Multiselect causing ANRs

[mchowning]

Description

With the 7.45 release, we've seen a significant increase in ANRs. They mostly seem related to multi-selection.

For example:

• https://a8c.sentry.io/issues/4127312862/events/38682e5581664ac0acc624aecd4c1f96/
• https://a8c.sentry.io/issues/4379367564/events/68534d8466fd4dada916a25d0daec7d7/
• https://a8c.sentry.io/issues/4379479942/events/49d29151c5bc45fea09bd02f990b5778/
• https://a8c.sentry.io/issues/4379054706/events/9813858b8d104c8c969da31d1b511a64/
• https://a8c.sentry.io/issues/4411476095/events/3ee1b7da704745768c7753a6a68b6b30/
• https://a8c.sentry.io/issues/4412473142/events/0a8a909811cf453ba28e117850a9a4af/

Step-by-step reproduction instructions

1. Make sure you have a bunch of episodes in your Up Next queue
2. Go to a filter with a lot of episodes
3. Enter multiselection
4. Select all
5. Tap the miniplayer and then swipe up to get your Up Next queue (don't close the filters screen)
6. Enter multiselect mode
7. Select all
8. Select None
9. Observe the app locks up for a while

Device, Operating system, and Pocket Casts app version

Samsung A13, Android 13, Pocket Casts 7.45

[mchowning]

I think there are two issues causing this.

1. Not batching multiselect updates

The main one is that there are a number of places in the app where we iterate through the multiselect items when a user does select all/none, instead of just replacing the selected items with a single, new, list. Fixing this seems pretty straightforward and seems to avoid the ANR issue on its own, so I've created a PR for this as a hotfix (#1315).

2. Storing multiselect state as global state

The second cause has to do with how we are using singletons for the multiselect helper classes. This means that different screens are sharing the same multiselect helpers. One issue with this is that many of the classes are listening, and responding, to changes on these helper classes. This means that screens that are not being presented to the user are responding to multi-select actions the user does on other screens.

I don't see that we need to be using singletons for these (and making them not be singletons avoids the ANR issue even without the other fix). In addition, this fixes the problem of having the multiselect state on one screen effect the multiselect state on another screen (i.e., entering multiselect mode and selecting some episodes effects the behavior on subsequent screens where you enter multi-select mode).

Because this fix seems riskier than the first one, I'm not making it a hotfix, but because it fixes a few other multiselect bugs that seem kinda rough, I'm targeting it as a betafix (#1316). Just let me know if you think a different approach makes more sense.

[mchowning]

Closing this because the ANRs were addressed by #1378 and the global state has been removed by #1579 and #1580.