I'm using such construction to handle multiple data loading responses. The problem in that this code affects on fragment start time (+2 about second). load() function is placed into ViewModel. Fragment#onResume() method calls ViewModel#load() method. How can I optimize this code to reduce Fragment startup time?
fun load() {
Single.zip(
apiDataManager1.getSingle().subscribeOnIo().observeOnMain(),
apiDataManager2.getSingle().subscribeOnIo().observeOnMain(),
apiDataManager3.getSingle().subscribeOnIo().observeOnMain(),
Function3<Any, Any, Any, Unit> { _, _, _ ->
// process data
}
)
.subscribeOnIo()
.observeOnMain()
.subscribe()
}
UPD
If I wrap this function into Thread {} everything works fine. How can I do this only with Rx?
try start the chain with something else, specify observer. not sure it is inteneded but combining data in Function3 probably shouldn't be deliveded to main thread:
Single.defer(() -> Single.just(true))
.observeOn(Schedulers.io())
.flatMap( any -> Single.zip(
apiDataManager1.getSingle().subscribeOnIo(),
apiDataManager2.getSingle().subscribeOnIo(),
apiDataManager3.getSingle().subscribeOnIo(), { _, _, _ ->
// process data
})).subscribeOnIo()
.observeOnMain()
.subscribe()
Related
I have This method that calls a Rest API and returns the result as an Observable (Single):
fun resetPassword(email: String): Single<ResetPassword> {
return Single.create { emitter ->
val subscription = mApiInterfacePanda.resetPassword(email)
.observeOn(AndroidSchedulers.mainThread())
.subscribeOn(Schedulers.io())
.subscribe({ resetPasswordResponse ->
when(resetPasswordResponse.code()) {
200 -> {
resetPasswordResponse?.body()?.let { resetPassword ->
emitter.onSuccess(resetPassword)
}
}
else -> emitter.onError(Exception("Server Error"))
}
}, { throwable ->
emitter.onError(throwable)
})
mCompositeDisposable.add(subscription)
}
}
Unit Test:
#Test
fun resetPassword_200() {
val response = Response.success(200, sMockResetPasswordResponse)
Mockito.`when`(mApiInterfacePanda.resetPassword(Mockito.anyString()))
.thenReturn(Single.just(response))
mTokenRepository.resetPassword(MOCK_EMAIL)
val observer = mApiInterfacePanda.resetPassword(MOCK_EMAIL)
val testObserver = TestObserver.create<Response<ResetPassword>>()
observer.subscribe(testObserver)
testObserver.assertSubscribed()
testObserver.awaitCount(1)
testObserver.assertComplete()
testObserver.assertResult(response)
}
My Problem is only this line gets covered and the other lines won't run and that has a lot of impact on my total test coverage:
return Single.create { emitter ->
There's more than one thing going on here if I'm not mistaken. Let's take it in parts.
First, your "internal" observer:
mApiInterfacePanda.resetPassword(email)
.observeOn(AndroidSchedulers.mainThread())
.subscribeOn(Schedulers.io())
.subscribe({ resetPasswordResponse -> ... })
Is observing on the android main thread and executing on a background thread. To the best of my knowledge, in most cases, the test thread will end before your mApiInterfacePanda .resetPassword has a chance to finish and run. You didn't really post the test setup, so I'm not sure if this is an actual issue, but in any case it's worth mentioning. Here's 2 ways to fix this:
RxJavaPlugins and RxAndroidPlugins
RxJava already provides a way to change the schedulers that are provided. An example is RxAndroidPlugins.setMainThreadSchedulerHandler. Here's how it could help:
#Before
fun setUp() {
RxAndroidPlugins.setInitMainThreadSchedulerHandler { Schedulers.trampoline() }
RxJavaPlugins.setInitIoSchedulerHandler { Schedulers.trampoline() }
}
The above methods make sure that everywhere you use the main thread scheduler and the io scheduler, it'll instead return the trampoline scheduler. This is a scheduler that guarantees that the code is executed in the same thread that was executing previously. In other words, it'll make sure you run it on the unit test main thread.
