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Tomcat example source code file (JniHandler.java)

This example Tomcat source code file (JniHandler.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

c2bconverter, can't, exception, io, ioexception, ioexception, jnihandler, management, msg, msgcontext, msgcontext, string, string, throwable, throwable, unitialized

The Tomcat JniHandler.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 javax.management.ObjectName;

import org.apache.jk.apr.AprImpl;
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.tomcat.util.buf.ByteChunk;
import org.apache.tomcat.util.buf.C2BConverter;
import org.apache.tomcat.util.buf.MessageBytes;
import org.apache.tomcat.util.modeler.Registry;


/**
 * Base class for components using native code ( libjkjni.so ).
 * It allows to access the jk_env and wrap ( 'box' ? ) a native
 * jk component, and call it's methods.
 *
 * Note that get/setAttribute are expensive ( Strings, etc ),
 * invoke() is were all optimizations are done. We do recycle
 * all memory on both C and java sides ( the only exception is
 * when we attempt pinning but the VM doesn't support it ). The
 * low level optimizations from ByteBuffer, etc are used to
 * reduce the overhead of passing strings.
 *
 * @author Costin Manolache
 */
public class JniHandler extends JkHandler {
    protected AprImpl apr;

    // The native side handler
    protected long nativeJkHandlerP;

    protected String jkHome;

    // Dispatch table codes. Hardcoded for now, will change when we have more handlers.
    public static final int JK_HANDLE_JNI_DISPATCH=0x15;
    public static final int JK_HANDLE_SHM_DISPATCH=0x16;


    public static final int MSG_NOTE=0;
    public static final int MB_NOTE=2;
    private boolean paused = false;


    public JniHandler() {
    }

    /**
     */
    public void setJkHome( String s ) {
        jkHome=s;
    }

    public String getJkHome() {
        return jkHome;
    }

    /** You must call initNative() inside the component init()
     */
    public void init() throws IOException {
        // static field init, temp
    }

    protected void initNative(String nativeComponentName) {
        apr=(AprImpl)wEnv.getHandler("apr");
        if( apr==null ) {
            // In most cases we can just load it automatically.
            // that requires all libs to be installed in standard places
            // ( LD_LIBRARY_PATH, /usr/lib
            try {
                apr=new AprImpl();
                wEnv.addHandler("apr", apr);
                apr.init();
                if( oname != null ) {
                    ObjectName aprname=new ObjectName(oname.getDomain() +
                            ":type=JkHandler, name=apr");
                    Registry.getRegistry(null, null).registerComponent(apr, aprname, null);
                }
            } catch( Throwable t ) {
                log.debug("Can't load apr", t);
                apr=null;
            }
        }
        if( apr==null || ! apr.isLoaded() ) {
            if( log.isDebugEnabled() )
                log.debug("No apr, disabling jni proxy ");
            apr=null;
            return;
        }

        try {
            long xEnv=apr.getJkEnv();
            nativeJkHandlerP=apr.getJkHandler(xEnv, nativeComponentName );
            
            if( nativeJkHandlerP==0 ) {
                log.debug("Component not found, creating it " + nativeComponentName );
                nativeJkHandlerP=apr.createJkHandler(xEnv, nativeComponentName);
            }
            log.debug("Native proxy " + nativeJkHandlerP );
            apr.releaseJkEnv(xEnv);
        } catch( Throwable t ) {
            apr=null;
            log.info("Error calling apr ", t);
        }
   }

    public void appendString( Msg msg, String s, C2BConverter charsetDecoder)
        throws IOException
    {
        ByteChunk bc=charsetDecoder.getByteChunk();
        charsetDecoder.recycle();
        charsetDecoder.convert( s );
        charsetDecoder.flushBuffer();
        msg.appendByteChunk( bc );
    }

    public void pause() throws Exception {
        synchronized(this) {
            paused = true;
        }
    }

    public void resume() throws Exception {
        synchronized(this) {
            paused = false;
            notifyAll();
        }
    }


