Programando en diferido(Get out of my thread)Jorge Juan Barroso Carmona

jorge@karumi.com@flipper83+JorgeJBarroso

Android expert

Basho. Poet

Karumi is the beauty of ordinary things spoken of in a simple way.

Miguel Noguera

Reactive Manifesto

Mem CacheResponsive

Mem CacheResilient

Mem CacheElastic

Mem CacheMessage Driven

Mem CacheThe manifesto is not concrete

Adam Tornhill

“First, solve the problem. Then, write the code.”

John Johnson.

Adam Tornhill

Async Task

Mem CacheReally close to the UI Thread and to the framework.

Mem Cache

task.execute()

vs task.executeOnExecutor

(AsyncTask.THREAD_POOL_EXECUTOR)

Mem Cache

Problems changing orientation.

Mem Cache

Priority Job Queue

Mem CacheProducer - consumer approach.

Mem CachePriorities, group, delay, store … jobs

Mem CacheNeed consumers configuration.

Mem Cache

Mem CacheWe need to find a way to notify

responders.Buses?

callbacks?post on handler?

Mem Cache“Callback hell” if we need coordinate a lot of Jobs.

Promises(JDeferred)

Mem CacheFuture and Promises

Mem CacheWe can choose execution and responses

thread with ExecutionServices and ExecutionScope.

Mem Cache

Mem Cache

We can coordinate promises.

DeferredManager dm = new DefaultDeferredManager();Promise p1, p2, p3;// initialize p1, p2, p3dm.when(p1, p2, p3) .done(…) .fail(…)

Mem Cache

We can do operations over the promises. Filter (Map)

Deferred d = …;Promise p = d.promise();Promise filtered = p.then(new DoneFilter<Integer, Integer>() { public Integer filterDone(Integer result) return result * 10; }});

RxJava

Mem CacheCombination of the best ideas from

the Observer pattern, the Iterator pattern, and functional programming

Mem CacheYou need to change your mind. You “observe” changes, don’t invoke it.

A lot of “Operators” that allow combination observables.

Example: Zip

You decide in which thread your observable will emit the stream of data

(onNext() on Subscriber). .subscribeOn(Schedulers.newThread())

You deciden in which thread Observables will execute their job.

.observeOn(AndroidSchedulers.mainThread())

It has a steep learning curve. Take time to understand the paradigma change and

learn the operators.

Debugging can be hell. Frodo is your friend.

Cold vs Hot observablesDefer vs Publish

Karumi Recommends

Mem CacheGet out from UI thread ASAP

Mem CacheApps are really dependent on state.Blocking threads.

Mem CacheBe careful with the number of threads that your are creating. A big number of

threads can overkill the system.

Mem CacheI don’t appreciate a big impact to the memory or to garbage collector.

Adam Tornhill

“Sometimes abstraction and encapsulation are at odds with

performance — although not nearly as often as many developers believe — but it is always a good practice first to make your code right, and then make it fast.”

Brian Goetz. Java Concurrency in Prac.

Readability is the must important thing always

Observable<List<User>> usersDb = db.getUsers().subscribeOn(Schedulers.newThread());Observable<List<User>> users = apiRest.getUsers().subscribeOn(Schedulers.newThread());Observable<Map<String, Integer>> likeCountPerUser = apiRest.getLikes();Observable<List<User>> obs = Observable.zip(users, likeCountPerUser, (users, likes) -> { for (User user: users) { if (likes.containsKey(user.getId())) { user.setNumLikes (likes.get(user.getId())); } } return users;}).merge(userDb);return obs;

Readability is the must important thing always

List<User> usersDb = db.getUsers();List<User> users = apiRest.getUsers();Map<String, Integer> likeCountPerUser = apiRest.getLikes();for (User user: users) { if (likes.containsKey(user.getId())) { user.setNumLikes(likes.get(user.getId())); }}List<User> usersFinal = new ArrayList<>();usersFinal.addAll(users);usersFinal.addAll(usersDb);

return usersFinal;

BibliographyThey’re the cracks!

Java Concurrency in Prac. Brian Goetzhttp://www.reactivemanifesto.org/http://reactivex.io/https://github.com/jdeferred/jdeferredhttps://github.com/BoltsFramework/Bolts-Androidhttps://github.com/android10/frodohttps://github.com/flipper83/trabajando-en-diferidoThanks to Pedro V Gomez, Fernando Cejas, Nuria Ruiz and karumi team for their support.

Find meI am very social!

jorge@karumi.com@flipper83+JorgeJBarroso

Questions?