Fixed
Status Update
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Comments
su...@google.com
Yigit, do you have time to fix it?
reemission of the same liveData is racy
reemission of the same liveData is racy
ro...@gmail.com
yea i'll take it.
su...@google.com
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.
ro...@gmail.com
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()
}
}
@Test
fun raceTest() {
val subLiveData = MutableLiveData(1)
val subject = liveData(testScope.coroutineContext) {
emitSource(subLiveData)
emitSource(subLiveData) //crashes
}
subject.addObserver().apply {
testScope.advanceUntilIdle()
}
}
su...@google.com
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)
su...@google.com
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} )
}
I actually have a WIP fix for it:
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} )
}
Description
Version used: alpha01
WorkManager exposes method for cancellation of work. However, I currently don't see how this could be used if the work has already started.
Arguably, being able to cancel an ongoing work is very basic and must have functionality. Not being able to do so will render the entire framework unusable in many scenarios. It can also negatively impact the end users (e.g. by consuming too much battery/bandwidth).
Cancellation mechanism should be given a very good thought. As a starting point for a discussion, I propose adding two methods to Worker:
1) protected final boolean isCancelled() - will return true if the work has been cancelled
2) protected void onCancelled() - will be called after WorkManager determines that a specific Worker needs to be cancelled. Default implementation will be no-op.