abstractplatformtransactionmanager.java

spring的源代码

/*
 * Copyright 2002-2004 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.transaction.support;

import java.util.Iterator;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.core.Constants;
import org.springframework.transaction.IllegalTransactionStateException;
import org.springframework.transaction.InvalidTimeoutException;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.TransactionDefinition;
import org.springframework.transaction.TransactionException;
import org.springframework.transaction.TransactionStatus;
import org.springframework.transaction.UnexpectedRollbackException;

/**
 * Abstract base class that allows for easy implementation of concrete
 * platform transaction managers like JtaTransactionManager and
 * HibernateTransactionManager.
 *
 * <p>Provides the following workflow handling:
 * <ul>
 * <li>determines if there is an existing transaction;
 * <li>applies the appropriate propagation behavior;
 * <li>suspends and resumes transactions if necessary;
 * <li>checks the rollback-only flag on commit;
 * <li>applies the appropriate modification on rollback
 * (actual rollback or setting rollback-only);
 * <li>triggers registered synchronization callbacks
 * (if transaction synchronization is active).
 * </ul>
 *
 * <p>Transaction synchronization is a generic mechanism for registering
 * callbacks that get invoked at transaction completion time. This is mainly
 * used internally by the data access support classes for JDBC, Hibernate,
 * and JDO: They register resources that are opened within the transaction
 * for closing at transaction completion time, allowing e.g. for reuse of
 * the same Hibernate Session within the transaction. The same mechanism
 * can also be used for custom synchronization efforts.
 *
 * @author Juergen Hoeller
 * @since 28.03.2003
 * @version $Id: AbstractPlatformTransactionManager.java,v 1.25 2004/03/26 16:33:12 jhoeller Exp $
 * @see #setTransactionSynchronization
 * @see TransactionSynchronizationManager
 * @see org.springframework.transaction.jta.JtaTransactionManager
 * @see org.springframework.orm.hibernate.HibernateTransactionManager
 */
public abstract class AbstractPlatformTransactionManager implements PlatformTransactionManager {

	/**
	 * Always activate transaction synchronization, even for "empty" transactions
	 * that result from PROPAGATION_SUPPORTS with no existing backend transaction.
	 */
	public static final int SYNCHRONIZATION_ALWAYS = 0;

	/**
	 * Activate transaction synchronization only for actual transactions,
	 * i.e. not for empty ones that result from PROPAGATION_SUPPORTS with no
	 * existing backend transaction.
	 */
	public static final int SYNCHRONIZATION_ON_ACTUAL_TRANSACTION = 1;

	/**
	 * Never active transaction synchronization.
	 */
	public static final int SYNCHRONIZATION_NEVER = 2;

	/** Constants instance for AbstractPlatformTransactionManager */
	private static final Constants constants = new Constants(AbstractPlatformTransactionManager.class);


	protected final Log logger = LogFactory.getLog(getClass());

	private int transactionSynchronization = SYNCHRONIZATION_ALWAYS;

	private boolean rollbackOnCommitFailure = false;


	/**
	 * Set the transaction synchronization by the name of the corresponding constant
	 * in this class, e.g. "SYNCHRONIZATION_ALWAYS".
	 * @param constantName name of the constant
	 * @see #SYNCHRONIZATION_ALWAYS
	 */
	public void setTransactionSynchronizationName(String constantName) {
		setTransactionSynchronization(constants.asNumber(constantName).intValue());
	}

	/**
	 * Set when this transaction manager should activate the thread-bound
	 * transaction synchronization support. Default is "always".
	 * <p>Note that transaction synchronization isn't supported for
	 * multiple concurrent transactions by different transaction managers.
	 * Only one transaction manager is allowed to activate it at any time.
	 * @see #SYNCHRONIZATION_ALWAYS
	 * @see #SYNCHRONIZATION_ON_ACTUAL_TRANSACTION
	 * @see #SYNCHRONIZATION_NEVER
	 * @see TransactionSynchronizationManager
	 * @see TransactionSynchronization
	 */
	public void setTransactionSynchronization(int transactionSynchronization) {
		this.transactionSynchronization = transactionSynchronization;
	}

	/**
	 * Return if this transaction manager should activate the thread-bound
	 * transaction synchronization support.
	 */
	public int getTransactionSynchronization() {
		return transactionSynchronization;
	}

	/**
	 * Set if a rollback should be performed on failure of the commit call.
	 * Typically not necessary and thus to be avoided as it can override the
	 * commit exception with a subsequent rollback exception. Default is false.
	 */
	public void setRollbackOnCommitFailure(boolean rollbackOnCommitFailure) {
		this.rollbackOnCommitFailure = rollbackOnCommitFailure;
	}

	/**
	 * Return if a rollback should be performed on failure of the commit call.
	 */
	public boolean isRollbackOnCommitFailure() {
		return rollbackOnCommitFailure;
	}


	/**
	 * This implementation of getTransaction handles propagation behavior.
	 * Delegates to doGetTransaction, isExistingTransaction, doBegin.
	 * @see #doGetTransaction
	 * @see #isExistingTransaction
	 * @see #doBegin
	 */
	public final TransactionStatus getTransaction(TransactionDefinition definition) throws TransactionException {
		Object transaction = doGetTransaction();

		// cache to avoid repeated checks
		boolean debugEnabled = logger.isDebugEnabled();

		if (debugEnabled) {
			logger.debug("Using transaction object [" + transaction + "]");
		}

		if (definition == null) {
			// use defaults
			definition = new DefaultTransactionDefinition();
		}

		if (isExistingTransaction(transaction)) {
			if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NEVER) {
				throw new IllegalTransactionStateException("Transaction propagation 'never' but existing transaction found");
			}
			if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_NOT_SUPPORTED) {
				if (debugEnabled) {
					logger.debug("Suspending current transaction");
				}
				Object suspendedResources = suspend(transaction);
				boolean newSynchronization = (this.transactionSynchronization == SYNCHRONIZATION_ALWAYS);
				return newTransactionStatus(null, false, newSynchronization,
				                            definition.isReadOnly(), debugEnabled, suspendedResources);
			}
			if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW) {
				if (debugEnabled) {
					logger.debug("Creating new transaction, suspending current one");
				}
				Object suspendedResources = suspend(transaction);
				doBegin(transaction, definition);
				boolean newSynchronization = (this.transactionSynchronization != SYNCHRONIZATION_NEVER);
				return newTransactionStatus(transaction, true, newSynchronization,
				                            definition.isReadOnly(), debugEnabled, suspendedResources);
			}
			else {
				if (debugEnabled) {
					logger.debug("Participating in existing transaction");
				}
				boolean newSynchronization = (this.transactionSynchronization != SYNCHRONIZATION_NEVER);
				return newTransactionStatus(transaction, false, newSynchronization,
				                            definition.isReadOnly(), debugEnabled, null);
			}
		}

		if (definition.getTimeout() < TransactionDefinition.TIMEOUT_DEFAULT) {
			throw new InvalidTimeoutException("Invalid transaction timeout", definition.getTimeout());
		}
		if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_MANDATORY) {
			throw new IllegalTransactionStateException("Transaction propagation 'mandatory' but no existing transaction found");
		}

		if (definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRED ||
		    definition.getPropagationBehavior() == TransactionDefinition.PROPAGATION_REQUIRES_NEW) {
			if (debugEnabled) {
				logger.debug("Creating new transaction");
			}
			doBegin(transaction, definition);
			boolean newSynchronization = (this.transactionSynchronization != SYNCHRONIZATION_NEVER);
			return newTransactionStatus(transaction, true, newSynchronization,
			                            definition.isReadOnly(), debugEnabled, null);
		}
		else {
			// "empty" (-> no) transaction
			boolean newSynchronization = (this.transactionSynchronization == SYNCHRONIZATION_ALWAYS);
			return newTransactionStatus(null, false, newSynchronization,
			                            definition.isReadOnly(), debugEnabled, null);
		}
	}

