Summary: This was a killswitch to be safe, so lets clean it up.
Differential Revision: D67072925
fbshipit-source-id: ac54972030e7d53e7abd95025e45773aa3c5efc6
Summary:
## Context
Merging multiple batch updates of the same section is inherently unsafe, because each block can mutate the underlaying list and lead to insert/deletes that operate on different before/after lists. The long term fix is to get rid of item level batch updates (insert/delete calls) and use diffing like for sections, but that's a much larger project.
Right now, we have a crash spiking because we're reloading the same cell multiple times. Each time `IGListDiff(...)` returns a pair of insert/delete for the same index (lets say 0). Once these updates are merge together, they look like this:
```
Item inserts = 0, 0
Item deletes = 0, 0
```
We dedupe deletes in `IGListBatchUpdateData`, but don't do anything for inserts, so it looks liket this:
```
Item inserts = 0, 0
Item deletes = 0
```
So we create an insert/delete unbalance and can crash. Tbh, not sure how this hasn't been a bigger issue in the past.
D21822502 tried to remove all duplicate inserts, but that caused other types of crashes, because multiple inserts are allowed.
## This diff
* Lets keep the net insert/delete count the same by keeping track of the number of deletes we remove and apply the same to inserts.
* Add some tests
* Add an experiment flag to kill this if needed to be safe. IG only: Note that I'm making the default true because the crash is happening pretty at start-up.
## Follow up
Over time, the batch update clean up logic was slowly added to multiple place (IGListBatchUpdateData, IGListAdapterUpdaterHelpers, IGListIndexPathResult), which is making it hard to follow. A first step would be to move it in 1 or 2 places and avoid redundant logic (like getting unique deletes). However, the real fix is getting rid of batch updates all together.
Differential Revision: D61719884
fbshipit-source-id: eda7c264c8239a6a106dbe0256fe777b38fae335
Summary:
The standardized Meta copyright notice is "Copyright (c) Meta Platforms, Inc. and affiliates." and not "Copyright (c) Meta Platforms, Inc. and its affiliates." (Dropping the "its")
This diff updates the copyright notice in each source file to the correct this.
Reviewed By: willbailey
Differential Revision: D44737667
fbshipit-source-id: 643bf36df76723e70d9d826c53cf8f29b8a0c8cc
Summary:
Five model classes in IGListDiffKit: `IGListBatchUpdateData`, `IGListIndexPathResult`, `IGListIndexSetResult`, `IGListMoveIndex`, and `IGListMoveIndexPath` didn't have 100% test coverage because their `description` debug string methods weren't being tested.
I added a new unit test file specifically for testing description strings in IGListDiffKit wrote a basic test to verify each one.
This brings IGListDiffKit's test coverage back up to 100%.
Differential Revision: D44002058
fbshipit-source-id: ebb1bbb3c9a6d380540fc6bbedf5b8c5e5b254f1
