Trip into the async world @ NYC Kotlin Meetup

These are the slides of my talk from NYC Kotlin Meetup @ Dropbox

Transcript

1. Trip into the
   async world
   

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2. Rob
   

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3. Why RxJava?
   

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4. Why RxJava?
   Retrofit
   

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5. Why RxJava?
   Retrofit
   Async ops
   

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6. Why RxJava?
   Retrofit
   Async ops
   Basic operators
   

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7. Why RxJava?
   Retrofit
   Async ops
   Basic operators
   Advanced operators
   

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8. Why RxJava?
   Retrofit
   Async ops
   Basic operators
   Advanced operators
   

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9. Why RxJava?
   Retrofit
   Async ops
   Basic operators
   Advanced operators
   

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10. implementation
    ‘com.squareup.retrofit2:retrofit:2.6.1’
    

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11. @GET("/path/to/resource")
    fun networkRequest(): Single
    @GET("/path/to/resource")
    suspend fun networkRequest(): Data
    

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12. Retrofit.Builder()
    ...
    .addCallAdapterFactory(CoroutineCallAdapterFactory())
    .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
    .build()
    

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13. CoroutineCallAdapterFactory()
    RxJava2CallAdapterFactory.create()
    

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14. @Test
    fun test() {
    runBlocking {
    val response =
    api.networkRequest()
    assertThat(response)...
    }
    api.networkRequest()
    .test()
    .assertValue { }
    }
    

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16. class DataViewModel()) : ViewModel() {
    private val subscriptions = CompositeDisposable()
    val output = BehaviorSubject>.create()
    fun loadCurrentStatus() {
    disposable +=
    store.get(BarCode.empty())
    .startWith(LceLoading())
    .onErrorReturn({e -> LceError(e)})
    .map({data -> mapEmptyData(data)})
    .observeOn(AndroidSchedulers.mainThread())
    .subscribeOn(Schedulers.io())
    .subscribe(output)
    }
    override fun onCleared() {
    disposable.clear()
    }
    }
    

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17. class DataViewModel()) : ViewModel() {
    private val subscriptions = CompositeDisposable()
    val output = BehaviorSubject>.create()
    fun loadCurrentStatus() {
    disposable +=
    store.get(BarCode.empty())
    .startWith(LceLoading())
    .onErrorReturn({e -> LceError(e)})
    .map({data -> mapEmptyData(data)})
    .observeOn(AndroidSchedulers.mainThread())
    .subscribeOn(Schedulers.io())
    .subscribe(output)
    }
    override fun onCleared() {
    disposable.clear()
    }
    }
    Hidden knowledge
    

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18. te val subscriptions = CompositeDisposable()
    utput = BehaviorSubject>.create()
    oadCurrentStatus() {
    isposable +=
    store.get(BarCode.empty())
    .startWith(LceLoading())
    .onErrorReturn({e -> LceError(e)})
    .map({data -> mapEmptyData(data)})
    .observeOn(AndroidSchedulers.mainThread())
    .subscribeOn(Schedulers.io())
    .subscribe(output)
    ide fun onCleared() {
    isposable.clear()
    Learning curve
    

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19. class DataViewModel()) : ViewModel() {
    val output = MutableLiveData()
    fun loadCurrentStatus() {
    output.postValue(LceLoading())
    viewModelScope.launch {
    try {
    val data = store.get(BarCode.empty()).await()
    if (data.isEmpty()) {
    output.postValue(LceError(EmptyResultSetException()))
    } else {
    output.postValue(LceSuccess(data))
    }
    } catch (e: Exception) {
    output.postValue(LceError(e))
    }
    }
    }
    }
    

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20. class DataViewModel()) : ViewModel() {
    val output = MutableLiveData()
    fun loadCurrentStatus() {
    output.postValue(LceLoading())
    viewModelScope.launch {
    try {
    val data = store.get(BarCode.empty()).await()
    if (data.isEmpty()) {
    output.postValue(LceError(EmptyResultSetException()))
    } else {
    output.postValue(LceSuccess(data))
    }
    } catch (e: Exception) {
    output.postValue(LceError(e))
    }
    }
    }
    }
    

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21. adCurrentStatus() {
    output.postValue(LceLoading())
    viewModelScope.launch {
    try {
    val data = store.get(BarCode.empty()).await()
    if (data.isEmpty()) {
    output.postValue(LceError(EmptyResultSetException()))
    } else {
    output.postValue(LceSuccess(data))
    }
    } catch (e: Exception) {
    output.postValue(LceError(e))
    }
    }
    

