Summary:
I'm removing an ill-informed "optimization" that resulted in some StateUpdates being dropped. For some components (including TextInput) we rely on State updates to request a layout from the ShadowNode layer.
In the past we were performing an optimization that didn't update the View layer if the data contained in the State container is identical, but in the case of TextInput and other components, we simply pass an opaque
object with no meaningful data to trigger the layouts. In those cases, it could cause a permanent rift between the View layer's StateWrapper and the most recent state object from the C++ perspective.
In the case of TextInput this didn't cause tangible bugs because you can always update state using an out-of-date State object, but it's better this way anyway.
The other issue is that for some components, we want to know when there's a State update from the Cxx layer. This optimization broke certain logic in those components.
Changelog: [Internal]
Reviewed By: mdvacca
Differential Revision: D23306222
fbshipit-source-id: 8ef83149b814de50776674b5fd22406be1db14ba
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:
Simplify the TextInput measurement mechanism.
Now, data only flows from JS->C++->Java and from Java->JS. C++ passes along AttributedStrings from JS if JS updates, and otherwise Java maintains the only source of truth.
Previously we tried to keep all three in sync. This was complicated, slow, and even lead to some crashes.
This feels a bit hacky but I believe it's the simplest way to achieve this short-term. Ideally, we would use something like `AttributedStringBox` and pass that to State from Java,
but currently everything passed through the State system from Java must be serializable as `folly::dynamic`. So, instead, we just cache one Spannable per TextInput component and
use ReactTag as the cache identifier for lookup.
An interesting side-effect is that `measure` could race with TextInput updates, but the race condition favors measuring the latest text, not outdated values.
Followups:
- Can we do this without copying the EditText Spannable on every keystroke? Maybe this approach is too aggressive, but I don't want a background thread measuring a Spannable as it's being mutated.
- Do we need to support measuring Attachments?
- How can we clean up this API? It should work for now, but feels a little hacky.
Changelog: [Internal]
Reviewed By: mdvacca
Differential Revision: D23290230
fbshipit-source-id: 832d2f397d30dfb17b77958af970d9c52a37e88b
Summary:
In MountingManager.java in Fabric, if we drop a view with any attached views, we also drop all children. If verbose logging is turned on, log all instances of that happening.
This has no impact unless you switch the flag on manually in debug mode.
Changelog: [Internal]
Differential Revision: D23257749
fbshipit-source-id: fce4476aa47cc1b7137cd9fd2fd0241af1593288
Summary:
This diff updates the directory hierarchy of AndroidTextInput C++ files to be compatible with Android OSS build system
changelog: [internal] Internal
Reviewed By: PeteTheHeat
Differential Revision: D23179390
fbshipit-source-id: 1c52e4f882853799a58d44876cadd392b4a35050
Summary:
This diff filters the iOS C++ friles that are generated by the oss-android-codegen script
Also, as part of this diff I'm inlcuding .cpp files into the output.
These files are only used and compiled in Android
changelog: [internal] internal
Reviewed By: fkgozali
Differential Revision: D23169268
fbshipit-source-id: 404607f3cd6e59197291ea67701774c9c492a282
Summary:
Twilight doesn't have TMPerfLogging enabled. However, the TurboModule infra uses the TMPerfLogger java class everywhere, which loads the turbomodulejsijni library on class load. For some reason, this class load doesn't work, and causes Twilight prod to crash.
To mitigate that crash, this diff delays the so load until it's absolutely necessary, which is by the time we call jniEnableCppLogging. This should never be called in Twilight, because it doesn't have TMPerfLogging enabled. Therefore, the crash should disappear on Twilight.
Changelog: [Internal]
Reviewed By: mdvacca
Differential Revision: D23192072
fbshipit-source-id: b73ece580e4345dbf835b0fc2f7d43b90f202411
Summary:
This diff extends test-react-native-oss-android-legocastle to test the build of RNTester with fabric enabled in Sandcastle
changelog: [internal] internal
Reviewed By: fkgozali
Differential Revision: D23141524
fbshipit-source-id: 396dae1c0a23ce03db1053de1627eacb09a6df94
Summary:
This diff reintroduces the CoreComponentsRegistry class to register core components in the RN Tester app.
This class was previously deleted as part of D23091020 (https://github.com/facebook/react-native/commit/7fb1afae7f4b78970463e272b7d4f3230e84887d). Different from a past approach, this diff doesn't use inheritance for Hybrid classes (which seems to bring problems in Android 4 devices)
I'm planning to land this diff after I verify that D23091020 (https://github.com/facebook/react-native/commit/7fb1afae7f4b78970463e272b7d4f3230e84887d) fixed RC (maybe I will wait until sunday's cut)
changelog: [internal] internal
Reviewed By: fkgozali
Differential Revision: D23109856
fbshipit-source-id: 5220e522e197f701c782ab5089f9f1036ec90c19
Summary:
This diff removes the CoreComponentsRegistry class that was recently created to expose Fabric components in OSS
changelog: [internal] internal
Reviewed By: JoshuaGross, shergin
Differential Revision: D23091020
fbshipit-source-id: 9d851608ed0eddb98367265b5e346d5298f5f732
Summary:
In the past I tried a few heuristics to guess when a batch of Animated Operations were ready, and none of these were super reliable. But it turns out we can safely allow JS to manage that explicitly.
Non-Fabric still uses the old behavior which seems fine.
