HSQLDB example source code file (ServerConnection.java)

This example HSQLDB source code file (ServerConnection.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - HSQLDB tags/keywords

datainputstream, hsqlexception, hsqlexception, io, ioexception, ioexception, net, network, result, result, rowinputbinary, rowoutputbinary, runtimeexception, server, serverconnection, string, string

The HSQLDB ServerConnection.java source code

/*
 * For work developed by the HSQL Development Group:
 *
 * Copyright (c) 2001-2010, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 *
 * For work originally developed by the Hypersonic SQL Group:
 *
 * Copyright (c) 1995-2000, The Hypersonic SQL Group.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the Hypersonic SQL Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE HYPERSONIC SQL GROUP,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * on behalf of the Hypersonic SQL Group.
 */


package org.hsqldb;

import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.net.Socket;

import org.hsqldb.lib.ArrayUtil;
import org.hsqldb.rowio.RowInputBinary;
import org.hsqldb.rowio.RowOutputBinary;

import java.io.BufferedInputStream;

// fredt@users 20020215 - patch 461556 by paul-h@users - server factory
// fredt@users 20020424 - patch 1.7.0 by fredt - shutdown without exit
// fredt@users 20021002 - patch 1.7.1 by fredt - changed notification method
// fredt@users 20030618 - patch 1.7.2 by fredt - changed read/write methods
// fredt@users 20091013 - move set session to null suggested by Otto Joyner

/**
 *  All ServerConnection objects are listed in a Set in server
 *  and removed by this class when closed.<p>
 *
 *  When the database or server is shutdown, the signalClose() method is called
 *  for all current ServerConnection instances. This will call the private
 *  close() method unless the ServerConnection thread itself has caused the
 *  shutdown. In this case, the keepAlive flag is set to false, allowing the
 *  thread to terminate once it has returned the result of the operation to
 *  the client.
 *  (fredt@users)<p>
 *
 * Rewritten in version HSQLDB 1.7.2, based on original Hypersonic code.
 *
 * @author Thomas Mueller (Hypersonic SQL Group)
 * @author fredt@users
 * @version 1.8.0
 * @since Hypersonic SQL
 */
class ServerConnection implements Runnable {

    boolean                      keepAlive;
    private String               user;
    private String               password;
    int                          dbID;
    private volatile Session     session;
    private Socket               socket;
    private Server               server;
    private DataInputStream      dataInput;
    private BufferedOutputStream dataOutput;
    private static int           mCurrentThread = 0;
    private int                  mThread;
    static final int             BUFFER_SIZE = 0x1000;
    final byte[]                 mainBuffer  = new byte[BUFFER_SIZE];
    RowOutputBinary              rowOut = new RowOutputBinary(BUFFER_SIZE);
    RowInputBinary               rowIn       = new RowInputBinary(rowOut);
    Thread                       runnerThread;

    /**
     * Creates a new ServerConnection to the specified Server on the
     * specified socket.
     *
     * @param socket the network socket on which Server communication
     *      takes place
     * @param server the Server instance to which the object
     *      represents a connection
     */
    ServerConnection(Socket socket, Server server) {

        this.socket = socket;
        this.server = server;

        synchronized (ServerConnection.class) {
            mThread = mCurrentThread++;
        }

        synchronized (server.serverConnSet) {
            server.serverConnSet.add(this);
        }
    }

    /**
     * Signals this object to close, including exiting the thread running
     * the request handling loop
     */
    void signalClose() {

        keepAlive = false;

        if (!Thread.currentThread().equals(runnerThread)) {
            close();
        }
    }

    /**
     * Closes this connection.
     */
    private void close() {

        if (session != null) {
            session.close();

            session = null;
        }

        // fredt@user - closing the socket is to stop this thread
        try {
            synchronized (this) {
                if (socket != null) {
                    socket.close();
                }
            }
        } catch (IOException e) {}

        socket = null;

        synchronized (server.serverConnSet) {
            server.serverConnSet.remove(this);
        }
    }

    /**
     * Initializes this connection.
     */
    private void init() {

        runnerThread = Thread.currentThread();
        keepAlive    = true;

        try {
            socket.setTcpNoDelay(true);

            dataInput = new DataInputStream(
                new BufferedInputStream(socket.getInputStream()));
            dataOutput = new BufferedOutputStream(socket.getOutputStream());

            Result resultIn = Result.read(rowIn, dataInput);
            Result resultOut;

            try {
                dbID     = server.getDBID(resultIn.subSubString);
                user     = resultIn.getMainString();
                password = resultIn.getSubString();

                if (!server.isSilent()) {
                    server.printWithThread(mThread
                                           + ":trying to connect user "
                                           + user);
                }

                session = DatabaseManager.newSession(dbID,
                                                     resultIn.getMainString(),
                                                     resultIn.getSubString());
                resultOut            = new Result(ResultConstants.UPDATECOUNT);
                resultOut.databaseID = session.getDatabase().databaseID;
                resultOut.sessionID  = session.getId();
            } catch (HsqlException e) {
                session   = null;
                resultOut = new Result(e, null);
            } catch (RuntimeException e) {
                session   = null;
                resultOut = new Result(e, null);
            }

            Result.write(resultOut, rowOut, dataOutput);

            return;
        } catch (Exception e) {
            server.printWithThread(mThread + ":couldn't connect " + user);
        }

        close();
    }

    /**
     * Initializes this connection and runs the request handling
     * loop until closed.
     */
    public void run() {

        init();

        if (session != null) {
            try {
                while (keepAlive) {
                    Result resultIn = Result.read(rowIn, dataInput);

                    server.printRequest(mThread, resultIn);

                    Result resultOut;

                    if (resultIn.mode == ResultConstants.HSQLRESETSESSION) {
                        resultOut = resetSession();
                    } else {
                        resultOut = session.execute(resultIn);
                    }

                    Result.write(resultOut, rowOut, dataOutput);
                    rowOut.setBuffer(mainBuffer);
                    rowIn.resetRow(mainBuffer.length);
                }
            } catch (IOException e) {

                // fredt - is thrown when connection drops
                server.printWithThread(mThread + ":disconnected " + user);
            } catch (HsqlException e) {

                // fredt - is thrown while constructing the result
                server.printStackTrace(e);
            }
        }

        close();
    }

    /**
     * Used by pooled connections to close the existing SQL session and open
     * a new one.
     */
    private Result resetSession() {

        Result resultOut;

        if (!server.isSilent()) {
            server.printWithThread(mThread + ":trying to connect user "
                                   + user);
        }

        try {
            session.close();

            session = DatabaseManager.newSession(dbID, user, password);
            resultOut            = new Result(ResultConstants.UPDATECOUNT);
            resultOut.databaseID = session.getDatabase().databaseID;
            resultOut.sessionID  = session.getId();
        } catch (HsqlException e) {
            session   = null;
            resultOut = new Result(e, null);
        }

        return resultOut;
    }

    /**
     * Retrieves the thread name to be used  when
     * this object is the Runnable object of a Thread.
     *
     * @return the thread name to be used  when this object is the Runnable
     * object of a Thread.
     */
    String getConnectionThreadName() {
        return "HSQLDB Connection @" + Integer.toString(hashCode(), 16);
    }
}