`Day23` - Lesson6 ◦ Rough OS recap ▪︎ ...

# 100daysofkotlin-2021

[JungIn Choi]

Day23
• Lesson6
◦ Rough OS recap
▪︎ Scheduler takes account of priorities, makes sure all the threads get to run and finish. Dispatcher sets up threads, specifies context
▪︎ (Android) _Main thread(_a.k.a. UI thread) handles UI updates. Calls click handlers & other UI, lifecycle callbacks
▪︎ Blocked process waits for some event / Non-blocking - not blocking the main thread / Examples of “Long” tasks - fetching data from internet, reading a large file, writing to database
▪︎ Asynchronous process runs independently from the main execution steps
◦ Callbacks
▪︎ When task completes, the callback supplied as an argument is called to inform the result to the main thread
▪︎ (Con) Readability, Seems sequential but actually asynchronous. Have to pass errors via another exception handler (result object)
◦ Coroutines
▪︎ Convert callback based code to sequential code. Coroutines can signal errors
▪︎ Asynchronous, Non-blocking, Use suspend functions to make asynchronous code sequential
▪︎ Blocked thread without coroutines - no other work happens / Suspended thread with coroutines - other work can happen until the result is available
▪︎ Jobs are used to cancel coroutine.
▪︎ Dispatcher sends off coroutines to run on various threads (Dispatcher.main, Dispatcher.io)
▪︎ Scopes combine information to define the context in which the coroutine runs.
• Did not understand Coroutine just by the lecture, so had some googling time. (1)
Self-Comment
• Whoa.. coroutines are difficult🥺 Should look more into it tomorrow.
Goals Tomorrow
• Finish lesson6, understand coroutines. Think I’ll have to view lesson6 again then.