业务场景

最近项目中场景需要get一批key的value，因为redis的get操作(不单单是get命令)是阻塞的，如果循环取值的话，就算是内网，耗时也是巨大的。所以想到了redis的pipeline命令。

pipeline简介

非pipeline：client一个请求，redis server一个响应，期间client阻塞

Pipeline：redis的管道命令，允许client将多个请求依次发给服务器（redis的客户端，如jedisCluster，lettuce等都实现了对pipeline的封装），过程中而不需要等待请求的回复，在最后再一并读取结果即可。

单机版

单机版比较简单，直接上代码

//换成真实的redis实例
Jedis jedis = new Jedis();
//获取管道
Pipeline p = jedis.pipelined();
for (int i = 0; i < 10000; i++) {
    p.get(i + "");
}
//获取结果
List<Object> results = p.syncAndReturnAll();

集群版

因为 JedisCluster 本身不支持 pipeline ，所以我们需要对 JedisCluster 进行一些封装。

还是一样，直接上代码


import lombok.extern.slf4j.Slf4j;
import redis.clients.jedis.*;
import redis.clients.jedis.exceptions.JedisMovedDataException;
import redis.clients.jedis.exceptions.JedisRedirectionException;
import redis.clients.util.JedisClusterCRC16;
import redis.clients.util.SafeEncoder;

import java.io.Closeable;
import java.lang.reflect.Field;
import java.util.*;
import java.util.function.BiConsumer;



@Slf4j
public class JedisClusterPipeline extends PipelineBase implements Closeable {


    /**
     * 用于获取 JedisClusterInfoCache
     */
    private JedisSlotBasedConnectionHandler connectionHandler;
    /**
     * 根据hash值获取连接
     */
    private JedisClusterInfoCache clusterInfoCache;

    /**
     * 也可以去继承JedisCluster和JedisSlotBasedConnectionHandler来提供访问接口
     * JedisCluster继承于BinaryJedisCluster
     * 在BinaryJedisCluster，connectionHandler属性protected修饰的，所以需要反射
     *
     *
     * 而 JedisClusterInfoCache 属性在JedisClusterConnectionHandler中，但是这个类是抽象类，
     * 但它有一个实现类JedisSlotBasedConnectionHandler
     */
    private static final Field FIELD_CONNECTION_HANDLER;
    private static final Field FIELD_CACHE;
    static {
        FIELD_CONNECTION_HANDLER = getField(BinaryJedisCluster.class, "connectionHandler");
        FIELD_CACHE = getField(JedisClusterConnectionHandler.class, "cache");
    }


    /**
     * 根据顺序存储每个命令对应的Client
     */
    private Queue<Client> clients = new LinkedList<>();
    /**
     * 用于缓存连接
     * 一次pipeline过程中使用到的jedis缓存
     */
    private Map<JedisPool, Jedis> jedisMap = new HashMap<>();
    /**
     * 是否有数据在缓存区
     */
    private boolean hasDataInBuf = false;

    /**
     * 根据jedisCluster实例生成对应的JedisClusterPipeline
     * 通过此方式获取pipeline进行操作的话必须调用close()关闭管道
     * 调用本类里pipelineXX方法则不用close(),但建议最好还是在finally里调用一下close()
     * @param
     * @return
     */
    public static JedisClusterPipeline pipelined(JedisCluster jedisCluster) {
        JedisClusterPipeline pipeline = new JedisClusterPipeline();
        pipeline.setJedisCluster(jedisCluster);
        return pipeline;
    }


    public JedisClusterPipeline() {
    }

    public void setJedisCluster(JedisCluster jedis) {
        connectionHandler = getValue(jedis, FIELD_CONNECTION_HANDLER);
        clusterInfoCache = getValue(connectionHandler, FIELD_CACHE);
    }

    /**
     * 刷新集群信息，当集群信息发生变更时调用
     * @param
     * @return
     */
    public void refreshCluster() {
        connectionHandler.renewSlotCache();
    }

    /**
     * 同步读取所有数据. 与syncAndReturnAll()相比，sync()只是没有对数据做反序列化
     */
    public void sync() {
        innerSync(null);
    }

    /**
     * 同步读取所有数据 并按命令顺序返回一个列表
     *
     * @return 按照命令的顺序返回所有的数据
     */
    public List<Object> syncAndReturnAll() {
        List<Object> responseList = new ArrayList<>();

        innerSync(responseList);

        return responseList;
    }


    @Override
    public void close() {
        clean();

        clients.clear();

        for (Jedis jedis : jedisMap.values()) {
            if (hasDataInBuf) {
                flushCachedData(jedis);
            }

            jedis.close();
        }

        jedisMap.clear();

        hasDataInBuf = false;
    }

    private void flushCachedData(Jedis jedis) {
        try {
            jedis.getClient().getAll();
        } catch (RuntimeException ex) {
        }
    }

    @Override
    protected Client getClient(String key) {
        byte[] bKey = SafeEncoder.encode(key);

        return getClient(bKey);
    }

    @Override
    protected Client getClient(byte[] key) {
        Jedis jedis = getJedis(JedisClusterCRC16.getSlot(key));

        Client client = jedis.getClient();
        clients.add(client);

        return client;
    }

    private Jedis getJedis(int slot) {
        JedisPool pool = clusterInfoCache.getSlotPool(slot);

