/*
* Copyright 2002-2017 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.jdbc.datasource;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.DataSource;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.transaction.CannotCreateTransactionException;
import org.springframework.transaction.TransactionDefinition;
import org.springframework.transaction.TransactionSystemException;
import org.springframework.transaction.support.AbstractPlatformTransactionManager;
import org.springframework.transaction.support.DefaultTransactionStatus;
import org.springframework.transaction.support.ResourceTransactionManager;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.transaction.support.TransactionSynchronizationUtils;
/**
* {@link org.springframework.transaction.PlatformTransactionManager}
* implementation for a single JDBC {@link javax.sql.DataSource}. This class is
* capable of working in any environment with any JDBC driver, as long as the setup
* uses a {@code javax.sql.DataSource} as its {@code Connection} factory mechanism.
* Binds a JDBC Connection from the specified DataSource to the current thread,
* potentially allowing for one thread-bound Connection per DataSource.
*
* <p><b>Note: The DataSource that this transaction manager operates on needs
* to return independent Connections.</b> The Connections may come from a pool
* (the typical case), but the DataSource must not return thread-scoped /
* request-scoped Connections or the like. This transaction manager will
* associate Connections with thread-bound transactions itself, according
* to the specified propagation behavior. It assumes that a separate,
* independent Connection can be obtained even during an ongoing transaction.
*
* <p>Application code is required to retrieve the JDBC Connection via
* {@link DataSourceUtils#getConnection(DataSource)} instead of a standard
* Java EE-style {@link DataSource#getConnection()} call. Spring classes such as
* {@link org.springframework.jdbc.core.JdbcTemplate} use this strategy implicitly.
* If not used in combination with this transaction manager, the
* {@link DataSourceUtils} lookup strategy behaves exactly like the native
* DataSource lookup; it can thus be used in a portable fashion.
*
* <p>Alternatively, you can allow application code to work with the standard
* Java EE-style lookup pattern {@link DataSource#getConnection()}, for example for
* legacy code that is not aware of Spring at all. In that case, define a
* {@link TransactionAwareDataSourceProxy} for your target DataSource, and pass
* that proxy DataSource to your DAOs, which will automatically participate in
* Spring-managed transactions when accessing it.
*
* <p>Supports custom isolation levels, and timeouts which get applied as
* appropriate JDBC statement timeouts. To support the latter, application code
* must either use {@link org.springframework.jdbc.core.JdbcTemplate}, call
* {@link DataSourceUtils#applyTransactionTimeout} for each created JDBC Statement,
* or go through a {@link TransactionAwareDataSourceProxy} which will create
* timeout-aware JDBC Connections and Statements automatically.
*
* <p>Consider defining a {@link LazyConnectionDataSourceProxy} for your target
* DataSource, pointing both this transaction manager and your DAOs to it.
* This will lead to optimized handling of "empty" transactions, i.e. of transactions
* without any JDBC statements executed. A LazyConnectionDataSourceProxy will not fetch
* an actual JDBC Connection from the target DataSource until a Statement gets executed,
* lazily applying the specified transaction settings to the target Connection.
*
* <p>This transaction manager supports nested transactions via the JDBC 3.0
* {@link java.sql.Savepoint} mechanism. The
* {@link #setNestedTransactionAllowed "nestedTransactionAllowed"} flag defaults
* to "true", since nested transactions will work without restrictions on JDBC
* drivers that support savepoints (such as the Oracle JDBC driver).
*
* <p>This transaction manager can be used as a replacement for the
* {@link org.springframework.transaction.jta.JtaTransactionManager} in the single
* resource case, as it does not require a container that supports JTA, typically
* in combination with a locally defined JDBC DataSource (e.g. an Apache Commons
* DBCP connection pool). Switching between this local strategy and a JTA
* environment is just a matter of configuration!
