/usr/bin/su - root -c "nohup java -server -Xms64m -Xmx256m -Dserver.port=8849 -Dcsp.sentinel.dashboard.server=localhost:8849 -Dproject.name=sentinel-dashboard -jar /work/sentinel-dashboard-1.7.1.jar 2>&1 &"

nohup java  -server -Xms64m -Xmx256m  -Dserver.port=8849 -Dcsp.sentinel.dashboard.server=localhost:8849 -Dproject.name=sentinel-dashboard -jar /work/sentinel-dashboard-1.7.1.jar &

https://github.com/alibaba/Sentinel/releases/download/1.6.3/sentinel-dashboard-1.7.1.jar

[root@192 ~]# java -Dserver.port=8888 -Dcsp.sentinel.dashboard.server=localhost:8888 -Dproject.name=sentinel-dashboard -jar sentinel-dashboard-1.6.3.jar
INFO: log base dir is: /root/logs/csp/
INFO: log name use pid is: false

  .   ____          _            __ _ _
 /\\ / ___‘_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | ‘_ | ‘_| | ‘_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  ‘  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.0.5.RELEASE)

2020-02-08 13:07:29.316  INFO 114031 --- [           main] c.a.c.s.dashboard.DashboardApplication   : Starting DashboardApplication on 192.168.180.137 with PID 114031 (/root/sentinel-dashboard-1.6.3.jar started by root in /root)
2020-02-08 13:07:29.319  INFO 114031 --- [           main] c.a.c.s.dashboard.DashboardApplication   : No active profile set, falling back to default profiles: default
2020-02-08 13:07:29.456  INFO 114031 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@59690aa4: startup date [Sat Feb 08 13:07:29 CST 2020]; root of context hierarchy
2020-02-08 13:07:33.783  INFO 114031 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8888 (http)

<dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.1.0.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

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

spring:
  cloud:
    sentinel:
      transport:
        dashboard: 192.168.180.137:8888   #sentinel控制台的请求地址

    Entry entry = null;
    try {
        // 定义一个sentinel保护的资源，名称为test-sentinel-api
        entry = SphU.entry(resourceName);
        // 模拟执行被保护的业务逻辑耗时
        Thread.sleep(100);
        return a;
    } catch (BlockException e) {
        // 如果被保护的资源被限流或者降级了，就会抛出BlockException
        log.warn("资源被限流或降级了", e);
        return "资源被限流或降级了";
    } catch (InterruptedException e) {
        return "发生InterruptedException";
    } finally {
        if (entry != null) {
            entry.exit();
        }
 
        ContextUtil.exit();
    }
}

public static void main(String[] args) {
    // 配置规则.
    initFlowRules();

    while (true) {
        // 1.5.0 版本开始可以直接利用 try-with-resources 特性
        try (Entry entry = SphU.entry("HelloWorld")) {
            // 被保护的逻辑
            System.out.println("hello world");
    } catch (BlockException ex) {
            // 处理被流控的逻辑
        System.out.println("blocked!");
    }
    }
}

@SentinelResource("HelloWorld")
public void helloWorld() {
    // 资源中的逻辑
    System.out.println("hello world");
}

private void initSystemRule() {
    List<SystemRule> rules = new ArrayList<>();
    SystemRule rule = new SystemRule();
    rule.setHighestSystemLoad(10);
    rules.add(rule);
    SystemRuleManager.loadRules(rules);
}

FlowRuleManager.loadRules(List<FlowRule> rules); // 修改流控规则
DegradeRuleManager.loadRules(List<DegradeRule> rules); // 修改降级规则
SystemRuleManager.loadRules(List<SystemRule> rules); // 修改系统规则
AuthorityRuleManager.loadRules(List<AuthorityRule> rules); // 修改授权规则

