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Redis Lettuce连接redis集群实现过程详细讲解

FlyLikeButterfly 人气:0

前言

Lettuce连接redis集群使用的都是集群专用类,像RedisClusterClient、StatefulRedisClusterConnection、RedisAdvancedClusterCommands、StatefulRedisClusterPubSubConnection等等;

Lettuce对rediscluster的支持:

启动时只需至少一个可以连接的集群节点就可以,能够自动拓扑出集群全部节点;也可以使用ReadFrom设置读取数据来源,跟主从模式一样;

虽然redis本身的多键命令要求key必须都在同一个槽位,但Lettuce对一部分命令多了优化,可以对多键命令进行跨槽位执行,通过将对不同槽位键的操作命令分解为多条命令,单个命令以fork/join方式并发运行,最后将结果合并返回;

可以跨槽位的命令有

提供跨槽位命令的api:RedisAdvancedClusterCommands、RedisAdvancedClusterAsyncCommands、RedisAdvancedClusterReactiveCommands;

可以在多个集群节点上执行的命令有

关于发布订阅

普通用户空间的发布订阅,redis集群会发送到每个节点,发布者和订阅者不需要在同一个节点,普通订阅发布消息可以在集群拓扑改变时重新连接。对于键空间事件,只会发到自己的节点,不会扩散到其他节点,要订阅键空间事件可以去适当的多个节点上订阅,或者使用RedisClusterClient消息传播和NodeSelectionAPI获得一个托管连接集合;

注意:由于主从同步,键会被复制到多个从节点上,特别是键过期事件,会在主从节点上都产生过期事件,如果订阅从节点,可能会收到多条相同的过期事件;订阅是通过NodeSelectionAPI或者单个节点调用subscribe(…)发出的,订阅对于新增的节点无效;

测试Demo:(redis版本7.0.2,Lettuce版本6.1.8)

集群节点:虚拟机 192.168.1.31,端口 9001-9006,集群节点已设置notify-keyspace-events AK;

