Load testing with Gatling

$ curl https://start.spring.io/starter.zip \
-d dependencies=webflux,lombok,actuator \
-d type=maven-project \
-d baseDir=greetings \
-d groupId=com.oxymorus.greetings \
-d artifactId=greetings \
-d bootVersion=2.1.9.RELEASE \
-o service.zip

$ unzip service.zip && rm service.zip && cd service

package com.oxymorus.greeting.domain;

import lombok.Value;

@Value
public class Greeting {

    public static final Greeting DEFAULT = new Greeting("<undefined>", "<undefined>");

    private String name;
    private String greeting;
}

package com.oxymorus.greeting.api;

import com.oxymorus.greeting.api.model.CreateGreetingRequest;
import com.oxymorus.greeting.api.model.CreateGreetingResponse;
import com.oxymorus.greeting.api.model.GetGreetingRequest;
import com.oxymorus.greeting.api.model.GetGreetingResponse;
import com.oxymorus.greeting.service.GreetingService;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import reactor.core.publisher.Mono;

@Slf4j
@RequiredArgsConstructor
@RestController
@RequestMapping("/greetings")
public class GreetingController {

    private final GreetingService service;

    @PostMapping(consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
    Mono<CreateGreetingResponse> createGreeting(@RequestBody CreateGreetingRequest request) {
        return service.createGreeting(request.getName(), request.getGreeting())
                .map(CreateGreetingResponse::new)
                .doOnSubscribe(subscription -> log.info("Create greeting '{}'", request));
    }

    @GetMapping(produces = MediaType.APPLICATION_JSON_VALUE)
    Mono<GetGreetingResponse> getGreeting(GetGreetingRequest request) {

        return service.findGreeting(request.getId())
                .map(greeting -> new GetGreetingResponse(greeting.getName(), greeting.getGreeting()))
                .doOnSubscribe(subscription -> log.info("Get greeting by id '{}'", request.getId()));
    }
}

package com.oxymorus.greeting.service;

import com.oxymorus.greeting.domain.Greeting;
import lombok.experimental.UtilityClass;
import reactor.core.publisher.Mono;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;

public class DefaultGreetingService implements GreetingService {

    private static final Map<Long, Greeting> GREETINGS_STORAGE = new ConcurrentHashMap<>();

    @Override
    public Mono<Long> createGreeting(String name, String greeting) {
        return Mono.fromCallable(Generator::next)
                .map(id -> {
                    GREETINGS_STORAGE.put(id, new Greeting(name, greeting));
                    return id;
                });
    }

    @Override
    public Mono<Greeting> findGreeting(Long id) {
        return Mono.fromCallable(() -> GREETINGS_STORAGE.getOrDefault(id, Greeting.DEFAULT));
    }

    @UtilityClass
    private static class Generator {
        private static final AtomicLong id = new AtomicLong(0);

        private static long next() {
            return id.incrementAndGet();
        }
    }
}