阿里巴巴开源 Sentinel 限流方案搭建

Sentinel是阿里开源的一个限流方案框架具有以下特征:

• 丰富的应用场景：Sentinel 承接了阿里巴巴近 10 年的双十一大促流量的核心场景，例如秒杀（即突发流量控制在系统容量可以承受的范围）、消息削峰填谷、集群流量控制、实时熔断下游不可用应用等。
• 完备的实时监控：Sentinel 同时提供实时的监控功能。您可以在控制台中看到接入应用的单台机器秒级数据，甚至 500 台以下规模的集群的汇总运行情况。
• 广泛的开源生态：Sentinel 提供开箱即用的与其它开源框架/库的整合模块，例如与 Spring Cloud、Dubbo、gRPC 的整合。您只需要引入相应的依赖并进行简单的配置即可快速地接入 Sentinel。
• 完善的 SPI 扩展点：Sentinel 提供简单易用、完善的 SPI 扩展接口。您可以通过实现扩展接口来快速地定制逻辑。例如定制规则管理、适配动态数据源等。

 一、搭建监控平台

       1.下载相应的jar包，地址https://github.com/alibaba/Sentinel/releases

       2.启动  java -Dserver.port=8080 -Dcsp.sentinel.dashboard.server=localhost:8080 -Dproject.name=sentinel-dashboard -jar                                        -Dsentinel.dashboard.auth.username=sentinel -Dsentinel.dashboard.auth.password=123456         sentinel-dashboard-1.6.3.jar

       -Dsentinel.dashboard.auth.username 指定登录名

       -Dsentinel.dashboard.auth.password  指定登录密码

      3.访问localhost:8080 ，输入用户密码

      

     4.看到如下效果搭建成功

二、客户端使用

以注解使用为例

1.maven依赖

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <artifactId>sentinel-demo-annotation-spring-aop</artifactId> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.6.RELEASE</version> </parent> <dependencies> <dependency> <groupId>com.alibaba.csp</groupId> <artifactId>sentinel-core</artifactId> <version>1.6.3</version> </dependency> <dependency> <groupId>com.alibaba.csp</groupId> <artifactId>sentinel-transport-simple-http</artifactId> <version>1.6.3</version> </dependency> <dependency> <groupId>com.alibaba.csp</groupId> <artifactId>sentinel-annotation-aspectj</artifactId> <version>1.6.3</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> </project>

2.配置限流规则方案

/* * Copyright 1999-2018 Alibaba Group Holding Ltd. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.alibaba.csp.sentinel.demo.annotation.aop.config; import com.alibaba.csp.sentinel.annotation.aspectj.SentinelResourceAspect; import com.alibaba.csp.sentinel.slots.block.RuleConstant; import com.alibaba.csp.sentinel.slots.block.flow.FlowRule; import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager; import java.util.ArrayList; import java.util.List; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; /** * @author Eric Zhao */ @Configuration public class AopConfiguration { @Bean public SentinelResourceAspect sentinelResourceAspect() { //配置固定限流规则，每秒为20qps,真对test List<FlowRule> rules = new ArrayList<>(); FlowRule rule = new FlowRule(); rule.setResource("test"); rule.setGrade(RuleConstant.FLOW_GRADE_QPS); // Set limit QPS to 20. rule.setCount(20); rules.add(rule); FlowRuleManager.loadRules(rules); return new SentinelResourceAspect(); } } 

