Exercise: Using dispatchers
For each of the functions below, decide if you need to set a dispatcher, and if so, which one:
createInvoice- prepares an invoice and sends it to the SaaS API using the Retrofit library. In this library, we define suspending functions. ThetoFakturowniaInvoiceDatafunction is a simple mapping.sendEmail- prepares an email and sends it using theapimethod of theSendGridclass. This is a blocking operation that returns aResponseobject.getUserOrders- gets orders made by the user from the database using the MongoDB Kotlin driver.toListis a suspending function that returns a list of orders.upscaleImage- a function that uses the TensorFlow library to upscale an image.
override suspend fun createInvoice(
invoiceData: InvoiceData,
) {
invoiceApi.postInvoice(
invoiceData.toFakturowniaInvoiceData()
)
}
interface InvoiceApi {
@POST("invoices.json")
suspend fun postInvoice(
@Body invoice: SendInvoiceData
): InvoiceCreationResponse
}
private val invoiceApi = retrofit2.Retrofit.Builder()
.baseUrl(invoiceBaseUrl)
.build()
.create(InvoiceApi::class.java)
private val sendGrid = SendGrid(API_KEY)
suspend fun sendEmail(email: Email) {
val request = Request().apply {
method = Method.POST
endpoint = "mail/send"
body = email.toSendGridEmail()
}
sendGrid.api(request)
}
private val orderCollection = mongoClient
.getDatabase("shop")
.getCollection<Order>("orders")
suspend fun getUserOrders(userId: String): List<Order> =
orderCollection
.find(eq("userId", userId))
.toList()
val model = TensorFlowModel()
suspend fun upscaleImage(image: Image): Image =
model.upscale(image)
Once you are done with the exercise, you can check your solution here.
