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Moti ZilbermanandFacebook GitHub Bot
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Summary: Pull Request resolved: https://github.com/facebook/react-native/pull/42587 Changelog: [Internal] * Introduces the Target Delegate and Target Controller concepts (see `CONCEPTS.md`). * Introduces the `PageTargetDelegate` interface and `PageTargetController` class (see doc comments). * Uses the above infra to implement support for the `Page.reload` CDP command. Each integration provides its own `PageTargetDelegate` that knows how to trigger a reload in a platform- and architecture-specific way. * iOS Bridge/Bridgeless and `PageTargetTest` are the only integrations that exist as of this diff, and are all updated here; Android will follow later. NOTE: `RCTBridge` = iOS Bridge, `RCTHost` = iOS Bridgeless. ## Object lifetimes `PageAgent` holds a raw `PageTargetController&` reference to a member of `PageTarget`, through which it gets access to that target's `PageTargetDelegate&` (another raw reference). Here's what makes this safe: 1. **`PageTargetDelegate` outlives `PageTarget`** - this is the responsibility of the platform integration ( = the code that instantiates `PageTarget`). 2. **`PageTarget` outlives its Sessions and Agents** - this is `PageTarget`'s "moral" responsibility, even though it doesn't own its Sessions outright (`InspectorPackagerConnection` does). We add an assertion in `PageTarget`'s destructor to catch violations, and document that the integrator must call `getInspectorInstance().removePage` (which terminates all remaining sessions) before destroying the corresponding `PageTarget`. NOTE: In upcoming diffs we'll use the new Target→Session references, currently used only for the assertion in (2), to power actual functionality (e.g. dispatching CDP events to the frontend when some imperative method is called on `PageTarget`). ## Thread safety `PageTargetDelegate::onReload` is guaranteed to be called synchronously on the thread where messages are dispatched to `PageTargetSession`, which on iOS is the main (UI) thread. Reviewed By: huntie Differential Revision: D51164125 fbshipit-source-id: 4c3eeb81a8df9677c173588eb5acfd686722c3c9