Kotlin Coroutines in Android Service

Question

I have an Android service which starts and syncs different types of data with the server when it's online. I'm new to Kotlin coroutines and I'm trying to accomplish the following:

fun syncData{
//Job1 make retrofit call to server
//Job2 make retrofit call to server after job1 is done.
//Job3 make retrofit call to server after job2 is done and so on. 
//After all jobs are done I'll stop service.
}

I'm following this post: Kotlin Coroutines the right way in Android

Which brought me to this solution:

fun syncData() = async(CommonPool){
    try{
        val sync1 = async(CommonPool){
            job1.sync()
        }

        val sync2 = async(CommonPool){
            job2.sync()
        }

        val sync3 = async(CommonPool){
            job3.sync()
        }

        val sync4 = async(CommonPool){
            job4.sync()
        }

        job1.await()
        job2.await()
        job3.await()
        job4.await()
    }catch (e: Exception){
    }finally {
        stopSelf()
    }
}

But when I get retrofit's log on logcat, every call is mixed. Calls from job3 comes before job1, and so on. How can I execute them in a pipeline? I'm kinda lost in Kotlin's coroutines so I don't know how exactly to implement this.

Answer 1

Agree with @s1m0nw1 and his answer

It's a way too hard to approach. All you need is as easy as this:

val job = SupervisorJob()

fun syncData() = launch(job) {
    try { 
        val result1 = makeRetrofitCall1()
        val result2 = makeRetrofitCall2(result1)
        ...
        val resultN = makeRetrofitCallN(resultNMinusOne)
    } catch(e: Exception) {
        // handle exception
    } finally {
        stopSelf()
    }
}

override fun onDestroy() {
    super.onDestroy()
    job.cancel()
}

Here makeRetrofitCall means a direct API call as retrofitClient.getData() where retrofitClient is

interface RetrofitClient {

    @GET("endpoint")
    suspend fun getData(): MyCustomResult
}