Ramanpreet Nara
553729f3d6
Summary: ## Problem: Let `A` be the set of all ObjC NativeModules that neither provide nor reqeust a method queue. The TurboModule system dispatches all method calls to NativeModules in `A` synchronously to the JS thread. Here is the relevant logic: **RCTTurboModule.mm:** Link: https://fburl.com/diffusion/nz9gqje8 ``` jsi::Value performMethodInvocation( // ... ) { // ... dispatch_queue_t methodQueue = NULL; if ([instance_ conformsToProtocol:protocol(RCTBridgeModule)] && [instance_ respondsToSelector:selector(methodQueue)]) { methodQueue = [instance_ performSelector:selector(methodQueue)]; } if (methodQueue == NULL || methodQueue == RCTJSThread) { // This is the default mode of execution: on JS thread. block(); } else if (methodQueue == dispatch_get_main_queue()) { ``` **Why does this end up happening?** 1. NativeModules that request a method queue have `synthesize methodQueue = _methodQueue` in their `implementation` section. This generates a `methodQueue` getter for the NativeModule, and also creates an ivar to back that getter. The TurboModule system generates a `dispatch_queue_t` and uses ObjC's KVC API to write to the ivar. So in the above logic, for NativeModules that provide a method queue, methodQueue will neither be `NULL` nor `RCTJSThread`, so we don't dispatch synchronously to the JS thread. 2. NativeModules that provide a method queue will return something that is not `NULL` or something that is `RCTJSThread`. If they return `NULL`, the infra will throw an error early. If they return `RCTJSThread`, we'll dispatch synchronously to the JS thread, as we should (...wait. For async NativeModule methods that dispatch to `RCTJSThread`, should we dispatch asynchronously to the JS thread, via jsInvoker? **Edit:** Nope: https://fburl.com/diffusion/ivt9b40s.). In all other cases, we dispatch to appropriately to the respective method queue. 3. For NativeModules that neither provide nor request a method queue (i.e: NativeModules in `A`), they don't implement the `methodQueue` selector. Therefore, we dispatch synchronously to the JS thread. ## The fix (Part 1): The first step towards fixing this problem is to generate `dispatch_queue_t`s for NativeModules in `A`. That's what this diff accomplishes. Changelog: [iOS][Fixed] - Create method queue for NativeModules that don't provide nor request one. Reviewed By: fkgozali Differential Revision: D20821054 fbshipit-source-id: 17a73550ad96766c5c7e719e28e1cc879e36465c
React Native
Learn once, write anywhere:
Build mobile apps with React.
Getting Started · Learn the Basics · Showcase · Contribute · Community · Support
React Native brings React's declarative UI framework to iOS and Android. With React Native, you use native UI controls and have full access to the native platform.
- Declarative. React makes it painless to create interactive UIs. Declarative views make your code more predictable and easier to debug.
- Component-Based. Build encapsulated components that manage their state, then compose them to make complex UIs.
- Developer Velocity. See local changes in seconds. Changes to JavaScript code can be live reloaded without rebuilding the native app.
- Portability. Reuse code across iOS, Android, and other platforms.
React Native is developed and supported by many companies and individual core contributors. Find out more in our ecosystem overview.
Contents
- Requirements
- Building your first React Native app
- Documentation
- Upgrading
- How to Contribute
- Code of Conduct
- License
📋 Requirements
React Native apps may target iOS 10.0 and Android 4.1 (API 16) or newer. You may use Windows, macOS, or Linux as your development operating system, though building and running iOS apps is limited to macOS. Tools like Expo can be used to work around this.
🎉 Building your first React Native app
Follow the Getting Started guide. The recommended way to install React Native depends on your project. Here you can find short guides for the most common scenarios:
📖 Documentation
The full documentation for React Native can be found on our website.
The React Native documentation discusses components, APIs, and topics that are specific to React Native. For further documentation on the React API that is shared between React Native and React DOM, refer to the React documentation.
The source for the React Native documentation and website is hosted on a separate repo, @facebook/react-native-website.
🚀 Upgrading
Upgrading to new versions of React Native may give you access to more APIs, views, developer tools, and other goodies. See the Upgrading Guide for instructions.
React Native releases are discussed in the React Native Community, @react-native-community/react-native-releases.
👏 How to Contribute
The main purpose of this repository is to continue evolving React Native core. We want to make contributing to this project as easy and transparent as possible, and we are grateful to the community for contributing bug fixes and improvements. Read below to learn how you can take part in improving React Native.
Code of Conduct
Facebook has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.
Contributing Guide
Read our Contributing Guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to React Native.
Open Source Roadmap
You can learn more about our vision for React Native in the Roadmap.
Good First Issues
We have a list of good first issues that contain bugs which have a relatively limited scope. This is a great place to get started, gain experience, and get familiar with our contribution process.
Discussions
Larger discussions and proposals are discussed in @react-native-community/discussions-and-proposals.
📄 License
React Native is MIT licensed, as found in the LICENSE file.
React Native documentation is Creative Commons licensed, as found in the LICENSE-docs file.