PollableNode.java

/*
 * This file is part of the OpenNMS(R) Application.
 *
 * OpenNMS(R) is Copyright (C) 2004-2006 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:
 * 
 * Created December 31, 2004
 *
 * Copyright (C) 2004-2006 The OpenNMS Group, Inc.  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       <license@opennms.org>
 *      http://www.opennms.org/
 *      http://www.opennms.com/
 */
package org.infosec.ismp.poller.pollable;

import java.net.InetAddress;
import java.util.Date;

import org.infosec.ismp.model.event.Event;
import org.infosec.ismp.model.event.EventConstants;
import org.infosec.ismp.model.poller.PollStatus;
import org.infosec.ismp.util.ThreadCategory;

/**
 * Represents a PollableNode 
 *
 * @author <a href="mailto:brozow@opennms.org">Mathew Brozowski</a>
 */
public class PollableNode extends PollableContainer {

	/**
	 * Represents a Lock 
	 *
	 * @author brozow
	 */
	public class Lock {
		private Thread m_owner = null;
		private int m_obtainCount = 0;

		public synchronized void obtain() {
			ThreadCategory log = ThreadCategory.getInstance(getClass());

			if (m_owner != Thread.currentThread()) {
				log.debug("Trying to obtain lock for " + PollableNode.this);
				while (m_owner != null) {
					try {
						wait();
					} catch (InterruptedException e) {
						throw new ThreadInterrupted("Lock for "
								+ PollableNode.this + " is unavailable", e);
					}
				}
				m_owner = Thread.currentThread();
				log.debug("Obtained lock for " + PollableNode.this);
			}
			m_obtainCount++;
		}

		public synchronized void obtain(long timeout) {
			ThreadCategory log = ThreadCategory.getInstance(getClass());

			if (m_owner != Thread.currentThread()) {
				log.debug("Trying to obtain lock for " + PollableNode.this);
				long now = System.currentTimeMillis();
				long endTime = (timeout == 0 ? Long.MAX_VALUE : now + timeout);
				while (m_owner != null) {
					try {
						wait(endTime - now);
					} catch (InterruptedException e) {
						throw new ThreadInterrupted("Lock for "
								+ PollableNode.this + " is unavailable", e);
					}
					now = System.currentTimeMillis();
					if (now >= endTime)
						throw new LockUnavailable("Unable to obtain lock for "
								+ PollableNode.this + " before timeout");
				}
				m_owner = Thread.currentThread();
				log.debug("Obtained lock for " + PollableNode.this);
			}
			m_obtainCount++;
		}

		public synchronized void release() {
			if (m_owner == Thread.currentThread()) {
				m_obtainCount--;
				if (m_obtainCount == 0) {
					ThreadCategory.getInstance(getClass()).debug(
							"Releasing lock for " + PollableNode.this);
					m_owner = null;
					notifyAll();
				}
			}
		}

		/**
		 * @return
		 */
		public synchronized boolean isLockAvailable() {
			return m_owner == null;
		}

	}

	private final int m_nodeId;
	private final String m_nodeLabel;
	private final Lock m_lock = new Lock();

	public PollableNode(PollableNetwork network, int nodeId, String nodeLabel) {
		super(network, Scope.NODE);
		m_nodeId = nodeId;
		m_nodeLabel = nodeLabel;
	}

	public int getNodeId() {
		return m_nodeId;
	}

	public String getNodeLabel() {
		return m_nodeLabel;
	}

	public PollableInterface createInterface(final InetAddress addr) {
		final PollableInterface[] retVal = new PollableInterface[1];
		Runnable r = new Runnable() {
			@Override
			public void run() {
				PollableInterface iface = new PollableInterface(
						PollableNode.this, addr);
				addMember(iface);
				retVal[0] = iface;
			}
		};
		withTreeLock(r);
		return retVal[0];
	}

	public PollableInterface getInterface(InetAddress addr) {
		return (PollableInterface) getMember(addr);
	}

	public PollableNetwork getNetwork() {
		return (PollableNetwork) getParent();
	}

	@Override
	public PollContext getContext() {
		return getNetwork().getContext();
	}

	@Override
	protected Object createMemberKey(PollableElement member) {
		PollableInterface iface = (PollableInterface) member;
		return iface.getAddress();
	}

	/**
	 * @param ipAddr
	 * @param svcName
	 * @return
	 */
	public PollableService createService(final InetAddress addr,
			final String svcName) {
		final PollableService retVal[] = new PollableService[1];

		Runnable r = new Runnable() {
			@Override
			public void run() {
				PollableInterface iface = getInterface(addr);
				if (iface == null)
					iface = createInterface(addr);
				retVal[0] = iface.createService(svcName);
			}
		};
		withTreeLock(r);
		return retVal[0];
	}

	/**
	 * @param ipAddr
	 * @param svcName
	 * @return
	 */
	public PollableService getService(InetAddress addr, String svcName) {
		PollableInterface iface = getInterface(addr);
		return (iface == null ? null : iface.getService(svcName));
	}

	@Override
	protected void visitThis(PollableVisitor v) {
		super.visitThis(v);
		v.visitNode(this);
	}

	@Override
	public Event createDownEvent(Date date) {
		return getContext().createEvent(EventConstants.NODE_DOWN_EVENT_UEI,
				getNodeId(), null, null, date, getStatus().getReason());
	}

	@Override
	public Event createUpEvent(Date date) {
		return getContext().createEvent(EventConstants.NODE_UP_EVENT_UEI,
				getNodeId(), null, null, date, getStatus().getReason());
	}

	@Override
	public String toString() {
		return String.valueOf(getNodeId());
	}

	@Override
	public PollableElement getLockRoot() {
		return this;
	}

	@Override
	public boolean isTreeLockAvailable() {
		return m_lock.isLockAvailable();
	}

	@Override
	public void obtainTreeLock(long timeout) {
		if (timeout == 0)
			m_lock.obtain();
		else
			m_lock.obtain(timeout);
	}

	@Override
	public void releaseTreeLock() {
		m_lock.release();
	}

	@Override
	public PollStatus doPoll(final PollableElement elem) {
		final PollStatus retVal[] = new PollStatus[1];
		Runnable r = new Runnable() {
			@Override
			public void run() {
				resetStatusChanged();
				retVal[0] = poll(elem);
			}
		};
		withTreeLock(r);
		return retVal[0];
	}

}