	/**
	 * Create a new TransactionStatus for the given arguments,
	 * initializing transaction synchronization if appropriate.
	 */
	private TransactionStatus newTransactionStatus(Object transaction, boolean newTransaction,
	                                               boolean newSynchronization, boolean readOnly,
	                                               boolean debug, Object suspendedResources) {
		boolean actualNewSynchronization = newSynchronization &&
				!TransactionSynchronizationManager.isSynchronizationActive();
		if (actualNewSynchronization) {
			TransactionSynchronizationManager.initSynchronization();
		}
		return new DefaultTransactionStatus(transaction, newTransaction, actualNewSynchronization,
		                                    readOnly, debug, suspendedResources);
	}

	/**
	 * Suspend the given transaction. Suspends transaction synchronization first,
	 * then delegates to the doSuspend template method.
	 * @param transaction the current transaction object
	 * @return an object that holds suspended resources
	 * @see #doSuspend
	 * @see #resume
	 */
	private Object suspend(Object transaction) throws TransactionException {
		List suspendedSynchronizations = null;
		Object holder = doSuspend(transaction);
		if (TransactionSynchronizationManager.isSynchronizationActive()) {
			suspendedSynchronizations = TransactionSynchronizationManager.getSynchronizations();
			for (Iterator it = suspendedSynchronizations.iterator(); it.hasNext();) {
				((TransactionSynchronization) it.next()).suspend();
			}
			TransactionSynchronizationManager.clearSynchronization();
		}
		return new SuspendedResourcesHolder(suspendedSynchronizations, holder);
	}

	/**
	 * Resume the given transaction. Delegates to the doResume template method
	 * first, then resuming transaction synchronization.
	 * @param transaction the current transaction object
	 * @param suspendedResources the object that holds suspended resources,
	 * as returned by suspend
	 * @see #doResume
	 * @see #suspend
	 */
	private void resume(Object transaction, Object suspendedResources) throws TransactionException {
		SuspendedResourcesHolder resourcesHolder = (SuspendedResourcesHolder) suspendedResources;
		if (resourcesHolder.getSuspendedSynchronizations() != null) {
			TransactionSynchronizationManager.initSynchronization();
			for (Iterator it = resourcesHolder.getSuspendedSynchronizations().iterator(); it.hasNext();) {
				TransactionSynchronization synchronization = (TransactionSynchronization) it.next();
				synchronization.resume();
				TransactionSynchronizationManager.registerSynchronization(synchronization);
			}
		}
		doResume(transaction, resourcesHolder.getSuspendedResources());
	}

	/**
	 * This implementation of commit handles participating in existing
	 * transactions and programmatic rollback requests.
	 * Delegates to isRollbackOnly, doCommit and rollback.
	 * @see org.springframework.transaction.TransactionStatus#isRollbackOnly
	 * @see #isRollbackOnly
	 * @see #doCommit
	 * @see #rollback
	 */
	public final void commit(TransactionStatus status) throws TransactionException {
		DefaultTransactionStatus defStatus = (DefaultTransactionStatus) status;
		if (status.isRollbackOnly() ||
		    (defStatus.getTransaction() != null && isRollbackOnly(defStatus.getTransaction()))) {
			if (defStatus.isDebug()) {
				logger.debug("Transactional code has requested rollback");
			}
			rollback(status);
		}

		else {
			try {
				boolean beforeCompletionInvoked = false;
				try {
					triggerBeforeCommit(defStatus);
					triggerBeforeCompletion(defStatus, null);
					beforeCompletionInvoked = true;
					if (status.isNewTransaction()) {
						logger.info("Initiating transaction commit");
						doCommit(defStatus);
					}
				}
				catch (UnexpectedRollbackException ex) {
					// can only be caused by doCommit
					triggerAfterCompletion(defStatus, TransactionSynchronization.STATUS_ROLLED_BACK, ex);
					throw ex;
				}
				catch (TransactionException ex) {