Changelog: [Internal]
Reviewed By: mdvacca
Differential Revision: D23010844
fbshipit-source-id: 4c688d3a61460118557a4971e549ec7457f3eb8f
Summary:
This diff extends fabric module to compile in OSS
NOTE: As a side effect of this diff, Fabric will be included into "reactnativejni" which is used by RN OSS.
I'm planning to remove this dependency in the near future - T71320460
changelog: [internal] internal
Reviewed By: JoshuaGross
Differential Revision: D22991877
fbshipit-source-id: 0ab3ee410dd448bbd87130114bec27c6e6bc65c6
Summary:
This diff introduces the class CoreComponentsRegistry that is responsible of registering core components in fabric.
This is required to make RN Tester to work in Fabric, in the future we'll extract this registry into another module (once we figure it out what's the best way to do this)
changelog: [internal] internal
Reviewed By: JoshuaGross
Differential Revision: D22991876
fbshipit-source-id: 15e85e15aac5dd981161d9eae35eb2cee4fa66b6
Summary:
This diff refactors the ComponentFactoryDelegate class. It also introduces a new class called ComponentRegistry that will be used to register components into fabric
changelog: [internal] internal
Reviewed By: JoshuaGross
Differential Revision: D22985313
fbshipit-source-id: e33a3d4fcb3a1c509b80c6ff1f43889480b1c2c3
Summary:
This diff refactors the class Runnable into a struct to make it work in OSS
changelog: [internal] internal
Reviewed By: JoshuaGross
Differential Revision: D22963704
fbshipit-source-id: 2212c8f1e4a62b2bcad5c061709e29b247454fc1
Summary:
New mechanism to soft-crash, or crash, and collect diagnostics in the mounting layer.
Changelog: [Internal]
Reviewed By: sammy-SC
Differential Revision: D22971260
fbshipit-source-id: 860cde3effa4a187f10f5dd1488dd41ace65e363
Summary:
Update FabricViewStateManager so that the caller can bail out of updates by returning null.
Changelog: [Internal]
Reviewed By: mdvacca
Differential Revision: D22966024
fbshipit-source-id: 31cd9ec8a9a9918fbb94844e30ed1a2fcc61997d
Summary:
Improve logging slightly.
One issue I ran into is that the "after" view hierarchy looks identical to "before" unless you schedule for the next UI tick.
Changelog: [Internal]
Reviewed By: mdvacca
Differential Revision: D22962116
fbshipit-source-id: c7a1e16e26d2aebefa3baf3acfef4e133b8fde70
Summary:
iOS will need to be implemented separately, but the shared C++ bits are in place.
Explanation: there is currently no way for the View layer to /know/ if an UpdateState call has succeeded or failed. Generally we just assume it succeeds, but if it fails we have no way of knowing or retrying.
This can cause some UI bugs. To mitigate this, I'm introducing a "failure" notification callback mechanism. The JNI bridging for this is a little complicated to avoid passing Runnable across the JNI, but it
should be much simpler on iOS.
In development this seems to make View components much more reliable.
Changelog: [Internal]
Reviewed By: mdvacca
Differential Revision: D22940187
fbshipit-source-id: 917f2932ae22d421f91fe8f4fca3f07dc089f820
Summary:
With BackgroundExecutor+State Reconciliation, it is pretty common to have races where View layer UpdateState calls are thrown away.
Theoretically this is /always/ possible since C++ doesn't retry failed UpdateStates, we just try once and then bail. This is part 1 of improving our mechanisms for ensuring that State stays up-to-date from the View layer.
Changelog: [Internal]
Reviewed By: mdvacca
Differential Revision: D22933927
fbshipit-source-id: 77b3b87402f772e3f149be0f9200e673bbed7b57
Summary:
Making error more explicit to assist in debugging.
Changelog: [Internal]
Reviewed By: sammy-SC
Differential Revision: D22929047
fbshipit-source-id: 4f26668a96868e7c5865a587142c3bcd10a26c90
Summary:
This diff creates the Android OSS build system for the module react/config
As part of this diff I also moved the module to react/config folder
changelog: [internal] internal
Reviewed By: JoshuaGross
Differential Revision: D22877264
fbshipit-source-id: 5b3c42580d2b1d73dc0abb48bcf4ff063b2f581f
Summary:
Hook up onSuccess and onFailure callbacks to LayoutAnimations.
Note that in non-Fabric RN, onSuccess is not known to work in Android. I could not find any uses of onFailure and it's not documented, so for now, it is only called if the setup of the animation fails.
Changelog: [Internal]
Reviewed By: shergin
Differential Revision: D22889352
fbshipit-source-id: 4306debb350388dd2b7a2cbfe295eb99723988e2
Summary:
This diff removes the fb/xplat_init dependency from fabric onLoad class
This is necessary to make RM compile in OSS
changelog: [Internal] Internal
Reviewed By: RSNara
Differential Revision: D22875531
fbshipit-source-id: cc4cd2af875fe7eadfb3a8f4a9f16acf5fa415d8
Summary:
This diff removes the fb/xplat_init dependency from fabric onLoad class
This is necessary to make fabric compile in OSS
changelog: [Internal] Internal
Reviewed By: RSNara
Differential Revision: D22874850
fbshipit-source-id: 0c61a366e09ab072215ba2fe651f96ef4c2e455a
Summary:
EZ refactor in ReactViewBackgroundDrawable to remove an unnecessary class variable
changelog: [internal] Internal
Reviewed By: RSNara
Differential Revision: D22874851
fbshipit-source-id: 16808809b196cba0dab5c9972359d7786939a7ce
Joshua Gross
David Vacca
Ramanpreet Nara
Oleg Lokhvitsky