Hystrix implements request consolidation

Add

@EnableHystrix
@EnableHystrixDashboard

Add dependencies on services that need to be merged

<!--hystrix rely on -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId>
</dependency>

Request interface

package com.leilei.controller;

import com.leilei.entity.AlarmDictionary;
import com.leilei.service.AlarmService;
import com.netflix.hystrix.strategy.concurrency.HystrixRequestContext;
import org.springframework.web.bind.annotation.*;

import java.util.concurrent.Future;

/** * @author lei * @create 2022-03-30 22:45 * @desc **/
@RequestMapping("/alarm")
@RestController
public class AlarmController {
    
    private final AlarmService alarmService;

    public AlarmController(AlarmService alarmService) {
    
        this.alarmService = alarmService;
    }

    /** *  External single request interface  * @param id * @return */
    @GetMapping(value = "/dictionary/{id}")
    public AlarmDictionary requestCollapseAnnotation(@PathVariable Integer id) {
    
        //  Note that it needs to be turned on Hystrix Environmental Science 
        try (HystrixRequestContext context = HystrixRequestContext.initializeContext()) {
    
            Future<AlarmDictionary> f1 = alarmService.find(id);
            return f1.get();
        } catch (Exception e) {
    
            e.printStackTrace();
        }
        return null;
    }
}

Aggregate batch processing inside the service

package com.leilei.service;

import com.leilei.entity.AlarmDictionary;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCollapser;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.concurrent.Future;

/** * @author lei * @create 2022-03-30 22:38 * @desc **/
@Service
public class AlarmService {
    

    private  final AlarmFeign alarmFeign;

    public AlarmService(AlarmFeign alarmFeign) {
    
        this.alarmFeign = alarmFeign;
    }

    /** * batchMethod  Set the interface name of the batch method  * HystrixProperty name  Set to time delay timerDelayInMilliseconds  That is, how long the request is submitted as a batch ;value  Is the time threshold , In milliseconds  * @param id * @return */
    @HystrixCollapser(batchMethod = "findBatch",
            collapserProperties = {
    @HystrixProperty(name = "timerDelayInMilliseconds", value = "1000")})
    public Future<AlarmDictionary> find(Integer id) {
    
        throw new RuntimeException("This method body should not be executed");
    }

    @HystrixCommand
    public List<AlarmDictionary> findBatch(List<Integer> alarms) {
    
        List<AlarmDictionary> alarmDictionaries = alarmFeign.getBatch(alarms);
        System.out.println(Thread.currentThread().getName() + ":" + alarmDictionaries);
        return alarmDictionaries;
    }
}

Service providers ( Of course, you can't use remote here , Using the internal batch logic of the service )

@RestController
@RequestMapping("/alarm/dictionary")
public class AlarmDictionaryController {
    static List<AlarmDictionary> alarms = new ArrayList<>();
    static {
        alarms.add(new AlarmDictionary(1,"808 First level alarm "));
        alarms.add(new AlarmDictionary(2,"808 Level two alarm "));
        alarms.add(new AlarmDictionary(3,"808 Three alarm "));
        alarms.add(new AlarmDictionary(4," Fatigue driving level 1 alarm "));
    }
    @PostMapping("/batch")
    public List<AlarmDictionary> getBatchAlarmById(@RequestBody List<Integer> alarmIds) {
        return alarms.stream().filter(x -> alarmIds.contains(x.getId())).collect(Collectors.toList());
    }
}

test result

problem :

Hystrix The request must be in the request response mode , That is to say , A request must have a corresponding result , If the response is empty , An exception will be thrown

Caused by: java.lang.RuntimeException: Failed to map all collapsed requests to response. The expected contract has not been respected. Collapser key: 'find', requests size: '1', response size: '0'
	at com.netflix.hystrix.contrib.javanica.collapser.CommandCollapser.mapResponseToRequests(CommandCollapser.java:76)
	at com.netflix.hystrix.contrib.javanica.collapser.CommandCollapser.mapResponseToRequests(CommandCollapser.java:33)
	at com.netflix.hystrix.HystrixCollapser$1$1.call(HystrixCollapser.java:171)
	at rx.internal.util.ActionObserver.onNext(ActionObserver.java:39)
	at rx.internal.operators.OnSubscribeDoOnEach$DoOnEachSubscriber.onNext(OnSubscribeDoOnEach.java:96)
	... 68 more

At present, we can try-catch Handle , Better solutions need to be updated …

TODO…

Attach project address :hystrix-batch-collapser