RoundRobinArbiter.java

/**
 * ****************************************************************************
 * Copyright (c) 2010-2016 by Min Cai (min.cai.china@gmail.com).
 * <p>
 * This file is part of the Archimulator multicore architectural simulator.
 * <p>
 * Archimulator 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 3 of the License, or
 * (at your option) any later version.
 * <p>
 * Archimulator 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.
 * <p>
 * You should have received a copy of the GNU General Public License
 * along with Archimulator. If not, see <http://www.gnu.org/licenses/>.
 * ****************************************************************************
 */
package archimulator.uncore.noc.util;

import com.google.common.collect.Iterators;

import java.util.Iterator;
import java.util.List;

/**
 * Round robin arbiter.
 *
 * @author Min Cai
 */
public abstract class RoundRobinArbiter<ResourceT, RequesterT> {
    private ResourceT resource;

    private Iterator<RequesterT> requestersIterator;

    /**
     * Create a round robin arbiter.
     *
     * @param resource the resource
     */
    public RoundRobinArbiter(ResourceT resource) {
        this.resource = resource;
    }

    /**
     * Get the list of requesters.
     *
     * @return the list of requesters
     */
    protected abstract List<RequesterT> getRequesters();

    /**
     * Get a boolean value indicating whether the resource is available or not.
     *
     * @param resource the resource
     * @return a boolean value indicating whether the resource is available or not
     */
    protected abstract boolean resourceAvailable(ResourceT resource);

    /**
     * Get a boolean value indicating whether the requester has requests or not.
     *
     * @param requester the requester
     * @return a boolean value indicating whether the requester has requests or not
     */
    protected abstract boolean requesterHasRequests(RequesterT requester);

    /**
     * Get the next requester.
     *
     * @return the next requester
     */
    public RequesterT next() {
        if(!this.resourceAvailable(resource)) {
            return null;
        }

        for(int i = 0; i < this.getRequesters().size(); i++) {
            RequesterT requester = this.getRequestersIterator().next();
            if(this.requesterHasRequests(requester)) {
                return requester;
            }
        }

        return null;
    }

    /**
     * Get the resource.
     *
     * @return the resource
     */
    public ResourceT getResource() {
        return resource;
    }

    private Iterator<RequesterT> getRequestersIterator() {
        if(requestersIterator == null) {
            this.requestersIterator = Iterators.cycle(this.getRequesters());
        }
        return requestersIterator;
    }
}