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What this is

This file is included in the "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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The source code

 *  Copyright 1999-2004 The Apache Software Foundation
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.

package org.apache.jk.common;

import java.util.Vector;

import org.apache.jk.apr.AprImpl;
import org.apache.jk.core.Msg;
import org.apache.jk.core.MsgContext;
import org.apache.jk.core.WorkerEnv;
import org.apache.tomcat.util.IntrospectionUtils;
import org.apache.tomcat.util.buf.C2BConverter;

/* The code is a bit confusing at this moment - the class is used as
   a Bean, or ant Task, or CLI - i.e. you set properties and call execute.

   That's different from the rest of jk handlers wich are stateless ( but
   similar with Coyote-http ).

/** Handle the shared memory objects.
 * @author Costin Manolache
public class Shm extends JniHandler {
    String file="/tmp/shm.file";
    int size;
    String host="localhost";
    int port=8009;
    String unixSocket;

    boolean help=false;
    boolean unregister=false;
    boolean reset=false;
    String dumpFile=null;

    Vector groups=new Vector();
    // Will be dynamic ( getMethodId() ) after things are stable 
    static final int SHM_WRITE_SLOT=2;
    static final int SHM_RESET=5;
    static final int SHM_DUMP=6;
    public Shm() {

    /** Scoreboard location
    public void setFile( String f ) {

    /** Copy the scoreboard in a file for debugging
     *  Will also log a lot of information about what's in the scoreboard.
    public void setDump( String dumpFile ) {
    /** Size. Used only if the scoreboard is to be created.
    public void setSize( int size ) {

    /** Set this to get the scoreboard reset.
     *  The shm segment will be destroyed and a new one created,
     *  with the provided size.
     *  Requires "file" and "size".
    public void setReset(boolean b) {

    /** Ajp13 host
    public void setHost( String host ) {;

    /** Mark this instance as belonging to a group
    public void setGroup( String grp ) {
        groups.addElement( grp );

    /** Ajp13 port
    public void setPort( int port ) {

    /** Unix socket where tomcat is listening.
     *  Use it only if tomcat is on the same host, of course
    public void setUnixSocket( String unixSocket  ) {

    /** Set this option to mark the tomcat instance as
        'down', so apache will no longer forward messages to it.
        Note that requests with a session will still try this
        host first.

        This can be used to implement gracefull shutdown.

        Host and port are still required, since they are used
        to identify tomcat.
    public void setUnregister( boolean unregister  ) {
    public void init() throws IOException {
        super.initNative( "shm" );
        if( apr==null ) return;
        if( file==null ) {
            log.error("No shm file, disabling shared memory");

        // Set properties and call init.
        setNativeAttribute( "file", file );
        if( size > 0 )
            setNativeAttribute( "size", Integer.toString( size ) );

    public void resetScoreboard() throws IOException {
        if( apr==null ) return;
        MsgContext mCtx=createMsgContext();
        Msg msg=(Msg)mCtx.getMsg(0);

        msg.appendByte( SHM_RESET );
        this.invoke( msg, mCtx );

    public void dumpScoreboard(String fname) throws IOException {
        if( apr==null ) return;
        MsgContext mCtx=createMsgContext();
        Msg msg=(Msg)mCtx.getMsg(0);
        C2BConverter c2b=(C2BConverter)mCtx.getNote(C2B_NOTE);

        msg.appendByte( SHM_DUMP );

        appendString( msg, fname, c2b);
        this.invoke( msg, mCtx );

    /** Register a tomcat instance
     *  XXX make it more flexible
    public void registerTomcat(String host, int port, String unixDomain)
        throws IOException
        String instanceId=host+":" + port;

        String slotName="TOMCAT:" + instanceId;
        MsgContext mCtx=createMsgContext();
        Msg msg=(Msg)mCtx.getMsg(0);
        C2BConverter c2b=(C2BConverter)mCtx.getNote(C2B_NOTE);
        msg.appendByte( SHM_WRITE_SLOT );
        appendString( msg, slotName, c2b );

        int channelCnt=1;
        if( unixDomain != null ) channelCnt++;

        // number of groups. 0 means the default lb.
        msg.appendInt( groups.size() );
        for( int i=0; i
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