在Scala中将AsyncStream [A]强制为Seq [A]

Question

I am specifically using twitter's AsyncStream and I need to take the results of concurrent processing, and make it into a Seq, but the only way I've managed to get working is horrendous. This feels like it should be a one liner, but all my attempts with Await and force have either hung or not processed the work.

Here's what I have working - what's a more idiomatic way of doing this?

  def processWork(work: AsyncStream[Work]): Seq[Result] = {
    // TODO: make less stupid
    val resultStream = work.flatMap { processWork }
    var results : Seq[Result] = Nil
    resultStream.foreach {
      result => {
        results = results :+ result
      }
    }
    results
  }

Answer 1

Like @MattFowler pointed out - you can force the stream and wait until it's complete using:

Await.result(resultStream.toSeq, 1.second)

toSeq will start realizing the stream and return a Future[Seq[A]] that completes once all the element are resolved, as documentated here .

You can then block until the future completes by using Await.result .

Make sure your stream is finite! Calling Await.result(resultStream.toSeq, 1.second) would hang forever.