Zookeeper::LeastConnectionBalancer

LeastConnectionBalancer.java

public class LeastConnectionBalancer implements Balancer {

    private CuratorFramework zkClient;

    public LeastConnectionBalancer(CuratorFramework zkClient){
        this.zkClient = zkClient;
    }

    @Override
    public String select() throws Exception {
        List<String> workers = zkClient.getChildren().forPath("/workers");
        if(workers == null){
            return null;
        }
        int size = workers.size();
        if(size == 0){
            return null;
        }
        int leastConnection = -1;
        int leastNode = -1;
        for(int i=0; i<size; i++){
            /**
             * 同时，在Server程序中，当channelActive的时候，ZooKeeper记录的连接数要增加1；
             * 当channelInactive的时候，ZooKeeper记录的连接数要减少1。
             */
            byte[] data = zkClient.getData().forPath("/workers/" + workers.get(i));
            int connection = Integer.parseInt(new String(data));
            if(leastConnection == -1 || connection < leastConnection){
                leastConnection = connection;
                leastNode = i;
            }
        }
        return workers.get(leastNode);
    }

}