    @PostConstruct
    public void initSentinelRule()
    {
        //熔断规则： 5s内调用接口出现异常次数超过5的时候, 进行熔断
        List<DegradeRule> degradeRules = new ArrayList<>();
        DegradeRule rule = new DegradeRule();
        rule.setResource("queryGoodsInfo");
        rule.setCount(5);

        rule.setGrade(RuleConstant.DEGRADE_GRADE_EXCEPTION_COUNT);//熔断规则
        rule.setTimeWindow(5);
        degradeRules.add(rule);
        DegradeRuleManager.loadRules(degradeRules);
    }

private static void initFlowRules(){
    List<FlowRule> rules = new ArrayList<>();
    FlowRule rule = new FlowRule();
    rule.setResource("HelloWorld");
    rule.setGrade(RuleConstant.FLOW_GRADE_QPS);
    // Set limit QPS to 20.
    rule.setCount(20);
    rules.add(rule);
    FlowRuleManager.loadRules(rules);
}

    /**
     * 限流实现方式一: 抛出异常的方式定义资源
     *
     * @param orderId
     * @return
     */
    @ApiOperation(value = "纯代码限流")
    @GetMapping("/getOrder")
    @ResponseBody
    public String getOrder(@RequestParam(value = "orderId", required = false)String orderId)
    {

        Entry entry = null;
        // 资源名
        String resourceName = "getOrder";
        try
        {
            // entry可以理解成入口登记
            entry = SphU.entry(resourceName);
            // 被保护的逻辑, 这里为订单查询接口
            return "正常的业务逻辑 OrderInfo :" + orderId;
        } catch (BlockException blockException)
        {
            // 接口被限流的时候, 会进入到这里
            log.warn("---getOrder1接口被限流了---, exception: ", blockException);
            return "接口限流, 返回空";
        } finally
        {
            // SphU.entry(xxx) 需要与 entry.exit() 成对出现,否则会导致调用链记录异常
            if (entry != null)
            {
                entry.exit();
            }
        }

    }

//限流规则 QPS mode,
        List<FlowRule> rules = new ArrayList<FlowRule>();
        FlowRule rule1 = new FlowRule();
        rule1.setResource("getOrder");
        // QPS控制在2以内
        rule1.setCount(2);
        // QPS限流
        rule1.setGrade(RuleConstant.FLOW_GRADE_QPS);
        rule1.setLimitApp("default");
        rules.add(rule1);
        FlowRuleManager.loadRules(rules);

设置 `strategy` 为 `RuleConstant.STRATEGY_RELATE` 
设置 `refResource` 为 `write_db`。
这样当写库操作过于频繁时，读数据的请求会被限流。

   @SentinelResource(value = "test1", blockHandler = "exceptionHandler")
    @GetMapping("/test1")
    public String test1()
    {
        log.info(Thread.currentThread().getName() + "\t" + "...test1");
        return "-------hello baby，i am test1";
    }


    // Block 异常处理函数，参数最后多一个 BlockException，其余与原函数一致.
    public String exceptionHandler(BlockException ex)
    {
        // Do some log here.
        ex.printStackTrace();
        log.info(Thread.currentThread().getName() + "\t" + "...exceptionHandler");
        return String.format("error: test1  is not OK");
    }

    @SentinelResource(value = "test1_ref")
    @GetMapping("/test1_ref")
    public String test1_ref()
    {
        log.info(Thread.currentThread().getName() + "\t" + "...test1_related");
        return "-------hello baby，i am test1_ref";
    }

        // 关联模式流控  QPS控制在1以内
        String refResource = "test1_ref";
        FlowRule rRule = new FlowRule("test1")
                .setCount(1)  // QPS控制在1以内
                .setStrategy(RuleConstant.STRATEGY_RELATE)
                .setRefResource(refResource);

        rules.add(rRule);
        FlowRuleManager.loadRules(rules);

    @SentinelResource(value = "testWarmUP", blockHandler = "exceptionHandlerOfWarmUp")
    @GetMapping("/testWarmUP")
    public String testWarmUP()
    {
        log.info(Thread.currentThread().getName() + "\t" + "...test1");
        return "-------hello baby，i am testWarmUP";
    }

