org.jactr.core.module.retrieval.time.DefaultRetrievalTimeEquation.java Source code

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Here is the source code for org.jactr.core.module.retrieval.time.DefaultRetrievalTimeEquation.java

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/**
 * Copyright (C) 2001-3, Anthony Harrison anh23@pitt.edu This library is free
 * software; you can redistribute it and/or modify it under the terms of the GNU
 * Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 * This library 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 Lesser General Public License for more
 * details. You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

package org.jactr.core.module.retrieval.time;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jactr.core.chunk.IChunk;
import org.jactr.core.logging.Logger;
import org.jactr.core.module.retrieval.four.IRetrievalModule4;

/**
 * 4.0 retrieval time equation
 * 
 * @author harrison
 * @created April 18, 2003
 */
public class DefaultRetrievalTimeEquation implements IRetrievalTimeEquation {

    private static transient Log LOGGER = LogFactory.getLog(DefaultRetrievalTimeEquation.class.getName());

    IRetrievalModule4 _retrievalModule;

    IChunk _errorChunk;

    boolean _warned = false;

    public DefaultRetrievalTimeEquation(IRetrievalModule4 module) {
        _retrievalModule = module;
    }

    /**
     * Description of the Method
     * 
     * @param model
     *            Description of the Parameter
     * @param chunk
     *            Description of the Parameter
     * @return Description of the Return Value
     */
    public double computeRetrievalTime(IChunk chunk) {
        double latencyFactor = _retrievalModule.getLatencyFactor();
        double latencyExponent = _retrievalModule.getLatencyExponent();
        double threshold = _retrievalModule.getRetrievalThreshold();
        double retrievalTime = 0;

        if (_errorChunk == null)
            _errorChunk = _retrievalModule.getModel().getDeclarativeModule().getErrorChunk();

        if (chunk.equals(_errorChunk)) {
            /*
             * if the retrieval threshold is inf, the time at which the retrieval will
             * fail will be inf as well, so we need to return something a little less
             * dangerous - so we use the error chunk activation to compute the
             * retrieval time.
             */
            if (Double.isInfinite(threshold) || Double.isNaN(threshold)) {
                retrievalTime = latencyFactor * Math.exp(-_errorChunk.getSubsymbolicChunk().getActivation());
                if (!_warned) {
                    StringBuilder msg = new StringBuilder(
                            "since retrieval threshold is not active, retrieval errors can take an infinite time. Returning in ");
                    msg.append(retrievalTime).append("s instead.");

                    if (LOGGER.isWarnEnabled())
                        LOGGER.warn(msg);
                    msg.insert(0, "Warning ");
                    if (Logger.hasLoggers(_retrievalModule.getModel()))
                        Logger.log(_retrievalModule.getModel(), Logger.Stream.RETRIEVAL, msg.toString());
                    _warned = true;
                }
            } else
                // otherwise, we fail using the normal math
                retrievalTime = latencyFactor * Math.exp(-threshold);
        } else {
            /*
             * everything is fine, calculate the retrieval time bsed on the chunks
             * activation
             */
            double activation = chunk.getSubsymbolicChunk().getActivation();

            retrievalTime = latencyFactor * Math.exp(-latencyExponent * activation);
        }

        return retrievalTime;
    }
}