Dropwizard AsyncResponse usage

DropwizardAsyncResource.java

package com.xyz.dw.resource;

import com.codahale.metrics.annotation.Timed;
import com.google.common.base.Optional;
import com.google.common.util.concurrent.SettableFuture;
import com.xyz.dw.model.Greeting;
import org.glassfish.jersey.server.ManagedAsync;
import rx.Observable;
import rx.schedulers.Schedulers;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.container.AsyncResponse;
import javax.ws.rs.container.Suspended;
import javax.ws.rs.core.MediaType;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicLong;

@Path("/hello")
@Produces(MediaType.APPLICATION_JSON)
public class HelloResource {
    private final String template;
    private final String defaultName;
    private final AtomicLong counter;
    private final ExecutorService executorService;

    public HelloResource(String template, String defaultName) {
        this.template = template;
        this.defaultName = defaultName;
        this.counter = new AtomicLong();
        this.executorService = Executors.newFixedThreadPool(100);
    }

    @GET
    @Timed
    public Greeting sayHello(@QueryParam("name") Optional<String> name){
        final String value = String.format(template, name.or(defaultName));
        try {
            Thread.sleep(50);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return new Greeting(counter.incrementAndGet(), value);
    }

    @GET
    @Path("/async")
    @Timed
    @ManagedAsync
    public void asyncHello(@QueryParam("name") Optional<String> name, @Suspended final AsyncResponse asyncResponse) throws InterruptedException {
        final String value = String.format(template, name.or(defaultName));
        Greeting greeting = new Greeting(counter.incrementAndGet(), value);
        Thread.sleep(50);
        asyncResponse.resume(greeting);
    }

    @GET
    @Path("/async_observable")
    @Timed
    public void asyncObservableHello(@QueryParam("name") Optional<String> name, @Suspended final AsyncResponse asyncResponse){
        Observable<Object> observable = Observable.create(s -> {
            final String value = String.format(template, name.or(defaultName));
            Greeting greeting = new Greeting(counter.incrementAndGet(), value);
            s.onNext(greeting);
            s.onCompleted();
        }).delay(50, TimeUnit.MILLISECONDS);
        observable.subscribeOn(Schedulers.from(executorService));
        observable.subscribe(greeting -> asyncResponse.resume(greeting));
    }

    @GET
    @Path("/async_future")
    @Timed
    public void asyncFutureHello(@QueryParam("name") Optional<String> name, @Suspended final AsyncResponse asyncResponse){
        CompletableFuture<Greeting> completableFuture = new CompletableFuture<>();
        executorService.submit(() -> {
            try {
                Thread.sleep(50);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            final String value = String.format(template, name.or(defaultName));
            Greeting greeting = new Greeting(counter.incrementAndGet(), value);
            completableFuture.complete(greeting);
        });
        completableFuture.thenAcceptAsync(greeting -> asyncResponse.resume(greeting));
    }

    @GET
    @Path("/sync_future")
    @Timed
    public Greeting syncFutureHello(@QueryParam("name") Optional<String> name) throws ExecutionException, InterruptedException {
        SettableFuture<Greeting> settableFuture = SettableFuture.create();
        executorService.submit(() -> {
            try {
                Thread.sleep(50);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            final String value = String.format(template, name.or(defaultName));
            Greeting greeting = new Greeting(counter.incrementAndGet(), value);
            settableFuture.set(greeting);
        });
        Greeting greeting = settableFuture.get();
        return greeting;
    }
}