        FlowRule warmUPRule = new FlowRule();
        warmUPRule.setResource("testWarmUP");
        warmUPRule.setCount(20);
        warmUPRule.setGrade(RuleConstant.FLOW_GRADE_QPS);
        warmUPRule.setLimitApp("default");
        warmUPRule.setControlBehavior(RuleConstant.CONTROL_BEHAVIOR_WARM_UP);
        warmUPRule.setWarmUpPeriodSec(10);

  
    
    @SentinelResource(value = "testLineUp",
                        blockHandler = "exceptionHandlerOftestLineUp")
    @GetMapping("/testLineUp")
        public String testLineUp()
    {
        log.info(Thread.currentThread().getName() + "\t" + "...test1");
        return "-------hello baby，i am testLineUp";
    }

    
        FlowRule lineUpRule = new FlowRule();
        lineUpRule.setResource("testLineUp");
        lineUpRule.setCount(10);
        lineUpRule.setGrade(RuleConstant.FLOW_GRADE_QPS);
        lineUpRule.setLimitApp("default");
        lineUpRule.setMaxQueueingTimeMs(20 * 1000);
        // CONTROL_BEHAVIOR_DEFAULT means requests more than threshold will be rejected immediately.
        // CONTROL_BEHAVIOR_DEFAULT将超过阈值的流量立即拒绝掉.
        lineUpRule.setControlBehavior(RuleConstant.CONTROL_BEHAVIOR_RATE_LIMITER);
        rules.add(lineUpRule);

    @GetMapping("/byHotKey")
    @SentinelResource(value = "byHotKey",
            blockHandler = "userAccessError")
    public String test4(@RequestParam(value = "userId", required = false) String userId,
                        @RequestParam(value = "goodId", required = false) int goodId)
    {
        log.info(Thread.currentThread().getName() + "\t" + "...byHotKey");
        return "-----------by HotKey： UserId";
    }

ParamFlowRule rule = new ParamFlowRule(resourceName)
    .setParamIdx(0)
    .setCount(5);
// 针对 int 类型的参数 PARAM_B，单独设置限流 QPS 阈值为 10，而不是全局的阈值 5.
ParamFlowItem item = new ParamFlowItem().setObject(String.valueOf(PARAM_B))
    .setClassType(int.class.getName())
    .setCount(10);
rule.setParamFlowItemList(Collections.singletonList(item));

ParamFlowRuleManager.loadRules(Collections.singletonList(rule));

        ParamFlowRule pRule = new ParamFlowRule("byHotKey")
                .setParamIdx(1)
                .setCount(1);
// 针对 参数值1000，单独设置限流 QPS 阈值为 5，而不是全局的阈值 1.
        ParamFlowItem item = new ParamFlowItem().setObject(String.valueOf(1000))
                .setClassType(int.class.getName())
                .setCount(5);
        pRule.setParamFlowItemList(Collections.singletonList(item));

        ParamFlowRuleManager.loadRules(Collections.singletonList(pRule));

       List<SystemRule> srules = new ArrayList<>();
        SystemRule srule = new SystemRule();
        srule.setAvgRt(3000);
        srules.add(srule);
        SystemRuleManager.loadRules(srules);

AuthorityRule rule = new AuthorityRule();
rule.setResource("test");
rule.setStrategy(RuleConstant.AUTHORITY_WHITE);
rule.setLimitApp("appA,appB");
AuthorityRuleManager.loadRules(Collections.singletonList(rule));

public class Context {
   // context名字，默认名字 "sentinel_default_context"
   private final String name;
   // context入口节点，每个context必须有一个entranceNode
   private DefaultNode entranceNode;
   // context当前entry，Context生命周期中可能有多个Entry，所有curEntry会有变化
   private Entry curEntry;
   // The origin of this context (usually indicate different invokers, e.g. service consumer name or origin IP).
   private String origin = "";
   private final boolean async;
}

protected static Context trueEnter(String name, String origin) {
    // 先从ThreadLocal中获取
    Context context = contextHolder.get();
    if (context == null) {
        // 如果ThreadLocal中获取不到Context
        // 则根据name从map中获取根节点，只要是相同的资源名，就能直接从map中获取到node
        Map<String, DefaultNode> localCacheNameMap = contextNameNodeMap;
        DefaultNode node = localCacheNameMap.get(name);
        if (node == null) {
            // 省略部分代码
            try {
                LOCK.lock();
                node = contextNameNodeMap.get(name);
                if (node == null) {
                    // 省略部分代码
                    // 创建一个新的入口节点
                    node = new EntranceNode(new StringResourceWrapper(name, EntryType.IN), null);
                    Constants.ROOT.addChild(node);
                    // 省略部分代码
                }
            } finally {
                LOCK.unlock();
            }
        }
        // 创建一个新的Context，并设置Context的根节点，即设置EntranceNode
        context = new Context(node, name);
        context.setOrigin(origin);
        // 将该Context保存到ThreadLocal中去
        contextHolder.set(context);
    }
    return context;
}

class CtEntry extends Entry {
   protected Entry parent = null;
   protected Entry child = null;

   protected ProcessorSlot<Object> chain;
   protected Context context;
}
public abstract class Entry implements AutoCloseable {
   private long createTime;
   private Node curNode;
   /**
    * {@link Node} of the specific origin, Usually the origin is the Service Consumer.
    */
   private Node originNode;
   private Throwable error; // 是否出现异常
   protected ResourceWrapper resourceWrapper; // 资源信息
}

public class DefaultNode extends StatisticNode {
private ResourceWrapper id;
/**
* The list of all child nodes.
* 子节点集合
/
private volatile Set childList = new HashSet<>();
/*
* Associated cluster node.
*/
private ClusterNode clusterNode;
}

一个Resouce只有一个clusterNode，多个defaultNode对应一个clusterNode，如果defaultNode.clusterNode为null，则在ClusterBuilderSlot.entry中会进行初始化。

同一个Resource，对应同一个ProcessorSlotChain，这块处理逻辑在lookProcessChain方法中，如下：

ProcessorSlot lookProcessChain(ResourceWrapper resourceWrapper) {
ProcessorSlotChain chain = chainMap.get(resourceWrapper);
if (chain == null) {
synchronized (LOCK) {
chain = chainMap.get(resourceWrapper);
if (chain == null) {
// Entry size limit.
if (chainMap.size() >= Constants.MAX_SLOT_CHAIN_SIZE) {
return null;
}
}
return chain;
}

           chain = SlotChainProvider.newSlotChain();
           Map<ResourceWrapper, ProcessorSlotChain> newMap = newHashMap<ResourceWrapper, ProcessorSlotChain>(
               chainMap.size() + 1);
           newMap.putAll(chainMap);
           newMap.put(resourceWrapper, chain);
           chainMap = newMap;
      }
  }

StatisticNode中保存了资源的实时统计数据（基于滑动时间窗口机制），通过这些统计数据，sentinel才能进行限流、降级等一系列操作。StatisticNode属性如下：

public class StatisticNode implements Node {
   /**
    * 秒级的滑动时间窗口（时间窗口单位500ms）
    */
   private transient volatile Metric rollingCounterInSecond = newArrayMetric(SampleCountProperty.SAMPLE_COUNT,
       IntervalProperty.INTERVAL);
   /**
    * 分钟级的滑动时间窗口（时间窗口单位1s）
    */
   private transient Metric rollingCounterInMinute = new ArrayMetric(60, 60 * 1000,false);
   /**
    * The counter for thread count.

