The Art of Rxpublic.jugru.org/mobius/2016/spb/day_1/track_1/malkovrx.pdf ·...

The Art of RxМатвей Мальков

2Обо мне

3Обо мне

4Обо мне

5Обо мне

Èñêóññòâî ðåàêòèâíîãî ïðîãðàììèðîâàíèÿ

Èñêóññòâî – âûñîêàÿ ñòåïåíü ìàñòåðñòâà â êàêîé-ëèáî

ñôåðå äåÿòåëüíîñòè.

Íàø ãëàâíûé íàâûê – óìåíèå äóìàòü

9Умение думать. Практика

• î ÷åì äóìàòü?


• î ÷åì äóìàòü?

• êàê äóìàòü?


10О чем думать мобильному разработчику

• ýíåðãîïîòðåáëåíèå



• ïëàâíîñòü èíòåðôåéñà (60 fps)




• ôðàãìåíòàöèÿ óñòðîéñòâ




• ôðàãìåíòàöèÿ óñòðîéñòâ

• ïîòðåáëåíèå ïàìÿòè


11Как думать мобильному разработчику?

• êàê ïîëüçîâàòåëü



• êàê äèçàéíåð



• êàê äèçàéíåð

• êàê ïðåäëàãàåò ôóíäàìåíòàëüíûé ôðåéìâîðê


12Фундаментальный фреймворк

• äåëàåò ðàçðàáîòêó ïðîùå/ëó÷øå/áûñòðåå



• ïðèâíîñèò ÷òî-òî êîíöåïòóàëüíî íîâîå




• ïðîðàñòàåò âî âñå ïîäñèñòåìû





• ñëîæíî óáðàòü





• ñëîæíî óáðàòü

• òðåáóåò íàâûêîâ îáðàùåíèÿ


Íàø ëþáèìûé ôóíäàìåíòàëüíûé ôðåéìâîðê – RxJava

Î ÷eì äóìàòü, èñïîëüçóÿ RxJava?

Î êîíòðàêòàõ

16О контрактах

• ïðîáëåìû:



• ïîíèìàíèå




• ñîáëþäåíèå





• âàæíî:





• âàæíî:

• îñíîâû


17Нотификации

• onNext – 0, n èëè inf



• onCompleted – 0 èëè 1




• onError – 0 èëè 1




• onError – 0 èëè 1

• onCompleted + onError <= 1


18Подписка и отписка

• íå íóæíî îòïèñûâàòüñÿ ïîñëå çàâåðøåíèÿ


• íå íóæíî îòïèñûâàòüñÿ ïîñëå çàâåðøåíèÿ

• ïðè îòïèñêå çàâåðøåíèå íå ãàðàíòèðîâàíî


19Observable<Response> obs = Observable .interval(1, TimeUnit.SECONDS) .map(this!::sendPing) .cache();

23Observable<Response> obs = Observable .interval(1, TimeUnit.SECONDS) .map(this!::sendPing) .cache();Subscription sub = obs.subscribe();

24Observable<Response> obs = Observable .interval(1, TimeUnit.SECONDS) .map(this!::sendPing) .cache();Subscription sub = obs.subscribe();!//позжеsub.unsubscribe();


Note: You sacrifice the ability to unsubscribe from the origin

• îòïðàâêà íîòèôèêàöèé


http://reactivex.io/documentation/contract.html


• çàâåðøåíèå ñ îøèáêîé




• çàâåðøåíèå ñ îøèáêîé

• ïîëíûé ñïèñîê : http://reactivex.io/documentation/contract.html



28Состояние системы

• èçîëèðîâàííî



• îäèí èñòî÷íèê




• íåèçìåíÿåìî





• ïîä÷èíÿåòñÿ êîíòðàêòó Observable


29

nameEditTextChanges.subscribe(this!::updateName);

30


PublishSubject<Integer> nameEditTextChanges = PublishSubject.create();

31


PublishSubject<Integer> nameEditTextChanges = PublishSubject.create();

nameEditTextChanges.onNext("хаха, обманул!");

Subject – âîçìîæíîå íàðóøåíèå êîíòðàêòà




• ïîä÷èíÿåòñÿ êîíòðàêòó Observable


35Subjects

• ñîåäèíåíèå èìïåðàòèâíîãî è ðåàêòèâíîãî ìèðà

35Subjects


• êîãäà íåâîçìîæíî ñäåëàòü ïî äðóãîìó

35Subjects



• ýòî âàø ñëó÷àé? ÍÅÒ!