You will have to undo these:
#After
fun tearDown() {
RxAndroidPlugins.reset()
RxJavaPlugins.reset()
}
You can also change other schedulers.
Inject the schedulers
You can use kotlin's default arguments to help out with injecting schedulers:
fun resetPassword(
email: String,
obsScheduler: Scheduler = AndroidSchedulers.mainThread(),
subScheduler: Scheduler = Schedulers.io()
): Single<ResetPassword> {
return Single.create { emitter ->
val subscription = mApiInterfacePanda.resetPassword(email)
.observeOn(obsScheduler)
.subscribeOn(subScheduler)
.subscribe({ resetPasswordResponse ->
when(resetPasswordResponse.code()) {
200 -> {
resetPasswordResponse?.body()?.let { resetPassword ->
emitter.onSuccess(resetPassword)
}
}
else -> emitter.onError(Exception("Server Error"))
}
}, { throwable ->
emitter.onError(throwable)
})
mCompositeDisposable.add(subscription)
}
}
At test time you can just call it like resetPassword("foo#bar.com", Schedulers.trampoline(), Schedulers.trampoline() and for the application just pass in the email.
The other thing I see here is maybe not related to the problem, but I think it's still good to know. First, you're creating a single, but you don't need to do this.
Single.create is usually used when you don't have reactive code. However, mApiInterfacePanda.resetPassword(email) already returns a reactive component and although I'm not sure, let's just assume it's a single. If not, it should be fairly simple to convert it to something else.
You're also holding on to a disposable, which from what I can tell shouldn't be necessary.
Lastly, you're using retrofit according to your tags so you don't need to make the call return a raw response unless extremely necessary. This is true because retrofit checks the status code for you and will deliver the errors inside onError with an http exception. This is the Rx way of handling the errors.
With all this in mind, I'd rewrite the entire method like this:
fun resetPassword(email: String) = mApiInterfacePanda.resetPassword(email)
(note that resetPassword must not return a raw response, but Single<ResetPassword>
It actually shouldn't need anything else. Retrofit will make sure things end up in either onSuccess or onError. You don't need to subscribe to the result of the api here and handle disposables - let whoever is calling this code handle it.
You may also notice that if this is the case, then the solution for the schedulers is not needed. I guess this is true in this case, just remember some operators operate in some default schedulers and you may need to override them in some cases.
So how would I test the above method?
Personally I'd just check if the method calls the api with the right parameters:
#Test
fun resetPassword() {
mTokenRepository.resetPassword(MOCK_EMAIL)
verify(mApiInterfacePanda).resetPassword(MOCK_EMAIL)
}
I don't think there's much more needed here. There's no more logic I can see in the rewritten method.
I am trying to chain two network calls in my Android app. I am using Retrofit. Basically I want to do :
Make API Call to login
Wait for the response of login, save the token to SharedPrefs
Make another API call right after I've saved the token
Wait for the response, save the data
I think I have chained the stream in the right way, the only thing is I want to update the UI in between. For example once the call starts I want to display a progressDialog ( I do that in doOnSubscribe ), or dismiss the Dialog once the call has completed ( I do that in doOnComplete ). However I get the exception Only the original thread that created a view hierarchy can touch its views. I subscribe on the io thread and observe on the mainThread so that I can make the changes to the UI, however I must be missing something.
I tried adding .subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
lower in the stream, but I still get the same error message.
getView().onLoginAction().subscribe(aVoid -> Observable.combineLatest(
getView().userNameObservable().map(CharSequence::toString),
getView().passwordObservable().map(CharSequence::toString),
Pair::new)
.first()
.subscribe(usernamePasswordPair -> {
User user = User.create(usernamePasswordPair.first, usernamePasswordPair.second, "");
RetrofitClientInstance.createService(AuthenticationNetworkApi.class).login(new Login(user.username(), user.password()))
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.doOnNext(loginResponse -> {
AuthorizationResponse responseBody = loginResponse.body();
if (responseBody != null && responseBody.getAccessToken() != null && !responseBody.getAccessToken().isEmpty()) {
if (localStorage.getAccessToken().isEmpty()) {
localStorage.saveAccessToken(responseBody.getAccessToken());
}
}
}
).