 线程个数用户触发线程数流控
*/
private LongAdder curThreadNum = new LongAdder();
}
public class ArrayMetric implements Metric {
      private final LeapArray<MetricBucket> data;
}
public class MetricBucket {
// 保存统计值
private final LongAdder[] counters;
// 最小rt
private volatile long minRt;
}

public enum MetricEvent {
   PASS, // Normal pass.
   BLOCK, // Normal block.
   EXCEPTION,
   SUCCESS,
   RT,
   OCCUPIED_PASS
}

// DefaultSlotChainBuilder
public ProcessorSlotChain build() {
   ProcessorSlotChain chain = new DefaultProcessorSlotChain();
   chain.addLast(new NodeSelectorSlot());
   chain.addLast(new ClusterBuilderSlot());
   chain.addLast(new LogSlot());
   chain.addLast(new StatisticSlot());
   chain.addLast(new SystemSlot());
   chain.addLast(new AuthoritySlot());
   chain.addLast(new FlowSlot());
   chain.addLast(new DegradeSlot());

   return chain;

CtEntry(ResourceWrapper resourceWrapper, ProcessorSlot<Object> chain, Context context) {
    super(resourceWrapper);
    this.chain = chain;
    this.context = context;
    // 获取「上下文」中上一次的入口
    parent = context.getCurEntry();
    if (parent != null) {
        // 然后将当前入口设置为上一次入口的子节点
        ((CtEntry)parent).child = this;
    }
    // 设置「上下文」的当前入口为该类本身
    context.setCurEntry(this);
}

@Override
public void entry(Context context, ResourceWrapper resourceWrapper, Object obj, int count, Object... args) throws Throwable {
    // 根据「上下文」的名称获取DefaultNode
    // 多线程环境下，每个线程都会创建一个context，
    // 只要资源名相同，则context的名称也相同，那么获取到的节点就相同
    DefaultNode node = map.get(context.getName());
    if (node == null) {
        synchronized (this) {
            node = map.get(context.getName());
            if (node == null) {
                // 如果当前「上下文」中没有该节点，则创建一个DefaultNode节点
                node = Env.nodeBuilder.buildTreeNode(resourceWrapper, null);
                // 省略部分代码
            }
            // 将当前node作为「上下文」的最后一个节点的子节点添加进去
            // 如果context的curEntry.parent.curNode为null，则添加到entranceNode中去
            // 否则添加到context的curEntry.parent.curNode中去
            ((DefaultNode)context.getLastNode()).addChild(node);
        }
    }
    // 将该节点设置为「上下文」中的当前节点
    // 实际是将当前节点赋值给context中curEntry的curNode
    // 在Context的getLastNode中会用到在此处设置的curNode
    context.setCurNode(node);
    fireEntry(context, resourceWrapper, node, count, args);
}

public Node getLastNode() {
    // 如果curEntry不存在时，返回entranceNode
    // 否则返回curEntry的lastNode，
    // 需要注意的是curEntry的lastNode是获取的parent的curNode，
    // 如果每次进入的资源不同，就会每次都创建一个CtEntry，则parent为null，
    // 所以curEntry.getLastNode()也为null
    if (curEntry != null && curEntry.getLastNode() != null) {
        return curEntry.getLastNode();
    } else {
        return entranceNode;
    }
}

@Override
public void entry(Context context, ResourceWrapper resourceWrapper, DefaultNode node, int count, Object... args) throws Throwable {
    if (clusterNode == null) {
        synchronized (lock) {
            if (clusterNode == null) {
                // Create the cluster node.
                clusterNode = Env.nodeBuilder.buildClusterNode();
                // 将clusterNode保存到全局的map中去
                HashMap<ResourceWrapper, ClusterNode> newMap = new HashMap<ResourceWrapper, ClusterNode>(16);
                newMap.putAll(clusterNodeMap);
                newMap.put(node.getId(), clusterNode);
 
                clusterNodeMap = newMap;
            }
        }
    }
    // 将clusterNode塞到DefaultNode中去
    node.setClusterNode(clusterNode);
 
