Separate ReportScreenContext to prevent cyclic re-renders #25948

ospfranco · 2023-08-25T14:44:14Z

Details

We are trying to optimize the ReportScreen. This is the first issue I found where a shared context to manipulate certain lists would cause parent components to re-render causing a cascade of cyclic renders.

By separating the context we limit the re-renders to the part of the tree that consume the specific contexts and win back some render cycles.

Fixed Issues

$ #26087

Tests

Verify that no errors appear in the JS console
Debugged the render stack via React DevTools
When long tapped a reaction emoji, the list of emojis should pop up
Scrolling events on ReportActionList should still work

Offline tests

None needed in offline mode

QA Steps

Verify that no errors appear in the JS console
When long tapped a reaction emoji, the list of emojis should pop up
When editing an action in the Report screen, after saving the Action/Comment the list should scroll to the correct position

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
- iOS / Safari
- MacOS / Chrome / Safari
- 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)
- I verified that the left part of a conditional rendering a React component is a boolean and NOT a string, e.g. myBool && <MyComponent />.
- I verified that comments were added to code that is not self explanatory
- I verified that any new or modified comments were clear, correct English, and explained "why" the code was doing something instead of only explaining "what" the code was doing.
- I verified any copy / text shown in the product is localized by adding it to src/languages/* files and using the translation method
  - If any non-english text was added/modified, I verified the translation was requested/reviewed in #expensify-open-source and it was approved by an internal Expensify engineer. Link to Slack message:
- I verified all numbers, amounts, dates and phone numbers shown in the product are using the localization methods
- I verified any copy / text that was added to the app is grammatically correct in English. It adheres to proper capitalization guidelines (note: only the first word of header/labels should be capitalized), and is approved by marketing by adding the Waiting for Copy label for a copy review on the original GH to get the correct copy.
- I verified proper file naming conventions were followed for any new files or renamed files. All non-platform specific files are named after what they export and are not named "index.js". All platform-specific files are named for the platform the code supports as outlined in the README.
- I verified the JSDocs style guidelines (in STYLE.md) were followed
If a new code pattern is added I verified it was agreed to be used by multiple Expensify engineers
I followed the guidelines as stated in the Review Guidelines
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:
- A similar component doesn't exist in the codebase
- All props are defined accurately and each prop has a /** comment above it */
- The file is named correctly
- The component has a clear name that is non-ambiguous and the purpose of the component can be inferred from the name alone
- 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

Here is a video showing the Report screen emoji list is still working.

Android.mp4

github-actions · 2023-08-25T14:44:29Z

CLA Assistant Lite bot All contributors have signed the CLA ✍️ ✅

melvin-bot · 2023-08-25T14:44:50Z

@tgolen Please copy/paste the Reviewer Checklist from here into a new comment on this PR and complete it. If you have the K2 extension, you can simply click: [this button]

ospfranco · 2023-08-25T15:04:48Z

I have read the CLA Document and I hereby sign the CLA

situchan · 2023-08-28T14:22:34Z

@ospfranco can you please link issue correctly in issue description? And please fix lint

Example:

### Fixed Issues

$ https://github.com/Expensify/App/issues/12345

mountiny · 2023-08-28T14:26:11Z

I have update the issue, there was no issue before

mountiny · 2023-08-28T14:39:21Z

@tgolen feel free to review this one if you interested

tgolen

Can you please make a couple of these changes?

I would also appreciate if the PR or the associated GH had a bit more information that:

Proves the extra re-rendering exists in the first place (I just have to take your word for it, which I can do, but 1 year in the future it might not be so great)
Proves the extra re-rendering is no longer happening

tgolen · 2023-08-28T14:46:01Z

src/pages/home/ReportScreen.js

-                    </FullPageNotFoundView>
-                </ScreenWrapper>
-            </ReportScreenContext.Provider>
+                                    {/* Note: The report should be allowed to mount even if the initial report actions are not loaded. If we prevent rendering the report while they are loading then


The report should be allowed to mount

Can you please clarify in this comment what "the report" is? Is it:

ReportActionsSkeletonView

ReportFooter

ReportFooter

All three?

Something else?

All these are part of linting (the component it is now wrapped into a new context provider), I have not changed or touched the internal logic. I can do it if you want, but it falls out of the scope of the performance improvements

Aren't you lucky that you stumbled into this code? 😀

I guess it's not a blocker for this particular PR, but I am always happy to see it when people leave the code better than how they found it.

ok, I will take care of it then :)

tgolen · 2023-08-28T14:47:14Z

src/pages/home/ReportScreen.js

+                                <View
+                                    style={[styles.flex1, styles.justifyContentEnd, styles.overflowHidden]}
+                                    onLayout={(event) => {
+                                        // Rounding this value for comparison because they can look like this: 411.9999694824219


Please move this logic to a method outside of the return()

