Java客户端Jedis的八种调用方式

redis是一个著名的key-value存储系统，而作为其官方推荐的java版客户端jedis也非常强大和稳定，支持事务、管道及有jedis自身实现的分布式。

在这里对jedis关于事务、管道和分布式的调用方式做一个简单的介绍和对比：
一、普通同步方式

最简单和基础的调用方式，

@Test
public void test1Normal() {
    Jedis jedis = new Jedis("localhost");
    long start = System.currentTimeMillis();
    for (int i = 0; i < 100000; i++) {
        String result = jedis.set("n" + i, "n" + i);
    }
    long end = System.currentTimeMillis();
    System.out.println("Simple SET: " + ((end - start)/1000.0) + " seconds");
    jedis.disconnect();
}

很简单吧，每次set之后都可以返回结果，标记是否成功。
二、事务方式(Transactions)

redis的事务很简单，他主要目的是保障，一个client发起的事务中的命令可以连续的执行，而中间不会插入其他client的命令。

看下面例子：

@Test
public void test2Trans() {
    Jedis jedis = new Jedis("localhost");
    long start = System.currentTimeMillis();
    Transaction tx = jedis.multi();
    for (int i = 0; i < 100000; i++) {
        tx.set("t" + i, "t" + i);
    }
    List<Object> results = tx.exec();
    long end = System.currentTimeMillis();
    System.out.println("Transaction SET: " + ((end - start)/1000.0) + " seconds");
    jedis.disconnect();
}

我们调用jedis.watch(…)方法来监控key，如果调用后key值发生变化，则整个事务会执行失败。另外，事务中某个操作失败，并不会回滚其他操作。这一点需要注意。还有，我们可以使用discard()方法来取消事务。
三、管道(Pipelining)

有时，我们需要采用异步方式，一次发送多个指令，不同步等待其返回结果。这样可以取得非常好的执行效率。这就是管道，调用方法如下：

@Test
public void test3Pipelined() {
    Jedis jedis = new Jedis("localhost");
    Pipeline pipeline = jedis.pipelined();
    long start = System.currentTimeMillis();
    for (int i = 0; i < 100000; i++) {
        pipeline.set("p" + i, "p" + i);
    }
    List<Object> results = pipeline.syncAndReturnAll();
    long end = System.currentTimeMillis();
    System.out.println("Pipelined SET: " + ((end - start)/1000.0) + " seconds");
    jedis.disconnect();
}

四、管道中调用事务

就Jedis提供的方法而言，是可以做到在管道中使用事务，其代码如下：

@Test
public void test4combPipelineTrans() {
    jedis = new Jedis("localhost");
    long start = System.currentTimeMillis();
    Pipeline pipeline = jedis.pipelined();
    pipeline.multi();
    for (int i = 0; i < 100000; i++) {
        pipeline.set("" + i, "" + i);
    }
    pipeline.exec();
    List<Object> results = pipeline.syncAndReturnAll();
    long end = System.currentTimeMillis();
    System.out.println("Pipelined transaction: " + ((end - start)/1000.0) + " seconds");
    jedis.disconnect();
}

但是经测试（见本文后续部分），发现其效率和单独使用事务差不多，甚至还略微差点。
五、分布式直连同步调用

@Test
public void test5shardNormal() {
    List<JedisShardInfo> shards = Arrays.asList(
            new JedisShardInfo("localhost",6379),
            new JedisShardInfo("localhost",6380));

    ShardedJedis sharding = new ShardedJedis(shards);

    long start = System.currentTimeMillis();
    for (int i = 0; i < 100000; i++) {
        String result = sharding.set("sn" + i, "n" + i);
    }
    long end = System.currentTimeMillis();
    System.out.println("Simple@Sharing SET: " + ((end - start)/1000.0) + " seconds");

    sharding.disconnect();
}

这个是分布式直接连接，并且是同步调用，每步执行都返回执行结果。类似地，还有异步管道调用。
六、分布式直连异步调用

@Test
public void test6shardpipelined() {
    List<JedisShardInfo> shards = Arrays.asList(
            new JedisShardInfo("localhost",6379),
            new JedisShardInfo("localhost",6380));

    ShardedJedis sharding = new ShardedJedis(shards);