35Subjects




• âñå òàêè âàø? Íåò, ýòî íå òàê!

35Subjects




• âñå òàêè âàø? Íåò, ýòî íå òàê!

• ìåíüøå – ëó÷øå

35Subjects

О тредах

37О тредах

• ïðîáëåìû

37О тредах


• íåò ïîíèìàÿ ðàáîòû

37О тредах



• ñóþò subscribeOn è observeOn âåçäå ïîäðÿä

37О тредах




• âàæíî :

37О тредах




• âàæíî :

• ðàçáèðàòüñÿ

37О тредах

38Scheduler

• ïëàíèðîâêà çàäà÷

38Scheduler


• ðàáîòà ñ òðåäàìè

38Scheduler



• subscribeOn

38Scheduler



• subscribeOn

• observeOn

38Scheduler

Äîãìû observeOn

subscribeOn

1. observeOn ìåíÿåò Scheduler äëÿ âñåãî, ÷òî íèæå ïî êîäó

2. subscribeOn ìåíÿåò Scheduler ñ ñàìîãî âåðõà öåïî÷êè

3. Êàæäûé ñëåäóþùèé observeOn çàìåíÿåò ïðåäûäóùèé

4. subscribeOn àêòóàëåí äî ïåðâîãî observeOn

Âñåãäà äóìàéòå î òîì, â êàêîì òðåäå âûïîëíÿåòñÿ ôóíêöèÿ

45

Observable<Response> requestObs = userDbChanges .filter(u 0-> u.age < 18) .map(this!::toRequestModel) .map(this!::doRequest) .onErrorReturn(this!::doRecoverReq) .map(this!::cacheAndModify);!//ui threadrequestObs.subscribe(this!::showOnUi);

46

Observable<Response> requestObs = userDbChanges .filter(u 0-> u.age < 18) .map(this!::toRequestModel) .map(this!::doRequest) .onErrorReturn(this!::doRecoverReq) .map(this!::cacheAndModify);!//ui threadrequestObs.subscribe(this!::showOnUi);

47

Observable<Response> requestObs = userDbChanges .filter(u 0-> u.age < 18) .map(this!::toRequestModel) .observeOn(networkScheduler) .map(this!::doRequest) .onErrorReturn(this!::doRecoverReq) .subscribeOn(Schedulers.computation()) .observeOn(mainThread) .map(this!::toUiModel);!//ui threadrequestObs.subscribe(this!::showOnUi);

48


49


50


51


52


53


Âåëèêîëåïíûé subscribeOn

55subscribeOn

public final Observable<T> subscribeOn(Scheduler scheduler) { !//какой-то неважный код return nest().lift(new OperatorSubscribeOn<T>(scheduler));}

56subscribeOn


57

public final Observable<Observable<T9>> nest() { return just(this);}

59

nest

60

nest

61subscribeOn


62subscribeOn


63subscribeOn


64

public class OperatorSubscribeOn<T> implements Operator<T, Observable<T9>> { private final Scheduler scheduler; public OperatorSubscribeOn(Scheduler scheduler) { this.scheduler = scheduler; } @Override public Subscriber<? super Observable<T9>> call(final Subscriber<? super T> subscriber) { … }

65


принимаетвозвращает

66


67@Overridepublic Subscriber<? super Observable<T9>> call(final Subscriber<? super T> subscriber) { final Worker inner = scheduler.createWorker(); subscriber.add(inner); return new Subscriber<Observable<T9>>(subscriber) { @Override public void onNext(final Observable<T> o) { inner.schedule(new Action0() { @Override public void call() { final Thread t = Thread.currentThread(); o.unsafeSubscribe(new Subscriber<T>(subscriber) { !//обычный inner subscribe } !//тут еще оооочень много закрывающихся скобочек}


Наш Observable

75

OperatorSubscribeOn(Scheduler)

76

OperatorSubscribeOn(Scheduler)

Ãåíèàëüíî!