    /** Create a msg context to be used with the shm channel
     */
    public MsgContext createMsgContext() {
        if( nativeJkHandlerP==0 || apr==null  )
            return null;

        synchronized(this) {
            try{ 
                while(paused) {
                    wait();
                }
            }catch(InterruptedException ie) {
                // Ignore, since it can't happen
            }
        }

        try {
            MsgContext msgCtx=new MsgContext();
            MsgAjp msg=new MsgAjp();

            msgCtx.setSource( (JkChannel)this );
            msgCtx.setWorkerEnv( wEnv );

            msgCtx.setNext( this );

            msgCtx.setMsg( MSG_NOTE, msg); // XXX Use noteId

            C2BConverter c2b=new C2BConverter(  "iso-8859-1" );
            msgCtx.setConverter( c2b );

            MessageBytes tmpMB= MessageBytes.newInstance();
            msgCtx.setNote( MB_NOTE, tmpMB );
            return msgCtx;
        } catch( Exception ex ) {
            log.error("Can't create endpoint", ex);
            return null;
        }
    }

    public void setNativeAttribute(String name, String val) throws IOException {
        if( apr==null ) return;

        if( nativeJkHandlerP == 0 ) {
            log.error( "Unitialized component " + name+ " " + val );
            return;
        }

        long xEnv=apr.getJkEnv();

        apr.jkSetAttribute( xEnv, nativeJkHandlerP, name, val );

        apr.releaseJkEnv( xEnv );
    }

    public void initJkComponent() throws IOException {
        if( apr==null ) return;

        if( nativeJkHandlerP == 0 ) {
            log.error( "Unitialized component " );
            return;
        }

        long xEnv=apr.getJkEnv();

        apr.jkInit( xEnv, nativeJkHandlerP );

        apr.releaseJkEnv( xEnv );
    }

    public void destroyJkComponent() throws IOException {
        if( apr==null ) return;

        if( nativeJkHandlerP == 0 ) {
            log.error( "Unitialized component " );
            return;
        }

        long xEnv=apr.getJkEnv();

        apr.jkDestroy( xEnv, nativeJkHandlerP );

        apr.releaseJkEnv( xEnv );
    }



    protected void setNativeEndpoint(MsgContext msgCtx) {
        long xEnv=apr.getJkEnv();
        msgCtx.setJniEnv( xEnv );

        long epP=apr.createJkHandler(xEnv, "endpoint");
        log.debug("create ep " + epP );
        if( epP == 0 ) return;
        apr.jkInit( xEnv, epP );
        msgCtx.setJniContext( epP );

    }

    protected void recycleNative(MsgContext ep) {
        apr.jkRecycle(ep.getJniEnv(), ep.getJniContext());
    }

    /** send and get the response in the same buffer. This calls the
    * method on the wrapped jk_bean object.
     */
    protected int nativeDispatch( Msg msg, MsgContext ep, int code, int raw )
        throws IOException
    {
        if( log.isDebugEnabled() )
            log.debug( "Sending packet " + code + " " + raw);

        if( raw == 0 ) {
            msg.end();

            if( log.isTraceEnabled() ) msg.dump("OUT:" );
        }

        // Create ( or reuse ) the jk_endpoint ( the native pair of
        // MsgContext )
        long xEnv=ep.getJniEnv();
        long nativeContext=ep.getJniContext();
        if( nativeContext==0 || xEnv==0 ) {
            setNativeEndpoint( ep );
            xEnv=ep.getJniEnv();
            nativeContext=ep.getJniContext();
        }

        if( xEnv==0 || nativeContext==0 || nativeJkHandlerP==0 ) {
            log.error("invokeNative: Null pointer ");
            return -1;
        }

        // Will process the message in the current thread.
        // No wait needed to receive the response, if any
        int status=AprImpl.jkInvoke( xEnv,
                                 nativeJkHandlerP,
                                 nativeContext,
                                 code, msg.getBuffer(), 0, msg.getLen(), raw );

        if( status != 0 && status != 2 ) {
            log.error( "nativeDispatch: error " + status, new Throwable() );
        }

        if( log.isDebugEnabled() ) log.debug( "Sending packet - done " + status);
        return status;
    }

    /** Base implementation for invoke. Dispatch the action to the native
    * code, where invoke() is called on the wrapped jk_bean.
    */
    public  int invoke(Msg msg, MsgContext ep )
        throws IOException
    {
        long xEnv=ep.getJniEnv();
        int type=ep.getType();

        int status=nativeDispatch(msg, ep, type, 0 );

        apr.jkRecycle(xEnv, ep.getJniContext());
        apr.releaseJkEnv( xEnv );
        return status;
    }

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

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