Transitions fail to return to original state after animateToStart() and beginDelayedTransition() [300157785]

Fixed

Bug

Status Update

No update yet.

Description

jb...@google.com

created issue #1

Sep 13, 2023 12:31AM

Component used: Transition Version used: 1.5.0-alpha02 Devices/Android versions reproduced on: API 34

If you do a gesture back in Fragments using transitions and cancel the gesture multiple times, after the first cancel, starting the gesture will result in the transition on the exiting view failing to run.

I believe the cause of this is that the beginDelayedTransition() called by with a 0 duration called by Fragment never triggers this onAnimatedEnd() callback in Visibility. That results in the visibility failing to be added removed from the overlay and so the subsequent transitions on the view do not run.

Here are logs synced with the calls from Fragment and Visibility. I would expect there to be an onAnimationEnd reversed=false log before the onTransitionEnd in Visibility.

 V  Animating to start (in Fragment)
 D  onAnimationEnd reversed=true (in Visibility)
 V  Calling beginDelayedTransition (in Fragment)
 D  onTransitionEnd (in Visibility)
 V  On transitionEnd of beginDelayedTransition (in Fragment)

The can be reproduced by patching in aosp/2748867 and doing the following in the navigation-integration app:

Launch App
Press the "Navigate Next" button 2 times to get to the "two" screen
Start a gesture back to the "one" screen and cancel it
Start another gesture back to the "one" screen and the "two" screen will immediately go blank

Comments

mo...@google.com <mo...@google.com> Sep 13, 2023 04:31PM

Accepted by mo...@google.com.

mo...@google.com <mo...@google.com> #2Sep 18, 2023 08:29PM

Assigned to jb...@google.com.

Yigit, do you have time to fix it?

reemission of the same liveData is racy

va...@google.com <va...@google.com> #3Sep 21, 2023 06:57PM

yea i'll take it.

va...@google.com <va...@google.com> #4Sep 21, 2023 07:08PM

Thanks for the detailed analysis. This may not be an issue anymore since we've started using Main.immediate there but I' not sure; I'll try to create a test case.

jb...@google.com <jb...@google.com> #5Sep 26, 2023 08:12PM

just emitting same live data reproduces the issue.

@Test
fun raceTest() {
val subLiveData = MutableLiveData(1)
val subject = liveData(testScope.coroutineContext) {
emitSource(subLiveData)
emitSource(subLiveData) //crashes
}
subject.addObserver().apply {
testScope.advanceUntilIdle()
}
}

jb...@google.com <jb...@google.com> #6Sep 26, 2023 08:46PM

With 2.2.0-alpha04 (that use Main.immediate), the issue seems to be still there (I tested it by calling emitSource() twice, like your test case)

ap...@google.com <ap...@google.com> #7Sep 26, 2023 08:56PM

yea sorry immediate does not fix it.
I actually have a WIP fix for it:

https://android-review.googlesource.com/c/platform/frameworks/support/+/1112186

if your case is the one i found (emitting same LiveData multiple times, as shown in #5) you can work around it by adding a dummy transformation.

val subLiveData = MutableLiveData(1)
val subject = liveData(testScope.coroutineContext) {
emitSource(subLiveData.map {it })
emitSource(subLiveData.map {it} )
}

jb...@google.com <jb...@google.com> #8Oct 25, 2023 12:42AM

Reassigned to mo...@google.com.

Project: platform/frameworks/support
Branch: androidx-master-dev

commit af12e75e6b4110f48e44ca121466943909de8f06
Author: Yigit Boyar <yboyar@google.com>
Date: Tue Sep 03 12:58:11 2019

Fix coroutine livedata race condition

This CL fixes a bug in liveData builder where emitting same
LiveData source twice would make it crash because the second
emission registry could possibly happen before first one is
removed as source.

We fix it by using a suspending dispose function. It does feel
a bit hacky but we cannot make DisposableHandle.dispose async
and we do not want to block there. This does not mean that there
is a problem if developer disposes it manually since our emit
functions take care of making sure it disposes (and there is
no other way to add source to the underlying MediatorLiveData)

Bug: 140249349
Test: BuildLiveDataTest#raceTest_*

Change-Id: I0b464c242a583da4669af195cf2504e2adc4de40

M lifecycle/lifecycle-livedata-ktx/api/2.2.0-alpha05.txt
M lifecycle/lifecycle-livedata-ktx/api/current.txt
M lifecycle/lifecycle-livedata-ktx/api/public_plus_experimental_2.2.0-alpha05.txt
M lifecycle/lifecycle-livedata-ktx/api/public_plus_experimental_current.txt
M lifecycle/lifecycle-livedata-ktx/api/restricted_2.2.0-alpha05.txt
M lifecycle/lifecycle-livedata-ktx/api/restricted_current.txt
M lifecycle/lifecycle-livedata-ktx/src/main/java/androidx/lifecycle/CoroutineLiveData.kt
M lifecycle/lifecycle-livedata-ktx/src/test/java/androidx/lifecycle/BuildLiveDataTest.kt

https://android-review.googlesource.com/1112186

https://goto.google.com/android-sha1/af12e75e6b4110f48e44ca121466943909de8f06

AnimateToStartAlpha03.zip

108 KB

Download

mo...@google.com <mo...@google.com> Nov 8, 2023 10:21PM

Accepted by mo...@google.com.

mo...@google.com <mo...@google.com> #9Nov 9, 2023 12:14AM

The API has changed since that project was created in a way that makes the API more robust. I'm hoping that has fixed this...

mo...@google.com <mo...@google.com> #10Nov 9, 2023 06:18PM

There appears to be a problem with the order of operations. I'm going to look into fixing that.

ap...@google.com <ap...@google.com> #11Nov 10, 2023 11:27PM

Marked as fixed.

Project: platform/frameworks/support
Branch: androidx-main

commit e57dd5f9ac6cbb8cf83b221e2d5b3fbd3e88ce6b
Author: George Mount <mount@google.com>
Date: Thu Nov 09 14:33:53 2023

Fix animateToStart with Slide.

Fixes: 300157785

Slide was not repositioning the View to its proper
translation after animating it to the start position.
This fixes that so that it is moved.

Test: new test
Change-Id: I698f4dbcef46304f9aa545847d205f7b70c80d63

M transition/transition/src/androidTest/java/androidx/transition/SlideEdgeTest.java
M transition/transition/src/androidTest/java/androidx/transition/TranslationAnimationCreatorTest.java
M transition/transition/src/main/java/androidx/transition/TranslationAnimationCreator.java

https://android-review.googlesource.com/2824840

pr...@google.com <pr...@google.com> #12Nov 29, 2023 09:39PM

The following release(s) address this bug.It is possible this bug has only been partially addressed:

androidx.transition:transition:1.5.0-alpha05