Question

jedis 和 strpin-data-redis 哪一个好

Answer 1

之前一直没仔细看过ShardedJedis的代码，最近遇到了shard后集群扩容后的数据迁移问题。

今天在看ShardedJedis源码的时候，发现ShardedJedis并没有使用节点的Ip和port做hash，而是用的instance的顺序或者name，太赞了。

private void initialize(List<S> shards) {
nodes = new TreeMap<Long, S>();

for (int i = 0; i != shards.size(); ++i) {
final S shardInfo = shards.get(i);
if (shardInfo.getName() == null)
for (int n = 0; n < 160 * shardInfo.getWeight(); n++) {
nodes.put(this.algo.hash("SHARD-" + i + "-NODE-" + n),
shardInfo);
}
else
for (int n = 0; n < 160 * shardInfo.getWeight(); n++) {
nodes.put(
this.algo.hash(shardInfo.getName() + "*"
+ shardInfo.getWeight() + n), shardInfo);
}
resources.put(shardInfo, shardInfo.createResource());
}
}

配置的时候也非常简单:

<bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig">
<property name="maxTotal" value="1000"/>
<property name="maxIdle" value="10"/>
<property name="minIdle" value="1"/>
<property name="maxWaitMillis" value="30000"/>
<property name="testOnBorrow" value="true"/>
<property name="testOnReturn" value="true"/>
<property name="testWhileIdle" value="true"/>
</bean>

<bean id="shardedJedisPool" class="redis.clients.jedis.ShardedJedisPool" destroy-method="destroy">
<constructor-arg ref="jedisPoolConfig"/>
<constructor-arg>
<list>
<bean class="redis.clients.jedis.JedisShardInfo">
<constructor-arg value="127.0.0.1"/>
<constructor-arg type="int" value="7000"/>
<constructor-arg value="instance:01"/>
</bean>
<bean class="redis.clients.jedis.JedisShardInfo">
<constructor-arg value="127.0.0.1"/>
<constructor-arg type="int" value="7001"/>
<constructor-arg value="instance:02"/>
</bean>
<bean class="redis.clients.jedis.JedisShardInfo">
<constructor-arg value="127.0.0.1"/>
<constructor-arg type="int" value="7003"/>
<constructor-arg value="instance:03"/>
</bean>
</list>
</constructor-arg>
</bean>
一开始你可以设置足够多的instance，数据扩容的时候，只需要将几个instance的数据copy到别的机器上。
然后修改配置文件的ip和端口即可。很方便吧？

另外，Jedis还提供了对jedis sentinel pool的封装，所以发生主从切换的时候，web server都不需要重新配置和deploy。高可用性的极佳体现啊。

@Autowired private JedisSentinelPool pool;

public void mymethod() {
Jedis jedis = null;
try {
jedis = pool.getResource();
jedis.hset(....
} catch (JedisException je) {
throw je;
} finally {
if (jedis != null) pool.returnResource(jedis);
}
}

spring bean的配置：

<bean id="redisSentinel" class="redis.clients.jedis.JedisSentinelPool">
<constructor-arg index="0" value="mymaster" />
<constructor-arg index="1">
<set>
<value>hostofsentinel:26379</value>
</set>
</constructor-arg>
<constructor-arg index="2" ref="jedisPoolConfig" />
</bean>