Coroutine Context

CoroutineContext serves as a vital interface and a cornerstone of coroutines.
A coroutine launches with a context and remains tied to it until the completion or cancellation of its job.
It represents an indexed set of Element instances.
- An indexed set combines the characteristics of a set and a map.
- Each element in this set possesses a unique key.
- Element implements the CoroutineContext interface.
  - An element within the coroutine context is a singleton context on its own.
By default, any coroutine builder or scope function utilizes an empty coroutine context known as EmptyCoroutineContext.
It is generally discouraged to access the coroutineContext property of a CoroutineScope in regular code
- except when accessing the Job instance for advanced purposes.

Code blocks

CoroutineContext interface holds these given below three blocks of code.

public interface CoroutineContext {
    public operator fun <E : Element> get(key: Key<E>): E?
    public operator fun plus(context: CoroutineContext): CoroutineContext {}
    public fun minusKey(key: Key<*>): CoroutineContext
    public fun <R> fold(initial: R, operation: (R, Element) -> R): R
}

public interface Key<E : Element>

public interface Element : CoroutineContext {
    // A key of this coroutine context element.
    public val key: Key<*>

    public override operator fun <E : Element> get(key: Key<E>): E? {}
    public override fun minusKey(key: Key<*>): CoroutineContext = {}
    public override fun <R> fold(initial: R, operation: (R, Element) -> R): R {}
}

A few examples of CoroutineContext's Element are:
- EmptyCoroutineContext, CombinedContext
- AbstractCoroutineContextElement
- EventLoop, BlockingEventLoop
- Dispatcher, DefaultScheduler

Example

@OptIn(ExperimentalStdlibApi::class)
suspend fun main() {

    val coroutineName = CoroutineName("Name: EmptyCoroutineContext") + EmptyCoroutineContext
    val job = GlobalScope.launch(coroutineName) {
        val dispatcher = coroutineContext[CoroutineDispatcher]
        val name = coroutineContext[CoroutineName]?.name
        println("Coroutine Context details: $name , Dispatcher: $dispatcher")
    }
    job.join()
}