Error handling in Scala with Futures

Question

The following method uses a future to send email and then catches any exception mail.send might throw:

sendEmail(from: String, recipients: Seq[String],
  subject: String, body: (Option[Txt], Option[Html])) = Try {

  import com.typesafe.plugin._
  import scala.concurrent.future
  import play.api.libs.concurrent.Execution.Implicits.defaultContext

  val mail = use[MailerPlugin].email

  mail.addFrom(from)
  recipients.map(mail.addRecipient(_))
  subject.map(mail.setSubject(subject)

  future {
    try {
      mail.send(body._1.map(_.body).getOrElse(""), body._2.map(_.body).getOrElse(""))
    } catch {
      case NonFatal(e) => Logger.warn("[%s] error sending email".format(ClassName, subject), e)
    }
  }
}

The method above returns either Successor Failure – for example mail.addFrom might throw an exception if the sender email is invalid. Having said that, is it correct the way I deal with possible exceptions thrown inside the future block?

senia senia · Accepted Answer · 2013-12-28T06:54:27

You don't need try in future.

val f = future {
  mail.send(body._1.map(_.body).getOrElse(""), body._2.map(_.body).getOrElse(""))
}

f.onFailure{
  case NonFatal(e) => Logger.warn("[%s] error sending email".format(ClassName, subject), e)
}

Future could contain successful result or failure in Try container. You could get Try in onComplete method, or transform Failure to Success using recover method.

Error handling in Scala with Futures

1 Answers