    001/**
    002 *
    003 * Licensed to the Apache Software Foundation (ASF) under one or more
    004 * contributor license agreements.  See the NOTICE file distributed with
    005 * this work for additional information regarding copyright ownership.
    006 * The ASF licenses this file to You under the Apache License, Version 2.0
    007 * (the "License"); you may not use this file except in compliance with
    008 * the License.  You may obtain a copy of the License at
    009 *
    010 *     http://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 *  Unless required by applicable law or agreed to in writing, software
    013 *  distributed under the License is distributed on an "AS IS" BASIS,
    014 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    015 *  See the License for the specific language governing permissions and
    016 *  limitations under the License.
    017 */
    018package org.apache.commons.dbcp2.managed;
    019
    020import java.sql.Connection;
    021import java.sql.SQLException;
    022import java.util.Map;
    023import java.util.Objects;
    024import java.util.WeakHashMap;
    025
    026import javax.transaction.SystemException;
    027import javax.transaction.Transaction;
    028import javax.transaction.TransactionManager;
    029import javax.transaction.xa.XAResource;
    030
    031import org.apache.commons.dbcp2.DelegatingConnection;
    032
    033/**
    034 * TransactionRegistry tracks Connections and XAResources in a transacted environment for a single XAConnectionFactory.
    035 * <p>
    036 * The TransactionRegistry hides the details of transaction processing from the existing DBCP pooling code, and gives
    037 * the ManagedConnection a way to enlist connections in a transaction, allowing for the maximal rescue of DBCP.
    038 * </p>
    039 *
    040 * @since 2.0
    041 */
    042public class TransactionRegistry {
    043    private final TransactionManager transactionManager;
    044    private final Map<Transaction, TransactionContext> caches = new WeakHashMap<>();
    045    private final Map<Connection, XAResource> xaResources = new WeakHashMap<>();
    046
    047    /**
    048     * Creates a TransactionRegistry for the specified transaction manager.
    049     *
    050     * @param transactionManager
    051     *            the transaction manager used to enlist connections.
    052     */
    053    public TransactionRegistry(final TransactionManager transactionManager) {
    054        this.transactionManager = transactionManager;
    055    }
    056
    057    /**
    058     * Registers the association between a Connection and a XAResource. When a connection is enlisted in a transaction,
    059     * it is actually the XAResource that is given to the transaction manager.
    060     *
    061     * @param connection
    062     *            The JDBC connection.
    063     * @param xaResource
    064     *            The XAResource which managed the connection within a transaction.
    065     */
    066    public synchronized void registerConnection(final Connection connection, final XAResource xaResource) {
    067        Objects.requireNonNull(connection, "connection is null");
    068        Objects.requireNonNull(xaResource, "xaResource is null");
    069        xaResources.put(connection, xaResource);
    070    }
    071
    072    /**
    073     * Gets the XAResource registered for the connection.
    074     *
    075     * @param connection
    076     *            the connection
    077     * @return The XAResource registered for the connection; never null.
    078     * @throws SQLException
    079     *             Thrown when the connection does not have a registered XAResource.
    080     */
    081    public synchronized XAResource getXAResource(final Connection connection) throws SQLException {
    082        Objects.requireNonNull(connection, "connection is null");
    083        final Connection key = getConnectionKey(connection);
    084        final XAResource xaResource = xaResources.get(key);
    085        if (xaResource == null) {
    086            throw new SQLException("Connection does not have a registered XAResource " + connection);
    087        }
    088        return xaResource;
    089    }
    090
    091    /**
    092     * Gets the active TransactionContext or null if not Transaction is active.
    093     *
    094     * @return The active TransactionContext or null if no Transaction is active.
    095     * @throws SQLException
    096     *             Thrown when an error occurs while fetching the transaction.
    097     */
    098    public TransactionContext getActiveTransactionContext() throws SQLException {
    099        Transaction transaction = null;
    100        try {
    101            transaction = transactionManager.getTransaction();
    102
    103            // was there a transaction?
    104            if (transaction == null) {
    105                return null;
    106            }
    107
    108            // This is the transaction on the thread so no need to check it's status - we should try to use it and
    109            // fail later based on the subsequent status
    110        } catch (final SystemException e) {
    111            throw new SQLException("Unable to determine current transaction ", e);
    112        }
    113
    114        // register the the context (or create a new one)
    115        synchronized (this) {
    116            TransactionContext cache = caches.get(transaction);
    117            if (cache == null) {
    118                cache = new TransactionContext(this, transaction);
    119                caches.put(transaction, cache);
    120            }
    121            return cache;
    122        }
    123    }
    124
    125    /**
    126     * Unregisters a destroyed connection from {@link TransactionRegistry}.
    127     *
    128     * @param connection
    129     *            A destroyed connection from {@link TransactionRegistry}.
    130     */
    131    public synchronized void unregisterConnection(final Connection connection) {
    132        final Connection key = getConnectionKey(connection);
    133        xaResources.remove(key);
    134    }
    135
    136    private Connection getConnectionKey(final Connection connection) {
    137        Connection result;
    138        if (connection instanceof DelegatingConnection) {
    139            result = ((DelegatingConnection<?>) connection).getInnermostDelegateInternal();
    140        } else {
    141            result = connection;
    142        }
    143        return result;
    144    }
    145}