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Apache Commons DBCP software implements Database Connection Pooling
/**
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.dbcp2.managed;
import javax.transaction.RollbackException;
import javax.transaction.Status;
import javax.transaction.Synchronization;
import javax.transaction.SystemException;
import javax.transaction.Transaction;
import javax.transaction.TransactionSynchronizationRegistry;
import javax.transaction.xa.XAResource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Objects;
import java.lang.ref.WeakReference;
/**
* TransactionContext represents the association between a single XAConnectionFactory and a Transaction. This context
* contains a single shared connection which should be used by all ManagedConnections for the XAConnectionFactory, the
* ability to listen for the transaction completion event, and a method to check the status of the transaction.
*
* @since 2.0
*/
public class TransactionContext {
private final TransactionRegistry transactionRegistry;
private final WeakReference transactionRef;
private final TransactionSynchronizationRegistry transactionSynchronizationRegistry;
private Connection sharedConnection;
private boolean transactionComplete;
/**
* Creates a TransactionContext for the specified Transaction and TransactionRegistry. The TransactionRegistry is
* used to obtain the XAResource for the shared connection when it is enlisted in the transaction.
*
* @param transactionRegistry
* the TransactionRegistry used to obtain the XAResource for the shared connection
* @param transaction
* the transaction
* @param transactionSynchronizationRegistry
* The optional TSR to register synchronizations with
* @since 2.6.0
*/
public TransactionContext(final TransactionRegistry transactionRegistry, final Transaction transaction,
final TransactionSynchronizationRegistry transactionSynchronizationRegistry) {
Objects.requireNonNull(transactionRegistry, "transactionRegistry is null");
Objects.requireNonNull(transaction, "transaction is null");
this.transactionRegistry = transactionRegistry;
this.transactionRef = new WeakReference<>(transaction);
this.transactionComplete = false;
this.transactionSynchronizationRegistry = transactionSynchronizationRegistry;
}
/**
* Provided for backwards compatibility
*
* @param transactionRegistry the TransactionRegistry used to obtain the XAResource for the
* shared connection
* @param transaction the transaction
*/
public TransactionContext(final TransactionRegistry transactionRegistry, final Transaction transaction) {
this (transactionRegistry, transaction, null);
}
/**
* Gets the connection shared by all ManagedConnections in the transaction. Specifically, connection using the same
* XAConnectionFactory from which the TransactionRegistry was obtained.
*
* @return the shared connection for this transaction
*/
public Connection getSharedConnection() {
return sharedConnection;
}
/**
* Sets the shared connection for this transaction. The shared connection is enlisted in the transaction.
*
* @param sharedConnection
* the shared connection
* @throws SQLException
* if a shared connection is already set, if XAResource for the connection could not be found in the
* transaction registry, or if there was a problem enlisting the connection in the transaction
*/
public void setSharedConnection(final Connection sharedConnection) throws SQLException {
if (this.sharedConnection != null) {
throw new IllegalStateException("A shared connection is already set");
}
// This is the first use of the connection in this transaction, so we must
// enlist it in the transaction
final Transaction transaction = getTransaction();
try {
final XAResource xaResource = transactionRegistry.getXAResource(sharedConnection);
if (!transaction.enlistResource(xaResource)) {
throw new SQLException("Unable to enlist connection in transaction: enlistResource returns 'false'.");
}
} catch (final IllegalStateException e) {
// This can happen if the transaction is already timed out
throw new SQLException("Unable to enlist connection in the transaction", e);
} catch (final RollbackException e) {
// transaction was rolled back... proceed as if there never was a transaction
} catch (final SystemException e) {
throw new SQLException("Unable to enlist connection the transaction", e);
}
this.sharedConnection = sharedConnection;
}
/**
* Adds a listener for transaction completion events.
*
* @param listener
* the listener to add
* @throws SQLException
* if a problem occurs adding the listener to the transaction
*/
public void addTransactionContextListener(final TransactionContextListener listener) throws SQLException {
try {
if (!isActive()) {
final Transaction transaction = this.transactionRef.get();
listener.afterCompletion(TransactionContext.this,
transaction == null ? false : transaction.getStatus() == Status.STATUS_COMMITTED);
return;
}
final Synchronization s = new Synchronization() {
@Override
public void beforeCompletion() {
// empty
}
@Override
public void afterCompletion(final int status) {
listener.afterCompletion(TransactionContext.this, status == Status.STATUS_COMMITTED);
}
};
if (transactionSynchronizationRegistry != null) {
transactionSynchronizationRegistry.registerInterposedSynchronization(s);
} else {
getTransaction().registerSynchronization(s);
}
} catch (final RollbackException e) {
// JTA spec doesn't let us register with a transaction marked rollback only
// just ignore this and the tx state will be cleared another way.
} catch (final Exception e) {
throw new SQLException("Unable to register transaction context listener", e);
}
}
/**
* True if the transaction is active or marked for rollback only.
*
* @return true if the transaction is active or marked for rollback only; false otherwise
* @throws SQLException
* if a problem occurs obtaining the transaction status
*/
public boolean isActive() throws SQLException {
try {
final Transaction transaction = this.transactionRef.get();
if (transaction == null) {
return false;
}
final int status = transaction.getStatus();
return status == Status.STATUS_ACTIVE || status == Status.STATUS_MARKED_ROLLBACK;
} catch (final SystemException e) {
throw new SQLException("Unable to get transaction status", e);
}
}
private Transaction getTransaction() throws SQLException {
final Transaction transaction = this.transactionRef.get();
if (transaction == null) {
throw new SQLException("Unable to enlist connection because the transaction has been garbage collected");
}
return transaction;
}
/**
* Sets the transaction complete flag to true.
*
* @since 2.4.0
*/
public void completeTransaction() {
this.transactionComplete = true;
}
/**
* Gets the transaction complete flag to true.
*
* @return The transaction complete flag.
*
* @since 2.4.0
*/
public boolean isTransactionComplete() {
return this.transactionComplete;
}
}