status) { if (status.isNewSynchronization()) { if (status.isDebug()) { logger.trace("Triggering afterCommit synchronization"); } TransactionSynchronizationUtils.triggerAfterCommit(); } } private void triggerAfterCompletion(DefaultTransactionStatus status, int completionStatus) { if (status.isNewSynchronization()) { List<TransactionSynchronization> synchronizations = TransactionSynchronizationManager.getSynchronizations(); if (!status.hasTransaction() || status.isNewTransaction()) { if (status.isDebug()) { logger.trace("Triggering afterCompletion synchronization"); } // No transaction or new transaction for the current scope -> // invoke the afterCompletion callbacks immediately invokeAfterCompletion(synchronizations, completionStatus); } else if (!synchronizations.isEmpty()) { // Existing transaction that we participate in, controlled outside // of the scope of this Spring transaction manager -> try to register // an afterCompletion callback with the existing (JTA) transaction. registerAfterCompletionWithExistingTransaction(status.getTransaction(), synchronizations); } } } protected final void invokeAfterCompletion(List<TransactionSynchronization> synchronizations, int completionStatus) { TransactionSynchronizationUtils.invokeAfterCompletion(synchronizations, completionStatus); } private void cleanupAfterCompletion(DefaultTransactionStatus status) { status.setCompleted(); if (status.isNewSynchronization()) { TransactionSynchronizationManager.clear(); } if (status.isNewTransaction()) { doCleanupAfterCompletion(status.getTransaction()); } if (status.getSuspendedResources() != null) { if (status.isDebug()) { logger.debug("Resuming suspended transaction after completion of inner transaction"); } resume(status.getTransaction(), (SuspendedResourcesHolder) status.getSuspendedResources()); } } //--------------------------------------------------------------------- // Template methods to be implemented in subclasses //--------------------------------------------------------------------- protected abstract Object doGetTransaction() throws TransactionException; protected boolean isExistingTransaction(Object transaction) throws TransactionException { return false; } protected boolean useSavepointForNestedTransaction() { return true; } protected abstract void doBegin(Object transaction, TransactionDefinition definition) throws TransactionException; protected Object doSuspend(Object transaction) throws TransactionException { throw new TransactionSuspensionNotSupportedException( "Transaction manager [" + getClass().getName() + "] does not support transaction suspension"); } protected void doResume(Object transaction, Object suspendedResources) throws TransactionException { throw new TransactionSuspensionNotSupportedException( "Transaction manager [" + getClass().getName() + "] does not support transaction suspension"); } protected boolean shouldCommitOnGlobalRollbackOnly() { return false; } protected void prepareForCommit(DefaultTransactionStatus status) { } protected abstract void doCommit(DefaultTransactionStatus status) throws TransactionException; protected abstract void doRollback(DefaultTransactionStatus status) throws TransactionException; protected void doSetRollbackOnly(DefaultTransactionStatus status) throws TransactionException { throw new IllegalTransactionStateException( "Participating in existing transactions is not supported - when 'isExistingTransaction' " + "returns true, appropriate 'doSetRollbackOnly' behavior must be provided"); } protected void registerAfterCompletionWithExistingTransaction( Object