model

public class InfoModelImpl implements InfoModel {

  @NonNull
  private final GithubService restApi;
  @NonNull
  private final String user;
  @NonNull
  private final RealmConfiguration configuration;
  @NonNull
  private final Scheduler scheduler;
  @Nullable
  private Realm realm;

  public InfoModelImpl(@NonNull String user,
                       @NonNull RealmConfiguration configuration,
                       @NonNull Scheduler scheduler,
                       @NonNull GithubService restApi) {
    this.user = user;
    this.configuration = configuration;
    this.scheduler = scheduler;
    this.restApi = restApi;
  }

  @AnyThread
  @NonNull
  @Override
  public Observable<GithubUser> updateInfo() {
    return restApi.getUser(user).observeOn(scheduler)
                  .doOnNext(user -> {
                    if (realm == null || realm.isClosed()) {
                      throw new IllegalStateException("You should subscribe on #observeInfo() first");
                    }
                    realm.executeTransaction(r -> {
                      GithubUser realmObject = realm.where(GithubUser.class).findFirst();
                      if (realmObject == null) {
                        realm.copyToRealmOrUpdate(user);
                      } else {
                        realmObject.setAvatarUrl(user.getAvatarUrl());
                        realmObject.setName(user.getName());
                      }
                    });
                  });
  }

  @AnyThread
  @NonNull
  @Override
  public Observable<GithubUser> observeInfo() {
    return Observable.defer(() -> {
      if (realm != null && !realm.isClosed()) {
        throw new IllegalStateException("You can't subscribe #observeInfo() twice");
      }
      realm = Realm.getInstance(configuration);
      return realm.where(GithubUser.class).findFirstAsync()
                     .<GithubUser>asObservable()
                     .filter(p -> p.isLoaded() && p.isValid())
                     .doOnUnsubscribe(() -> {
                       realm.close();
                       realm = null;
                     })
                     .distinctUntilChanged();
    }).subscribeOn(scheduler);
  }

}