*
* <p>As of 4.3.4, this transaction manager triggers flush callbacks on registered
* transaction synchronizations (if synchronization is generally active), assuming
* resources operating on the underlying JDBC {@code Connection}. This allows for
* setup analogous to {@code JtaTransactionManager}, in particular with respect to
* lazily registered ORM resources (e.g. a Hibernate {@code Session}).
*
* @author Juergen Hoeller
* @since 02.05.2003
* @see #setNestedTransactionAllowed
* @see java.sql.Savepoint
* @see DataSourceUtils#getConnection(javax.sql.DataSource)
* @see DataSourceUtils#applyTransactionTimeout
* @see DataSourceUtils#releaseConnection
* @see TransactionAwareDataSourceProxy
* @see LazyConnectionDataSourceProxy
* @see org.springframework.jdbc.core.JdbcTemplate
*/
@SuppressWarnings("serial")
public class DataSourceTransactionManager extends AbstractPlatformTransactionManager
implements ResourceTransactionManager, InitializingBean {
private DataSource dataSource;
private boolean enforceReadOnly = false;
/**
* Create a new DataSourceTransactionManager instance.
* A DataSource has to be set to be able to use it.
* @see #setDataSource
*/
public DataSourceTransactionManager() {
setNestedTransactionAllowed(true);
}
/**
* Create a new DataSourceTransactionManager instance.
* @param dataSource JDBC DataSource to manage transactions for
*/
public DataSourceTransactionManager(DataSource dataSource) {
this();
setDataSource(dataSource);
afterPropertiesSet();
}
/**
* Set the JDBC DataSource that this instance should manage transactions for.
* <p>This will typically be a locally defined DataSource, for example an
* Apache Commons DBCP connection pool. Alternatively, you can also drive
* transactions for a non-XA J2EE DataSource fetched from JNDI. For an XA
* DataSource, use JtaTransactionManager.
* <p>The DataSource specified here should be the target DataSource to manage
* transactions for, not a TransactionAwareDataSourceProxy. Only data access
* code may work with TransactionAwareDataSourceProxy, while the transaction
* manager needs to work on the underlying target DataSource. If there's
* nevertheless a TransactionAwareDataSourceProxy passed in, it will be
* unwrapped to extract its target DataSource.
* <p><b>The DataSource passed in here needs to return independent Connections.</b>
* The Connections may come from a pool (the typical case), but the DataSource
* must not return thread-scoped / request-scoped Connections or the like.
* @see TransactionAwareDataSourceProxy
* @see org.springframework.transaction.jta.JtaTransactionManager
*/
public void setDataSource(DataSource dataSource) {
if (dataSource instanceof TransactionAwareDataSourceProxy) {
// If we got a TransactionAwareDataSourceProxy, we need to perform transactions
// for its underlying target DataSource, else data access code won't see
// properly exposed transactions (i.e. transactions for the target DataSource).
this.dataSource = ((TransactionAwareDataSourceProxy) dataSource).getTargetDataSource();
}
else {
this.dataSource = dataSource;
}
}
/**
* Return the JDBC DataSource that this instance manages transactions for.
*/
public DataSource getDataSource() {
return this.dataSource;
}
/**
* Specify whether to enforce the read-only nature of a transaction
* (as indicated by {@link TransactionDefinition#isReadOnly()}
* through an explicit statement on the transactional connection:
* "SET TRANSACTION READ ONLY" as understood by Oracle, MySQL and Postgres.
* <p>The exact treatment, including any SQL statement executed on the connection,
* can be customized through through {@link #prepareTransactionalConnection}.
* <p>This mode of read-only handling goes beyond the {@link Connection#setReadOnly}
* hint that Spring applies by default. In contrast to that standard JDBC hint,
* "SET TRANSACTION READ ONLY" enforces an isolation-level-like connection mode
* where data manipulation statements are strictly disallowed. Also, on Oracle,
* this read-only mode provides read consistency for the entire transaction.
