Storm4

package storm.scheduler;

import java.lang.management.ManagementFactory;
import java.lang.management.ThreadMXBean;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import cpuinfo.CPUInfo;

/**
 * 负载监视器
 * @author wxweven
 * @version 1.0
 * @email wxweven@qq.com
 * @blog http://wxweven.com
 * @Copyright: Copyright (c) wxweven 2009 - 2016
 */
public class LoadMonitor {

    private static final int SECS_TO_NANOSECS = 1000000000;
    private static LoadMonitor instance = null;
    private final long cpuSpeed; // Hz
    Map<Long, Long> loadHistory;

    public static LoadMonitor getInstance() {
        if (instance == null) {
            instance = new LoadMonitor();
        }
        return instance;
    }

    private LoadMonitor() {
        cpuSpeed = CPUInfo.getInstance().getCoreInfo(0).getSpeed();
    }

    public Map<Long, Long> getLoadInfo(Set<Long> threadIds) {
        // get current load
        Map<Long, Long> currentLoadInfo = new HashMap<Long, Long>();
        ThreadMXBean threadBean = ManagementFactory.getThreadMXBean();
        for (long id : threadIds) {
            currentLoadInfo.put(id, threadBean.getThreadCpuTime(id));
        }

        // compute difference wrt history
        Map<Long, Long> loadInfo = new HashMap<Long, Long>();
        for (long id : threadIds) {
            // Long oldObj = (loadHistory != null)?loadHistory.get(id):0;
            // long old = (oldObj != null)?oldObj.longValue():0;
            long old = 0;
            if (loadHistory != null && loadHistory.get(id) != null) {
                old = loadHistory.get(id);
            }
            double deltaTime = (double)(currentLoadInfo.get(id) - old) / SECS_TO_NANOSECS; // sec
            loadInfo.put(id, (long)(deltaTime * cpuSpeed));
        }

        // replace history with current
        loadHistory = currentLoadInfo;

        return loadInfo;
    }
}