doOnSubscribe( action -> getView().showProgressDialog())
.doOnError(error -> {
getView().dismissProgressDialog();
getView().showErrorMessage("Login Unsuccessful");
}).doOnComplete(() -> getView().dismissProgressDialog()
)
.flatMap(response -> RetrofitClientInstance.createService(ActivitiesApi.class).getUserActivities())
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.doOnNext(activities -> {
for (UserActivityApiModel useractivity : activities
) {
activityService.addActivity(Activity.create(Integer.parseInt(useractivity.getId()), useractivity.getActivityName(), useractivity.getDate(),
Integer.parseInt(useractivity.getValue()), Integer.parseInt(useractivity.getSubCategory().getId())));
}
}).doOnError(error -> getView().showErrorMessage(error.getMessage()))
.doOnComplete(() -> getView().redirectToHomeScreen())
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe();
}));
The error occurs here :
.doOnError(error -> {
getView().dismissProgressDialog();
getView().showErrorMessage("Login Unsuccessful");
})
It seems you are using a different thread to execute your backend. In that case, you can't touch the main UI thread from the second one. You need to execute first runOnUiThread { //your code }
In //your code, call the two lines of code that you put on doOnError.
I want to write a function that automatically subsbcribes to RxJava's Flowable<T> and get the resulting data. This data will then be passed as an argument to another method that does the processing. I am struggling with Kotlin's extension function syntax and generics.
I want to convert this call:
val scheduler = Schedulers.newThread()
disposable.add(
viewModel.getExams().subscribeOn(scheduler)
.observeOn(scheduler)
.subscribe({ exams ->
exams.forEach {
getSubjectOfExam(it, Schedulers.newThread())
}
}, { error ->
Log.e(
"OverviewFragment",
"Unable to fetch list, $error"
)
})
)
which is very lengthy in my Activity code, to a method that returns the data that I want to process.
In this case I'd like a list of exams (List<Exam>) passed into the argument of getSubjectOfExam(), which is the method for the list processing.
My function so far, which compiles but does not work at all:
/**
* General subscription of items in a Flowable list
* #param f method to be executed when list is loaded
* #param scheduler scheduling units
*/
private fun Flowable<out List<Any>>.listSubscribe(
f: (List<Any>) -> Unit,
scheduler: Scheduler
) {
disposable.add(
this.subscribeOn(scheduler)
.observeOn(scheduler)
.subscribe({
f(it)
}, { error ->
Log.e(
"OverviewFragment",
"Unable to fetch list, $error"
)
})
)
}
it will be called like so:
viewModel.getExams().listSubscribe({ resultData ->
resultData.forEach {
val exam = it as Exam
getSubjectOfExam(exam, Schedulers.newThread())
}
}, Schedulers.newThread())
So yeah, I tried to make an extension function and passing a function as one of its arguments (called a higher-order function I believe).
With my method, the getSubjectOfExam doesn't get called at all. Is there something I'm missing?
I'll be subscribing to Flowable's all the time in my Activity so this function will really help me.
I tried your code and it seems it is working okay. Is there any chance that viewModel.getExams() or getSubjectOfExam() is not working?
Also I could suggest few optimizations:
protected fun <T> Flowable<out List<T>>.listSubscribe(
f: (List<T>) -> Unit,
scheduler: Scheduler
) {
disposable.add(
this.subscribeOn(scheduler)
.observeOn(scheduler)
.subscribe(f, { error ->
Log.e(
"OverviewFragment",
"Unable to fetch list, $error"
)
})
)
}
Then you won't need type conversion:
viewModel.getExams().listSubscribe({ resultData ->
resultData.forEach {
getSubjectOfExam(exam, Schedulers.newThread())
}
}, Schedulers.newThread())
In fact you can replace List<T> with just T and make it work with any types. Also, observing and subscribing with same scheduler doesn't make a lot of sense to me. I think you can remove.observeOn completely and the code will still observe on the same scheduler you put in .subscribeOn
I'm trying to use Kotlin's coroutines to avoid callback hell, but it doesnt look like I can in this specific situation, I would like some thougths about it.
