AsyncHttp.kt

open class SuspendAwareThrowable(message: String?) : Throwable(message) {
    companion object : KLogging()

    private val _cause = AtomicReference<Throwable>(null)

    override fun fillInStackTrace(): Throwable {
        return if (logger.isDebugEnabled) {
            super.fillInStackTrace()
        } else {
            this
        }
    }

    override var cause: Throwable?
        get() = _cause.get()
        set(value) {
            if (!_cause.compareAndSet(null, value)) {
                throw IllegalStateException("Cannot modify cause because it's already set (see cause of this one)", _cause.get())
            }
        }
}

class CallNotExecutedException(message: String?) : SuspendAwareThrowable(message)

internal class CallFailedException(message: String?) : Throwable(message)

// retrofit2 async Call to suspend fun interoperability
suspend fun <T> Call<T>.invokeAsync(): T {
    val channel = Channel<T>(capacity = UNLIMITED)
    val callSite = CallNotExecutedException(request().url()?.toString()) // remember invocation point
    enqueue(object : Callback<T> {
        override fun onResponse(call: Call<T>, response: retrofit2.Response<T>) {
            val result = response.body()
            if (result != null && call.isExecuted && response.isSuccessful) {
                channel.offer(result)
            } else {
                channel.cancel(CallFailedException(response.errorBody()?.string()))
            }
        }

        override fun onFailure(call: Call<T>, t: Throwable) {
            channel.cancel(t)
        }
    })
    return try {
        channel.receive()
    } catch (t: Throwable) {
        callSite.cause = t
        throw callSite
    }
}