Sentinel 鏈路限流

https://github.com/alibaba/Sentinel/wiki/%E6%B5%81%E9%87%8F%E6%8E%A7%E5%88%B6

NodeSelectorSlot 中記錄了資源之間的調用鏈路，這些資源通過調用關系，相互之間構成一棵調用樹。這棵樹的根節點是一個名字為 machine-root 的虛擬節點，調用鏈的入口都是這個虛節點的子節點。

一棵典型的調用樹如下圖所示：

     	          machine-root
                    /       \
                   /         \
             Entrance1     Entrance2
                /             \
               /               \
      DefaultNode(nodeA)   DefaultNode(nodeA)

上圖中來自入口 Entrance1 和 Entrance2 的請求都調用到了資源 NodeA，Sentinel 允許只根據某個入口的統計信息對資源限流。比如我們可以設置 strategy 為 RuleConstant.STRATEGY_CHAIN，同時設置 refResource 為 Entrance1 來表示只有從入口 Entrance1 的調用才會記錄到 NodeA 的限流統計當中，而不關心經 Entrance2 到來的調用。

調用鏈的入口（上下文）是通過 API 方法 ContextUtil.enter(contextName) 定義的，其中 contextName 即對應調用鏈路入口名稱。詳情可以參考 ContextUtil 文檔。

web-context-unify: false #默認將調用鏈路收斂

 

 application.yml

server:
  port: 8052
  #應用名稱  （sentinel 會將該名稱當作服務名稱）
spring:
  application:
    name: order-sentinel
  cloud:
    sentinel:
      transport:
        dashboard: 127.0.0.1:8858
      web-context-unify: false #默認將調用鏈路收斂

 

package com.wsm.order.service;

public interface OrderService {
    public String getUser();
}

 

package com.wsm.order.service.impl;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.wsm.order.service.OrderService;
import org.springframework.stereotype.Service;

@Service
public class OrderServiceImpl implements OrderService {

    @Override
    @SentinelResource(value = "getUser",blockHandler = "blockHandlerGetUser")
    public String getUser() {
        return "查詢用戶";
    }

    public String blockHandlerGetUser(BlockException e){
        return "流控用戶";
    }

}

 

package com.wsm.order.controller;

import com.alibaba.csp.sentinel.annotation.SentinelResource;
import com.alibaba.csp.sentinel.slots.block.BlockException;
import com.wsm.order.service.OrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.concurrent.TimeUnit;

@RestController
@RequestMapping("/order")
public class OrderController {

    @Autowired
    OrderService orderService;

    @RequestMapping("/add")
    public String add(){
        System.out.println("下單成功！");
        return "生成訂單";
    }

    @RequestMapping("/get")
    public String get(){
        System.out.println("查詢訂單！");
        return "查詢訂單";
    }

    @RequestMapping("/test1")
    public String test1(){
        return orderService.getUser();
    }

    @RequestMapping("/test2")
    public String test2(){
        return orderService.getUser();
    }

    @RequestMapping("/flow")
//    @SentinelResource(value = "flow",blockHandler = "flowBlockHandler")
    public String flow(){
        System.out.println("========flow====");
        return "正常訪問";
    }

    public String flowBlockHandler(BlockException e){
        return "流控了";
    }

    @RequestMapping("/flowThread")
//    @SentinelResource(value = "flowThread",blockHandler = "flowThreadBlockHandler")
    public String flowThread() throws InterruptedException {
        TimeUnit.SECONDS.sleep(5);
        System.out.println("========flowThread====");
        return "正常訪問";
    }

    public String flowThreadBlockHandler(BlockException e){
        return "flowThread流控了";
    }




}