        // 根据pool从缓存中获取Jedis
        Jedis jedis = jedisMap.get(pool);
        if (null == jedis) {
            jedis = pool.getResource();
            jedisMap.put(pool, jedis);
        }

        hasDataInBuf = true;
        return jedis;
    }



    public static void pipelineSetEx(String[] keys, String[] values, int[] exps,JedisCluster jedisCluster) {
        operate(new Command() {
            @Override
            public List execute() {
                JedisClusterPipeline p = pipelined(jedisCluster);
                for (int i = 0, len = keys.length; i < len; i++) {
                    p.setex(keys[i], exps[i], values[i]);
                }
                return p.syncAndReturnAll();
            }
        });
    }

    public static List<Map<String, String>> pipelineHgetAll(String[] keys,JedisCluster jedisCluster) {
        return operate(new Command() {
            @Override
            public List execute() {
                JedisClusterPipeline p = pipelined(jedisCluster);
                for (int i = 0, len = keys.length; i < len; i++) {
                    p.hgetAll(keys[i]);
                }
                return p.syncAndReturnAll();
            }
        });
    }



    public static List<Boolean> pipelineSismember(String[] keys, String members,JedisCluster jedisCluster) {
        return operate(new Command() {
            @Override
            public List execute() {
                JedisClusterPipeline p = pipelined(jedisCluster);
                for (int i = 0, len = keys.length; i < len; i++) {
                    p.sismember(keys[i], members);
                }
                return p.syncAndReturnAll();
            }
        });
    }



    public static <O> List pipeline(BiConsumer<O, JedisClusterPipeline> function, O obj,JedisCluster jedisCluster) {
        return operate(new Command() {
            @Override
            public List execute() {
                JedisClusterPipeline jcp = JedisClusterPipeline.pipelined(jedisCluster);
                function.accept(obj, jcp);
                return jcp.syncAndReturnAll();
            }
        });
    }



    private void innerSync(List<Object> formatted) {
        HashSet<Client> clientSet = new HashSet<>();

        try {
            for (Client client : clients) {
                // 在sync()调用时其实是不需要解析结果数据的，但是如果不调用get方法，发生了JedisMovedDataException这样的错误应用是不知道的，因此需要调用get()来触发错误。
                // 其实如果Response的data属性可以直接获取，可以省掉解析数据的时间，然而它并没有提供对应方法，要获取data属性就得用反射，不想再反射了，所以就这样了
                Object data = generateResponse(client.getOne()).get();
                if (null != formatted) {
                    formatted.add(data);
                }

                // size相同说明所有的client都已经添加，就不用再调用add方法了
                if (clientSet.size() != jedisMap.size()) {
                    clientSet.add(client);
                }
            }
        } catch (JedisRedirectionException jre) {
            if (jre instanceof JedisMovedDataException) {
                // if MOVED redirection occurred, rebuilds cluster's slot cache,
                // recommended by Redis cluster specification
                refreshCluster();
            }

            throw jre;
        } finally {
            if (clientSet.size() != jedisMap.size()) {
                // 所有还没有执行过的client要保证执行(flush)，防止放回连接池后后面的命令被污染
                for (Jedis jedis : jedisMap.values()) {
                    if (clientSet.contains(jedis.getClient())) {
                        continue;
                    }

                    flushCachedData(jedis);
                }
            }

            hasDataInBuf = false;
            close();
        }
    }


    private static Field getField(Class<?> cls, String fieldName) {
        try {
            Field field = cls.getDeclaredField(fieldName);
            field.setAccessible(true);

            return field;
        } catch (NoSuchFieldException | SecurityException e) {
            throw new RuntimeException("cannot find or access field '" + fieldName + "' from " + cls.getName(), e);
        }
    }

    @SuppressWarnings({"unchecked" })
    private static <T> T getValue(Object obj, Field field) {
        try {
            return (T)field.get(obj);
        } catch (IllegalArgumentException | IllegalAccessException e) {
            log.error("get value fail", e);

            throw new RuntimeException(e);
        }
    }

    private static <T> T operate(Command command) {
        try  {
            return command.execute();
        } catch (Exception e) {
            log.error("redis operate error");
            throw new RuntimeException(e);
        }
    }

    interface Command {
        /**
         * 具体执行命令
         *
         * @param <T>
         * @return
         */
        <T> T execute();
    }

}

使用demo

    public Object testPipelineOperate() {
        //        String[] keys = {"dylan1","dylan2"};
        //        String[] values = {"dylan1-v1","dylan2-v2"};
        //        int[] exps = {100,200};
        //        JedisClusterPipeline.pipelineSetEx(keys, values, exps, jedisCluster);
        long start = System.currentTimeMillis();

        List<String> keyList = new ArrayList<>();
        for (int i = 0; i < 1000; i++) {
            keyList.add(i + "");
        }
        //        List<String> pipeline = JedisClusterPipeline.pipeline(this::getValue, keyList, jedisCluster);
        //        List<String> pipeline = JedisClusterPipeline.pipeline(this::getHashValue, keyList, jedisCluster);
        String[] keys = {"dylan-test1", "dylan-test2"};

        List<Map<String, String>> all = JedisClusterPipeline.pipelineHgetAll(keys, jedisCluster);
        long end = System.currentTimeMillis();
        System.out.println("testPipelineOperate cost:" + (end-start));

        return Response.success(all);
    }