Summary:
The "reparenting differ" has been the default differ for several months; ship it by removing config and the old differ.
Some functions can't be deleted yet because unit testing relies on it heavily; this can be refactored in the future if we care a lot.
Changelog: [Internal]
Reviewed By: mdvacca
Differential Revision: D25257205
fbshipit-source-id: 6f1dcc490bb1efe3d12506addf5f0843ca48c5c6
Summary:
Changelog: [internal]
Background executor performs unnecessary operations when second `completeRoot` message from React arrives before first `completeRoot` was finished. This produces unnecessary `ShadowViewMutations`.
Mechanism:
Everytime `completeRoot` is received, before the call is dispatched on the background queue, `completeRootEventCounter_DO_NOT_USE_` is incremented.
Inside `ShadowTree::tryCommit` we check if the value has been incremented to determine if another `completeRoot` is queued.
Reviewed By: JoshuaGross
Differential Revision: D24419160
fbshipit-source-id: 11e19026feca01db6c8981b093a691a6b58a006f
Summary:
We don't need a shared_ptr here and without it the code will be faster and simpler.
This change is aligned with any clone-line callbacks we have in the Core which accepts a `const &` and return `shared_ptr<>`.
Changelog: [Internal] Fabric-specific internal change.
Reviewed By: JoshuaGross, sammy-SC
Differential Revision: D23725687
fbshipit-source-id: 1cd959f4273913175d342302e2f12752f0114768
Summary:
Previously, to get a current root shadow node for a shadow tree, we called `tryCommit` method and stole a pointer from this. That was not a very straightforward method to get things done, and most importantly we need to do this to change the shape of the ShadowTreeCommitTransaction signature (remove a shared pointer from the callback) to make it simpler, faster and allow future improvements (see the next diff).
Changelog: [Internal] Fabric-specific internal change.
Reviewed By: JoshuaGross, sammy-SC
Differential Revision: D23725689
fbshipit-source-id: 51950b843a0e401828b6c6a38e5e2aaaf21ec166
Summary:
Instead of storing tree separate instance variables, we now store a single object that contains them. We will need it to be able to postpone the mounting stage (we save all info we need for mounting inside the new instance variable).
Changelog: [Internal] Fabric-specific internal change.
Reviewed By: sammy-SC
Differential Revision: D23725690
fbshipit-source-id: 09dd4a0912c6f5b34d805636b62f73ca12287329
Summary:
We need it to stop repeating to commit new shadow tree in `ShadowTree::commit` when a transaction cancels the commit.
Changelog: [Internal] Fabric-specific internal change.
Reviewed By: JoshuaGross, sammy-SC
Differential Revision: D23603959
fbshipit-source-id: d279fb3bf4190e860740a6450595d6f2fc3117f7
Summary:
# Summary
In previous diffs earlier in 2020, we made changes to detect and optimize reordering of views when the order of views changed underneath the same parent.
However, until now we have ignored reparenting and there's evidence of issues because of that. Because Fabric flattens views more aggressively, reparenting is also marginally more likely to happen.
This diff introduces a very general Reparenting detection. It will work with view flattening/unflattening, as well as tree grafting - subtrees moved to entirely different parts of the tree, not just a single
parent disappearing or reappearing because of flattening/unflattening.
There is also another consideration: previously, we were generating strictly too many Create+Delete operations that were redundant and could cause consistency issues, crashes, or bugs on platforms that do not handle that gracefully -
especially since the ordering of the Create+Delete is not guaranteed (a reparented view could be created "first" and then the differ could later issue a "delete" for the same view).
Intuition behind how it works: we know the cases where we can detect reparenting: it's when nodes are *not* matched up with another node from the other tree, and we're either trying to delete an entire subtree, or create an entire subtree. For perf reasons, we generate whatever set of operations comes first (say, we generate all the Delete and Remove instructions) and take note in the `ReparentingMetadata` data-structure that Delete and/or Remove have been performed for each tag (if ordering is different, we do the same for Create+Insert if those come first). Then if we later detect a corresponding subtree creation/deletion, we don't generate those mutations and we mark the previous mutations for deletion. This incurs some map lookup cost, but this is only wasteful for commits where a large tree is deleted and a large tree is created, without reparenting.
We may be able to improve perf further for certain edge-cases in the future.
# Why can't we solve this in JS?
Two things:
1. We certainly can avoid reparenting situations in JS, but it's trickier than before because of Fabric's view flattening logic - product engineers would have to think much harder about how to prevent reparenting in the general case.
2. In the case of specific views like BottomSheet that may crash if they're reparented, the solution is to make sure that the BottomSheet and the first child of the BottomSheet is never memoized, so that lifecycle functions and render are called more often; and that in every render, the BottomSheet manually clones its child, so that when the Views are recreated, the child of the BottomSheet has a tag and is an entirely different instance. This is certainly possible to do but feels like an onerous requirement for product teams, and it could be challenging to track down every specific BottomSheet that is memoized and/or hoist them higher in the view hierarchy so they're not reparented as often.
Reviewed By: shergin
Differential Revision: D23123575
fbshipit-source-id: 2fa7e1f026f87b6f0c60cad469a3ba85cdc234de
Summary:
This diff moves fabric C++ code from ReactCommon/fabric to ReactCommon/react/renderer
As part of this diff I also refactored components, codegen and callsites on CatalystApp, FB4A and venice
Script: P137350694
changelog: [internal] internal refactor
Reviewed By: fkgozali
Differential Revision: D22852139
fbshipit-source-id: f85310ba858b6afd81abfd9cbe6d70b28eca7415
Joshua Gross
Samuel Susla
Valentin Shergin
Stephy Ma
David Vacca