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import com.twitter.concurrent.AsyncStream | |
import com.twitter.util._ | |
object Merge { | |
def merge[E](streams: Seq[AsyncStream[E]]): AsyncStream[E] = { | |
def inner(next: Seq[Future[Option[(E, () => AsyncStream[E])]]]): AsyncStream[E] = { | |
AsyncStream.fromFuture(Future.select(next)) flatMap { | |
case (Return(Some((head, tail))), tails) => | |
AsyncStream(head) ++ inner(tail().uncons +: tails) | |
case (Return(None), Nil) => | |
AsyncStream.empty | |
case (Throw(cause), tails) => | |
AsyncStream.fromFuture(Future.exception(cause)) | |
case (_, tails) => | |
inner(tails) | |
} | |
} | |
inner(streams.map(_.uncons)) | |
} | |
def short[E](stream: AsyncStream[E]): (AsyncStream[E], Closable) = { | |
def inner(data: AsyncStream[E], control: AsyncStream[E]): AsyncStream[E] = { | |
AsyncStream.fromFuture(Future.select(Seq(data.uncons, control.uncons))) flatMap { | |
case (Return(None), _) => | |
AsyncStream.empty | |
case (Return(Some((head, tail))), _) => | |
AsyncStream(head) ++ inner(tail(), control) | |
case (Throw(cause), _) => | |
AsyncStream.fromFuture(Future.exception(cause)) | |
} | |
} | |
val promise = Promise[Unit]() | |
val trigger = AsyncStream.fromFuture( | |
promise.map(_ => AsyncStream.empty) | |
).flatten | |
val closable = Closable.make { _ => | |
promise.updateIfEmpty(Return.Unit) | |
Future.Done | |
} | |
(inner(stream, trigger), closable) | |
} | |
} |
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