transaction, List<TransactionSynchronization> synchronizations) throws TransactionException { logger.debug("Cannot register Spring after-completion synchronization with existing transaction - " + "processing Spring after-completion callbacks immediately, with outcome status 'unknown'"); invokeAfterCompletion(synchronizations, TransactionSynchronization.STATUS_UNKNOWN); } protected void doCleanupAfterCompletion(Object transaction) { } //--------------------------------------------------------------------- // Serialization support //--------------------------------------------------------------------- private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException { // Rely on default serialization; just initialize state after deserialization. ois.defaultReadObject(); // Initialize transient fields. this.logger = LogFactory.getLog(getClass()); } /** * Holder for suspended resources. * Used internally by {@code suspend} and {@code resume}. */ protected static class SuspendedResourcesHolder { private final Object suspendedResources; private List<TransactionSynchronization> suspendedSynchronizations; private String name; private boolean readOnly; private Integer isolationLevel; private boolean wasActive; private SuspendedResourcesHolder(Object suspendedResources) { this.suspendedResources = suspendedResources; } private SuspendedResourcesHolder( Object suspendedResources, List<TransactionSynchronization> suspendedSynchronizations, String name, boolean readOnly, Integer isolationLevel, boolean wasActive) { this.suspendedResources = suspendedResources; this.suspendedSynchronizations = suspendedSynchronizations; this.name = name; this.readOnly = readOnly; this.isolationLevel = isolationLevel; this.wasActive = wasActive; } } }
- hibernate事务管理
hibernate的事务实现类为：HibernateTransactionManager - java持久化api事务
java 持久化事务的实现类为：JpaTransactionManager - java原生api事务
java原生事务的实现类为：JtaTransactionManager
- 事务的基本属性：
- 事务的传播行为
spring的传播行为有七种，其分别为：
PROPAGATION_REQUIRED ：表示当前方法必须运行在事务中，如果当前有事务，则在当前事务中运行，如果不存在测新建事务。
PROPAGATION_SUPPORTS :表示当前方法不需要在事务中，如果当前存在事务，则在当前事务中运行，如果不存在，则不会启动新事务，会正常运行。
PROPAGATION_MANDATORY ：表示当前方法必须在事务中运行，如果当前不存在事务，则会抛出异常。
PROPAGATION_REQUIRED_NEW ：表示当前方法必须在自己的事务中运行，首先会启动自己的事务，如果当前存在事务，则会在执行该方法时挂起当前事务，
PROPAGATION_NOT_SUPPORTED ：表示当前事务不支持事务，如果执行该方法并且当前存在事务，则会挂起当前事务。
PROPAGATION_NEVER ：表示当前方法不支持事务，如果当前存在事务则会抛出异常。
PROPAGATION_NESTED ：表示当前方法必须运行在事务中，如果当前存在事务则会在当前事务中运行，但是该方法的有自己独立的事务管理，就是该方法的commit和rollback。如果不存在会启动新的事务。 - 事务的隔离级别
ISOLATION_DEFAULT ：数据库默认的隔离级别。
ISOLATION_READ_UNCOMMITTED ：最低的隔离级别，允许读取尚未提交的数据变更，可能会导致脏读、幻读或不可重复读
ISOLATION_READ_COMMITTED ：允许读取并发事务已经提交的数据，可以阻止脏读，但是幻读或不可重复读仍有可能发生
ISOLATION_REPEATABLE_READ ：读已提交导致的幻读。对同一字段的多次读取结果都是一致的，除非数据是被本身事务自己所修改，可以阻止脏读和不可重复读，但幻读仍有可能发生
ISOLATION_SERIALIZABLE ：最高的隔离级别，完全服从ACID的隔离级别，确保阻止脏读、不可重复读以及幻读，也是最慢的事务隔离级别，因为它通常是通过完全锁定事务相关的数据库表来实现的 - 只读
事务的第三个特性是它是否为只读事务。如果事务只对后端的数据库进行该操作，数据库可以利用事务的只读特性来进行一些特定的优化。通过将事务设置为只读，你就可以给数据库一个机会，让它应用它认为合适的优化措施。、 - 事务超时
为了使应用程序很好地运行，事务不能运行太长的时间。因为事务可能涉及对后端数据库的锁定，所以长时间的事务会不必要的占用数据库资源。事务超时就是事务的一个定时器，在特定时间内事务如果没有执行完毕，那么就会自动回滚，而不是一直等待其结束。 - 回滚事务
事务五边形的最后一个方面是一组规则，这些规则定义了哪些异常会导致事务回滚而哪些不会。默认情况下，事务只有遇到运行期异常时才会回滚，而在遇到检查型异常时不会回滚（这一行为与EJB的回滚行为是一致的）
但是你可以声明事务在遇到特定的检查型异常时像遇到运行期异常那样回滚。同样，你还可以声明事务遇到特定的异常不回滚，即使这些异常是运行期异常。
- 事务状态
上面讲到的调用PlatformTransactionManager接口的getTransaction()的方法得到的是TransactionStatus接口的一个实现，这个接口的内容如下：public interface TransactionStatus{ boolean isNewTransaction(); // 是否是新的事物 boolean hasSavepoint(); // 是否有恢复点 void setRollbackOnly(); // 设置为只回滚 boolean isRollbackOnly(); // 是否为只回滚 boolean isCompleted; // 是否已完成 }