server.java

Java的面向对象数据库系统的源代码

// You can redistribute this software and/or modify it under the terms of
// the Ozone Core License version 1 published by ozone-db.org.
//
// The original code and portions created by SMB are
// Copyright (C) 1997-@year@ by SMB GmbH. All rights reserved.
//
// $Id: Server.java,v 1.6 2002/09/21 16:06:35 per_nyfelt Exp $

package org.ozoneDB.core;

import java.lang.reflect.*;
import java.io.*;
import org.ozoneDB.DxLib.*;
import org.ozoneDB.*;
import org.ozoneDB.util.*;
import org.ozoneDB.tools.*;


/**
 * Main class to start the stand-alone server.
 *
 * @author <a href="http://www.softwarebuero.de/">SMB</a>
 * @version $Revision: 1.6 $Date: 2002/09/21 16:06:35 $
 */
public class Server {

    public static Env env;

    public static boolean stop;

    public static boolean stopped;


    public static void main( String[] args ) throws Exception {
        String dir = File.separator + "tmp" + File.separator + "db";
        String debugLevel = null;
        boolean help = false;
        boolean verbose = false;
        boolean createDB = false;
        DxArrayBag users = new DxArrayBag();

        for (int i = 0; i < args.length; i++) {
            if (args[i].startsWith( "-debug" )) {
                debugLevel = args[i].substring("-debug".length());
            } else if (args[i].startsWith( "-d" )) {
                dir = args[i].substring( 2 );
            } else if (args[i].startsWith( "-c" )) {
                createDB = true;
            } else if (args[i].startsWith( "-u" )) {
                String name = args[i].substring( 2 );
                users.add( name );
            } else if (args[i].startsWith( "-h" )) {
                help = true;
            } else {
                System.out.println( "illegal option: " + args[i] );
                help = true;
            }
        }

        if (args.length == 0 || help) {
            System.out.println( "usage: ozone -d<dir> [-h] [-debug] [-v]" );
            System.out.println( "   -d<directory>         database directory" );
            System.out.println( "   -debug<level>         debug level, levels are one of the string constants in the OzoneDebugLevel class" );
            System.out.println( "   -v                    starts the ozonometer (broken)" );
            System.out.println( "   -c                    create a database if neccessary" );
            System.out.println( "   -u<name>              add user <name>" );
            System.out.println( "   -h                    shows this help" );
            System.exit( 0 );
        }

        try {
            if (createDB) {

                // Check if a DB exists and make a new database if not.
                if (!Install.dbExists(dir)) {
                    System.out.println( "Installing new database in " + dir + "..." );

                    Setup defaults = new Setup( null );
                    defaults.addProperties( System.getProperties(), "ozoneDB." );
                    Install.createDB( dir, defaults, new PrintWriter( System.out, true ) );

                    System.out.println( "Edit " + dir + Env.CONFIG_FILE + " to change settings." );
                    System.out.println( "install complete\n" );
                }
            }

            System.out.println( "initializing environment..." );
            env = new Env( dir, debugLevel);

            // This is a good place to set up our shutdown hook. Doing it
            // earlier would case a NullPointerException in race conditions.
            // Doing it now is fine in terms of preventing database corruption
            // because request processing has no yet begun.
            setupShutdownHook();

            int freeSlot = 101;
            for (int i = 0; i < users.count(); i++) {
                String name = (String)users.elementAtIndex( i );
                // don't insert a name twice
                if (env.userManager.userForName( name ) != null) {
                    env.logWriter.newEntry( env, "User " + name + " already exists.", LogWriter.INFO );
                    continue;
                }
                // find a free id
                while (env.userManager.userForID( freeSlot ) != null) {
                    freeSlot++;
                }
                // add the user
                env.userManager.newUser( name, freeSlot );
                env.logWriter.newEntry( env, "user added: " + name + " ID: " + freeSlot, LogWriter.INFO );
            }
            env.storeSetup();

            env.startExternalEventProcessing();
            env.startDeadlockRecognition();

            System.out.println( "(Ctrl-C or 'q' to shutdown without admin tool)" );

