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}