RxUtils.java

package com.tevinjeffrey.rutgersct.utils;

import java.util.concurrent.TimeUnit;

import rx.Observable;
import rx.Subscription;
import rx.functions.Func1;
import rx.subscriptions.CompositeSubscription;
import timber.log.Timber;

public class RxUtils {

    public static void unsubscribeIfNotNull(Subscription subscription) {
        if (subscription != null) {
            subscription.unsubscribe();
        }
    }

    public static CompositeSubscription getNewCompositeSubIfUnsubscribed(CompositeSubscription subscription) {
        if (subscription == null || subscription.isUnsubscribed()) {
            return new CompositeSubscription();
        }

        return subscription;
    }

    //https://github.com/kaushikgopal/RxJava-Android-Samples/blob/master/app/src/main/java/com/morihacky/android/rxjava/ExponentialBackoffFragment.java
    @SuppressWarnings("ValueOfIncrementOrDecrementUsed")
    public static class RetryWithDelay
            implements Func1<Observable<? extends Throwable>, Observable<?>> {
        private final int _maxRetries;
        private final int _retryDelayMillis;
        private int _retryCount;


        public RetryWithDelay(final int maxRetries, final int retryDelayMillis) {
            _maxRetries = maxRetries;
            _retryDelayMillis = retryDelayMillis;
            _retryCount = 0;
        }


        @Override
        public Observable<?> call(Observable<? extends Throwable> attempts) {
            return attempts.flatMap(new Func1<Throwable, Observable<?>>() {
                @Override
                public Observable<?> call(Throwable throwable) {
                    if (++_retryCount < _maxRetries) {
                        // When this Observable calls onNext, the original
                        // Observable will be retried (i.e. re-subscribed).
                        Timber.d("Retry %d", _retryCount);
                        Timber.d("Retrying in %d ms", _retryCount * _retryDelayMillis);
                        return Observable.timer(_retryCount * _retryDelayMillis,
                                TimeUnit.MILLISECONDS);
                    }
                    // Max retries hit. Just pass the error along.
                    return Observable.error(throwable);
                }
            });
        }

        @Override
        public String toString() {
            return "RetryWithDelay{" +
                    "_maxRetries=" + _maxRetries +
                    ", _retryDelayMillis=" + _retryDelayMillis +
                    ", _retryCount=" + _retryCount +
                    '}';
        }
    }
}