    ShardedJedisPipeline pipeline = sharding.pipelined();
    long start = System.currentTimeMillis();
    for (int i = 0; i < 100000; i++) {
        pipeline.set("sp" + i, "p" + i);
    }
    List<Object> results = pipeline.syncAndReturnAll();
    long end = System.currentTimeMillis();
    System.out.println("Pipelined@Sharing SET: " + ((end - start)/1000.0) + " seconds");

    sharding.disconnect();
}

七、分布式连接池同步调用（适用于2.2及以下版本）

如果，你的分布式调用代码是运行在线程中，那么上面两个直连调用方式就不合适了，因为直连方式是非线程安全的，这个时候，你就必须选择连接池调用。

@Test
public void test7shardSimplePool() {
    List<JedisShardInfo> shards = Arrays.asList(
            new JedisShardInfo("localhost",6379),
            new JedisShardInfo("localhost",6380));

    ShardedJedisPool pool = new ShardedJedisPool(new JedisPoolConfig(), shards);

    ShardedJedis one = pool.getResource();

    long start = System.currentTimeMillis();
    for (int i = 0; i < 100000; i++) {
        String result = one.set("spn" + i, "n" + i);
    }
    long end = System.currentTimeMillis();
    pool.returnResource(one);
    System.out.println("Simple@Pool SET: " + ((end - start)/1000.0) + " seconds");

    pool.destroy();
}

上面是同步方式，当然还有异步方式。
八、分布式连接池异步调用（适用于2.2及以下版本）

@Test
public void test8shardPipelinedPool() {
    List<JedisShardInfo> shards = Arrays.asList(
            new JedisShardInfo("localhost",6379),
            new JedisShardInfo("localhost",6380));

    ShardedJedisPool pool = new ShardedJedisPool(new JedisPoolConfig(), shards);

    ShardedJedis one = pool.getResource();

    ShardedJedisPipeline pipeline = one.pipelined();

    long start = System.currentTimeMillis();
    for (int i = 0; i < 100000; i++) {
        pipeline.set("sppn" + i, "n" + i);
    }
    List<Object> results = pipeline.syncAndReturnAll();
    long end = System.currentTimeMillis();
    pool.returnResource(one);
    System.out.println("Pipelined@Pool SET: " + ((end - start)/1000.0) + " seconds");
    pool.destroy();
}

九、需要注意的地方

    事务和管道都是异步模式。在事务和管道中不能同步查询结果。比如下面两个调用，都是不允许的：

     Transaction tx = jedis.multi();
     for (int i = 0; i < 100000; i++) {
         tx.set("t" + i, "t" + i);
     }
     System.out.println(tx.get("t1000").get()); //不允许

     List<Object> results = tx.exec();

     …
     …

     Pipeline pipeline = jedis.pipelined();
     long start = System.currentTimeMillis();
     for (int i = 0; i < 100000; i++) {
         pipeline.set("p" + i, "p" + i);
     }
     System.out.println(pipeline.get("p1000").get()); //不允许

     List<Object> results = pipeline.syncAndReturnAll();

    事务和管道都是异步的，个人感觉，在管道中再进行事务调用，没有必要，不如直接进行事务模式。

    分布式中，连接池的性能比直连的性能略好(见后续测试部分)。

    分布式调用中不支持事务。

    因为事务是在服务器端实现，而在分布式中，每批次的调用对象都可能访问不同的机器，所以，没法进行事务。

十、测试

运行上面的代码，进行测试，其结果如下：

Simple SET: 5.227 seconds

Transaction SET: 0.5 seconds
Pipelined SET: 0.353 seconds
Pipelined transaction: 0.509 seconds

Simple@Sharing SET: 5.289 seconds
Pipelined@Sharing SET: 0.348 seconds

Simple@Pool SET: 5.039 seconds
Pipelined@Pool SET: 0.401 seconds

另外，经测试分布式中用到的机器越多，调用会越慢。上面是2片，下面是5片：

Simple@Sharing SET: 5.494 seconds
Pipelined@Sharing SET: 0.51 seconds
Simple@Pool SET: 5.223 seconds
Pipelined@Pool SET: 0.518 seconds

下面是10片：

Simple@Sharing SET: 5.9 seconds
Pipelined@Sharing SET: 0.794 seconds
Simple@Pool SET: 5.624 seconds
Pipelined@Pool SET: 0.762 seconds

下面是100片：

Simple@Sharing SET: 14.055 seconds
Pipelined@Sharing SET: 8.185 seconds
Simple@Pool SET: 13.29 seconds
Pipelined@Pool SET: 7.767 seconds