I have this SyncService class which calls series of different methods to send data to the server like the following:
SyncService calls Sync Student, which calls Student Repository, which calls DataSource that makes a server request sending the data through Apollo's Graphql Client.
The same pattern follows in each of my features:
SyncService -> Sync Feature -> Feature Repository -> DataSource
So every one of the method that I call has this signature:
fun save(onSuccess: ()-> Unit, onError:()->Unit) {
//To Stuff here
}
The problem is:
When I sync and successfully save the Student on server, I need to sync his enrollment, and if I successfully save the enrollment, I need to sync another object and so on.
It all depends on each other and I need to do it sequentially, that's why I was using callbacks.
But as you can imagine, the code result is not very friendly, and me and my team starting searching for alternatives to keep it better. And we ended up with this extension function:
suspend fun <T> ApolloCall<T>.execute() = suspendCoroutine<Response<T>> { cont ->
enqueue(object: ApolloCall.Callback<T>() {
override fun onResponse(response: Response<T>) {
cont.resume(response)
}
override fun onFailure(e: ApolloException) {
cont.resumeWithException(e)
}
})
}
But the function in DataSource still has a onSuccess() and onError() as callbacks that needs to be passed to whoever call it.
fun saveStudents(
students: List<StudentInput>,
onSuccess: () -> Unit,
onError: (errorMessage: String) -> Unit) {
runBlocking {
try {
val response = GraphQLClient.apolloInstance
.mutate(CreateStudentsMutation
.builder()
.students(students)
.build())
.execute()
if (!response.hasErrors())
onSuccess()
else
onError("Response has errors!")
} catch (e: ApolloException) {
e.printStackTrace()
onError("Server error occurred!")
}
}
}
The SyncService class code changed to be like:
private fun runSync(onComplete: () -> Unit) = async(CommonPool) {
val syncStudentProcess = async(coroutineContext, start = CoroutineStart.LAZY) {
syncStudents()
}
val syncEnrollmentProcess = async(coroutineContext, start = CoroutineStart.LAZY) {
syncEnrollments()
}
syncStudentProcess.await()
syncEnrollmentProcess.await()
onComplete()
}
It does execute it sequentially, but I need a way to stop every other coroutine if any got any errors. Error that might come only from Apollo's
So I've been trying a lot to find a way to simplify this code, but didn't get any good result. I don't even know if this chaining of callbacks can be simplify at all. That's why I came here to see some thoughts on it.
TLDR: I want a way to execute all of my functions sequentially, and still be able to stop all coroutines if any got an exception without a lot o chaining callbacks.
Hi i am trying to implement a Single observable that chains two requests together.
In between the two requests i make, i notify a callback to update the UI with the response from request one and then launch the next request in the Schedulaers.io thread.
The issue i am having is that it tries to update the UI from the schedulars.io thread too and results to nothing being updated in the ui thread.
i cold wrap the calback on RunOnUiThread code block in android but wondering if there is a more elegant way of doing it?
i checked couroutines and it seems to just deal with putting a block of code in a seperate thread.
Here is my current code
override fun getHomeScreenInformation() {
delegator.requestOne()
.flatMap { responseOne->
homeScreenCallBack.onResponseOneRecieved(responseOne)
delegator.requestTwo()
}
.observeOn(AndroidSchedulers.mainThread())
.subscribeOn(Schedulers.io())
.subscribe(
{responseTwo-> homeScreenCallBack.onResponseTwoRecieved(responseTwo)},
{error -> homeScreenCallBack.onError()}
)
}
Apply observeOn(AndroidSchedulers.mainThread()) as many times as necessary:
delegator.requestOne()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread()) // <----------------------
.flatMap { responseOne ->
homeScreenCallBack.onResponseOneRecieved(responseOne)
delegator.requestTwo()
.subscribeOn(Schedulers.io()) // <----------------------
}
.observeOn(AndroidSchedulers.mainThread())
.subscribe(
{responseTwo-> homeScreenCallBack.onResponseTwoRecieved(responseTwo)},
{error -> homeScreenCallBack.onError()}
)