* Import Scheduler directly, not via host config
We currently schedule asynchronous tasks via the host config. (The host
config is a static/build-time dependency injection system that varies
across different renderers — DOM, native, test, and so on.) Instead of
calling platform APIs like `requestIdleCallback` directly, each renderer
implements a method called `scheduleDeferredCallback`.
We've since discovered that when scheduling tasks, it's crucial that
React work is placed in the same queue as other, non-React work on the
main thread. Otherwise, you easily end up in a starvation scenario where
rendering is constantly interrupted by less important tasks. You need a
centralized coordinator that is used both by React and by other
frameworks and application code. This coordinator must also have a
consistent API across all the different host environments, for
convention's sake and so product code is portable — e.g. so the same
component can work in both React Native and React Native Web.
This turned into the Scheduler package. We will have different builds of
Scheduler for each of our target platforms. With this approach, we treat
Scheduler like a built-in platform primitive that exists wherever React
is supported.
Now that we have this consistent interface, the indirection of the host
config no longer makes sense for the purpose of scheduling tasks. In
fact, we explicitly do not want renderers to scheduled task via any
system except the Scheduler package.
So, this PR removes `scheduleDeferredCallback` and its associated
methods from the host config in favor of directly importing Scheduler.
* Missed an extraneous export
* Warn on mount when deps are not an array
* Check other Hooks
* I can't figure out how to fix error/warning nesting lint
But it doesn't really matter much because we test other cases in the other test.
* Revert #14756 changes to ReactFiberScheduler
This PR introduced some bugs in concurrent mode during internal testing.
Until we figure out a proper solution, I'm going to try reverting it.
Not totally certain this is sufficient to unbreak the bugs we found, but
I'm using this branch to determine that.
* Add back commented out Scheduler import
With a note not to use named imports next time we import Scheduler
in this module.
This required a bit of unusual CSS but seems to work well for Firefox and Chrome. We can remove it and revisit other approaches (like PR#24) in the future if needed.
* ReactDebugHooks identifies State and Reducer hooks as editable
* Inject overrideHookState() method to DevTools to support editing in DEV builds
* Added an integration test for React DevTools, react-debug-tools, and overrideHookState
* Swap expect(ReactNoop) for expect(Scheduler)
In the previous commits, I upgraded our custom Jest matchers for the
noop and test renderers to use Scheduler under the hood.
Now that all these matchers are using Scheduler, we can drop
support for passing ReactNoop and test roots and always pass
Scheduler directly.
* Externalize Scheduler in noop and test bundles
I also noticed we don't need to regenerator runtime in noop anymore.
* Replace test renderer's fake Scheduler implementation with mock build
The test renderer has its own mock implementation of the Scheduler
interface, with the ability to partially render work in tests. Now that
this functionality has been lifted into a proper mock Scheduler build,
we can use that instead.
* Fix Profiler tests in prod
* Replace noop's fake Scheduler implementation with mock Scheduler build
The noop renderer has its own mock implementation of the Scheduler
interface, with the ability to partially render work in tests. Now that
this functionality has been lifted into a proper mock Scheduler build,
we can use that instead.
Most of the existing noop tests were unaffected, but I did have to make
some changes. The biggest one involved passive effects: previously, they
were scheduled on a separate queue from the queue that handles
rendering. After this change, both rendering and effects are scheduled
in the Scheduler queue. I think this is a better approach because tests
no longer have to worry about the difference; if you call `flushAll`,
all the work is flushed, both rendering and effects. But for those few
tests that do care to flush the rendering without the effects, that's
still possible using the `yieldValue` API.
Follow-up: Do the same for test renderer.
* Fix import to scheduler/unstable_mock
Brian Vaughn
Dan Abramov
Andrew Clark
Farhad Yasir
Brian Vaughn
Gaurav Gupta