Server polling and retry operations when failed. With Retrofit and RxJava.

retryWhen_repeatWhen.java

retryWhen(new Func1<Observable<? extends Throwable>, Observable<?>>() {
     @Override
     public Observable<?> call(Observable<? extends Throwable> observable) {
         Log.v(TAG, "retryWhen, call");
         return observable.compose(zipWithFlatMap());
     }
 }).repeatWhen(new Func1<Observable<? extends Void>, Observable<?>>() {
     @Override
     public Observable<?> call(Observable<? extends Void> observable) {
         Log.v(TAG, "repeatWhen, call");
         return observable.compose(zipWithFlatMap());
     }
})

<T> Observable.Transformer<T, Long> zipWithFlatMap() {
        return new Observable.Transformer<T, Long>() {

            @Override
            public Observable<Long> call(Observable<T> observable) {
                return observable.zipWith(Observable.range(COUNTER_START, ATTEMPTS), new Func2<T, Integer, Integer>() {
                    @Override
                    public Integer call(T t, Integer repeatAttempt) {
                        Log.v(TAG, "zipWith, call, repeatAttempt " + repeatAttempt);
                        return repeatAttempt;
                    }
                }).flatMap(new Func1<Integer, Observable<Long>>() {
                    @Override
                    public Observable<Long> call(Integer repeatAttempt) {
                        Log.v(TAG, "flatMap, call, repeatAttempt " + repeatAttempt);
                        // increase the waiting time
                        return Observable.timer(repeatAttempt * 5, TimeUnit.SECONDS);
                    }
                });
            }
        };
    }