分布式中，连接池方式调用不但线程安全外，根据上面的测试数据，也可以看出连接池比直连的效率更好。
十一、完整的测试代码

package com.example.nosqlclient;

import java.util.Arrays;
import java.util.List;

import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test; import redis.clients.jedis.Jedis; import redis.clients.jedis.JedisPoolConfig; import redis.clients.jedis.JedisShardInfo; import redis.clients.jedis.Pipeline; import redis.clients.jedis.ShardedJedis; import redis.clients.jedis.ShardedJedisPipeline; import redis.clients.jedis.ShardedJedisPool; import redis.clients.jedis.Transaction; import org.junit.FixMethodOrder; import org.junit.runners.MethodSorters; @FixMethodOrder(MethodSorters.NAME_ASCENDING) public class TestJedis {     private static Jedis jedis;     private static ShardedJedis sharding;     private static ShardedJedisPool pool;     @BeforeClass     public static void setUpBeforeClass() throws Exception {         List<JedisShardInfo> shards = Arrays.asList(                 new JedisShardInfo("localhost",6379),                 new JedisShardInfo("localhost",6379)); //使用相同的ip:port,仅作测试         jedis = new Jedis("localhost");         sharding = new ShardedJedis(shards);         pool = new ShardedJedisPool(new JedisPoolConfig(), shards);     }     @AfterClass     public static void tearDownAfterClass() throws Exception {         jedis.disconnect();         sharding.disconnect();         pool.destroy();     }     @Test     public void test1Normal() {         long start = System.currentTimeMillis();         for (int i = 0; i < 100000; i++) {             String result = jedis.set("n" + i, "n" + i);         }         long end = System.currentTimeMillis();         System.out.println("Simple SET: " + ((end - start)/1000.0) + " seconds");     }     @Test     public void test2Trans() {         long start = System.currentTimeMillis();         Transaction tx = jedis.multi();         for (int i = 0; i < 100000; i++) {             tx.set("t" + i, "t" + i);         }         //System.out.println(tx.get("t1000").get());         List<Object> results = tx.exec();         long end = System.currentTimeMillis();         System.out.println("Transaction SET: " + ((end - start)/1000.0) + " seconds");     }     @Test     public void test3Pipelined() {         Pipeline pipeline = jedis.pipelined();         long start = System.currentTimeMillis();         for (int i = 0; i < 100000; i++) {             pipeline.set("p" + i, "p" + i);         }         //System.out.println(pipeline.get("p1000").get());         List<Object> results = pipeline.syncAndReturnAll();         long end = System.currentTimeMillis();         System.out.println("Pipelined SET: " + ((end - start)/1000.0) + " seconds");     }     @Test     public void test4combPipelineTrans() {         long start = System.currentTimeMillis();         Pipeline pipeline = jedis.pipelined();         pipeline.multi();         for (int i = 0; i < 100000; i++) {             pipeline.set("" + i, "" + i);         }         pipeline.exec();         List<Object> results = pipeline.syncAndReturnAll();         long end = System.currentTimeMillis();         System.out.println("Pipelined transaction: " + ((end - start)/1000.0) + " seconds");     }     @Test     public void test5shardNormal() {         long start = System.currentTimeMillis();         for (int i = 0; i < 100000; i++) {             String result = sharding.set("sn" + i, "n" + i);         }         long end = System.currentTimeMillis();         System.out.println("Simple@Sharing SET: " + ((end - start)/1000.0) + " seconds");     }     @Test     public void test6shardpipelined() {         ShardedJedisPipeline pipeline = sharding.pipelined();         long start = System.currentTimeMillis();         for (int i = 0; i < 100000; i++) {             pipeline.set("sp" + i, "p" + i);         }         List<Object> results = pipeline.syncAndReturnAll();         long end = System.currentTimeMillis();         System.out.println("Pipelined@Sharing SET: " + ((end - start)/1000.0) + " seconds");     }     @Test     public void test7shardSimplePool() {         ShardedJedis one = pool.getResource();         long start = System.currentTimeMillis();         for (int i = 0; i < 100000; i++) {             String result = one.set("spn" + i, "n" + i);         }         long end = System.currentTimeMillis();         pool.returnResource(one);         System.out.println("Simple@Pool SET: " + ((end - start)/1000.0) + " seconds");     }     @Test     public void test8shardPipelinedPool() {         ShardedJedis one = pool.getResource();         ShardedJedisPipeline pipeline = one.pipelined();         long start = System.currentTimeMillis();         for (int i = 0; i < 100000; i++) {             pipeline.set("sppn" + i, "n" + i);         }         List<Object> results = pipeline.syncAndReturnAll();         long end = System.currentTimeMillis();         pool.returnResource(one);         System.out.println("Pipelined@Pool SET: " + ((end - start)/1000.0) + " seconds");     } }