Sentinel is a current limiting scheme framework of Ali Open Source, which has the following characteristics:
- Rich application scenarios: Sentinel takes over the core scenarios of Alibaba's "Twenty-Eleven" traffic promotion in recent 10 years, such as second killing (i.e., burst traffic control within the system capacity can be tolerated), message peak shaving and valley filling, cluster traffic control, real-time fusing downstream unavailable applications, etc.
- Complete real-time monitoring: Sentinel also provides real-time monitoring functions. You can see in the console the second-level data of a single machine accessing the application, or even the aggregate operation of a cluster of less than 500 units.
- Widespread open source ecology: Sentinel provides out-of-the-box integration modules with other open source frameworks/libraries, such as Spring Cloud, Dubbo, and gRPC. You can quickly access Sentinel by simply introducing the corresponding dependencies and configuring them.
- Perfect SPI Extension Point: Sentinel provides a simple, easy-to-use and perfect SPI Extension Interface. You can quickly customize logic by implementing an extended interface. For example, customizing rule management, adapting dynamic data sources, etc.
1. Building Monitoring Platform
Download the corresponding jar package at https://github.com/alibaba/Sentinel/releases
Start java-Dserver.port=8080-Dcsp.sentinel.dashboard.server=localhost:8080-Dproject.name=sentinel-dashboard-jar.- Dashboard-1.6.3.jar
- Dsentinel.dashboard.auth.username Specifies the login name
- Dsentinel.dashboard.auth.password Specifies the login password
3. Access localhost:8080 and enter user password
4. See the following effects build successfully
2. Client use
Take the use of annotations as an example
1.maven dependence
<?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. Configuration of Current Limiting Rules
/* * 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() { //Configuration of fixed current limiting rules, 20 QPS per second, true to 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. Practical application
/* * 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. Start the application, - Dproject.name=test -Dcsp.sentinel.dashboard.server=localhost:8080 access interface to see the monitoring information
- Dproject.name=test specifies the monitoring name
- Dcsp.sentinel.dashboard.server Specifies the address of the monitoring platform
3. Simple Analysis Based on Annotation Principle
1.sentinel's main core functions are provided by sentinel-core. Annotation-based applications mainly depend on the use of aspects. The specific implementation is as follows.
/* * 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()); } } } }
In fact, it is the same as single-machine application. Initialize rules, call the entry method of SphU, and judge the current limiting mechanism.