All these are part of linting (the component it is now wrapped into a new context provider), I have not changed or touched the internal logic. I can do it if you want, but it falls out of the scope of the performance improvements

tgolen · 2023-08-28T14:47:55Z

src/pages/home/ReportScreen.js

+                                    {this.isReportReadyForDisplay() && (
+                                        <>
+                                            <ReportFooter
+                                                pendingAction={addWorkspaceRoomOrChatPendingAction}
+                                                isOffline={this.props.network.isOffline}
+                                                reportActions={this.props.reportActions}
+                                                report={this.props.report}
+                                                isComposerFullSize={this.props.isComposerFullSize}
+                                                onSubmitComment={this.onSubmitComment}
+                                                policies={this.props.policies}
+                                            />
+                                        </>
+                                    )}
+
+                                    {!this.isReportReadyForDisplay() && (
+                                        <ReportFooter
+                                            shouldDisableCompose
+                                            isOffline={this.props.network.isOffline}
+                                        />
+                                    )}


These should be a ternary

All these are part of linting (the component it is now wrapped into a new context provider), I have not changed or touched the internal logic. I can do it if you want, but it falls out of the scope of the performance improvements

tgolen · 2023-08-28T14:48:26Z

src/pages/home/ReportScreen.js

-            </ReportScreenContext.Provider>
+                                    {/* Note: The report should be allowed to mount even if the initial report actions are not loaded. If we prevent rendering the report while they are loading then
+                            we'll unnecessarily unmount the ReportActionsView which will clear the new marker lines initial state. */}
+                                    {(!this.isReportReadyForDisplay() || isLoadingInitialReportActions || isLoading) && (


I think making this a ternary with the block above it will improve readability. It makes it easier to understand that the intention is that either one or the other should be displayed, never both.

All these are part of linting (the component it is now wrapped into a new context provider), I have not changed or touched the internal logic. I can do it if you want, but it falls out of the scope of the performance improvements

situchan

ReportScreen is now refactored to functional component. Please fix conflict and lint

# Conflicts: # src/pages/home/ReportScreen.js

ospfranco · 2023-08-29T07:52:35Z

ReportScreen is now refactored to functional component. Please fix conflict and lint

Done! Thanks!

ospfranco · 2023-08-29T08:20:43Z

For commit 3be5e69 (separating the contexts to prevent cyclic re-renders), here is the react devtools trace, you can see before the change there are at least 7 renders, this is also a parent component, so it triggers a cascade of re-renders on the children. Afer the change this has gone down to 3.

ospfranco · 2023-08-29T08:25:07Z

For commit 6125c38 (Get rid of full list re-render when marking messages as unread) Here is the trace before and after

You can see a reduction of 2 renders, but again this being a parent component it triggers a re-render of the entire list elements

tgolen · 2023-08-29T16:16:42Z

Thanks for those images and showing the change to the re-renders!

ospfranco requested a review from a team as a code owner August 25, 2023 14:44

ospfranco marked this pull request as draft August 25, 2023 14:44

melvin-bot bot requested review from tgolen and removed request for a team August 25, 2023 14:44

ospfranco force-pushed the osp/ReportScreen-optimizations branch from ba7f424 to 8de3031 Compare August 25, 2023 14:49

Separate ReportScreenContext to prevent cyclic re-renders

3be5e69

ospfranco force-pushed the osp/ReportScreen-optimizations branch from 8de3031 to 3be5e69 Compare August 25, 2023 15:03

Get rid of full list re-render when marking messages as unread

6125c38

ospfranco marked this pull request as ready for review August 28, 2023 14:05

mountiny assigned ospfranco Aug 28, 2023

mountiny requested a review from situchan August 28, 2023 14:08

Linting

be7ea56

mountiny self-requested a review August 28, 2023 14:32

tgolen requested changes Aug 28, 2023

View reviewed changes

situchan reviewed Aug 28, 2023

View reviewed changes

ospfranco added 2 commits August 29, 2023 09:44

Merge branch 'main' into osp/ReportScreen-optimizations

caed994

Merge branch 'main' into osp/ReportScreen-optimizations

37926ee

# Conflicts: # src/pages/home/ReportScreen.js

tgolen approved these changes Aug 29, 2023

View reviewed changes

ospfranco closed this Aug 30, 2023

ospfranco deleted the osp/ReportScreen-optimizations branch August 30, 2023 07:35

ospfranco restored the osp/ReportScreen-optimizations branch August 30, 2023 07:35

ospfranco mentioned this pull request Aug 30, 2023

Create REPORT_METADATA onyx key to separate report loading logic from the report data #26173

Closed

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ospfranco deleted the osp/ReportScreen-optimizations branch September 8, 2023 14:06

Separate ReportScreenContext to prevent cyclic re-renders #25948

Separate ReportScreenContext to prevent cyclic re-renders #25948

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ospfranco commented Aug 25, 2023 • edited by mountiny Loading Uh oh! There was an error while loading. Please reload this page.

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Details

Fixed Issues

Tests

Offline tests

QA Steps

PR Author Checklist

Screenshots/Videos

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ospfranco commented Aug 25, 2023 •

edited by mountiny

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