            InputStreamReader is = new InputStreamReader( System.in );
            Thread.currentThread().setPriority( Env.SERVER_THREAD_PRIORITY );

            stop = false;
            stopped = false;
            // the main loop
            while (!stop) {
                int gcCount = 0;
                int stateCount = 0;
                while (!is.ready() && !env.shuttingdown && !stop) {
                    final int sleepMillis = 250;

                    // this forces also task switches
                    Thread.currentThread().sleep( sleepMillis );

                    // check component states every 5sec; this is not really a
                    // good solution but it works for now
//                    if (stateCount++ >= (5000/sleepMillis)) {
//                        stateCount = 0;
//                        if (env.isComponentStateChanged()) {
//                            env.logWriter.newEntry( env, "storing server state...", LogWriter.DEBUG );
//                            env.storeSetup();
//                        }
//                    }

                    // force GC
                    if (env.transactionManager.taTableCount() == 0) {
                        gcCount++;
                    }
                    else {
                        gcCount = 0;
                    }
                    if (gcCount >= (10000/sleepMillis)) {
//                      env.logWriter.newEntry( env, "forcing GC...", LogWriter.DEBUG3 );
                        System.gc();
                        gcCount = 0;
                    }
                }

                if (is.ready()) {
                    int c = is.read();
                    if (c == 'q') {
                        stop = true;
                    }
                }
            }
            // wait for the admin thread to deconnect
            Thread.sleep( 1000 );

            // shutdown the system
            env.shutdown();
            stopped = true;
        }
        catch (Exception e) {
            if (env != null) {
                env.shutdown();
            }
            // env.logWriter.newEntry (null, "", e, LogWriter.ERROR);
            System.out.println( "Unable to initialize server." );
            e.printStackTrace();
        }
        System.exit( 1 );
    }


    /**
     * Attempt to add the shutdown hook using reflection.
     */
    private static void setupShutdownHook() {
        try {
           // We will now attempt to add the shutdown hook
           // using reflection. If we're running in a VM that does
           // not support shutdown hooks (i.e., pre-1.3), it will yield
           // a NoSuchMethodException, which we quietly ignore.
           Class runtimeClass = Runtime.class;
           Method hookMethod = runtimeClass.getMethod("addShutdownHook", new Class[]{Thread.class});
           Runtime rt = Runtime.getRuntime();
           hookMethod.invoke(rt, new Object[]{createShutdownHook()});

           env.logWriter.newEntry(Server.class, "Shutdown hook successfully added.",
                   LogWriter.INFO);
        }
        catch (NoSuchMethodException nsme) {
           /* Pre-1.3 VM. */
           env.logWriter.newEntry(Server.class, "Running on pre-1.3 VM; no shutdown hook added.", LogWriter.INFO);
        }
        catch (SecurityException se) {
           /* Either a screwy setup, or permission deliberately denied. */
           env.logWriter.newEntry(Server.class, "Shutdown hook not added; permission denied.", LogWriter.WARN);
        }
        catch (InvocationTargetException ite) {
           /* Runtime.addShutdownHook() failed */
           Throwable te = ite.getTargetException();
           env.logWriter.newEntry(Server.class, "WARNING: Shutdown hook addition failed: "
                   + te.getClass().getName() + ": " + te.getMessage(),
                   LogWriter.ERROR);
        }
        catch (IllegalAccessException iae) {
           /* The VM is FUBAR. */
           env.logWriter.newEntry(Server.class,"Runtime.addShutdownHook() not public? VM bug?", LogWriter.ERROR);
        }
    }

    /**
     * Constructs and returns a Thread to be used as a shutdown hook.
     */
    private static Runnable createShutdownHook() {
        return new Thread() {
            public void run() {
                if (env.shuttingdown == false) {
                    env.logWriter.newEntry(Server.class, "Shutdown hook...", LogWriter.INFO);
                    try {
                        // signal the main loop to stop
                       stop = true;

                       // wait for the mail thread to finish shutdown
                       while (!stopped) {
                           sleep(500);
                       }
                    }
                    catch (Exception e) {
                    }
                    env.logWriter.newEntry(Server.class, "Shutdown hook... shutdown finished.", LogWriter.INFO);
                }
            }
        };
    }
}