* <p>Note that older Oracle JDBC drivers (9i, 10g) used to enforce this read-only
* mode even for {@code Connection.setReadOnly(true}. However, with recent drivers,
* this strong enforcement needs to be applied explicitly, e.g. through this flag.
* @since 4.3.7
* @see #prepareTransactionalConnection
*/
public void setEnforceReadOnly(boolean enforceReadOnly) {
this.enforceReadOnly = enforceReadOnly;
}
/**
* Return whether to enforce the read-only nature of a transaction
* through an explicit statement on the transactional connection.
* @since 4.3.7
* @see #setEnforceReadOnly
*/
public boolean isEnforceReadOnly() {
return this.enforceReadOnly;
}
@Override
public void afterPropertiesSet() {
if (getDataSource() == null) {
throw new IllegalArgumentException("Property 'dataSource' is required");
}
}
@Override
public Object getResourceFactory() {
return getDataSource();
}
@Override
protected Object doGetTransaction() {
DataSourceTransactionObject txObject = new DataSourceTransactionObject();
txObject.setSavepointAllowed(isNestedTransactionAllowed());
ConnectionHolder conHolder =
(ConnectionHolder) TransactionSynchronizationManager.getResource(this.dataSource);
txObject.setConnectionHolder(conHolder, false);
return txObject;
}
@Override
protected boolean isExistingTransaction(Object transaction) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) transaction;
return (txObject.getConnectionHolder() != null && txObject.getConnectionHolder().isTransactionActive());
}
/**
* This implementation sets the isolation level but ignores the timeout.
*/
@Override
protected void doBegin(Object transaction, TransactionDefinition definition) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) transaction;
Connection con = null;
try {
if (txObject.getConnectionHolder() == null ||
txObject.getConnectionHolder().isSynchronizedWithTransaction()) {
Connection newCon = this.dataSource.getConnection();
if (logger.isDebugEnabled()) {
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);
// Switch to manual commit if necessary. This is very expensive in some JDBC drivers,
// so we don't want to do it unnecessarily (for example if we've explicitly
// configured the connection pool to set it already).
if (con.getAutoCommit()) {
txObject.setMustRestoreAutoCommit(true);
if (logger.isDebugEnabled()) {
logger.debug("Switching JDBC Connection [" + con + "] to manual commit");
}
con.setAutoCommit(false);
}
prepareTransactionalConnection(con, definition);
txObject.getConnectionHolder().setTransactionActive(true);
int timeout = determineTimeout(definition);
if (timeout != TransactionDefinition.TIMEOUT_DEFAULT) {
txObject.getConnectionHolder().setTimeoutInSeconds(timeout);
}
// Bind the connection holder to the thread.
if (txObject.isNewConnectionHolder()) {
TransactionSynchronizationManager.bindResource(getDataSource(), txObject.getConnectionHolder());
}
}
catch (Throwable ex) {
if (txObject.isNewConnectionHolder()) {
DataSourceUtils.releaseConnection(con, this.dataSource);
txObject.setConnectionHolder(null, false);
}
throw new CannotCreateTransactionException("Could not open JDBC Connection for transaction", ex);
}
}
@Override
protected Object doSuspend(Object transaction) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) transaction;
txObject.setConnectionHolder(null);
return TransactionSynchronizationManager.unbindResource(this.dataSource);
}
@Override
protected void doResume(Object transaction, Object suspendedResources) {
TransactionSynchronizationManager.bindResource(this.dataSource, suspendedResources);
}
@Override
protected void doCommit(DefaultTransactionStatus status) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) status.getTransaction();
Connection con = txObject.getConnectionHolder().getConnection();
if (status.isDebug()) {
logger.debug("Committing JDBC transaction on Connection [" + con + "]");
}
try {
con.commit();
}
catch (SQLException ex) {
throw new TransactionSystemException("Could not commit JDBC transaction", ex);
}
}
@Override
protected void doRollback(DefaultTransactionStatus status) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) status.getTransaction();
Connection con = txObject.getConnectionHolder().getConnection();
if (status.isDebug()) {
logger.debug("Rolling back JDBC transaction on Connection [" + con + "]");
}
try {
con.rollback();
}
catch (SQLException ex) {
throw new TransactionSystemException("Could not roll back JDBC transaction", ex);
}
}
@Override
protected void doSetRollbackOnly(DefaultTransactionStatus status) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) status.getTransaction();
if (status.isDebug()) {
logger.debug("Setting JDBC transaction [" + txObject.getConnectionHolder().getConnection() +
"] rollback-only");
}
txObject.setRollbackOnly();
}
@Override
protected void doCleanupAfterCompletion(Object transaction) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) transaction;
// Remove the connection holder from the thread, if exposed.
