Job‐Hierarchy
- We have all co-routines launched in the same scope
- Note that
grand-Parent,parent-1, andparent-2launched and completed, They did not wait for the left co-routines to complete. - When we click cancel,
exceptionis caught, and theninvokeOnCompletionis triggered. - Also the exception occurs inside the scope and not outside.
- 🚨🚨 Also I observed when you use
launch, You cannot make the parents wait for the children to complete. If that behaviour is needed, We need to use async and await 🚨 🚨
GrandParent invokeOnCompletion triggered
Parent-2 invokeOnCompletion triggered
Parent-1-child-1 ------------------>0
Parent-1-child-2 ------------------>0
Parent-1 invokeOnCompletion triggered
Parent-2-child-2 ------------------>0
Parent-2-child-1 ------------------>0
Parent-1-child-1 ------------------>1
Parent-1-child-2 ------------------>1
Parent-2-child-2 ------------------>1
Parent-2-child-1 ------------------>1
Parent-1-child-1 ------------------>2
Parent-1-child-2 ------------------>2
Parent-2-child-2 ------------------>2
Parent-2-child-1 ------------------>2
<------------------ User presses cancel ------------------>
Exception caught inside Parent-1-child-1 scope
Parent-1-child-1 invokeOnCompletion triggered
Exception caught inside Parent-2-child-1 scope
Parent-2-child-1 invokeOnCompletion triggered
Exception caught inside Parent-2-child-2 scope
Parent-2-child-2 invokeOnCompletion triggered
Exception caught inside Parent-1-child-2 scope
Parent-1-child-2 invokeOnCompletion triggeredclass JobDemoSelectionVm @Inject constructor( ) : ViewModel() {
private val scopeJob = Job()
private val ourScope = CoroutineScope(scopeJob + Dispatchers.Default)
fun demo() {
try {
ourScope.launch(CoroutineName("GrandParent")) {
try {
parent1Block()
parent2Block()
}catch (ex:Exception){
println("Exception caught inside GrandParent scope")
}
}.invokeOnCompletion {
println("GrandParent invokeOnCompletion triggered")
}
}catch (ex:Exception){
println("Exception caught outside GrandParent scope")
}
}
private fun parent1Block(){
try {
ourScope.launch(CoroutineName("Parent-1")) {
try {
parent1Child1Block()
parent1Child2Block()
}catch (ex:Exception){
println("Exception caught inside Parent-1 scope")
}
}.invokeOnCompletion {
println("Parent-1 invokeOnCompletion triggered")
}
}catch (ex:Exception){
println("Exception caught outside Parent-1 scope")
}
}
private fun parent2Block(){
try {
ourScope.launch(CoroutineName("Parent-2")) {
try {
parent2Child1Block()
parent2Child2Block()
}catch (ex:Exception){
println("Exception caught inside Parent-2 scope")
}
}.invokeOnCompletion {
println("Parent-2 invokeOnCompletion triggered")
}
}catch (ex:Exception){
println("Exception caught outside Parent-2 scope")
}
}
private fun parent1Child1Block(){
try {
ourScope.launch(CoroutineName("Parent-1-child-1")) {
try {
repeat(10){
println("Parent-1-child-1 ------------------>$it")
delay(1000)
}
}catch (ex:Exception){
println("Exception caught inside Parent-1-child-1 scope")
}
}.invokeOnCompletion {
println("Parent-1-child-1 invokeOnCompletion triggered")
}
}catch (ex:Exception){
println("Exception caught outside Parent-1-child-1 scope")
}
}
private fun parent1Child2Block(){
try {
ourScope.launch(CoroutineName("Parent-1-child-2")) {
try {
repeat(10){
println("Parent-1-child-2 ------------------>$it")
delay(1000)
}
}catch (ex:Exception){
println("Exception caught inside Parent-1-child-2 scope")
}
}.invokeOnCompletion {
println("Parent-1-child-2 invokeOnCompletion triggered")
}
}catch (ex:Exception){
println("Exception caught outside Parent-1-child-2 scope")
}
}
private fun parent2Child1Block(){
try {
ourScope.launch(CoroutineName("Parent-2-child-1")) {
try {
repeat(10){
println("Parent-2-child-1 ------------------>$it")
delay(1000)
}
}catch (ex:Exception){
println("Exception caught inside Parent-2-child-1 scope")
}
}.invokeOnCompletion {
println("Parent-2-child-1 invokeOnCompletion triggered")
}
}catch (ex:Exception){
println("Exception caught outside Parent-2-child-1 scope")
}
}
private fun parent2Child2Block(){
try {
ourScope.launch(CoroutineName("Parent-2-child-2")) {
try {
repeat(10){
println("Parent-2-child-2 ------------------>$it")
delay(1000)
}
}catch (ex:Exception){
println("Exception caught inside Parent-2-child-2 scope")
}
}.invokeOnCompletion {
println("Parent-2-child-2 invokeOnCompletion triggered")
}
}catch (ex:Exception){
println("Exception caught outside Parent-2-child-2 scope")
}
}
fun rootCancel() {
scopeJob?.cancel()
}
}