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队列中的顺序处理。有多种方法fs2.Stream可以管理元素的发射方式。 fixedRate, fixedDelay, awakeEvery, awakeDelay. 我想要一个顺序处理。例如，没有元素被推入队列，直到其中的元素被拉出。

我发现 fixedDelay 方法可以做到这一点，但是当我使用它时，它并没有按预期工作。这是我尝试过的：

import cats.effect.{ExitCode, IO, IOApp, Timer}
import fs2._
import fs2.concurrent.Queue

import scala.concurrent.duration._
import scala.util.Random
class Tst(q1: Queue[IO, (Double, IO[Long])])(
  implicit timer: Timer[IO]
) {

  val streamData = Stream.emit(1)
  val scheduledStream = Stream.fixedDelay[IO](10.seconds) >> streamData

  def storeInQueue: Stream[IO, Unit] = {
    scheduledStream
      .evalTap(n => IO.delay(println(s"Pushing $n to Queue")))
      .map { n =>
        val entryTime =
          timer.clock.realTime(java.util.concurrent.TimeUnit.SECONDS)
        (n.toDouble, entryTime)
      }
      .through(q1.enqueue)
  }
  def getFromQueue: Stream[IO, Unit] = {
    q1.dequeue
      .evalTap(_ => timer.sleep(Random.between(10, 30).seconds))
      .map { n =>
        val exitTime =
          timer.clock.realTime(java.util.concurrent.TimeUnit.SECONDS)
        (n._1, exitTime)
      }
      .evalMap(n => IO.delay(println(s"Pulling from queue $n")))
  }
}

object Five2 extends IOApp {

  override def run(args: List[String]): IO[ExitCode] = {
    val program = for {
      q <- Queue.bounded[IO, (Double, IO[Long])](1)
      b = new Tst(q)
      _ <- b.storeInQueue.compile.drain.start

      _ <- b.getFromQueue.compile.drain

    } yield ()
    program.as(ExitCode.Success)
  }
}

我得到这个：

Pushing 1 to Queue
Pushing 1 to Queue
Pulling from queue (1.0,IO$301748227)
Pushing 1 to Queue
Pulling from queue (1.0,IO$914911384)
Pushing 1 to Queue
Pulling from queue (1.0,IO$1022209005)
Pushing 1 to Queue
Pushing 1 to Queue
Pulling from queue (1.0,IO$1801897948)

预期输出：

Pushing 1 to Queue
Pulling from queue (1.0,IO$1022209005)
Pushing 1 to Queue
Pulling from queue (1.0,IO$1801897948)
Pushing 1 to Queue
Pulling from queue (1.0,IO$1801897948)
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