2.6 preliminary cognition of synergetic couroutines

coroutines Couroutines My initial understanding

One 、 What is? Kotlin coroutines

coroutines （Coroutine） Is the collaborative program , and Kotlin Synergy is a process based on Java Thread API Packaged toolkit , Help us easily write complex concurrent code

kotlin Compared with thread pool , There is no performance advantage

Non blocking suspension is nothing special ,java Sub threads are also non blocking

If you are familiar with Rxjava, Compare the process again , You will find that the synergy ratio Rxjava It works

Solve the problem of callback to hell

Two 、Coroutines The advantages of 、 characteristic

• Light weight

• The essence , Convenient for multi-threaded development

• Thread pool

• Network library support , Light and elegant

3、 ... and 、 Quick view of knowledge points

Common coprocessing functions

Function name	Brief features
runBlocking:T	Internal coordination process started , Meeting Blocking Current thread , until block The execution of the coordination process in the end . Common methods of calling coprocessor functions
launch:Job	The most commonly used way to start the process ; return Job object , operational Job; It won't block Current calling thread ;
async:Deferred	Be similar to launch, Start asynchronous ; Can be used for multiple concurrency ;await Consolidated results

• CoroutineContext

  • Dispatchers.Main、

  • Dispatchers.IO、Dispatchers.default（ Execute... In the process pool ）

  • Dispatchers.Unconfined

• LauncherMode

  Mode	Value
  default	Default , Execute the program immediately
  lazy	Execute when needed
  atomic	Execute now , Operation atomization , Cannot cancel before starting
  undispatched	Execute immediately on the current thread , Until the first one suspend call

• suspend function

  • suspend function Will bring the whole coroutines Hang up , Not just this suspend function , That is to say a coroutines There are multiple Suspend function when , They are executed sequentially

  • resume

  • The call stack

• Scope

  • UI

  • ViewModel

Four 、 The way to deal with asynchrony

• Threads

  • Commonly used , Simple and convenient

  • resource consumption

    The number is limited

    Platform support （JS There is no thread ）

    Inconvenient to debug

• Callback

  • Hierarchical call

  • Multiple nesting

    Error handling is troublesome

• Futures、 Promise

  • Programming elegance

  • Change the programming method , Such as exception handling and circulation , Invalid in

    Api Study , Platform differences

    Return type qualification promise

    Exception handling is complex

• Rx Reactive expansion

  • The design idea of observable flow , Elegant and convenient

  • The learning curve

    Api

    Behavior is hard to estimate

• coroutines

  • studies of the Book of Changes 、 Easy to use

  • jetpack,kotlin,aac,scope/vvm

  • Learning cost