Adds experimental flag to yield many times per frame using a message
event loop, instead of the current approach of guessing the next vsync
and yielding at the end of the frame.
This new approach forgoes a `requestAnimationFrame` entirely. It posts a
message event and performs a small amount of work (5ms) before yielding
to the browser, regardless of where it might be in the vsync cycle. At
the end of the event, if there's work left over, it posts another
message event.
This should keep the main thread responsive even for really high frame
rates. It also shouldn't matter if the hardware frame rate changes after
page load (our current heuristic only detects if the frame rate
increases, not decreases).
The main risk is that yielding more often will exacerbate main thread
contention with other browser tasks.
Let's try it and see.
* Do not hyphenate custom CSS property
* Move check into the processStyleName fn
* Formatting
* add test
* Put isCustomProperty check after conditional return
* add test to `ReactDOMServerIntegration` and supress warning
* Don't indexOf twice
* Simpler fix
Not returning the value of flushPassiveEffects() in flushWork() meant that with async act, we wouldn't flush all work with cascading effects. This PR fixes that oversight, and adds some tests to catch this in the future.
The Scheduler implementation uses browser APIs like `MessageChannel`,
`requestAnimationFrame`, and `setTimeout` to schedule work on the main
thread. Most of our tests treat these as implementation details;
however, the sequence and timing of these APIs are not precisely
specified, and can vary wildly across browsers.
To prevent regressions, we need the ability to simulate specific edge
cases that we may encounter in various browsers.
This adds a new test suite that mocks all browser methods used in our
implementation. It assumes as little as possible about the order and
timing of events. The only thing it assumes is that
requestAnimationFrame is passed a frame time that is equal to or less
than the time returned by performance.now. Everything else can be
controlled at will.
It also includes Scheduler-specific invariants, e.g. only one rAF
callback can be scheduled at a time.
It overlaps slightly with the existing SchedulerDOM-test suite, which
also mocks the browser APIs, but exposes a higher-level set of testing
primitives. I will consolidate the two suites in a follow-up.
This adds a 'SuspenseCallback' feature flag. When the property is set on
a suspense component it will be called during the commit phase with a
set of the immediate thenable for this component. This will allow user
code to build runtime tracing of the cause for a suspense boundary.
Given this snippet:
```jsx
TestRenderer.act(() => {
TestUtils.act(() => {
TestRenderer.create(<Effecty />);
});
});
```
We want to make sure that all work is only flushed on exiting the outermost act().
Now, naively doing this based on actingScopeDepth would work with a mocked scheduler, where flushAll() would flush all work across renderers.
This doesn't work without mocking the scheduler though; and where flushing work only works per renderer. So we disable this behaviour for a non-mocked scenario. This seems like an ok tradeoff.
Noticed when looking at the performance profiler with Luna that it's
hard to tell which event causes `performWorkUntilDeadline` to fire
because these functions are anonymous.
Always sets `isRAFLoopRunning` back to false when an animation frame is
scheduled. Fixes a bug where two rAFs fire in the same frame, but the
second one exits and fails to schedule a new rAF.
Fixes bug observed in Safari.
Prevents Spacebar from scrolling the window.
Prevents Enter from triggering a navigation if preventDefault is true.
Fixes the emulated mouse events test.
Improved warning whenever lower priority events (ex. data fetching, page load) happen during a high priority update (ex. hover/click events) to include:
1.) Name of component that triggered the high priority update or
2.) Information that the update was triggered on the root
Scheduler uses `requestAnimationFrame` to post tasks to the browser.
If this happens at the beginning of a frame, the callback might not
fire until the subsequent frame, even if the main thread is idle.
Our theory was that this wouldn't be an issue in practice, because once
the first rAF fires, we schedule the next rAF as early as possible in
that frame. Combined with our heuristic for computing frame deadlines,
we shouldn't get any idle time in between frames — only before the
*first* frame.
This reasoning holds true when you have a small number of large tasks,
such as the ones posted by React. The idle time before the task starts
is negligible relative to the lifetime of the entire task.
However, it does not hold if you have many small tasks posted over a
span of time, perhaps spawned by a flurry of IO events. In this case,
instead of single, contiguous rAF loop preceded by an idle frame, you
get many rAF loops preceded by many idle frames. Our new theory is that
this is contributing to poor main thread utilization during page loads.
To try to reclaim as much idle time as possible, this PR adds two
experimental flags. The first one adds a `requestIdleCallback` call to
start the rAF loop, which will fire before rAF if there's idle time left
in the frame. (We still call rAF in case there isn't. We start working
in whichever event fires first.)
The second flag tries a similar strategy using `setTimeout(fn, 0)`. If
the timer fires before rAF, we'll assume that the main thread is idle.
If either `requestIdleCallback` or `setTimeout` fires before rAF, we'll
immediately peform some work. Since we don't have a real frame time that
we can use to compute the frame deadline, we'll do an entire frame
length of work. This will probably push us past the vsync, but this is
fine because we can catch up during the next frame, by which point a
real rAF will have fired and the loop can proceed the same way it
does today.
Test plan: Try this on Facebook to see if it improves load times
- redoes #15431 from scratch, taking on the feedback there
- unifies the messaging between "deprecated" and UNSAFE_ lifecycle messages. It reorganizes ReactStrictModeWarnings.js to capture and flush all the lifecycle warnings in one procedure each.
- matches the warning from ReactPartialRenderer to match the above change
- passes all the tests
- this also turns on `warnAboutDeprecatedLifecycles` for the test renderer. I think we missed doing so it previously. In a future PR, I'll remove the feature flag altogether.
- this DOES NOT do the same treatment for context warnings, I'll do that in another PR too
This returns the current value of ReactCurrentFiber and enables DevTools to append a custom (owner-only) component stack to warnings and errors in DEV mode.
Real Maps should now be used in RN JS engines. In theory this should
be faster (but might not actually be in practice), and it avoids hitting
upper bounds of property max counts.
We don't use these types of Maps in Fabric.
When executing a task, wraps the callback in an extra function whose
name includes the current priority level. Profiling tools with access
to function names can use this to determine the priority of the task.
1. Allow auxillary button clicks (i.e., middle mouse button) to trigger 'onPressStart' and 'onPressEnd', but never 'onPress'.
2. Report the button type – 'primary' or 'auxillary' – on the press event.