3.实际应用

/* * Copyright 1999-2018 Alibaba Group Holding Ltd. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.alibaba.csp.sentinel.demo.annotation.aop.service; import org.springframework.stereotype.Service; import com.alibaba.csp.sentinel.annotation.SentinelResource; /** * @author Eric Zhao */ @Service public class TestServiceImpl implements TestService { @Override @SentinelResource(value = "test", blockHandler = "handleException", blockHandlerClass = {ExceptionUtil.class}) public void test() { System.out.println("Test"); } @Override @SentinelResource(value = "hello", fallback = "helloFallback") public String hello(long s) { if (s < 0) { throw new IllegalArgumentException("invalid arg"); } return String.format("Hello at %d", s); } @Override @SentinelResource(value = "helloAnother", defaultFallback = "defaultFallback", exceptionsToIgnore = {IllegalStateException.class}) public String helloAnother(String name) { if (name == null || "bad".equals(name)) { throw new IllegalArgumentException("oops"); } if ("foo".equals(name)) { throw new IllegalStateException("oops"); } return "Hello, " + name; } public String helloFallback(long s, Throwable ex) { // Do some log here. ex.printStackTrace(); return "Oops, error occurred at " + s; } public String defaultFallback() { System.out.println("Go to default fallback"); return "default_fallback"; } } 

/* * Copyright 1999-2018 Alibaba Group Holding Ltd. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.alibaba.csp.sentinel.demo.annotation.aop.controller; import com.alibaba.csp.sentinel.demo.annotation.aop.service.TestService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.RestController; /** * @author Eric Zhao */ @RestController public class DemoController { @Autowired private TestService service; @GetMapping("/foo") public String apiFoo(@RequestParam(required = false) Long t) throws Exception { if (t == null) { t = System.currentTimeMillis(); } service.test(); return service.hello(t); } @GetMapping("/baz/{name}") public String apiBaz(@PathVariable("name") String name) { return service.helloAnother(name); } } 

4.启动应用，-Dproject.name=test -Dcsp.sentinel.dashboard.server=localhost:8080 访问接口就可以看到监控信息了

-Dproject.name=test  指定监控名称

-Dcsp.sentinel.dashboard.server 指定监控平台地址

三、简单基于注解原理分析

1.sentinel 主要的核心功能由sentinel-core 提供，基于注解的应用主要是依赖于切面的使用，具体的实现如下

/* * Copyright 1999-2018 Alibaba Group Holding Ltd. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.alibaba.csp.sentinel.annotation.aspectj; import com.alibaba.csp.sentinel.Entry; import com.alibaba.csp.sentinel.EntryType; import com.alibaba.csp.sentinel.SphU; import com.alibaba.csp.sentinel.annotation.SentinelResource; import com.alibaba.csp.sentinel.slots.block.BlockException; import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Pointcut; import java.lang.reflect.Method; /** * Aspect for methods with {@link SentinelResource} annotation. * * @author Eric Zhao */ @Aspect public class SentinelResourceAspect extends AbstractSentinelAspectSupport { @Pointcut("@annotation(com.alibaba.csp.sentinel.annotation.SentinelResource)") public void sentinelResourceAnnotationPointcut() { } @Around("sentinelResourceAnnotationPointcut()") public Object invokeResourceWithSentinel(ProceedingJoinPoint pjp) throws Throwable { Method originMethod = resolveMethod(pjp); SentinelResource annotation = originMethod.getAnnotation(SentinelResource.class); if (annotation == null) { // Should not go through here. throw new IllegalStateException("Wrong state for SentinelResource annotation"); } String resourceName = getResourceName(annotation.value(), originMethod); EntryType entryType = annotation.entryType(); int resourceType = annotation.resourceType(); Entry entry = null; try { entry = SphU.entry(resourceName, resourceType, entryType, pjp.getArgs()); Object result = pjp.proceed(); return result; } catch (BlockException ex) { return handleBlockException(pjp, annotation, ex); } catch (Throwable ex) { Class<? extends Throwable>[] exceptionsToIgnore = annotation.exceptionsToIgnore(); // The ignore list will be checked first. if (exceptionsToIgnore.length > 0 && exceptionBelongsTo(ex, exceptionsToIgnore)) { throw ex; } if (exceptionBelongsTo(ex, annotation.exceptionsToTrace())) { traceException(ex, annotation); return handleFallback(pjp, annotation, ex); } // No fallback function can handle the exception, so throw it out. throw ex; } finally { if (entry != null) { entry.exit(1, pjp.getArgs()); } } } } 

与单机的应用其实是一样的，初始化规则，调用SphU的entry方法，判断限流机制