RxIntentService.java

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.support.annotation.Nullable;

import java.util.concurrent.atomic.AtomicInteger;

import rx.Completable;
import rx.Subscription;
import rx.schedulers.Schedulers;
import rx.subjects.ReplaySubject;

/**
 * Service that runs {@link Completable}s sequentially and stops itself if there are no more {@link Completable}s in queue.
 */
public abstract class RxIntentService extends Service {
    private final AtomicInteger queueSize = new AtomicInteger();
    private final ReplaySubject<Intent> subject = ReplaySubject.create();
    private Subscription subscription;

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        subscription = subject
                .doOnNext(intent -> queueSize.incrementAndGet())
                .onBackpressureBuffer()
                .flatMapCompletable(intent -> onHandleIntent(intent)
                        .onErrorComplete()
                        .doAfterTerminate(() -> {
                            if (queueSize.decrementAndGet() == 0) {
                                stopSelf();
                            }
                        }), false, 1)
                .subscribeOn(Schedulers.newThread())
                .subscribe();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        subscription.unsubscribe();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        subject.onNext(intent);
        return START_NOT_STICKY;
    }

    protected abstract Completable onHandleIntent(Intent intent);
}