Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
import java.time.Instant
import scala.concurrent.ExecutionContext.Implicits.global
import scala.concurrent.{Await, Future}
import scala.concurrent.duration._
case class UserInfo(userId: Int, nickname: String, emailAddress: String, account: Option[Long])
def getNicknameById(userId: Int): Future[String] = Future {
Thread.sleep(2000)
"ktz"
}
def getEmailAddressByNickname(nickname: String): Future[String] = Future {
Thread.sleep(2000)
"helloworld@example.com"
}
def getAccountInfoByNickname(nickname: String): Future[Option[Long]] = Future {
Thread.sleep(3000)
None
}
def printInterval(userInfo: UserInfo, start: Instant, end: Instant): String =
s"$userInfo take ${(end.toEpochMilli - start.toEpochMilli) / 1000} seconds"
val userId: Int = 31337
/**
* Just use for comprehension
*/
val start1: Instant = Instant.now
val fUserInfo1 = for {
nickname <- getNicknameById(userId)
emailAddr <- getEmailAddressByNickname(nickname)
accountInfo <- getAccountInfoByNickname(nickname)
} yield UserInfo(userId, nickname, emailAddr, accountInfo)
val userInfo1 = Await.result(fUserInfo1, 10 second)
val end1: Instant = Instant.now
println(printInterval(userInfo1, start1, end1)) // UserInfo(31337,ktz,helloworld@example.com,None) take 7 seconds
/**
* Calling first and use next
*/
def getEmailAndAccountTuple(fNickname: Future[String]): Future[(String, Option[Long])] =
fNickname.flatMap(nickname => {
val fEmailAddr = getEmailAddressByNickname(nickname)
val fAccountInfo = getAccountInfoByNickname(nickname)
fEmailAddr.flatMap(email => fAccountInfo.map(account => (email, account)))
})
val start2: Instant = Instant.now
val fNickname: Future[String] = getNicknameById(userId)
val fUserInfo2 = for {
nickname <- fNickname
(email, accountInfo) <- getEmailAndAccountTuple(fNickname)
} yield UserInfo(userId, nickname, email, accountInfo)
val userInfo2 = Await.result(fUserInfo2, 10 second)
val end2: Instant = Instant.now
println(printInterval(userInfo2, start2, end2)) // UserInfo(31337,ktz,helloworld@example.com,None) take 5 seconds
/**
* Use cats applicative
*/
import cats.syntax.all._
import cats.instances.future._
val start3: Instant = Instant.now
val fUserInfo3 = for {
nickname <- getNicknameById(userId)
(email, account) <- (getEmailAddressByNickname(nickname) |@| getAccountInfoByNickname(nickname)).tupled
} yield UserInfo(userId, nickname, email, account)
val userInfo3: UserInfo = Await.result(fUserInfo3, 10 second)
val end3: Instant = Instant.now
println(printInterval(userInfo3, start3, end3)) // UserInfo(31337,ktz,helloworld@example.com,None) take 5 seconds
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment