[C+ Checklist Needs Completion] [$500] Android - Scan - Second tap on capture button causes error to show up

[lanitochka17]

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---

Version Number: 1.4.41-3
Reproducible in staging?: Y
Reproducible in production?: Y
If this was caught during regression testing, add the test name, ID and link from TestRail:
Email or phone of affected tester (no customers):
Logs: https://stackoverflow.com/c/expensify/questions/4856
Expensify/Expensify Issue URL:
Issue reported by: Applause - Internal Team
Slack conversation:

Action Performed:

Precondition: Camera access is allowed

1. Launch New Expensify app
2. Tap + > Request money
3. Go to Scan
4. Tap on the capture button twice

Expected Result:

The second tap on the capture button should be disabled and no error will show up

Actual Result:

The second tap on the capture button is enabled, causing error to show up

Workaround:

Unknown

Platforms:

Which of our officially supported platforms is this issue occurring on?

• Android: Native
• Android: mWeb Chrome
• iOS: Native
• iOS: mWeb Safari
• MacOS: Chrome / Safari
• MacOS: Desktop

Screenshots/Videos

Add any screenshot/video evidence

Bug6379529_1707925292817.Screen_Recording_20240214_215216_New_Expensify.mp4

View all open jobs on GitHub

Upwork Automation - Do Not Edit

• Upwork Job URL: https://www.upwork.com/jobs/~017ba8b79a30323bee
• Upwork Job ID: 1757796267721375744
• Last Price Increase: 2024-02-14
• Automatic offers:
• hoangzinh | Reviewer | 0

[melvin-bot]

Job added to Upwork: https://www.upwork.com/jobs/~017ba8b79a30323bee

[melvin-bot]

Triggered auto assignment to Contributor-plus team member for initial proposal review - @hoangzinh (External)

[melvin-bot]

Triggered auto assignment to @greg-schroeder (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details.

[lanitochka17]

We think that this bug might be related to #wave5
CC @quinthar

[agent3bood]

Proposal

Please re-state the problem that we are trying to solve in this issue.

Android - Scan - Second tap on capture button causes error to show up

What is the root cause of that problem?

This is multiple levels of issues causing the problem.

• In src/pages/iou/request/step/IOURequestStepScan/index.native.js the capturePhoto has an async operation, we need to return a Promise to make it work with the native implementation of singleExecution.
• The native implementation expects a promise to be returned for it to work, if we don't return a promise then the singleExecution will exit before the async operation has completed which means the function can be called again before the async function is completed.
• Current code execution flow is like this

// 1. `singleExecution` will make sure this is called just once 
capturePhoto() {
  // ... code
  
  // 2. this async callback function is added to the event loop to be executed in future tick/time.
  camera.current.takePhoto().then() => {
    // 4. some time later, the event loop will execute this code, it has nothing to do with `singleExecution`, and if the camera is busy it will throw.
  } 

  //
  // ... code
 // 3. function code is completed, `singleExecution` job is done here.
}

• We need to fix all components that wrap capturePhoto to return a Promise, and not ignore it, for example in here the promise is not returned properly.
• As for web, this is not an issue because the capturePhoto function is completely sync.

What changes do you think we should make in order to solve the problem?

• Make capturePhoto return a Promise.
• Fix all components that wrap capturePhoto to return a Promise, and not ignore it.
• Make sure I am not introducing new async operation when the callback is just a sync operation (i.e. do not do return new Promise(/* some sync result */))

// bad
return new Promise((resolve) => {
  const results = onPress(event);
  if(results instanceof Promise) {
    return results.finally(() => {resolve();});
  } 
});

// good
const results = onPress(event);
... other code might live here
return results;

What alternative solutions did you explore? (Optional)

See previous proposal.

original proposal

Proposal

Please re-state the problem that we are trying to solve in this issue.

Android - Scan - Second tap on capture button causes error to show up

What is the root cause of that problem?

In IOURequestStepScan.capturePhoto there is an async operation to capture the photo camera.current.takePhoto().then(), only after the async operation we do the navigation/error handling.
Between the time of requesting the first photo and getting the results if the user calls the capture button again, the camera is already busy and we get an error.

What changes do you think we should make in order to solve the problem?

Add a new flag capturePhotoInProgress and return early from capturePhoto if it is true. Set the variable to true when we start the function and reset it when it is done.

What alternative solutions did you explore? (Optional)

[Krishna2323]

Proposal

Please re-state the problem that we are trying to solve in this issue.

