redis cluster使用pipeline

为什么cluster无法使用pipeline

主要是因为redis-cluster的hash分片。具体的redis命令，会根据key计算出一个槽位（slot）,然后根据槽位去特定的节点redis上执行操作。那么pipeline中每个单独的操作，需要根据“key”运算一个槽位（JedisClusterCRC16.getSlot(key)），然后根据槽位去特定的机器执行命令。也就是说一次pipeline操作会使用多个节点的redis连接，而目前JedisCluster是无法支持的。

基于redisCluster整合pipeline

设计思路

1. 首先创建RedisCluster客户端 --------------getCluster()

2. 获取RedisCluster的哈希槽分布情况-----------------getSlotHostMap(params)

3. 通过key计算出所属redis的节点，并获取redis客户端----------------------getJedisByKey(params)

4. 通过redis客户端完成pipeline操作----------------main(args)

代码实现

import redis.clients.jedis.*;
import redis.clients.util.JedisClusterCRC16;

import java.util.*;

/**
 * nifiDefined
 * Created by NightWatch on 2018/12/10.
 */
public class PipelineTest {

    public static void main(String[] args) throws InterruptedException, IOException {


        String key ="key";

        Jedis jedis = getJedisByKey(key);

        Pipeline pipeline = jedis.pipelined();

		 pipeline.somecommend...

		 pipeline.sync();

        pipelined.close();
        jedis.close();


    }
    private static TreeMap<Long, String> getSlotHostMap(String anyHostAndPortStr) {
        TreeMap<Long, String> tree = new TreeMap<>();
        String parts[] = anyHostAndPortStr.split(":");
        HostAndPort anyHostAndPort = new HostAndPort(parts[0], Integer.parseInt(parts[1]));
        try{
            Jedis jedis = new Jedis(anyHostAndPort.getHost(), anyHostAndPort.getPort());
            jedis.auth("RedisPass");
            List<Object> list = jedis.clusterSlots();

            //TODO:list 结构
//            1) 1) (integer) 5461
//               2) (integer) 10922
//               3) 1) "10.1.2.159"
//                  2) (integer) 27002
//                  3) "4689bdf95317bb61dfa6bf67f292a0be5c574aa4"
//               4) 1) "10.1.2.159"
//                  2) (integer) 27005
//                  3) "673ae869ef903d485d75804cf20881fd706fe7ae"
//            2) 1) (integer) 0
//               2) (integer) 5460
//               3) 1) "10.1.2.159"
//                  2) (integer) 27001
//                  3) "82ca45fd7e195c4a966a17b0b830a6fa44d04688"
//               4) 1) "10.1.2.159"
//                  2) (integer) 27004
//                  3) "e005323689107d78c7c9396c2fdafce4bf07e586"
//            3) 1) (integer) 10923
//               2) (integer) 16383
//               3) 1) "10.1.2.159"
//                  2) (integer) 27003
//                  3) "4ce08f73db3258b8b4b4abfb7a79dd4838cd3729"
//               4) 1) "10.1.2.159"
//                  2) (integer) 27006
//                  3) "668691597f9b990cd62354b34819b935f522f0ca"


            //TODO:list 结构


            for (Object object : list) {
                List<Object> masterAndSlave = (List<Object>) object;
                List<Object> master = (List<Object>) masterAndSlave.get(2);
                String hostAndPort = new String((byte[]) master.get(0)) + ":" + master.get(1);
                tree.put((Long) masterAndSlave.get(0), hostAndPort);
                tree.put((Long) masterAndSlave.get(1), hostAndPort);
            }
            jedis.close();
        }catch(Exception e){

            e.printStackTrace();
        }
        return tree;
    }

    private static JedisCluster getCluster() {
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(10);
        Set<HostAndPort> hostAndPorts = new HashSet<>();
        hostAndPorts.add(new HostAndPort("localhost", 27006));
        hostAndPorts.add(new HostAndPort("localhost", 27005));
        hostAndPorts.add(new HostAndPort("localhost", 27004));
        hostAndPorts.add(new HostAndPort("localhost", 27003));
        hostAndPorts.add(new HostAndPort("localhost", 27002));
        hostAndPorts.add(new HostAndPort("localhost", 27001));
        JedisCluster cluster = new JedisCluster(hostAndPorts, 1000, 1000, 5, "RedisPass", config);
        return cluster;
    }

    private static Jedis getJedisByKey(String key) {
        JedisCluster cluster = getCluster();
        Map<String, JedisPool> nodes = cluster.getClusterNodes();
        String anyHost = nodes.keySet().iterator().next();
        TreeMap<Long, String> slotHostMap = getSlotHostMap(anyHost);
        int slot = JedisClusterCRC16.getSlot(key);
        Map.Entry<Long, String> entry = slotHostMap.lowerEntry(Long.valueOf(slot));
        Jedis jedis = nodes.get(entry.getValue()).getResource();
        return jedis;
    }
}