    // 省略部分代码
 
    fireEntry(context, resourceWrapper, node, count, args);
}

@Override
public void entry(Context context, ResourceWrapper resourceWrapper, DefaultNode node, int count, Object... args) throws Throwable {
    try {
        // 触发下一个Slot的entry方法
        fireEntry(context, resourceWrapper, node, count, args);
        // 如果能通过SlotChain中后面的Slot的entry方法，说明没有被限流或降级
        // 统计信息
        node.increaseThreadNum();
        node.addPassRequest();
        // 省略部分代码
    } catch (BlockException e) {
        context.getCurEntry().setError(e);
        // Add block count.
        node.increaseBlockedQps();
        // 省略部分代码
        throw e;
    } catch (Throwable e) {
        context.getCurEntry().setError(e);
        // Should not happen
        node.increaseExceptionQps();
        // 省略部分代码
        throw e;
    }
}

@Override
public void exit(Context context, ResourceWrapper resourceWrapper, int count, Object... args) {
    DefaultNode node = (DefaultNode)context.getCurNode();
    if (context.getCurEntry().getError() == null) {
        long rt = TimeUtil.currentTimeMillis() - context.getCurEntry().getCreateTime();
        if (rt > Constants.TIME_DROP_VALVE) {
            rt = Constants.TIME_DROP_VALVE;
        }
        node.rt(rt);
        // 省略部分代码
        node.decreaseThreadNum();
        // 省略部分代码
    } 
    fireExit(context, resourceWrapper, count);
}

@Override
public void entry(Context context, ResourceWrapper resourceWrapper, DefaultNode node, int count,
                  boolean prioritized, Object... args) throws Throwable {
    SystemRuleManager.checkSystem(resourceWrapper);
    fireEntry(context, resourceWrapper, node, count, prioritized, args);
}

public static void checkSystem(ResourceWrapper resourceWrapper) throws BlockException {
    if (resourceWrapper == null) {
        return;
    }
    // Ensure the checking switch is on.
    if (!checkSystemStatus.get()) {
        return;
    }

    // for inbound traffic only
    if (resourceWrapper.getEntryType() != EntryType.IN) {
        return;
    }

    // total qps
    double currentQps = Constants.ENTRY_NODE == null ? 0.0 : Constants.ENTRY_NODE.successQps();
    if (currentQps > qps) {
        throw new SystemBlockException(resourceWrapper.getName(), "qps");
    }

    // total thread
    int currentThread = Constants.ENTRY_NODE == null ? 0 : Constants.ENTRY_NODE.curThreadNum();
    if (currentThread > maxThread) {
        throw new SystemBlockException(resourceWrapper.getName(), "thread");
    }

    double rt = Constants.ENTRY_NODE == null ? 0 : Constants.ENTRY_NODE.avgRt();
    if (rt > maxRt) {
        throw new SystemBlockException(resourceWrapper.getName(), "rt");
    }

    // BBR算法
    // load. BBR algorithm.
    if (highestSystemLoadIsSet && getCurrentSystemAvgLoad() > highestSystemLoad) {
        if (!checkBbr(currentThread)) {
            throw new SystemBlockException(resourceWrapper.getName(), "load");
        }
    }

    // cpu usage
    if (highestCpuUsageIsSet && getCurrentCpuUsage() > highestCpuUsage) {
        throw new SystemBlockException(resourceWrapper.getName(), "cpu");
    }
}

@Override
public void entry(Context context, ResourceWrapper resourceWrapper, DefaultNode node, int count, boolean prioritized, Object... args)
    throws Throwable {
    checkBlackWhiteAuthority(resourceWrapper, context);
    fireEntry(context, resourceWrapper, node, count, prioritized, args);
}

void checkBlackWhiteAuthority(ResourceWrapper resource, Context context) throws AuthorityException {
    // 通过监听来的规则集
    Map<String, Set<AuthorityRule>> authorityRules = AuthorityRuleManager.getAuthorityRules();

    if (authorityRules == null) {
        return;
    }


    // 根据资源名称获取相应的规则
    Set<AuthorityRule> rules = authorityRules.get(resource.getName());
    if (rules == null) {
        return;
    }

    for (AuthorityRule rule : rules) {
        // 黑名单白名单验证
        // 只要有一条规则校验不通过，就抛出AuthorityException
        if (!AuthorityRuleChecker.passCheck(rule, context)) {
            throw new AuthorityException(context.getOrigin(), rule);
        }
    }
}

