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Tomcat example source code file (ChannelJni.java)

This example Tomcat source code file (ChannelJni.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 - Tomcat tags/keywords

channeljni, channeljni, io, ioexception, ioexception, jk_handle_jni_dispatch, jkchannel, jnihandler, msg, msg, msgcontext, msgcontext, no, setting, string

The Tomcat ChannelJni.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  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.io.IOException;

import org.apache.jk.core.JkHandler;
import org.apache.jk.core.Msg;
import org.apache.jk.core.MsgContext;
import org.apache.jk.core.JkChannel;

import org.apache.coyote.Request;
/** Pass messages using jni 
 *
 * @author Costin Manolache
 */
public class ChannelJni extends JniHandler implements JkChannel {
    int receivedNote=1;

    public ChannelJni() {
        // we use static for now, it's easier on the C side.
        // Easy to change after we get everything working
    }

    public void init() throws IOException {
        super.initNative("channel.jni:jni");

        if( apr==null ) return;
        
        // We'll be called from C. This deals with that.
        apr.addJkHandler( "channelJni", this );        
        log.info("JK: listening on channel.jni:jni" );
        
        if( next==null ) {
            if( nextName!=null ) 
                setNext( wEnv.getHandler( nextName ) );
            if( next==null )
                next=wEnv.getHandler( "dispatch" );
            if( next==null )
                next=wEnv.getHandler( "request" );
            if( log.isDebugEnabled() )
                log.debug("Setting default next " + next.getClass().getName());
        }
    }

    /** Receives does nothing - send will put the response
     *  in the same buffer
     */
    public int receive( Msg msg, MsgContext ep )
        throws IOException
    {
        Msg sentResponse=(Msg)ep.getNote( receivedNote );
        ep.setNote( receivedNote, null );

        if( sentResponse == null ) {
            if( log.isDebugEnabled() )
                log.debug("No send() prior to receive(), no data buffer");
            // No sent() was done prior to receive.
            msg.reset();
            msg.end();
            sentResponse = msg;
        }
        
        sentResponse.processHeader();

        if( log.isTraceEnabled() )
            sentResponse.dump("received response ");

        if( msg != sentResponse ) {
            log.error( "Error, in JNI mode the msg used for receive() must be identical with the one used for send()");
        }
        
        return 0;
    }

    /** Send the packet. XXX This will modify msg !!!
     *  We could use 2 packets, or sendAndReceive().
     *    
     */
    public int send( Msg msg, MsgContext ep )
        throws IOException
    {
        ep.setNote( receivedNote, null );
        if( log.isDebugEnabled() ) log.debug("ChannelJni.send: "  +  msg );

        int rc=super.nativeDispatch( msg, ep, JK_HANDLE_JNI_DISPATCH, 0);

        // nativeDispatch will put the response in the same buffer.
        // Next receive() will just get it from there. Very tricky to do
        // things in one thread instead of 2.
        ep.setNote( receivedNote, msg );
        
        return rc;
    }

    public int flush(Msg msg, MsgContext ep) throws IOException {
        ep.setNote( receivedNote, null );
        return OK;
    }

    public boolean isSameAddress(MsgContext ep) {
        return true;
    }

    public void registerRequest(Request req, MsgContext ep, int count) {
        // Not supported.
    }

    public String getChannelName() {
        return getName();
    }
    /** Receive a packet from the C side. This is called from the C
     *  code using invocation, but only for the first packet - to avoid
     *  recursivity and thread problems.
     *
     *  This may look strange, but seems the best solution for the
     *  problem ( the problem is that we don't have 'continuation' ).
     *
     *  sendPacket will move the thread execution on the C side, and
     *  return when another packet is available. For packets that
     *  are one way it'll return after it is processed too ( having
     *  2 threads is far more expensive ).
     *
     *  Again, the goal is to be efficient and behave like all other
     *  Channels ( so the rest of the code can be shared ). Playing with
     *  java objects on C is extremely difficult to optimize and do
     *  right ( IMHO ), so we'll try to keep it simple - byte[] passing,
     *  the conversion done in java ( after we know the encoding and
     *  if anyone asks for it - same lazy behavior as in 3.3 ).
     */
    public  int invoke(Msg msg, MsgContext ep )  throws IOException {
        if( apr==null ) return -1;
        
        long xEnv=ep.getJniEnv();
        long cEndpointP=ep.getJniContext();

        int type=ep.getType();
        if( log.isDebugEnabled() ) log.debug("ChannelJni.invoke: "  + ep + " " + type);

        switch( type ) {
        case JkHandler.HANDLE_RECEIVE_PACKET:
            return receive( msg, ep );
        case JkHandler.HANDLE_SEND_PACKET:
            return send( msg, ep );
        case JkHandler.HANDLE_FLUSH:
            return flush(msg, ep);
        }

        // Reset receivedNote. It'll be visible only after a SEND and before a receive.
        ep.setNote( receivedNote, null );

        // Default is FORWARD - called from C 
        try {
            // first, we need to get an endpoint. It should be
            // per/thread - and probably stored by the C side.
            if( log.isDebugEnabled() ) log.debug("Received request " + xEnv);
            
            // The endpoint will store the message pt.
            msg.processHeader();

            if( log.isTraceEnabled() ) msg.dump("Incoming msg ");

            int status= next.invoke(  msg, ep );
            
            if( log.isDebugEnabled() ) log.debug("after processCallbacks " + status);
            
            return status;
        } catch( Exception ex ) {
            ex.printStackTrace();
        }
        return 0;
    }    

    private static org.apache.juli.logging.Log log=
        org.apache.juli.logging.LogFactory.getLog( ChannelJni.class );

}

Other Tomcat examples (source code examples)

Here is a short list of links related to this Tomcat ChannelJni.java source code file:

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