Android - Scan - Second tap on capture button causes error to show up

What is the root cause of that problem?

When we call capturePhoto is called we call camera.current.takePhoto which is a async operation and if we immediately call capturePhoto again the camera is busy and !camera.current is true.

App/src/pages/iou/request/step/IOURequestStepScan/index.native.js

Lines 234 to 237 in 04d7efd

	if (!camera.current) {
	showCameraAlert();
	return;
	}

What changes do you think we should make in order to solve the problem?

We need to use useSingleExecution to solve this bug.

Result

[EnderKilledYou]

So I see these on upwork. Are they taken or finished since they have a proposal? If I apply there am I wasting connects? I can update this one for sure. You can also disable the button or remove the click handler and add it back later.

[melvin-bot]

📣 @EnderKilledYou! 📣
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[EnderKilledYou]

Contributor details
Your Expensify account email: kooshesh@gmail.com
Upwork Profile Link: https://www.upwork.com/freelancers/sterlingkooshesh

[melvin-bot]

✅ Contributor details stored successfully. Thank you for contributing to Expensify!

[EnderKilledYou]

Proposal

Update the button handler to disable the button to prevent further inputs

Please re-state the problem that we are trying to solve in this issue.

The button is able to be clicked multiple times before being prevented

What is the root cause of that problem?

Not disabling the button via a state on first click

What changes do you think we should make in order to solve the problem?

Update the button handler to disable the button to prevent further inputs
On success or error, reenable it.

USe the disabled tag. This is very common practice and is well tested.

[hoangzinh]

Minor update from me, I'm getting infinite loading after granting camera access on my Android simulator. I'm trying to figure out how to fix it.

[hoangzinh]

@agent3bood @Krishna2323 @EnderKilledYou Thanks for proposals, everyone. I think we found the reason why it shows error but I don't think we found the root cause yet. The capture button is using Button component, which is already using useSingleExecution hook underneath => Expecting it already supported preventing double click issue

App/src/components/Pressable/GenericPressable/BaseGenericPressable.tsx

Line 44 in 9843f66

const {isExecuting, singleExecution} = useSingleExecution();

We need to find out why it doesn't work in this case.

[greg-schroeder]

Still waiting on new proposals given @hoangzinh's comment above

[agent3bood]

@agent3bood @Krishna2323 @EnderKilledYou Thanks for proposals, everyone. I think we found the reason why it shows error but I don't think we found the root cause yet. The capture button is using Button component, which is already using useSingleExecution hook underneath => Expecting it already supported preventing double click issue

App/src/components/Pressable/GenericPressable/BaseGenericPressable.tsx

Line 44 in 9843f66

const {isExecuting, singleExecution} = useSingleExecution();

We need to find out why it doesn't work in this case.

The issue is because of the async function .then(), so useSingleExecution will not work here.
Let me explain

// 1. `useSingleExecution` will make sure this is called just once 
capturePhoto() {
  // ... code
  
  // 2. this async callback function is added to the event loop to be executed in future tick/time.
  camera.current.takePhoto().then() => {
    // 4. some time later, the event loop will execute this code, it has nothing to do with `useSingleExecution`, and if the camera is busy it will throw.
  } 

  //
  // ... code
 // 3. function code is completed, `useSingleExecution` job is done here.
}

Buy why are we still to click twice?
Because useSingleExecution will prevent second execution in the same "tick", but it does not work for async functions, and for that we need a lock/mutex.

[Krishna2323]

I think @agent3bood is correct here.

[hoangzinh]

great found @agent3bood. Btw useSingleExecution also supports async callbacks, is there any way to make it work in this case?

App/src/hooks/useSingleExecution/index.native.ts

Lines 25 to 34 in e3331db

	const execution = action(...params);
	InteractionManager.runAfterInteractions(() => {
	if (!(execution instanceof Promise)) {
	setIsExecuting(false);
	return;
	}
	execution.finally(() => {
	setIsExecuting(false);
	});
	});

[agent3bood]

@hoangzinh yes it is possible, I have checked the code, for the native singleExecution to work the action must return a Promise.
But because the onPress handler is passed on multiple levels it is not returning the value of the original.
To make it work first we do return camera.current.takePhoto(.....
Then on every child component that wraps the handler it has to return the result as well.
For example this must do

const res = onPress(event);
Accessibility.moveAccessibilityFocus(nextFocusRef);
return res;

Should I update my proposal with the new fix?