if (txObject.isNewConnectionHolder()) {
TransactionSynchronizationManager.unbindResource(this.dataSource);
}
// Reset connection.
Connection con = txObject.getConnectionHolder().getConnection();
try {
if (txObject.isMustRestoreAutoCommit()) {
con.setAutoCommit(true);
}
DataSourceUtils.resetConnectionAfterTransaction(con, txObject.getPreviousIsolationLevel());
}
catch (Throwable ex) {
logger.debug("Could not reset JDBC Connection after transaction", ex);
}
if (txObject.isNewConnectionHolder()) {
if (logger.isDebugEnabled()) {
logger.debug("Releasing JDBC Connection [" + con + "] after transaction");
}
DataSourceUtils.releaseConnection(con, this.dataSource);
}
txObject.getConnectionHolder().clear();
}
/**
* Prepare the transactional {@code Connection} right after transaction begin.
* <p>The default implementation executes a "SET TRANSACTION READ ONLY" statement
* if the {@link #setEnforceReadOnly "enforceReadOnly"} flag is set to {@code true}
* and the transaction definition indicates a read-only transaction.
* <p>The "SET TRANSACTION READ ONLY" is understood by Oracle, MySQL and Postgres
* and may work with other databases as well. If you'd like to adapt this treatment,
* override this method accordingly.
* @param con the transactional JDBC Connection
* @param definition the current transaction definition
* @throws SQLException if thrown by JDBC API
* @since 4.3.7
* @see #setEnforceReadOnly
*/
protected void prepareTransactionalConnection(Connection con, TransactionDefinition definition)
throws SQLException {
if (isEnforceReadOnly() && definition.isReadOnly()) {
Statement stmt = con.createStatement();
try {
stmt.executeUpdate("SET TRANSACTION READ ONLY");
}
finally {
stmt.close();
}
}
}
/**
* DataSource transaction object, representing a ConnectionHolder.
* Used as transaction object by DataSourceTransactionManager.
*/
private static class DataSourceTransactionObject extends JdbcTransactionObjectSupport {
private boolean newConnectionHolder;
private boolean mustRestoreAutoCommit;
public void setConnectionHolder(ConnectionHolder connectionHolder, boolean newConnectionHolder) {
super.setConnectionHolder(connectionHolder);
this.newConnectionHolder = newConnectionHolder;
}
public boolean isNewConnectionHolder() {
return this.newConnectionHolder;
}
public void setMustRestoreAutoCommit(boolean mustRestoreAutoCommit) {
this.mustRestoreAutoCommit = mustRestoreAutoCommit;
}
public boolean isMustRestoreAutoCommit() {
return this.mustRestoreAutoCommit;
}
public void setRollbackOnly() {
getConnectionHolder().setRollbackOnly();
}
@Override
public boolean isRollbackOnly() {
return getConnectionHolder().isRollbackOnly();
}
@Override
public void flush() {
if (TransactionSynchronizationManager.isSynchronizationActive()) {
TransactionSynchronizationUtils.triggerFlush();
}
}
}
}