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RSF远程服务调用框架

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package com.hc360.rsf.rpc.loadbalance;

import java.util.List;
import java.util.Random;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.hc360.rsf.common.URL;
import com.hc360.rsf.registry.Provider;
import com.hc360.rsf.rpc.RpcInvocation;

/**
 * random load balance.
 *
 */
public class RandomLoadBalance extends AbstractLoadBalance {
	private static Logger logger = LoggerFactory.getLogger(RandomLoadBalance.class);
	
    public static final String NAME = "random";

    private final Random random = new Random();

    protected Provider doSelect(List invokers, RpcInvocation invocation) {
        int length = invokers.size(); // 总个数
        int totalWeight = 0; // 总权重
        boolean sameWeight = true; // 权重是否都一样
        for (int i = 0; i < length; i++) {
            int weight = getWeight(invokers.get(i), invocation);
            totalWeight += weight; // 累计总权重
            if (sameWeight && i > 0
                    && weight != getWeight(invokers.get(i - 1), invocation)) {
                sameWeight = false; // 计算所有权重是否一样
            }
        }
        if (totalWeight > 0 && ! sameWeight) {
            // 如果权重不相同且权重大于0则按总权重数随机
            int offset = random.nextInt(totalWeight);
            // 并确定随机值落在哪个片断上
            for (int i = 0; i < length; i++) {
                offset -= getWeight(invokers.get(i), invocation);
                if (offset < 0) {
                    return invokers.get(i);
                }
            }
        }
        // 如果权重相同或权重为0则均等随机
        logger.debug("负载均衡=RandomLoadBalance,{}选1",invokers.size());
        return invokers.get(random.nextInt(length));
    }

}