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JDBC Driver for the Firebird RDBMS
There is a newer version: 4.0.10.java7
/*
 * $Id$
 * 
 * Firebird Open Source JavaEE Connector - JDBC Driver
 *
 * Distributable under LGPL license.
 * You may obtain a copy of the License at http://www.gnu.org/copyleft/lgpl.html
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * LGPL License for more details.
 *
 * This file was created by members of the firebird development team.
 * All individual contributions remain the Copyright (C) of those
 * individuals.  Contributors to this file are either listed here or
 * can be obtained from a source control history command.
 *
 * All rights reserved.
 */
package org.firebirdsql.gds.ng;

import org.firebirdsql.gds.ISCConstants;
import org.firebirdsql.gds.ng.listeners.ExceptionListener;
import org.firebirdsql.gds.ng.listeners.ExceptionListenerDispatcher;
import org.firebirdsql.gds.ng.listeners.TransactionListener;
import org.firebirdsql.gds.ng.listeners.TransactionListenerDispatcher;

import java.sql.SQLException;
import java.util.Collections;
import java.util.EnumSet;
import java.util.Set;

import static org.firebirdsql.gds.VaxEncoding.iscVaxInteger2;
import static org.firebirdsql.gds.VaxEncoding.iscVaxLong;

/**
 * @author Mark Rotteveel
 * @since 3.0
 */
public abstract class AbstractFbTransaction implements FbTransaction {

    private static final Set ALLOWED_INITIAL_STATES = Collections.unmodifiableSet(
            EnumSet.of(TransactionState.ACTIVE, TransactionState.PREPARED));
    protected final ExceptionListenerDispatcher exceptionListenerDispatcher = new ExceptionListenerDispatcher(this);
    private final FbDatabase database;
    private final Object syncObject;
    protected final TransactionListenerDispatcher transactionListenerDispatcher = new TransactionListenerDispatcher();
    private volatile TransactionState state = TransactionState.ACTIVE;

    /**
     * Initializes AbstractFbTransaction.
     *
     * @param initialState
     *         Initial transaction state (allowed values are {@link org.firebirdsql.gds.ng.TransactionState#ACTIVE}
     *         and {@link org.firebirdsql.gds.ng.TransactionState#PREPARED}.
     * @param database
     *         FbDatabase that created this handle.
     */
    protected AbstractFbTransaction(TransactionState initialState, FbDatabase database) {
        if (!ALLOWED_INITIAL_STATES.contains(initialState)) {
            throw new IllegalArgumentException(String.format("Illegal initial transaction state: %s, allowed states are: %s", initialState, ALLOWED_INITIAL_STATES));
        }
        this.syncObject = database.getSynchronizationObject();
        this.state = initialState;
        this.database = database;
    }

    @Override
    public final TransactionState getState() {
        return state;
    }

    /**
     * Switches current state to the supplied newState.
     *
     * @param newState
     *         New state to switch to
     * @throws SQLException
     *         If the requested state transition is not allowed or if the
     *         current state is also changed in a concurrent thread.
     */
    protected final void switchState(final TransactionState newState) throws SQLException {
        synchronized (getSynchronizationObject()) {
            final TransactionState currentState = state;
            if (currentState == newState) return;
            if (currentState.isValidTransition(newState)) {
                state = newState;
                transactionListenerDispatcher.transactionStateChanged(this, newState, currentState);
            } else {
                // TODO Include sqlstate or use ISCConstants.isc_tra_state instead
                throw new SQLException(String.format("Unable to change transaction state: state %s is not valid after %s",
                        newState, currentState));
            }
        }
    }

    @Override
    public final void addTransactionListener(TransactionListener listener) {
        transactionListenerDispatcher.addListener(listener);
    }

    @Override
    public final void addWeakTransactionListener(TransactionListener listener) {
        transactionListenerDispatcher.addWeakListener(listener);
    }

    @Override
    public final void removeTransactionListener(TransactionListener listener) {
        transactionListenerDispatcher.removeListener(listener);
    }

    @Override
    public final void addExceptionListener(ExceptionListener listener) {
        exceptionListenerDispatcher.addListener(listener);
    }

    @Override
    public final void removeExceptionListener(ExceptionListener listener) {
        exceptionListenerDispatcher.removeListener(listener);
    }

    @Override
    public  T getTransactionInfo(byte[] requestItems, int bufferLength, InfoProcessor infoProcessor)
            throws SQLException {
        final byte[] responseBuffer = getTransactionInfo(requestItems, bufferLength);
        try {
            return infoProcessor.process(responseBuffer);
        } catch (SQLException e) {
            exceptionListenerDispatcher.errorOccurred(e);
            throw e;
        }
    }

    @Override
    public long getTransactionId() throws SQLException {
        // TODO As separate class?
        return getTransactionInfo(new byte[] { ISCConstants.isc_info_tra_id }, 16, new InfoProcessor() {
            @Override
            public Long process(byte[] infoResponse) throws SQLException {
                if (infoResponse[0] != ISCConstants.isc_info_tra_id) {
                    // TODO Message, SQL state, error code?
                    throw new SQLException("Unexpected response buffer");
                }
                int length = iscVaxInteger2(infoResponse, 1);
                return iscVaxLong(infoResponse, 3, length);
            }
        });
    }

    /**
     * Get synchronization object.
     *
     * @return object, cannot be null.
     */
    protected final Object getSynchronizationObject() {
        return syncObject;
    }

    @Override
    protected void finalize() throws Throwable {
        try {
            try {
                if (getState() == TransactionState.ACTIVE)
                    rollback();
            } catch (Throwable t) {
                // ignore TODO: Log?
            }
        } finally {
            super.finalize();
        }
    }

    protected FbDatabase getDatabase() {
        return database;
    }
}