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2 Commits

Author SHA1 Message Date
Rubén Norte 4409642811 Migrate large amount of modules to flow strict and strict-local 
Summary:
| Group | Before | After | Change |
| Untyped | 50 | 49 | -1 |
| flow | 197 | 155 | -42 |
| flow strict-local | 226 | 185 | -41 |
| flow strict | 33 | 117 | +84

Changelog: [Changed] Improved Flow typing of multiple modules (with migrations to `flow strict` and `flow strict-local`

Reviewed By: motiz88

Differential Revision: D22549140

fbshipit-source-id: ed29415332cfce15b244ee4dea9e13d035543175
 2020-07-22 09:46:16 -07:00
Emilis Baliukonis 232517a574 Implement nativePerformanceNow to improve Profiler API results (#27885) 
Summary:
When experimenting with React Profiler API (https://reactjs.org/docs/profiler.html), I noticed that durations are integers without a debugger, but they are doubles with higher precision when debugger is attached. After digging into React Profiler code, I found out that it's using `performance.now()` to accumulate execution times of individual units of work. Since this method does not exist in React Native, it falls back to Javascript `Date`, leading to imprecise results.

This PR introduces `global.nativePerformanceNow` function which returns precise native time, and a very basic `performance` polyfill with `now` function.

This will greatly improve React Profiler API results, which is essential for profiling and benchmark tools.

Solves https://github.com/facebook/react-native/issues/27274

## Changelog

[General] [Added] - Implement `nativePerformanceNow` and `performance.now()`
Pull Request resolved: https://github.com/facebook/react-native/pull/27885

Test Plan:
```
const initialTime = global.performance.now();
setTimeout(() => {
  const newTime = global.performance.now();
  console.warn('duration', newTime - initialTime);
}, 1000);
```

### Android + Hermes

![Screenshot_1580198068](https://user-images.githubusercontent.com/13116854/73245757-af0d6c80-41b5-11ea-8130-dde14ebd41a3.png)

### Android + JSC

![Screenshot_1580199089](https://user-images.githubusercontent.com/13116854/73246157-92256900-41b6-11ea-87a6-ac222383200c.png)

### iOS

![Simulator Screen Shot - iPhone 8 - 2020-01-28 at 10 06 49](https://user-images.githubusercontent.com/13116854/73245871-f136ae00-41b5-11ea-9e31-b1eff5717e62.png)

Reviewed By: ejanzer

Differential Revision: D19888289

Pulled By: rickhanlonii

fbshipit-source-id: ab8152382da9aee9b4b3c76f096e45d40f55da6c
 2020-03-31 10:23:51 -07:00