Summary:
Fix todo and inconsistency across codebase. It's better to have just one way to refer to these types.
Changelog: [Internal]
Reviewed By: philIip
Differential Revision: D37653146
fbshipit-source-id: e82f09caa6cd6eec5512b78f413708d9c04a7a83
Summary:
The new C++ Differ has been validated on Android and iOS. Delete the old code path.
Changelog: [Internal]
Reviewed By: sammy-SC
Differential Revision: D28904330
fbshipit-source-id: 2e0d8682f6b2a79f9758ed8b7b92809060835815
Summary:
Add unit tests for Layout Animations.
This first batch generates a random mutation, then animates it to completion.
I found one issue with UPDATE+REMOVE+INSERT animation consistency. That shouldn't cause any crashes in production, but is a chance to improve consistency of mutations overall - and could in theory point to memory corruption, though it's somewhat unlikely.
I ran with randomized seeds, found issues, fixed them, re-ran to ensure issues were fixed, rinsed and repeated. At the end I was able to run dozens of times (with random seeds) and found nothing.
The next step is to repeatedly generate mutations that conflict with ongoing animations.
Changelog: [Internal]
Reviewed By: sammy-SC
Differential Revision: D28343750
fbshipit-source-id: c1c60d89a31be3ac05d57482f0af3c482b866abe
Summary:
Found by running random tests and extracting a failing seed.
This error existed in master (and existed prior to recent refactors) and will be fixed by the end of this stack.
Changelog: [Internal]
Reviewed By: sammy-SC
Differential Revision: D28003332
fbshipit-source-id: 9c4a10d236c24337b089c44e8c1beb22358cfb05
Summary:
This code can be uncommented locally and run several times to discover new failing seeds.
Changelog: [Internal]
Reviewed By: sammy-SC
Differential Revision: D28003333
fbshipit-source-id: 6a3b6c08ae02bccc5c4d26067409ff6c736f8a89
Summary:
Calling `FAIL()` doesn't flush glog, but `react_native_assert(false)` does. Both will have the effect of failing the test.
Changelog: [Internal]
Reviewed By: sammy-SC
Differential Revision: D28003334
fbshipit-source-id: 802ad1f59e46eb048fd6ca95f5978eeaaad83f3a
Summary:
Add mounting layer test that stress-tests differ on (un)flattening.
This fails before D27759380 and D27730952, and passes after.
Changelog: [Internal]
Reviewed By: mdvacca
Differential Revision: D27767219
fbshipit-source-id: a7e186e510f95792da6f98f80fcae5ff8ac74775
Summary:
Changes in following diffs will be gated by this feature flag.
The differ in the new file is copied from the current stable implementation and will not be modified until it's deleted.
Changelog: [Internal]
Reviewed By: sammy-SC, mdvacca
Differential Revision: D27775698
fbshipit-source-id: 03d9518ffd2b1f25712386c56a38bd2b4d839fc2
Summary:
After fixing `calculateShadowViewMutationsForNewTree` I realized that it will be even better to test Stacking Context and mutation instructions infra using both functions: `calculateShadowViewMutationsForNewTree` (used for testing) and the Differentiator itself. This diff implements it.
Now we have two similarly working functions with different implementations that we can use for testing Differentiator and other parts of the infra.
Changelog: [Internal] Fabric-specific internal change.
Reviewed By: sammy-SC
Differential Revision: D25576922
fbshipit-source-id: 7922e9ebfb9d6ef1792566554ba0c4a14f835ae2
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:
See additional assertion. Tests still pass, so no other change was necessary.
Changelog: [Internal]
Differential Revision: D23775553
fbshipit-source-id: 57d3191f25dd55ab4da189207f6d201a31b175e0
Summary:
# What is this?
For a very long time, we've discussed the possibility of detecting Node Reparenting in the Fabric Differ. Practically, from the developer perspective, ReactJS and React Native do not allow reparenting: nodes cannot be reparented, only deleted and then recreated with entirely new tags.
However, Fabric introduced the idea of View Flattening where views deemed unnecessary would be removed from the View hierarchy entirely. This is great and improves memory usage, except for one issue: if a View becomes unflattened, or becomes flattened, the entire tree underneath it must be rebuilt.
In a past diff we introduced a mechanism to detect sibling reordering cleverly, and produce a minimal instruction set. This diff is very similar: we know the invariants around flattening and unflattening of views and we take advantage of them to produce an optimal set of instructions efficiently.
# What's different from previous attempts?
No global maps! Those are slow!