78

Observable.just(1) .subscribeOn(scheduler1) .subscribeOn(scheduler2) .subscribe();

79

Observable.just(1) .subscribeOn(scheduler1) .subscribeOn(scheduler2) .subscribe(); !//scheduler1

2. subscribeOn ìåíÿåò Scheduler ñ ñàìîãî âåðõà öåïî÷êè

2. Ïåðâûé subscribeOn ìåíÿåò Scheduler ñ ñàìîãî âåðõà öåïî÷êè

82

!//computationObservable<Long> o1 = Observable.interval(1, TimeUnit.SECONDS); !//networkObservable<Integer> o2 = Observable.just(1) .observeOn(networkScheduler);Observable.zip(o1, o2, o3, (r1, r2) 0-> r1 * r2);

83

!//computationObservable<Long> o1 = Observable.interval(1, TimeUnit.SECONDS); !//networkObservable<Integer> o2 = Observable.just(1) .observeOn(networkScheduler);Observable.zip(o1, o2, o3, (r1, r2) 0-> r1 * r2);

84

!//computationObservable<Long> o1 = Observable.interval(1, TimeUnit.SECONDS); !//networkObservable<Integer> o2 = Observable.just(1) .observeOn(networkScheduler);Observable.zip(o1, o2, o3, (r1, r2) 0-> r1 * r2); !//computation or network

85final class InnerSubscriber extends Subscriber { @Override public void onNext(Object t) { try { items.onNext(t); } catch (MissingBackpressureException e) { onError(e); } tick(); }};

86final class InnerSubscriber extends Subscriber { @Override public void onNext(Object t) { try { items.onNext(t); } catch (MissingBackpressureException e) { onError(e); } tick(); }};

87

void tick() { !//тут много кода, не имеющего сейчас значения if (requested.get() > 0 !&& allHaveValues) { try { !// всем потокам есть что zip’ать child.onNext(zipFunction.call(vs));

} !// еще много кода и скобочки

88



89



Âñåãäà äóìàéòå î òîì, â êàêîì òðåäå âûïîëíÿåòñÿ ôóíêöèÿ

О количестве элементов

92Количество элементов


• áîëüøå ýëåìåíòîâ – áîëüøå ìóñîðà




• RxJava ïîñòîÿííî âñå êîïèðóåò





• âàæíî:





• âàæíî:

• íå ïàíèêîâàòü





• âàæíî:

• íå ïàíèêîâàòü

• çàáîòèòüñÿ î GC


93Не паниковать

• «×òî ñ GC?» : ñàìûé æàðêèé âîïðîñ



• êîïèðîâàíèå òîëüêî ïðè íîòèôèêàöèÿõ



• êîïèðîâàíèå òîëüêî ïðè íîòèôèêàöèÿõ

• âñå îïòèìèçèðîâàííî


94

locationUpdates() .distinctUntilChanged() .subscribe();

95


96


touchEvents(view) .filter(e 0-> e.x > minWidth !&& e.y > minHeight) .doOnNext(this!::processEvents) .subscribe();

97


touchEvents(view) .filter(e 0-> e.x > minWidth !&& e.y > minHeight) .doOnNext(this!::processEvents) .subscribe();

98

nameEditTextChanges .map(this!::prepareForSending) .map(this!::sendName) .map(this!::cacheAndModify);

99

nameEditTextChanges .map(this!::prepareForSending) !//раз .map(this!::sendName) .map(this!::cacheAndModify);

100

nameEditTextChanges .map(this!::prepareForSending) !//раз .map(this!::sendName) !// два .map(this!::cacheAndModify);

101

nameEditTextChanges .map(this!::prepareForSending) !//раз .map(this!::sendName) !// два .map(this!::cacheAndModify); !// три

102

nameEditTextChanges .debounce(500, TimeUnit.MILLISECONDS) .map(this!::prepareForSending) .map(this!::sendName) .map(this!::cacheAndModify);

103debounce

• áåðåæåò GC

103debounce


• áåðåæåò òðàôèê ïîëüçîâàòåëÿ

103debounce


• áåðåæåò òðàôèê ïîëüçîâàòåëÿ

• áåðåæåò íàñ îò BackPressure

103debounce

104Backpressure

• îòäàþùèé òðåä äàåò ìíîãî

104Backpressure


• ïðèíèìàþùèé òðåä íå óñïåâàåò

104Backpressure



• â ìíîãîïîòî÷íîé ñðåäå ìíîãîâåðîÿòíî

104Backpressure



• â ìíîãîïîòî÷íîé ñðåäå ìíîãîâåðîÿòíî

• ïåðâûé ïðèçíàê – observeOn

104Backpressure

105

events

touchEvents(view)

