Spring Boot Asynchronous Controller

1. Create Async Thread Pool

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;

import java.util.concurrent.Executor;

@Configuration
@EnableAsync
public class MainConfiguration {

    @Bean(name = "asyncExecutor")
    public Executor asyncExecutor()
    {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(5);
        executor.setMaxPoolSize(5);
        executor.setQueueCapacity(100);
        executor.setThreadNamePrefix("AsynchThreadNo-");
        executor.initialize();
        return executor;
    }
}

สร้าง Data Model สำหรับ Customer

public class Customer {

    private String name;
    private Integer age;

    public Customer(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "name='" + name + '\'' +
                ", age='" + age + '\'' +
                '}';
    }
}

MySevice สำหรับ get ข้อมูล Customer

import com.ringzero.research.model.Customer;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;

import javax.annotation.PostConstruct;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CompletableFuture;

@Service
public class MyService {

    private List<Customer> customerList = new ArrayList<>();

    @PostConstruct
    public void initialize() {
        for (int i=1; i <= 1000; i++) {
            customerList.add(new Customer("name-" + i, i));
        }
    }

    @Async("asyncExecutor")
    public CompletableFuture<List<Customer>> getCustomer1() throws InterruptedException
    {
        Thread.sleep(1000L);    //Intentional delay
        return CompletableFuture.completedFuture(customerList.subList(1, 500));
    }
    @Async("asyncExecutor")
    public CompletableFuture<List<Customer>> getCustomer2() throws InterruptedException
    {
        Thread.sleep(2000L);    //Intentional delay
        return CompletableFuture.completedFuture(customerList.subList(300, 700));
    }

    @Async("asyncExecutor")
    public CompletableFuture<List<Customer>> getCustomer3() throws InterruptedException
    {
        Thread.sleep(3000L);    //Intentional delay
        return CompletableFuture.completedFuture(customerList.subList(600, 900));
    }


}

Controller

import com.ringzero.research.model.Customer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;

import static org.apache.kafka.common.requests.DeleteAclsResponse.log;

@RestController
public class MyController {

    @Autowired
    private MyService service;

    @RequestMapping(value = "/getAsynchData", method = RequestMethod.GET)
    public String getAsynchData() throws InterruptedException, ExecutionException
    {
        final long startTime = System.currentTimeMillis();
        CompletableFuture<List<Customer>> customer1 = service.getCustomer1();
        CompletableFuture<List<Customer>> customer2 = service.getCustomer2();
        CompletableFuture<List<Customer>> customer3 = service.getCustomer3();

        // Wait until they are all done
        CompletableFuture.allOf(customer1, customer2, customer3).join();

        log.info("customer1--> " + customer1.get());
        log.info("customer2--> " + customer2.get());
        log.info("customer3--> " + customer3.get());

        final long duration = (System.currentTimeMillis() - startTime) / 1000;
        return "" + duration + " secs";
    }

}

ถ้าเราไม่ทำ Asynch Controller เวลาการทำงานจะประมาณ 6 sec
แต่ถอทำ Asynch แล้วจะเหลือประมาณ 3 sec คือที่ sleep นานที่สุด