This seems to work and (hopefully) might even improve performance, since way less work is being done on the UI thread in cases when views are (un)flattened.
This *only* does extra work when flattening/unflattening happens, which gives product engineers a little more control over perf.
# So, how's it work?
This algorithm is intuitively simple (I think) but tricky to pull off, because there are lots of edge-cases.
In short: In the past, that information was hidden from the Differ: the differ didn't know if views were being reparented, it would see them
as entirely new views or as views being deleted if a View was flattened or unflattened. We very subtly change the information given to the differ:
all nodes are visible to the differ, but marked as Flattened or Unflattened. Thus, when the differ compares two nodes in the "old" and "new" tree,
it can tell not just if there are updates to the node but if it has been unflattened or flattened as well.
For example, take this tree, where * indicates that a View is flattened:
```
A
+
+----+---+
B* X
+ +
| |
+---+--+ +
E F Y
```
When the Differ asks for the children of A, in the past it would get a list `[E, F, X]`. That is, B* and X are both its children, but since B is flattened, it is omitted entirely from the list and
its children are substituted.
Now, when the Differ asks for the children of A, we give it this list instead: `[B*, E, F, X]`. That is: we give it a list which includes B, but B is marked as flattened.
Another wrinkle: A node `X` could have its children flattened, but still be a concrete view: so flattening/unflattening is a different operation from making a view "concrete" or "unconcrete", which can change independently of flattening.
There is one additional wrinkle: because of zIndex/stacking order, the children of `B` might not actually appear after `B` in the list. Depending on zIndex, a tree that looks like this:
```
A
+
+------+------+
B* C*
+ +
| |
+--+--+ +--+--+
D E F G
```
Could actually be linearized as: `[D G B* F C* E]` (as an extreme example; but basically all permutations as possible).
This is the reason, and the *only* reason that the inner Flattener/Unflattener
## The cases we need to handle
There are 7 cases/edge-cases of flattening and unflattening that we need to handle. Practically, all cases of reordering + flattening/unflattening, and taking recursive cases into account:
1. View A and A' (A in the old tree, A' in the new tree) are matched in the differ, and A* has been flattened or unflattened. These two cases are the easiest to handle.
2. View A' has been reordered with its siblings, and has been flattened or unflattened. These cases are slightly trickier to handle.
3. While flattening or unflattening, we encounter a child that has also been unflattened or flattened. So we need to handle four cases here in total: Flatten-Flatten, Flatten-Unflatten, Unflatten-Flatten, and Unflatten-Unflatten.
Other things to think about, also covered above:
1. Ordering. Views can be reordered and flattened/unflattened at the same time.
2. zIndex ordering: children in a certain order from the ShadowNode perspective may be stacked differently from a View perspective. We use the zIndex ordering for everything in the differ, and this prevents us from performing certain optimizations (see above: we cannot assume that children come after their parent in a list; they may come before, may be interwoven with children from other parents, etc).
# Perf Implications?
Practically, there should be very little negative overhead. There is some overhead in actually performing a flattening/unflattening operation, but... not much more than before. We don't use global maps, so the cost of flattening/unflattening is basically `O(number of nodes reparented)` - note that that's direct nodes reparented, *not* descendants.
tl;dr the perf hit should be similar to reordering, which is non-zero, but close to zero, and zero-cost for any diff operations on parts of the tree that don't involve flattening/unflattening. AFAICT this is very close to an ideal solution for that reason (but I wish it was simpler overall).
# In Summary?
I hope this works out and I think it could improve a number of things downstream: perf, LayoutAnimations, Bindings, certain crashes because of platform assumptions about mutations, etc.
Is it worth it? This new implementation is substantially harder to reason about, harder to read, and harder to understand. This is an important consideration. All I can say there is that I trust the test suite I've been using, but
the decreased readability is a big negative. Hopefully we can improve this in the future.
The rest is fiddly implementation details that I sincerely hope can be improved and simplified in the future.
# Followups?
The part that makes this algorithm the most expensive is that because of zIndex ordering, we cannot assume that children are linearized after their parents and so we rely more heavily on maps for the flattening/unflattening. Our TinyMap implementation should make these `find` operations fast enough unless trees' children are constantly being reordered, but it's still worth thinking of ways to make this even faster.
Changelog: [Internal]
Reviewed By: shergin, mdvacca
Differential Revision: D23259341
fbshipit-source-id: 35d9b90caf262d601a31996ea2cb37e329c61ffc
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
Pieter De Baets
Andres Suarez
Joshua Gross
Valentin Shergin
generatedunixname89002005287564
David Vacca