106

events filter

touchEvents(view) .filter(e 0-> e.x > minWidth)

107

events filter map

touchEvents(view) .filter(e 0-> e.x > minWidth) .map(this!::normalize)

108

events filter map observeOn

touchEvents(view) .filter(e 0-> e.x > minWidth) .map(this!::normalize) .observeOn(networkScheduler)

109


touchEvents(view) .filter(e 0-> e.x > minWidth) .map(this!::normalize) .observeOn(networkScheduler) .map(this!::prepareForSending)

map

110


touchEvents(view) .filter(e 0-> e.x > minWidth) .map(this!::normalize) .observeOn(networkScheduler) .map(this!::prepareForSending) .map(this!::doMotionRequest)

map map

111


touchEvents(view) .filter(e 0-> e.x > minWidth) .map(this!::normalize) .observeOn(networkScheduler) .map(this!::prepareForSending) .map(this!::doMotionRequest) .subscribe()

map map subscriber

112



map map subscriber

113



map map subscriber

114



map map subscriber

115


map map subscribertouchEvents(view) .filter(e 0-> e.x > minWidth) .map(this!::normalize) .observeOn(networkScheduler) .map(this!::prepareForSending) .map(this!::doMotionRequest) .subscribe()

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map map subscriber

2


126


map map subscriber

2


127


map map subscriber

2


128


map map subscriber

2


129


map map subscriber

3


130


map map subscriber

3


131


map map subscriber

3

Устал


132


map map subscriber

3

Устал


133


map map subscriber

4

rx.exceptions.MissingBackpressureException

134

Observable.zip( Observable.interval(10, TimeUnit.MILLISECONDS), Observable.interval(20, TimeUnit.MILLISECONDS), (r1, r2) 0-> r1 * r2).subscribe();

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136


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138


rx.exceptions.MissingBackpressureException

139Борьба с Backpressure

• debounce, throttle



• window, buffer



• window, buffer

• onBackpressureBuffer



• window, buffer

• onBackpressureBuffer

• onBackpressureDrop


Âñåãäà äóìàéòå î òîì, ñêîëüêî ýëåìåíòîâ âàì íóæíî

îò Observable

Êàê äóìàòü, èñïîëüçóÿ RxJava?

Как инженер

145Как инженер

• íå áîéñÿ ðàñøèðÿòü ôðåéìâîðê


• íå áîéñÿ ðàñøèðÿòü ôðåéìâîðê

• ïîíèìàé, êàê îí ðàáîòàåò âíóòðè


146DoOnNextAsync

• doOnNext == ñàéä ýôôåêò

146DoOnNextAsync


• íå áëîêèðîâàòü âûïîëíåíèå ðîäèòåëÿ

146DoOnNextAsync



• áûë ïðèâÿçàí ê æèçíåííîìó öèêëó ðîäèòåëÿ

146DoOnNextAsync



• áûë ïðèâÿçàí ê æèçíåííîìó öèêëó ðîäèòåëÿ

• íå ÷åðåç Subjects

146DoOnNextAsync

147

userDbChanges .map(this!::doRequest) .doOnNext(resp 0-> { globalSubscription = createCacheObs(resp) .subscribe(); }) .map(this!::doAnotherRequest);

148

userDbChanges .map(this!::doRequest) .doOnNext(resp 0-> { globalSubscription = createCacheObs(resp) .subscribe(); }) .map(this!::doAnotherRequest);

149

userDbChanges .map(this!::doRequest) .lift(new DoOnNextAsyncG<>(this!::cacheObs)) .map(this!::doAnotherRequest);

150

userDbChanges .map(this!::doRequest) .lift(new DoOnNextAsyncG<>(this!::cacheObs)) .map(this!::doAnotherRequest);

151

class DoOnNextAsync<F, T> implements Observable.Operator<F, F> { private final Func1<F, Observable<T9>> nested; public DoOnNextAsync(Func1<F, Observable<T9>> func) { this.nested = func; } !//больше кода дальше

