findCollidingIds AssertionError exception keeps crashing the app

[DarkionAvey]

Hi!
I've been using the app for couple of days now, and I must say I'm impressed, well done! But I noticed that the app crashes when scrolling very far down the list. According to logcat, it's caused by SubredditSubmissionsAdapter#findCollidingIds.

I didn't go through the code so I just silenced the exception in a fork. For now I haven't faced any side effects, but have a look at the issue and possibly fix it when you have time.

Thanks

[Tunous]

I would like to try and fix this too.
@saket is there a way for us to know the reason why you added said method in this commit:
c6b6114 ? The link added in comment doesn't work for me.

[saket]

findCollidingIds() throws an error if two SubmissionRowUiModel items in the data-set have the same IDs. In this case, the collision is happening between items of SubredditSubmission.

The adapterId is generated here: JrawUtils2#L20. Fortunately or unfortunately this function is used for generating the adapter ID of multiple types of Reddit related objects.

I'm using a combination of hashcode + created-at-time in hopes that they'll be unique, but clearly that's wrong. Multiple submissions can have the same created-at timestamp, increasing their likelihood of collision.

@Tunous unfortunately, the Bugsnag dashboard is private so you won't be able to open the link. It doesn't have anything useful except for links to the two colliding submissions. I wonder if I can make my bugsnag dashboard public.

[DarkionAvey]

But if you read the printed logcat (using Log.e), SubmissionRowUiModel 'existing' and 'row' are basically the same entry, so the issue isn't in findCollidingIds but somewhere upstream where an article is retrieved twice (?)

[saket]

You're right. The rows point to the same submission. Looks like the problem lies somewhere else upstream.

[Tunous]

I've debugged the bug a bit and found that the problem lies in part of code which deals with saving new submissions to local database:

Dank/app/src/main/java/me/saket/dank/ui/submission/SubmissionRepository.java

Line 445 in b429407

if (insertedRowId != -1) {

The code inside of the linked if statement executes basically every time because saveTimeMillis is a part of primary key for CachedSubmissionId2. Since everything (including duplicates) fetched from the API is saved to the database we are getting id collisions.

I've fixed this bug by removing saveTimeMillis from the primary key for CachedSubmissionId2 and adding id here instead which seems to be something that is supposed to uniquely identify submissions.

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@saket are you interested in accepting pull requests to this repository or would you prefer to leave everything up to forks?

[saket]

@Tunous just an information about the bug fix is sufficient, don't bother sending back patches to Dank. As much as I'd like them, I don't think I have enough time to maintain this app anymore.

[saket]

Will be fixed with #6