package testlettuce;
import java.time.Duration;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import io.lettuce.core.ClientOptions.DisconnectedBehavior;
import io.lettuce.core.KeyScanCursor;
import io.lettuce.core.KeyValue;
import io.lettuce.core.ReadFrom;
import io.lettuce.core.RedisURI;
import io.lettuce.core.ScanCursor;
import io.lettuce.core.SocketOptions;
import io.lettuce.core.SslOptions;
import io.lettuce.core.TimeoutOptions;
import io.lettuce.core.cluster.ClusterClientOptions;
import io.lettuce.core.cluster.ClusterTopologyRefreshOptions;
import io.lettuce.core.cluster.RedisClusterClient;
import io.lettuce.core.cluster.api.StatefulRedisClusterConnection;
import io.lettuce.core.cluster.api.sync.Executions;
import io.lettuce.core.cluster.api.sync.NodeSelection;
import io.lettuce.core.cluster.api.sync.NodeSelectionCommands;
import io.lettuce.core.cluster.api.sync.RedisAdvancedClusterCommands;
import io.lettuce.core.cluster.pubsub.StatefulRedisClusterPubSubConnection;
import io.lettuce.core.cluster.pubsub.api.async.NodeSelectionPubSubAsyncCommands;
import io.lettuce.core.cluster.pubsub.api.async.PubSubAsyncNodeSelection;
import io.lettuce.core.cluster.pubsub.api.reactive.RedisClusterPubSubReactiveCommands;
import io.lettuce.core.protocol.DecodeBufferPolicies;
import io.lettuce.core.protocol.ProtocolVersion;
import io.lettuce.core.pubsub.RedisPubSubListener;
import io.lettuce.core.pubsub.api.async.RedisPubSubAsyncCommands;
public class TestLettuceCluster {
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		List<RedisURI> nodeList = new ArrayList<>();
		nodeList.add(RedisURI.builder().withHost("192.168.1.31").withPort(9001).withAuthentication("default", "123456").build());
		nodeList.add(RedisURI.builder().withHost("192.168.1.31").withPort(9002).withAuthentication("default", "123456").build());
		nodeList.add(RedisURI.builder().withHost("192.168.1.31").withPort(9003).withAuthentication("default", "123456").build());
		nodeList.add(RedisURI.builder().withHost("192.168.1.31").withPort(9004).withAuthentication("default", "123456").build());
		nodeList.add(RedisURI.builder().withHost("192.168.1.31").withPort(9005).withAuthentication("default", "123456").build());
		nodeList.add(RedisURI.builder().withHost("192.168.1.31").withPort(9006).withAuthentication("default", "123456").build());
		RedisClusterClient clusterClient = RedisClusterClient.create(nodeList);
		ClusterTopologyRefreshOptions clusterTopologyRefreshOptions = ClusterTopologyRefreshOptions.builder()
	            .adaptiveRefreshTriggersTimeout(Duration.ofSeconds(5L))//设置自适应拓扑刷新超时,每次超时刷新一次,默认30s;
	            .closeStaleConnections(false)//刷新拓扑时是否关闭失效连接,默认true,isPeriodicRefreshEnabled()为true时生效;
	            .dynamicRefreshSources(true)//从拓扑中发现新节点,并将新节点也作为拓扑的源节点,动态刷新可以发现全部节点并计算每个客户端的数量,设置false则只有初始节点为源和计算客户端数量;
	            .enableAllAdaptiveRefreshTriggers()//启用全部触发器自适应刷新拓扑,默认关闭;
	            .enablePeriodicRefresh(Duration.ofSeconds(5L))//开启定时拓扑刷新并设置周期;
	            .refreshTriggersReconnectAttempts(3)//长连接重新连接尝试n次才拓扑刷新
	            .build();
		ClusterClientOptions clusterClientOptions = ClusterClientOptions.builder()
				.autoReconnect(true)//在连接丢失时开启或关闭自动重连,默认true;
				.cancelCommandsOnReconnectFailure(true)//允许在重连失败取消排队命令,默认false;
				.decodeBufferPolicy(DecodeBufferPolicies.always())//设置丢弃解码缓冲区的策略,以回收内存;always:解码后丢弃,最大内存效率;alwaysSome:解码后丢弃一部分;ratio(n)基于比率丢弃,n/(1+n),通常用1-10对应50%-90%;
				.disconnectedBehavior(DisconnectedBehavior.DEFAULT)//设置连接断开时命令的调用行为,默认启用重连;DEFAULT:启用时重连中接收命令,禁用时重连中拒绝命令;ACCEPT_COMMANDS:重连中接收命令;REJECT_COMMANDS:重连中拒绝命令;
//				.maxRedirects(5)//当键从一个节点迁移到另一个节点,集群重定向次数,默认5;
//				.nodeFilter(nodeFilter)//设置节点过滤器
//				.pingBeforeActivateConnection(true)//激活连接前设置PING,默认true;
//				.protocolVersion(ProtocolVersion.RESP3)//设置协议版本,默认RESP3;
//				.publishOnScheduler(false)//使用专用的调度器发出响应信号,默认false,启用时数据信号将使用服务的多线程发出;
//				.requestQueueSize(requestQueueSize)//设置每个连接请求队列大小;
//				.scriptCharset(scriptCharset)//设置Lua脚本编码为byte[]的字符集,默认StandardCharsets.UTF_8;
//				.socketOptions(SocketOptions.builder().connectTimeout(Duration.ofSeconds(10)).keepAlive(true).tcpNoDelay(true).build())//设置低级套接字的属性
//				.sslOptions(SslOptions.builder().build())//设置ssl属性
//				.suspendReconnectOnProtocolFailure(false)//当重新连接遇到协议失败时暂停重新连接(SSL验证,连接失败前PING),默认值为false;
//				.timeoutOptions(TimeoutOptions.enabled(Duration.ofSeconds(10)))//设置超时来取消和终止命令;
				.topologyRefreshOptions(clusterTopologyRefreshOptions)//设置拓扑更新设置
				.validateClusterNodeMembership(true)//在允许连接到集群节点之前,验证集群节点成员关系,默认值为true;
				.build();
		clusterClient.setDefaultTimeout(Duration.ofSeconds(5L));
		clusterClient.setOptions(clusterClientOptions);
		StatefulRedisClusterConnection<String, String> clusterConn = clusterClient.connect();
		clusterConn.setReadFrom(ReadFrom.ANY);//设置从哪些节点读取数据;
		RedisAdvancedClusterCommands<String, String> clusterCmd = clusterConn.sync();