@Override
public void entry(Context context, ResourceWrapper resourceWrapper, DefaultNode node, int count,
                  boolean prioritized, Object... args) throws Throwable {
    checkFlow(resourceWrapper, context, node, count, prioritized);

    fireEntry(context, resourceWrapper, node, count, prioritized, args);
}

void checkFlow(ResourceWrapper resource, Context context, DefaultNode node, int count, boolean prioritized)
    throws BlockException {
    checker.checkFlow(ruleProvider, resource, context, node, count, prioritized);
}

@Override
public void entry(Context context, ResourceWrapper resourceWrapper, DefaultNode node, int count,
                  boolean prioritized, Object... args) throws Throwable {
    performChecking(context, resourceWrapper);

    fireEntry(context, resourceWrapper, node, count, prioritized, args);
}

void performChecking(Context context, ResourceWrapper r) throws BlockException {
    List<CircuitBreaker> circuitBreakers =         
        DegradeRuleManager.getCircuitBreakers(r.getName());
    
    if (circuitBreakers == null || circuitBreakers.isEmpty()) {
        return;
    }
    for (CircuitBreaker cb : circuitBreakers) {
        if (!cb.tryPass(context)) {
            throw new DegradeException(cb.getRule().getLimitApp(), cb.getRule());
        }
    }
}

public class DefaultProcessorSlotChain extends ProcessorSlotChain {

    AbstractLinkedProcessorSlot<?> first = new AbstractLinkedProcessorSlot<Object>() {

        @Override
        public void entry(Context context, ResourceWrapper resourceWrapper, Object t, int count, boolean prioritized, Object... args)
            throws Throwable {
            super.fireEntry(context, resourceWrapper, t, count, prioritized, args);
        }

        @Override
        public void exit(Context context, ResourceWrapper resourceWrapper, int count, Object... args) {
            super.fireExit(context, resourceWrapper, count, args);
        }

    };
    AbstractLinkedProcessorSlot<?> end = first;

    @Override
    public void addFirst(AbstractLinkedProcessorSlot<?> protocolProcessor) {
        protocolProcessor.setNext(first.getNext());
        first.setNext(protocolProcessor);
        if (end == first) {
            end = protocolProcessor;
        }
    }

    @Override
    public void addLast(AbstractLinkedProcessorSlot<?> protocolProcessor) {
        end.setNext(protocolProcessor);
        end = protocolProcessor;
    }

    /**
     * Same as {@link #addLast(AbstractLinkedProcessorSlot)}.
     *
     * @param next processor to be added.
     */
    @Override
    public void setNext(AbstractLinkedProcessorSlot<?> next) {
        addLast(next);
    }

    @Override
    public AbstractLinkedProcessorSlot<?> getNext() {
        return first.getNext();
    }

    @Override
    public void entry(Context context, ResourceWrapper resourceWrapper, Object t, int count, boolean prioritized, Object... args)
        throws Throwable {
        first.transformEntry(context, resourceWrapper, t, count, prioritized, args);
    }

    @Override
    public void exit(Context context, ResourceWrapper resourceWrapper, int count, Object... args) {
        first.exit(context, resourceWrapper, count, args);
    }

}

在数组的位置 = 算出秒 %数组长度

窗口startTime = 1609085401454 - 1609085401454%1000（窗口长度）=454

public enum MetricEvent {
    /**
     * Normal pass.
     */
    PASS,// 通过
    /**
     * Normal block.
     */
    BLOCK,// 拒绝的
    EXCEPTION,// 异常
    SUCCESS,//成功
    RT,// 耗时
    /**
     * Passed in future quota (pre-occupied, since 1.5.0).
     */
    OCCUPIED_PASS
}
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