firstSucceededOf, returns a future containing the first successful result or contains the last failure if all futures have failed. What's wrong with it?

firstSucceededOf.scala

import scala.concurrent._
import scala.concurrent.ExecutionContext.Implicits.global
import scala.util._
import java.util.concurrent.atomic.AtomicInteger

def firstSucceededOf[T](futures: TraversableOnce[Future[T]])(implicit executor: ExecutionContext): Future[T] = {
    val p = Promise[T]()
    val size = futures.size
    val failureCount = new AtomicInteger(0)

    futures foreach { _.onComplete{
        case Success(v) => p.trySuccess(v)
        case Failure(e) =>
          val count = failureCount.incrementAndGet
          if(count == size) p.tryFailure(e)
      }
    }
    p.future
  }  

There's a bug in there: volatile isn't safe for atomic increments (use AtomicInteger).

Thanks Johannes! fixed.