[WIP] Performance: chat input

[hannojg]

Details

This PR improves the performance of the ReportActionCompose component greatly.
The main improvement is that we moved state down into separated components. In the ReportActionCompose component we render a lot of items, such as the send button, emoji button, a menu for attachments, attachment picker popups, the composer itself, comment exceeding notice, mention suggestions, emoji suggestions, etc. When we entered one letter all the top level state was updated multiple times, leading into a lot of re-renders for all the mentioned components.

So, to achieve a better performance we needed to break out more separate components. This also cleaned up the ReportActionCompose component, it went down from 1362 lines to 410 lines, thus becoming a lot easier to read and maintain.

However, this made the PR a bit larger than anticipated. The following gives an overview of the changes to help review this PR.

Note

I'd recommend first looking at the code itself and understanding its structure, and then checking the specific diffs of this PR.

The ReportActionCompose was moved into its own folder under src/pages/home/report/ReportActionCompose. Here are all new split out components placed:

• SendButton.js: The JSX of the send button was moved into its own component for cleanup
• Suggestions.js: Before the mention and emoji suggestions were part of the main composer, and also their state was placed there. The composer itself doesn't have to re-render when we change the suggestion state, so it was moved into its own component.
  • SuggestionMention.js: Before the mention suggestion were re-rendering when e.g. the emoji suggestions were changing. Now they are decoupled into their own places.
  • SuggestionEmoji.js: Separate implementation for emoji suggestions
• AttachmentPickerWithMenuItems.js: This contains the options we show when pressing the + in the composer. The options need access to the attachment picker, so they are grouped together. They also had state that's unnecessary to other parts of the composer.
• ComposerWithSuggestions.js: Here lives the actual <Composer /> and its value and selection state. Only the <Composer /> and the <Suggestions /> need to re-render when any of the two states are changing, hence they are grouped together.
• SilentCommentUpdater.js: This components subscribes to the actual draft comment, and fires a side effect for certain conditions. For the other components we don't need the draft comment, so it makes no sense re-rendering these. That's why it was split out into its own component for performance.

Another note: Initially I wanted to make separate PRs for each split out component, but: the components were so entangled with each other, that it was only possible to make a full clean up 🍝😅 .

Fixed Issues

$
PROPOSAL:

Tests

1. Open the expensify desktop app
2. Let the app open, login, navigate to a chat
3. (If you have a powerful PC and usually don't experience a lag typing:)

• Open the developer tools
• Go to performance
• Enable CPU Throttle: 6x
• Enable Hardware concurrency limit: 8

4. Just press your keys as fast as you can (typing random stuff)
5. Notice, that there is a lag while typing
6. Checkout this branch / changes
7. Run the same steps 2.-5. as above and confirm that the lag is gone (Note: There might be a lag for the very first letter that you type, for which this PR doesn't optimise)

From main branch

main.mov

From this branch

improved.mov

Offline tests

n/a

QA Steps

• Run every test for the composer and check that there are no regressions.

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
  • I added steps to cover failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android / native
  • Android / Chrome
  • iOS / native
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  • MacOS / Desktop
• I verified there are no console errors (if there's a console error not related to the PR, report it or open an issue for it to be fixed)
• I followed proper code patterns (see Reviewing the code)
  • I verified that any callback methods that were added or modified are named for what the method does and never what callback they handle (i.e. toggleReport and not onIconClick)
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• I tested other components that can be impacted by my changes (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar are working as expected)
• I verified all code is DRY (the PR doesn't include any logic written more than once, with the exception of tests)
• I verified any variables that can be defined as constants (ie. in CONST.js or at the top of the file that uses the constant) are defined as such
• I verified that if a function's arguments changed that all usages have also been updated correctly
• If a new component is created I verified that:
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  • The file is named correctly
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  • The only data being stored in the state is data necessary for rendering and nothing else
  • If we are not using the full Onyx data that we loaded, I've added the proper selector in order to ensure the component only re-renders when the data it is using changes
  • For Class Components, any internal methods passed to components event handlers are bound to this properly so there are no scoping issues (i.e. for onClick={this.submit} the method this.submit should be bound to this in the constructor)
  • Any internal methods bound to this are necessary to be bound (i.e. avoid this.submit = this.submit.bind(this); if this.submit is never passed to a component event handler like onClick)
  • All JSX used for rendering exists in the render method
  • The component has the minimum amount of code necessary for its purpose, and it is broken down into smaller components in order to separate concerns and functions
• If any new file was added I verified that:
  • The file has a description of what it does and/or why is needed at the top of the file if the code is not self explanatory
• If a new CSS style is added I verified that:
  • A similar style doesn't already exist
  • The style can't be created with an existing StyleUtils function (i.e. StyleUtils.getBackgroundAndBorderStyle(themeColors.componentBG))
• If the PR modifies code that runs when editing or sending messages, I tested and verified there is no unexpected behavior for all supported markdown - URLs, single line code, code blocks, quotes, headings, bold, strikethrough, and italic.
• If the PR modifies a generic component, I tested and verified that those changes do not break usages of that component in the rest of the App (i.e. if a shared library or component like Avatar is modified, I verified that Avatar is working as expected in all cases)
• If the PR modifies a component related to any of the existing Storybook stories, I tested and verified all stories for that component are still working as expected.
• If the PR modifies a component or page that can be accessed by a direct deeplink, I verified that the code functions as expected when the deeplink is used - from a logged in and logged out account.
• If a new page is added, I verified it's using the ScrollView component to make it scrollable when more elements are added to the page.
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.
• I have checked off every checkbox in the PR author checklist, including those that don't apply to this PR.

Screenshots/Videos

Web

Mobile Web - Chrome

Mobile Web - Safari

Desktop

iOS

Android