redis 集群批量操作实现
Redis集群是没法执行批量操作命令的，如mget，pipeline等。这是因为redis将集群划分为16383个哈希槽，不同的key会划分到不同的槽中。但是，Jedis客户端提供了计算key的slot方法，已经slot和节点之间的映射关系，通过这两个数据，就可以计算出每个key所在的节点，然后使用pipeline获取数据。具体代码如下：
初始化 JedisCluster类
@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);
}
}
工具类 JedisClusterUtil
@Component
public class JedisClusterUtil {
@Autowired
private JedisCluster jedisCluster;
@Resource(name = "redisTemplate4Json")
protected RedisTemplate<String, Object> redisTemplate;
/**
* ZSet批量查询
* @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<>();
//执行
for (Map.Entry<JedisPool, List<String>> entry : jedisPoolMap.entrySet()) {
Jedis jedis = null;
try {
currentJedisPool = entry.getKey();
keyList = entry.getValue();
//获取pipeline
jedis = currentJedisPool.getResource();
currentPipeline = jedis.pipelined();
for (String key : keyList) {
currentPipeline.zrevrange(key, 0, 0);
}
//从pipeline中获取结果
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批量查询
* @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();
//获取pipeline
jedis = currentJedisPool.getResource();
currentPipeline = jedis.pipelined();
for (String key : keyList) {
currentPipeline.get(key);
}
//从pipeline中获取结果
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继承了BinaryJedisCluster
//BinaryJedisCluster的JedisClusterConnectionHandler属性
//里面有JedisClusterInfoCache，根据这一条继承链，可以获取到JedisClusterInfoCache
//从而获取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) {
//计算哈希槽
int crc = JedisClusterCRC16.getSlot(key);
//通过哈希槽获取节点的连接
currentJedisPool = cache.getSlotPool(crc);
//由于JedisPool作为value保存在JedisClusterInfoCache中的一个map对象中，每个节点的
//JedisPool在map的初始化阶段就是确定的和唯一的，所以获取到的每个节点的JedisPool都是一样
//的，可以作为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;
}
/**
* 释放jedis资源
*
* @param jedis
*/
public void returnResource(Jedis jedis, JedisPool jedisPool) {
if (jedis != null && jedisPool != null) {
jedisPool.returnResource(jedis);
}
}
注意：一定要完成后释放 jedis 资源 不然会造成卡死现象
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