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22. map
    flatmap
    filter
    first
    last
    

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23. map
    flatmap
    filter
    first
    last
    forEach
    orEmpty
    mapNotNull
    

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24. @NotNull public static Observable> from(@NotNull final ApolloCall call) {
    checkNotNull(call, "call == null");
    return Observable.create(new ObservableOnSubscribe>() {
    @Override public void subscribe(final ObservableEmitter> emitter) throws Exception {
    cancelOnObservableDisposed(emitter, call);
    call.enqueue(new ApolloCall.Callback() {
    @Override public void onResponse(@NotNull Response response) {
    if (!emitter.isDisposed()) {
    emitter.onNext(response);
    }
    }
    @Override public void onFailure(@NotNull ApolloException e) {
    Exceptions.throwIfFatal(e);
    if (!emitter.isDisposed()) {
    emitter.onError(e);
    }
    }
    @Override public void onStatusEvent(@NotNull ApolloCall.StatusEvent event) {
    if (event == ApolloCall.StatusEvent.COMPLETED && !emitter.isDisposed()) {
    emitter.onComplete();
    }
    }
    });
    }
    });
    }
    

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25. @NotNull public static Observable> from(@NotNull final ApolloCall call) {
    checkNotNull(call, "call == null");
    return Observable.create(new ObservableOnSubscribe>() {
    @Override public void subscribe(final ObservableEmitter> emitter) throws Exception {
    cancelOnObservableDisposed(emitter, call);
    call.enqueue(new ApolloCall.Callback() {
    @Override public void onResponse(@NotNull Response response) {
    if (!emitter.isDisposed()) {
    emitter.onNext(response);
    }
    }
    @Override public void onFailure(@NotNull ApolloException e) {
    Exceptions.throwIfFatal(e);
    if (!emitter.isDisposed()) {
    emitter.onError(e);
    }
    }
    @Override public void onStatusEvent(@NotNull ApolloCall.StatusEvent event) {
    if (event == ApolloCall.StatusEvent.COMPLETED && !emitter.isDisposed()) {
    emitter.onComplete();
    }
    }
    });
    }
    });
    }
    suspend fun ApolloCall.await(): Response =
    suspendCancellableCoroutine { cont ->
    enqueue(object : ApolloCall.Callback() {
    override fun onFailure(e: ApolloException) {
    cont.resumeWithException(e)
    }
    override fun onResponse(response: Response) {
    cont.resume(response)
    }
    })
    cont.invokeOnCancellation { cancel() }
    }
    

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26. suspend fun ApolloCall.await(): Response =
    suspendCancellableCoroutine { cont ->
    enqueue(object : ApolloCall.Callback() {
    override fun onFailure(e: ApolloException) {
    cont.resumeWithException(e)
    }
    override fun onResponse(response: Response) {
    cont.resume(response)
    }
    })
    cont.invokeOnCancellation { cancel() }
    }
    

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27. val job = Job()
    val scope = CoroutineScope(Dispatchers.IO + job)
    fun doThings() {
    scope.launch {
    ...
    }
    }
    fun inTheEnd() {
    job.cancel()
    }
    

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28. val job = Job()
    val scope = CoroutineScope(Dispatchers.IO + job)
    fun doThings() {
    scope.launch {
    ...
    }
    }
    fun inTheEnd() {
    job.cancelChildren()
    scope.coroutineContext.cancelChildren()
    }
    

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29. job.cancelChildren()
    scope.coroutineContext.cancelChildren()
    public fun Job.cancelChildren(cause: CancellationException? = null) {
    children.forEach { it.cancel(cause) }
    }
    public fun CoroutineContext.cancelChildren(cause: CancellationException? = null) {
    this[Job]?.children?.forEach { it.cancel(cause) }
    }
    

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31. kotlinx-coroutines-rx2
    

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32. class RxThing {
    fun doStuff() : Single
    }
    

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33. suspend fun doThings() {
    val my data =
    rxThing.doStuff().await()
    }
    

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34. class CoroutineThing {
    suspend fun doStuff() : MyData
    }
    

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35. fun doStuff() : Single =
    rxSingle {
    coroutineThing.doStuff()
    }
    

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36. fun doStuff() : Single =
    rxSingle(RxCoroutineExceptionHandler) {
    coroutineThing.doStuff()
    }
    

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38. open.nytimes.com
    @nytdev
    github.com/NYTimes
    developers.nytimes.com
    

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39. QA
    &
    

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