Sentinel源码(流量入口)

package com.alibaba.cloud.sentinel;

/*省略部分代码。。。。。。*/
public class SentinelWebAutoConfiguration {
        /*省略部分代码。。。。。。*/
  @Bean
  @ConditionalOnProperty(name = "spring.cloud.sentinel.filter.enabled", matchIfMissing = true)
  public FilterRegistrationBean sentinelFilter() {
        /*Step 1 : 创建一个FilterRegistrationBean*/
    FilterRegistrationBean<Filter> registration = new FilterRegistrationBean<>();

    SentinelProperties.Filter filterConfig = properties.getFilter();

    if (filterConfig.getUrlPatterns() == null
        || filterConfig.getUrlPatterns().isEmpty()) {
      List<String> defaultPatterns = new ArrayList<>();
      defaultPatterns.add("/*");
      filterConfig.setUrlPatterns(defaultPatterns);
    }

    registration.addUrlPatterns(filterConfig.getUrlPatterns().toArray(new String[0]));
         /*重点Step 2 ：创建一个CommonFilter*/
    Filter filter = new CommonFilter();
         /*Step 3 : 将CommonFilter放入FilterRegistrationBean*/
    registration.setFilter(filter);
    registration.setOrder(filterConfig.getOrder());
    registration.addInitParameter("HTTP_METHOD_SPECIFY",
    String.valueOf(properties.getHttpMethodSpecify()));
         /*省略部分代码。。。。。。*/
    return registration;
  }
}

package com.alibaba.csp.sentinel.adapter.servlet;

public class CommonFilter implements Filter {
             /*省略部分代码。。。。。。*/
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
             /*省略部分代码。。。。。。*/
        try {
             /*Step 1 :截取请求URL作为资源名赋予target */
            String target = FilterUtil.filterTarget(sRequest);
             /*省略部分代码。。。。。。*/
             /*Step 2 :创建一个target名称的上下文*/
            ContextUtil.enter(target, origin);
             /*Step 3 :执行Sentinel的核心功能*/
            entry = SphU.entry(target, EntryType.IN);
             /*省略部分代码。。。。。。*/
            chain.doFilter(request, response);
        } 
             /*省略部分代码。。。。。。*/
            ContextUtil.exit();
        }
    }
             /*省略部分代码。。。。。。*/
}

package com.alibaba.cloud.sentinel.custom;
             /*省略部分代码。。。。。。*/
public class SentinelAutoConfiguration {
          /*省略部分代码。。。。。。*/
          /*注入切面SentinelResourceAspect*/
  @Bean
  @ConditionalOnMissingBean
  public SentinelResourceAspect sentinelResourceAspect() {
    return new SentinelResourceAspect();
  }
}

package com.alibaba.csp.sentinel.annotation.aspectj;

@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);
        /*Step 1 ：获取@SentinelResource注解*/
        SentinelResource annotation = originMethod.getAnnotation(SentinelResource.class);
        /*Step 2 ：获取@SentinelResource中的资源名*/
        String resourceName = getResourceName(annotation.value(), originMethod);
        EntryType entryType = annotation.entryType();
        Entry entry = null;
        try {
        /*Step 3 ：执行Sentinel核心功能*/
            entry = SphU.entry(resourceName, entryType, 1, pjp.getArgs());
            Object result = pjp.proceed();
            return result;
        } catch (BlockException ex) {
            return handleBlockException(pjp, annotation, ex);
        } catch (Throwable ex) {
            traceException(ex, annotation);
            throw ex;
        } finally {
            if (entry != null) {
                entry.exit(1, pjp.getArgs());
            }
        }
    }
}

private Entry entryWithPriority(ResourceWrapper resourceWrapper, int count, boolean prioritized, Object... args)
        throws BlockException {
               /*Step 1-1 :创建上下文，如果在ThreadLocal中已存在，则直接返回上下文*/
        Context context = ContextUtil.getContext();
               /*省略部分代码。。。。。。*/
               /*Step 1-2 :创建一条Slot Chain*/
        ProcessorSlot<Object> chain = lookProcessChain(resourceWrapper);
               /*省略部分代码。。。。。。*/
               /*Step 2 :将Chain和当前Context结合*/
        Entry e = new CtEntry(resourceWrapper, chain, context);
        try {
               /*Step 3 :Slot Chain入口，开始规则检查*/
            chain.entry(context, resourceWrapper, null, count, prioritized, args);
        } catch (BlockException e1) {
            e.exit(count, args);
            throw e1;
        } catch (Throwable e1) {
            RecordLog.info("Sentinel unexpected exception", e1);
        }
        return e;
    }