udpuuidsender.java

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//
// This file is part of the OpenNMS(R) Application.
//
// OpenNMS(R) is Copyright (C) 2002-2003 The OpenNMS Group, Inc.  All rights reserved.
// OpenNMS(R) is a derivative work, containing both original code, included code and modified
// code that was published under the GNU General Public License. Copyrights for modified 
// and included code are below.
//
// OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
//
// Modifications:
//
// 2003 Jan 31: Cleaned up some unused imports.
//
// Original code base Copyright (C) 1999-2001 Oculan Corp.  All rights reserved.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.                                                            
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//       
// For more information contact: 
//      OpenNMS Licensing       <[e-mail]>
//      http://www.opennms.org/
//      http://www.opennms.com/
//

package org.opennms.netmgt.eventd.adaptors.udp;

import java.io.IOException;
import java.io.StringWriter;
import java.io.UnsupportedEncodingException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.log4j.Category;
import org.exolab.castor.xml.MarshalException;
import org.exolab.castor.xml.Marshaller;
import org.exolab.castor.xml.ValidationException;
import org.opennms.core.utils.ThreadCategory;
import org.opennms.netmgt.eventd.adaptors.EventHandler;
import org.opennms.netmgt.xml.event.Event;
import org.opennms.netmgt.xml.event.EventReceipt;

/**
 * This class implements the User Datagram Protocol (UDP) event receiver. When
 * the an agent sends an event via UDP/IP the receiver will process the event
 * and then add the UUIDs to the internal list. If the event is successfully
 * processed then an event-receipt is returned to the caller.
 * 
 * @author <a href="mailto:[e-mail]">Brian Weaver </a>
 * @author <a href="http://www.oculan.com">Oculan Corporation </a>
 * 
 */
final class UdpUuidSender implements Runnable {
    /**
     * The list of outgoing event-receipts by UUID.
     */
    private List m_eventUuidsOut;

    /**
     * The stop flag
     */
    private volatile boolean m_stop;

    /**
     * The UDP socket for receipt and transmission of packets from agents.
     */
    private DatagramSocket m_dgSock;

    /**
     * The thread context
     */
    private Thread m_context;

    /**
     * The list of handlers
     */
    private List m_handlers;

    /**
     * The log prefix
     */
    private String m_logPrefix;

    /**
     * Constructs a new instance of this runnable.
     */
    UdpUuidSender(DatagramSocket sock, List uuidsOut, List handlers) {
        m_context = null;
        m_dgSock = sock;
        m_stop = false;
        m_eventUuidsOut = uuidsOut;
        m_handlers = handlers;
        m_logPrefix = org.opennms.netmgt.eventd.Eventd.LOG4J_CATEGORY;
    }

    /**
     * Stops the current context.
     */
    void stop() throws InterruptedException {
        m_stop = true;
        if (m_context != null) {
            Category log = ThreadCategory.getInstance(getClass());
            if (log.isDebugEnabled())
                log.debug("Stopping and joining thread context " + m_context.getName());

            m_context.interrupt();
            m_context.join();

            if (log.isDebugEnabled())
                log.debug("Thread context stopped and joined");
        }
    }

    /**
     * Returns true if the runnable is still running in its context
     */
    boolean isAlive() {
        return (m_context == null ? false : m_context.isAlive());
    }

    public void run() {
        // get the context
        //
        m_context = Thread.currentThread();

        // get a logger
        //
        ThreadCategory.setPrefix(m_logPrefix);
        Category log = ThreadCategory.getInstance(getClass());
        boolean isTracing = log.isDebugEnabled();

        if (m_stop) {
            if (isTracing)
                log.debug("Stop flag set before thread started, exiting");
            return;
        } else if (isTracing)
            log.debug("Thread context started");

        // This loop is labeled so that it can be
        // exited quickly when the thread is interrupted
        //
        ArrayList eventHold = new ArrayList(30);
        Map receipts = new HashMap();

        RunLoop: while (!m_stop) {
            if (isTracing)
                log.debug("Waiting on event receipts to be generated");

            synchronized (m_eventUuidsOut) {
                // wait for an event to show up.
                // wait in 1 second intervals
                //
                while (m_eventUuidsOut.isEmpty()) {
                    try {
                        // use wait instead of sleep to
                        // release the lock!
                        //
                        m_eventUuidsOut.wait(1000);
                    } catch (InterruptedException ie) {
                        if (isTracing)
                            log.debug("Thread context interrupted");
                        break RunLoop;
                    }
                }

                eventHold.addAll(m_eventUuidsOut);
                m_eventUuidsOut.clear();
            }

            if (isTracing) {
                log.debug("Received " + eventHold.size() + " event receipts to process");
                log.debug("Processing receipts");
            }

            // build an event-receipt
            //
            Iterator iter = eventHold.iterator();
            while (iter.hasNext()) {
                UdpReceivedEvent re = (UdpReceivedEvent) iter.next();
                Iterator xiter = re.getAckedEvents().iterator();
                while (xiter.hasNext()) {
                    Event e = (Event) xiter.next();
                    if (e.getUuid() != null) {
                        EventReceipt receipt = (EventReceipt) receipts.get(re);
                        if (receipt == null) {
                            receipt = new EventReceipt();
                            receipts.put(re, receipt);
                        }
                        receipt.addUuid(e.getUuid());
                    }
                }
            }
            eventHold.clear();

            if (isTracing)
                log.debug("Event receipts sorted, transmitting receipts");

            // turn them into XML and send it out the socket
            // 
            iter = receipts.entrySet().iterator();
            while (iter.hasNext()) {
                Map.Entry entry = (Map.Entry) iter.next();
                UdpReceivedEvent re = (UdpReceivedEvent) entry.getKey();
                EventReceipt receipt = (EventReceipt) entry.getValue();

                StringWriter writer = new StringWriter();
                try {
                    Marshaller.marshal(receipt, writer);
                } catch (ValidationException e) {
                    log.warn("Failed to build event receipt for agent " + re.getSender().getHostAddress() + ":" + re.getPort(), e);
                } catch (MarshalException e) {
                    log.warn("Failed to build event receipt for agent " + re.getSender().getHostAddress() + ":" + re.getPort(), e);
                }

                String xml = writer.getBuffer().toString();
                try {
                    byte[] xml_bytes = xml.getBytes("US-ASCII");
                    DatagramPacket pkt = new DatagramPacket(xml_bytes, xml_bytes.length, re.getSender(), re.getPort());

                    if (isTracing) {
                        log.debug("Transmitting receipt to destination " + re.getSender().getHostAddress() + ":" + re.getPort());
                    }

                    m_dgSock.send(pkt);
                    synchronized (m_handlers) {
                        Iterator i = m_handlers.iterator();
                        while (i.hasNext()) {
                            try {
                                ((EventHandler) i.next()).receiptSent(receipt);
                            } catch (Throwable t) {
                                log.warn("Error processing event receipt", t);
                            }
                        }
                    }

                    if (isTracing) {
                        log.debug("Receipt transmitted OK {");
                        log.debug(xml);
                        log.debug("}");
                    }
                } catch (UnsupportedEncodingException e) {
                    log.warn("Failed to convert XML to byte array", e);
                } catch (IOException e) {
                    log.warn("Failed to send packet to host" + re.getSender().getHostAddress() + ":" + re.getPort(), e);
                }
            }
            receipts.clear();

        } // end RunLoop

        if (isTracing)
            log.debug("Context finished, returning");

    } // end run()

    void setLogPrefix(String prefix) {
        m_logPrefix = prefix;
    }
} // end EventProcessor Class