Is there a way to get the parent Job from coroutin...

# coroutines

[sitepodmatt]

Is there a way to get the parent Job from coroutinecontext's Job without using reflection to get privates?

[gildor]

Reflection???

[gildor]

Just use val parentJob: Job? = coroutineContext[Job]

[sitepodmatt]

That's not the parent job, that's the existing job

[sitepodmatt]

runBlocking {


val job1 = this.coroutineContext[Job]

launch {

val job2 = this.coroutineContext[Job]
println(job1 == job2)

launch {

val job3 = this.coroutineContext[Job]
println(job2 == job3)
}
}
}

[gildor]

🤔

[gildor]

What is your use case for this?

[sitepodmatt]

job2 has a reference to job1 internally as it's created with Job(parentJob) but it doesnt seem to expose parentHandle

[gildor]

Yes, and it sounds reasonable

[sitepodmatt]

I want to play with the idea of getting the tree of jobs that lead to a failure by walking Job.parentJob until null for some logging purposes

[sitepodmatt]

It might turn out a bad idea, but I'm surprise that Job? parentJob isn't exposed on Job

[sitepodmatt]

Able to do it with

@UseExperimental(InternalCoroutinesApi::class)
fun Job.getParent() : Job? {
    return (AbstractCoroutine::class.java as Class<*>)?.
        getDeclaredField("parentContext")?.
        also { it.isAccessible = true }?.
        let { it.get(this) as? CoroutineContext? }?.
        let { it[Job] }
}

[sitepodmatt]

then get true

runBlocking {


            val job1 = this.coroutineContext[Job]

            launch {

                val job2 = this.coroutineContext[Job]
                val parent = job2!!.getParent()
                println(parent == job1)


            }
        }