gridool.routing.selector.LoadBalancingNodeSelector.java Source code

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Here is the source code for gridool.routing.selector.LoadBalancingNodeSelector.java

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/*
 * @(#)$Id$
 *
 * Copyright 2006-2008 Makoto YUI
 *
 * Licensed 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.
 * 
 * Contributors:
 *     Makoto YUI - initial implementation
 */
package gridool.routing.selector;

import gridool.GridConfiguration;
import gridool.GridNode;
import gridool.loadblancing.GridLoadProbe;
import gridool.routing.GridNodeSelector;

import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * 
 * <DIV lang="en"></DIV>
 * <DIV lang="ja"></DIV>
 * 
 * @author Makoto YUI (yuin405@gmail.com)
 */
public final class LoadBalancingNodeSelector implements GridNodeSelector {
    private static final Log LOG = LogFactory.getLog(LoadBalancingNodeSelector.class);

    public LoadBalancingNodeSelector() {
    }

    @Override
    public GridNode selectNode(List<GridNode> nodeList, GridConfiguration config) {
        final int size = nodeList.size();
        if (size == 0) {
            return null;
        } else if (size == 1) {
            return nodeList.get(0);
        }

        final GridLoadProbe probe = config.getProbe();
        GridNode node = null;
        float minLoad = Float.MAX_VALUE;
        for (int i = 0; i < size; i++) {
            GridNode n = nodeList.get(i);
            float load = probe.getLoad(n);
            if (load < minLoad) {
                node = n;
                minLoad = load;
            }
        }
        if (LOG.isInfoEnabled()) {
            LOG.info("Node `" + node + "' of load=" + minLoad + " is selected");
        }
        return node;
    }

}