There are not so many changes, most of them are changing imports,
because I've moved types for UI in a single file.
In https://github.com/facebook/react/pull/27357 I've added support for
pausing polling events: when user inspects an element, we start polling
React DevTools backend for updates in props / state. If user switches
tabs, extension's service worker can be killed by browser and this
polling will start spamming errors.
What I've missed is that we also have a separate call for this API, but
which is executed only once when user selects an element. We don't
handle promise rejection here and this can lead to some errors when user
selects an element and switches tabs right after it.
The only change here is that this API now has
`shouldListenToPauseEvents` param, which is `true` for polling, so we
will pause polling once user switches tabs. It is `false` by default, so
we won't pause initial call by accident.
af8beeebf6/packages/react-devtools-shared/src/backendAPI.js (L96)
The old version of prettier we were using didn't support the Flow syntax
to access properties in a type using `SomeType['prop']`. This updates
`prettier` and `rollup-plugin-prettier` to the latest versions.
I added the prettier config `arrowParens: "avoid"` to reduce the diff
size as the default has changed in Prettier 2.0. The largest amount of
changes comes from function expressions now having a space. This doesn't
have an option to preserve the old behavior, so we have to update this.
* Facebook -> Meta in copyright
rg --files | xargs sed -i 's#Copyright (c) Facebook, Inc. and its affiliates.#Copyright (c) Meta Platforms, Inc. and affiliates.#g'
* Manual tweaks
Reverts part of #22275 (adding .catch() to Thenables in Suspense caches) in response to #22275 (comment).
After taking another look with fresh eyes, I think I see the "uncaught error" issue I initially noticed was in checkForUpdate() (which did not pass an error handler to .then)
This commit builds on PR #22260 and makes the following changes:
* Adds a DevTools feature flag for named hooks support. (This allows us to disable it entirely for a build via feature flag.)
* Adds a new Suspense cache for dynamically imported modules. (This allows a component to suspend while importing an external code chunk– like the hook names parsing code).
* DevTools supports a hookNamesModuleLoaderFunction param to import the hook names module. I wish this could be handles as part of the react-devtools-shared package, but I'm not sure how to configure Webpack (4) to serve the chunk from react-devtools-inline. This seemed like a reasonable workaround.
The PR also contains an additional unrelated change:
* Removes pre-fetch optimization (added in DevTools: Improve named hooks network caching #22198). This optimization was mostly only important for cases where sources needed to be re-downloaded, something which we can now avoid in most cases¹ thanks to using cached responses already loaded by the page. (I tested this locally on Facebook and this change has no negative performance impact. There is still some overhead from serializing the JS through the Bridge but that's constant between the two approaches.)
¹ The case where we don't benefit from cached responses is when DevTools are opened after the page has already loaded certain scripts. This seems uncommon enough that I don't think it justified the added complexity of prefetching.
While testing the recently-launched named hooks feature, I noticed that one of the two big performance bottlenecks is fetching the source file. This was unexpected since the source file has already been loaded by the page. (After all, DevTools is inspecting a component defined in that same file.)
To address this, I made the following changes:
- [x] Keep CPU bound work (parsing source map and AST) in a worker so it doesn't block the main thread but move I/O bound code (fetching files) to the main thread.
- [x] Inject a function into the page (as part of the content script) to fetch cached files for the extension. Communicate with this function using `eval()` (to send it messages) and `chrome.runtime.sendMessage()` to return its responses to the extension).
With the above changes in place, the extension gets cached responses from a lot of sites- but not Facebook. This seems to be due to the following:
* Facebook's response headers include [`vary: 'Origin'`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Vary).
* The `fetch` made from the content script does not include an `Origin` request header.
To reduce the impact of cases where we can't re-use the Network cache, this PR also makes additional changes:
- [x] Use `devtools.network.onRequestFinished` to (pre)cache resources as the page loads them. This allows us to avoid requesting a resource that's already been loaded in most cases.
- [x] In case DevTools was opened _after_ some requests were made, we also now pre-fetch (and cache in memory) source files when a component is selected (if it has hooks). If the component's hooks are later evaluated, the source map will be faster to access. (Note that in many cases, this prefetch is very fast since it is returned from the disk cache.)
With the above changes, we've reduced the time spent in `loadSourceFiles` to nearly nothing.
Made several changes to the hooks name cache to avoid losing cached data between selected elements:
1. No longer use React-managed cache. This had the unfortunate side effect of the inspected element cache also clearing the hook names cache. For now, instead, a module-level WeakMap cache is used. This isn't great but we can revisit it later.
2. Hooks are no longer the cache keys (since hook objects get recreated between element inspections). Instead a hook key string made of fileName + line number + column number is used.
3. If hook names have already been loaded for a component, skip showing the load button and just show the hook names by default when selecting the component.
* Add named hooks test case built with Rollup
* Fix prepareStackTrace unpatching, remove sourceURL
* Prettier
* Resolve source map URL/path relative to the script
* Add failing tests for multi-module bundle
* Parse hook names from multiple modules in a bundle
* Create a HookSourceData per location key (file, line, column).
* Cache the source map per runtime URL ( = file part of location key).
* Don't store sourceMapContents - only store a consumer instance.
* Look up original source URLs in the source map correctly.
* Cache the code + AST per original URL.
* Fix off-by-one column number lookup.
* Some naming and typing tweaks related to the above.
* Stop storing the consumer outside the with() callback, which is a bug.
* Lint fix for 8d8dd25
* Added devDependencies to react-devtools-extensions package.json
* Added some debug logging and TODO comments
* Added additional DEBUG logging to hook names cache
Co-authored-by: Brian Vaughn <bvaughn@fb.com>