[hoangzinh]

@agent3bood yes please, could you check if it works on Web platform as well?

[agent3bood]

@hoangzinh proposal updates, web is not affected by this issue.

[hoangzinh]

Thanks @agent3bood. Could you include your previous root cause analytics in your current proposal? Because your current root cause is explaining why useSingleExecution doesn't work in this case, but it does not include how it's related to the current issue. It's hard for internal engineers to understand the root cause without reading all the comments.

Beside that,

Fix all components that wrap capturePhoto to return a Promise

Do you mean child components in IOURequestStepScan?

Make sure I am not introducing new async operation when the callback is just a sync operation

Could you elaborate on what you mean here? Thanks

[agent3bood]

@hoangzinh updated.

Fix all components that wrap capturePhoto to return a Promise

I added two places where it need to be updated, GenericPressable.

[hoangzinh]

Thanks. @agent3bood proposal #36520 (comment) looks good to me. He pointed out the correct root cause and provided a solution that helped solve the issue well.

🎀👀🎀 C+ reviewed

[melvin-bot]

@agent3bood @hoangzinh @greg-schroeder @techievivek this issue is now 4 weeks old and preventing us from maintaining WAQ, can you:

• Decide whether any proposals currently meet our guidelines and can be approved as-is today
• If no proposals meet that standard, please take this issue internal and treat it as one of your highest priorities
• If you have any questions, don't hesitate to start a discussion in #expensify-open-source

Thanks!

[melvin-bot]

Current assignee @hoangzinh is eligible for the Internal assigner, not assigning anyone new.

[greg-schroeder]

PR is merged. Awaiting deploy to staging -> prod

[melvin-bot]

Reviewing label has been removed, please complete the "BugZero Checklist".

[melvin-bot]

The solution for this issue has been 🚀 deployed to production 🚀 in version 1.4.60-13 and is now subject to a 7-day regression period 📆. Here is the list of pull requests that resolve this issue:

• Issue/36520 android scan second tap on capture button causes error to show up #38320

If no regressions arise, payment will be issued on 2024-04-15. 🎊

For reference, here are some details about the assignees on this issue:

• @agent3bood requires payment (Needs manual offer from BZ)
• @hoangzinh requires payment automatic offer (Reviewer)

[melvin-bot]

BugZero Checklist: The PR fixing this issue has been merged! The following checklist (instructions) will need to be completed before the issue can be closed:

• [@hoangzinh] The PR that introduced the bug has been identified. Link to the PR:
• [@hoangzinh] The offending PR has been commented on, pointing out the bug it caused and why, so the author and reviewers can learn from the mistake. Link to comment:
• [@hoangzinh] A discussion in #expensify-bugs has been started about whether any other steps should be taken (e.g. updating the PR review checklist) in order to catch this type of bug sooner. Link to discussion:
• [@hoangzinh] Determine if we should create a regression test for this bug.
• [@hoangzinh] If we decide to create a regression test for the bug, please propose the regression test steps to ensure the same bug will not reach production again.
• [@greg-schroeder] Link the GH issue for creating/updating the regression test once above steps have been agreed upon:

[greg-schroeder]

Payment summary:

@agent3bood - $500 - C
@hoangzinh - $500 - C+

[greg-schroeder]

The upwork issue closed for inactivity, creating a new one via #40222

Offers sent manually - please accept them and I can pay them out tomorrow.

Last up is @hoangzinh to take care of the checklist :)

[hoangzinh]

Accepeted. Thanks @greg-schroeder. I will complete the checklist today

[hoangzinh]

Regression Test Proposal

On Native Apps/mWeb:

1. Open Expensify app
2. Tap + > Request money
3. Go to Scan
4. Tap on the capture button multiple times
5. Verify that the App captures successfully and no errors popup

Do we agree 👍 or 👎

[hoangzinh]

BugZero Checklist:

• The PR that introduced the bug has been identified. Link to the PR: https://github.com/Expensify/App/pull/28618/files
• The offending PR has been commented on, pointing out the bug it caused and why, so the author and reviewers can learn from the mistake. Link to comment: https://github.com/Expensify/App/pull/28618/files#r1567290949
• A discussion in #expensify-bugs has been started about whether any other steps should be taken (e.g. updating the PR review checklist) in order to catch this type of bug sooner. Link to discussion: N/A
• Determine if we should create a regression test for this bug: Yes

[techievivek]

Regression test looks good to me. @greg-schroeder Can we get this added? Thanks.