152


153


154

@Overridepublic Subscriber<? super F> call(Subscriber<? super F> subscriber) { return new Subscriber<F>() { @Override public void onNext(F next) { if (!subscriber.isUnsubscribed()) { Subscription s = nested.call(next).subscribe(); subscriber.add(s); } }

!//тривиальные onError и onCompleted здесь };}

155



156



157



158



• Operator, lift,

• subscribeOn, observeOn

• nest, defer, create

159Понимай, как работает внутри

Думай реактивно

161Думать реактивно

• ñîåäèíÿòü èìïåðàòèâíûé è ðåàêòèâíûé ìèð



• íå èñïîëüçîâàòü ñàáäæåêòû



• íå èñïîëüçîâàòü ñàáäæåêòû

• îïèñûâàòü, «êàê äåëàòü», à íå «÷òî äåëàòü»


162AutoLoadingRecyclerView

• íàó÷èòü RecycerView àâòîïîäãðóçêå



• ñäåëàòü ñ ïîìîùüþ RxJava



• ñäåëàòü ñ ïîìîùüþ RxJava

• â ðåàêòèâíîì ñòèëå


163

public class AutoLoadingRecyclerView<T> extends RecyclerView { protected PublishSubject<Pair<Integer, Integer9>> scrollLoadingChannel = PublishSubject.create(); protected void startScrollingChannel() { addOnScrollListener(new RecyclerView.OnScrollListener() { @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { if (shouldLoad()) { int offset = getAdapter().getItemCount(); scrollLoadingChannel.onNext(new Pair(offset, limit)); } } }); }

164


165


166


167


168

public class AutoLoadingRecyclerView<T> extends RecyclerView { protected PublishSubject<OffsetAndLimit> scrollLoadingChannel = PublishSubject.create(); protected Subscription loadNewItemsSubscription; protected Subscription subscribeToLoadingChannelSubscription;

169


170


171

private static Observable<Integer>getScrollObservable(RecyclerView recyclerView, int limit) { return Observable.create(subscriber 0-> { final RecyclerView.OnScrollListener sl = new RecyclerView.OnScrollListener() { @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { if (!subscriber.isUnsubscribed() !&& shouldLoad()) { subscriber.onNext(recyclerView.getAdapter().getItemCount()); } } }; recyclerView.addOnScrollListener(sl); subscriber.add(Subscriptions.create(() 0-> recyclerView.removeOnScrollListener(sl))); });}

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177

getScrollObservable() .distinctUntilChanged() .switchMap(offset 0-> getLoadingObservable(offset)) .subscribeOn(Schedulers .from(BackgroundExecutor.getSafeBackgroundExecutor()) ) .observeOn(AndroidSchedulers.mainThread()) .subscribe(loadNewItemsSubscriber);

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182


• èñïîëüçîâàòü ñòàíäàðòíûå ñðåäñòâà RxJava



• íî íå ñàáäæåêòû




• ïðè íåîáõîäèìîñòè – ïèñàòü ñâîå





• îáîðà÷èâàòü ñîñòîÿíèå â Observable





• îáîðà÷èâàòü ñîñòîÿíèå â Observable

• ñòàðàòüñÿ è íå ñäàâàòüñÿ


184The Art of Rx

• äóìàòü î

184The Art of Rx

• äóìàòü î

• î êîíòðàêòàõ

184The Art of Rx

• äóìàòü î


• î òðåäàõ

184The Art of Rx

• äóìàòü î


• î òðåäàõ

• î êîëè÷åñòâå ýëåìåíòîâ

184The Art of Rx

• äóìàòü î


• î òðåäàõ


• äóìàòü êàê

184The Art of Rx

• äóìàòü î


• î òðåäàõ



• èíæåíåð

184The Art of Rx

• äóìàòü î


• î òðåäàõ



• èíæåíåð

• ðåàêòèâíî

184The Art of Rx

Ñòàòü ïðîôåññèîíàëîì – íåïðîñòî

Íå ëåíèòåñü

Äóìàéòå ìíîãî

Äóìàéòå ìíîãî Î âàæíûõ âåùàõ

189

Ìàëüêîâ Ìàòâåé

Ñïàñèáî

matveyka_jj

The Art of Rxpublic.jugru.org/mobius/2016/spb/day_1/track_1/malkovrx.pdf ·...

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