sentinel流控与限流源码解析

           if (currentState.get() == State.OPEN) {            return;           }                if (currentState.get() == State.HALF_OPEN) {            // In detecting request            if (error == null) {                fromHalfOpenToClose();            } else {                fromHalfOpenToOpen(1.0d);            }            return;        }         。。。。断路器close 正常计数

com.alibaba.csp.sentinel.slots.block.degrade.DegradeSlot#performChecking

 @Bean @ConditionalOnMissingBean public SentinelResourceAspect sentinelResourceAspect() {  return new SentinelResourceAspect(); } 

根据@Spi的order排序执行负值越大，则先执行

①构建slot责任链

使用SPI技术加载所有slotMETA-INF/services/

DegradeSlot

spring.factories

exit执行

com.alibaba.csp.sentinel.slots.block.degrade.DegradeSlot#entry

com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.ResponseTimeCircuitBreaker#onRequestComplete

com.alibaba.csp.sentinel.slotchain.ProcessorSlot#exit

com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.ExceptionCircuitBreaker#onRequestComplete

com.alibaba.csp.sentinel.CtSph#lookProcessChain

com.alibaba.csp.sentinel.slots.block.degrade.DegradeSlot#exit

        <dependency>            <groupId>com.alibaba.cloud</groupId>            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>            <version>2.2.6.RELEASE</version>        </dependency>

响应时间

ClusterBuilderSlot

NodeSelectorSlot

com.alibaba.csp.sentinel.CtEntry#trueExit

com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.ResponseTimeCircuitBreaker#handleStateChangeWhenThresholdExceeded

com.alibaba.csp.sentinel.annotation.aspectj.AbstractSentinelAspectSupport#handleBlockException

AuthoritySlot

com.alibaba.csp.sentinel.CtEntry#exitForContext

②使用责任链，依次执行

①流控策略

异常数、异常比例

com.alibaba.csp.sentinel.annotation.aspectj.SentinelResourceAspect#invokeResourceWithSentinel

FlowSlot

firstAbstractLinkedProcessorSlot

null

com.alibaba.csp.sentinel.slotchain.SlotChainProvider#newSlotChain

com.alibaba.cloud.sentinel.custom.SentinelAutoConfiguration

com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.CircuitBreaker#tryPass

    @Override    public boolean tryPass(Context context) {        // Template implementation.        if (currentState.get() == State.CLOSED) {            return true;        }        if (currentState.get() == State.OPEN) {            // For half-open state we allow a request for probing.           超过一段时间，允许一个请求过来，从open到halfOpen            return retryTimeoutArrived() && fromOpenToHalfOpen(context);        }        return false;    }

抛出业务异常，走自定义处理函数

责任链模式，构建全部SLOT

②指定业务流程

③finally

com.alibaba.csp.sentinel.spi.SpiLoader#loadFirstInstanceOrDefault

         if (currentState.get() == State.OPEN) {            return;           }                if (currentState.get() == State.HALF_OPEN) {            // In detecting request            // TODO: improve logic for half-open recovery            if (rt > maxAllowedRt) {                fromHalfOpenToOpen(1.0d);            } else {         font color=\"#ff0000\

com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.ExceptionCircuitBreaker#handleStateChangeWhenThresholdExceeded

com.alibaba.csp.sentinel.spi.SpiLoader#load

标准的切点/切面在方法执行前后流控策略

LogSlot

如果被流控/降级会抛出blockException处理异常

SystemSlot

Object result = pjp.proceed();

entry执行

com.alibaba.csp.sentinel.slotchain.ProcessorSlot#entry

StatisticSlot