		clusterCmd.set("a", "A");
		clusterCmd.set("b", "B");
		clusterCmd.set("c", "C");
		clusterCmd.set("d", "D"); 
		System.out.println("get a=" + clusterCmd.get("a"));
		System.out.println("get b=" + clusterCmd.get("b"));
		System.out.println("get c=" + clusterCmd.get("c"));
		System.out.println("get d=" + clusterCmd.get("d"));
		//跨槽位命令
		Map<String, String> kvmap = new HashMap<>();
		kvmap.put("a", "AA");
		kvmap.put("b", "BB");
		kvmap.put("c", "CC");
		kvmap.put("d", "DD");
		clusterCmd.mset(kvmap);//Lettuce做了优化,支持一些命令的跨槽位命令;
		System.out.println("Lettuce mget:" + clusterCmd.mget("a", "b", "c", "d"));
		//选定部分节点操作
		NodeSelection<String, String> replicas = clusterCmd.replicas();
		NodeSelectionCommands<String, String> replicaseCmd = replicas.commands();
		Executions<KeyScanCursor<String>> executions = replicaseCmd.scan(ScanCursor.INITIAL);
		executions.forEach(s -> {System.out.println(s.getKeys());});
		//订阅发布消息
		StatefulRedisClusterPubSubConnection<String, String> pubSubConn = clusterClient.connectPubSub();
		pubSubConn.addListener(new RedisPubSubListener<String, String>() {
			@Override
			public void message(String channel, String message) {
				System.out.println("[message]ch:" + channel + ",msg:" + message);
			}
			@Override
			public void message(String pattern, String channel, String message) {
			}
			@Override
			public void subscribed(String channel, long count) {
				System.out.println("[subscribed]ch:" + channel);
			}
			@Override
			public void psubscribed(String pattern, long count) {
			}
			@Override
			public void unsubscribed(String channel, long count) {
			}
			@Override
			public void punsubscribed(String pattern, long count) {
			}
		});
		pubSubConn.sync().subscribe("TEST_Ch");//(回调内部使用阻塞调用或者lettuce同步api调用,需使用异步订阅)
		clusterCmd.publish("TEST_Ch", "MSGMSGMSG");
		//响应式订阅,可以监听ChannelMessage和PatternMessage,使用链式过滤处理计算等操作
		RedisClusterPubSubReactiveCommands<String, String> pubsubReactive = pubSubConn.reactive();
		pubsubReactive.subscribe("TEST_Ch2").subscribe();
		pubsubReactive.observeChannels()
			.filter(chmsg -> {return chmsg.getMessage().contains("tom");})
			.doOnNext(chmsg -> {System.out.println("<tom>" + chmsg.getChannel() + ">>" + chmsg.getMessage());})
			.subscribe();
		clusterCmd.publish("TEST_Ch2", "send to jerry");
		clusterCmd.publish("TEST_Ch", "tom MSG");
		clusterCmd.publish("TEST_Ch2", "this is tom");
		//keySpaceEvent事件
		StatefulRedisClusterPubSubConnection<String, String> clusterPubSubConn = clusterClient.connectPubSub();
		clusterPubSubConn.setNodeMessagePropagation(true);//启用禁用节点消息传播到该listener,例如只能在本节点通知的键事件通知;
		RedisPubSubListener<String, String> listener  = new RedisPubSubListener<String, String>() {
			@Override
			public void unsubscribed(String channel, long count) {
				System.out.println("unsubscribed_ch:" + channel);
			}
			@Override
			public void subscribed(String channel, long count) {
				System.out.println("subscribed_ch:" + channel);
			}
			@Override
			public void punsubscribed(String pattern, long count) {
				System.out.println("punsubscribed_pattern:" + pattern);
			}
			@Override
			public void psubscribed(String pattern, long count) {
				System.out.println("psubscribed_pattern:" + pattern);
			}
			@Override
			public void message(String pattern, String channel, String message) {
				System.out.println("message_pattern:" + pattern + " ch:" + channel + " msg:" + message);
			}
			@Override
			public void message(String channel, String message) {
				System.out.println("message_ch:" + channel + " msg:" + message);
			}
		};
		clusterPubSubConn.addListener(listener);
		PubSubAsyncNodeSelection<String, String> allPubSubAsyncNodeSelection = clusterPubSubConn.async().all();
		NodeSelectionPubSubAsyncCommands<String, String> pubsubAsyncCmd = allPubSubAsyncNodeSelection.commands();
		clusterCmd.setex("a", 1, "A");
		pubsubAsyncCmd.psubscribe("__keyspace@0__:*");
		try {
			Thread.sleep(3000);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		System.out.println("end");
	}
}

运行结果:

另外,还有一个cluster专用的Listener:RedisClusterPubSubListener,可以从listener里获得发布消息的节点信息:

RedisClusterPubSubListener<String, String> clusterListener = new RedisClusterPubSubListener<String, String>() {
			@Override
			public void message(RedisClusterNode node, String channel, String message) {
			}
			@Override
			public void message(RedisClusterNode node, String pattern, String channel, String message) {
			}
			@Override
			public void subscribed(RedisClusterNode node, String channel, long count) {
			}
			@Override
			public void psubscribed(RedisClusterNode node, String pattern, long count) {
			}
			@Override
			public void unsubscribed(RedisClusterNode node, String channel, long count) {
			}
			@Override
			public void punsubscribed(RedisClusterNode node, String pattern, long count) {
			}
		};

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