redis 集羣批量操做

Redis集羣是無法執行批量操做命令的，如mget，pipeline等。這是由於redis將集羣劃分爲16383個哈希槽，不一樣的key會劃分到不一樣的槽中。可是，Jedis客戶端提供了計算key的slot方法，已經slot和節點之間的映射關係，經過這兩個數據，就能夠計算出每一個key所在的節點，而後使用pipeline獲取數據。具體代碼以下：

初始化    JedisCluster類

@Configuration
public class JedisClusterConfig {

    @Value("${spring.redis.cluster.nodes}")
    private String clusterNodes;

    @Value("${spring.redis.cache.commandTimeout}")
    private Integer commandTimeout;

    @Bean
    public JedisCluster getJedisCluster() {

        String[] serverArray = clusterNodes.split(",");
        Set<HostAndPort> nodes = new HashSet<>();
        for (String ipPort : serverArray) {
            String[] ipPortPair = ipPort.split(":");
            nodes.add(new HostAndPort(ipPortPair[0].trim(), Integer.valueOf(ipPortPair[1].trim())));
        }
        return new JedisCluster(nodes, commandTimeout);
    }
}

工具類 JedisClusterUtil

@Component
public class JedisClusterUtil {

    @Autowired
    private JedisCluster jedisCluster;

    @Resource(name = "redisTemplate4Json")
    protected RedisTemplate<String, Object> redisTemplate;

    /**
     * ZSet批量查詢
     * @param keys
     * @return
     */
    public List<Object> batchZRange(List<String> keys) {

        List<Object> resList = new ArrayList<>();
        if (keys == null || keys.size() == 0) {
            return resList;
        }

        if (keys.size() == 1) {
            BoundZSetOperations<String, Object> operations = redisTemplate.boundZSetOps(keys.get(0));
            Set<Object> set = operations.reverseRange(0, 0);
            resList.add(set.iterator().next());
            return resList;
        }

        Map<JedisPool, List<String>> jedisPoolMap = getJedisPool(keys);

        List<String> keyList;
        JedisPool currentJedisPool = null;
        Pipeline currentPipeline;
        List<Object> res = new ArrayList<>();
        Map<String, Object> resultMap = new HashMap<>();

        //執行
        for (Map.Entry<JedisPool, List<String>> entry : jedisPoolMap.entrySet()) {
            Jedis jedis = null;
            try {
                currentJedisPool = entry.getKey();
                keyList = entry.getValue();
                //獲取pipeline
                jedis = currentJedisPool.getResource();
                currentPipeline = jedis.pipelined();
                for (String key : keyList) {
                    currentPipeline.zrevrange(key, 0, 0);
                }
                //從pipeline中獲取結果
                res = currentPipeline.syncAndReturnAll();
                currentPipeline.close();
                for (int i = 0; i < keyList.size(); i++) {
                    if (null == res.get(i)) {
                        resultMap.put(keyList.get(i), null);
                    } else {
                        Set<Object> set = (Set<Object>) res.get(i);
                        if (null == set || set.isEmpty()) {
                            resultMap.put(keyList.get(i), null);
                        } else {
                            byte[] byteStr = set.iterator().next().toString().getBytes();
                            Object obj = redisTemplate.getDefaultSerializer().deserialize(byteStr);
                            resultMap.put(keyList.get(i), obj);
                        }
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                returnResource(jedis, currentJedisPool);
            }
        }
        resList = sortList(keys, resultMap);
        return resList;
    }

    /**
     * Value批量查詢
     * @param keys
     * @return
     */
    public List<Object> batchGet(List<String> keys){
        List<Object> resList = new ArrayList<>();
        if (keys == null || keys.size() == 0) {
            return resList;
        }

        if (keys.size() == 1) {
            BoundValueOperations<String, Object> operations = redisTemplate.boundValueOps(keys.get(0));
            resList.add(operations.get());
            return resList;
        }

        Map<JedisPool, List<String>> jedisPoolMap = getJedisPool(keys);

        List<String> keyList;
        JedisPool currentJedisPool = null;
        Pipeline currentPipeline;
        List<Object> res = new ArrayList<>();
        Map<String, Object> resultMap = new HashMap<>();

        for (Map.Entry<JedisPool, List<String>> entry : jedisPoolMap.entrySet()) {
            Jedis jedis = null;
            try {
                currentJedisPool = entry.getKey();
                keyList = entry.getValue();
                //獲取pipeline
                jedis = currentJedisPool.getResource();
                currentPipeline = jedis.pipelined();
                for (String key : keyList) {
                    currentPipeline.get(key);
                }
                //從pipeline中獲取結果
                res = currentPipeline.syncAndReturnAll();
                currentPipeline.close();
                for (int i = 0; i < keyList.size(); i++) {
                    if (null == res.get(i)) {
                        resultMap.put(keyList.get(i), null);
                    } else {
                        byte[] byteStr = keyList.get(i).toString().getBytes();
                        Object obj = redisTemplate.getDefaultSerializer().deserialize(byteStr);
                        resultMap.put(keyList.get(i), obj);
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                returnResource(jedis, currentJedisPool);
            }
        }
        resList = sortList(keys, resultMap);
        return resList;
    }

    private Map<JedisPool, List<String>> getJedisPool(List<String> keys){
        //JedisCluster繼承了BinaryJedisCluster
        //BinaryJedisCluster的JedisClusterConnectionHandler屬性
        //裏面有JedisClusterInfoCache，根據這一條繼承鏈，能夠獲取到JedisClusterInfoCache
        //從而獲取slot和JedisPool直接的映射
        MetaObject metaObject = SystemMetaObject.forObject(jedisCluster);
        JedisClusterInfoCache cache = (JedisClusterInfoCache) metaObject.getValue("connectionHandler.cache");
        //保存地址+端口和命令的映射
        Map<JedisPool, List<String>> jedisPoolMap = new HashMap<>();

        JedisPool currentJedisPool = null;
        List<String> keyList;
        for (String key : keys) {
            //計算哈希槽
            int crc = JedisClusterCRC16.getSlot(key);
            //經過哈希槽獲取節點的鏈接
            currentJedisPool = cache.getSlotPool(crc);

            //因爲JedisPool做爲value保存在JedisClusterInfoCache中的一個map對象中，每一個節點的
            //JedisPool在map的初始化階段就是肯定的和惟一的，因此獲取到的每一個節點的JedisPool都是同樣
            //的，能夠做爲map的key
            if (jedisPoolMap.containsKey(currentJedisPool)) {
                jedisPoolMap.get(currentJedisPool).add(key);
            } else {
                keyList = new ArrayList<>();
                keyList.add(key);
                jedisPoolMap.put(currentJedisPool, keyList);
            }
        }
        return jedisPoolMap;
    }

    private List<Object> sortList(List<String> keys, Map<String, Object> params) {
        List<Object> resultList = new ArrayList<>();
        Iterator<String> it = keys.iterator();
        while (it.hasNext()) {
            String key = it.next();
            resultList.add(params.get(key));
        }
        return resultList;
    }

    /**
     * 釋放jedis資源
     *
     * @param jedis
     */
    public void returnResource(Jedis jedis, JedisPool jedisPool) {
        if (jedis != null && jedisPool != null) {
            jedisPool.returnResource(jedis);
        }
    }

 注意：必定要完成後釋放 jedis 資源  否則會形成卡死現象