Between Love and Hate: Coroutines

Transcript

1. Between Love and Hate: Coroutines Maryna Shaposhnikova Android dev Glindev
2. Languages:
3. There are two types of Coroutines Stackfull Stackless
5. Why we need it? asynchronous, non-blocking code light-weight threads
6. What does it means light-weight threads? - don’t have an own stack - don’t map on native thread - don’t require context switching on processor conclusion : they are lighter than threads
7. How it works? Callback?!?
8. State machine - if-conditions - switch structures.
10. Continuation is a state of the suspended coroutine at suspension point CoroutineContext like a collection of thread-local variables, but… persistent
11. start get my wizzard add to list get a user get a wizard suspend suspend wizard :) suspend
12. - Do background task - Switch to UI - Show user launch (UI) || launch(CommonPool)
13. UI { background { load() //suspend function } show() } Suspend functions are only allowed to be called from a coroutine or another suspend function.
14. launch {} async {} Job Deferred aka promise join() await() w/o result with result
15. Compare
16. launch (UI) { launch (CommonPool) {}.join() launch (CommonPool) {}.join() launch (CommonPool) {}.join() } launch (UI) { async (CommonPool) {}.await() async (CommonPool) {}.await() async (CommonPool) {}.await() }
17. withContext() ONE or MANY?
18. launch (UI) { launch (CommonPool) { getRandomUser() getRandomUser() getRandomUser() }.join() } launch (UI) { withContext (CommonPool) { getRandomUser() getRandomUser() getRandomUser() } }
19. = 3000 ms 1000 ms 1000 ms 1000 ms
20. = 1000 ms
21. launch (UI) { val def1 = async (CommonPool) {} val def2 = async (CommonPool) {} val def3 = async (CommonPool) {} def1.await() def2.await() def3.await() } joinAll(job1, job2, job3) awaitAll(job1, job2, job3) launch (UI) { val job1 = launch (CommonPool) {} val job2 = launch (CommonPool) {} val job3 = launch (CommonPool) {} job1.join() job2.join() job3.join() }
23. Exception
24. suspendCoroutine callback { callback { callback { callback { print(‘I hate callback hell”) } } } }
26. Retrofit?
28. - Build abstraction - Use Channels for modularization - Avoid to use CommonPool - Avoid to use UI
29. Could coroutines replace Rx?
31. Thank you! Maryna Shaposhnikova Android dev Glindev Sample project https://github.com/MarinaShaposhnikova/M agicCoroutines