Add RetryWhen to Single When DB Insert Fails

Question

I've been trying to figure this out still new to RXJava and still not liking it, rather use Livedata and coroutines but anyway.. I have this:

Single.just(entity)
    .map {
         insertDb(it)
         return@map it
    }
.doOnSubscribe { Timber.d("Updating in database") }
.doOnSuccess { Timber.d("Added row in database") }
.doOnError { Timber.e(it, "Unable to insert object in db") }


fun insertDb(entity: T) {
    try {
       // basic update or insert database.begingTransaction() and endTransaction()
    } catch (e: SQLiteDatabaseLockedException) {}
}

So when the error of DB locked occurs I want to catch it and retry the insert using the Single with a retryWhen(). The examples I read are very convoluted and not quite what I want. And don't worry about the locked DB stuff this is just an example of how I would catch DB errors.

Answer 1

You can use a PublishProcessor:

 val retryProcessor = PublishProcessor.create<Unit>()

 Single.just("Entity")
       .map { insertDB(it) }
       .doOnError { Log.e(TAG, "Error") }
       .retryWhen { retryProcessor }
       .subscribe { entity -> Log.i(TAG, "Success: $entity") }

Insert to DB:

fun insertDB(entity: String): String {
    // Insert to DB
    return entity
}

Whenever you want to perform a retry, call onNext on the PublishProcessor:

retryProcessor.onNext(Unit)