ds

markerAllocator.scala

abstract class Marker(val g: AnyRef)
// Codegen 100 - 1000 of these, or use ASM to generate them on the fly
class Marker1(g: AnyRef) extends Marker(g)
class Marker2(g: AnyRef) extends Marker(g)

type Fn = (AnyRef) => Marker

class Markers(markers: List[(Fn, Class[_])], mmap: Map[Manifest[T], (Fn, Class[_])] = Map.empty) {
  def get[T](implicit mf: Manifest[T]): (Fn, Class[_], Markers) = {
    mmap.get(mf) { case (fn,cls) =>
      (fn, cls, this)
    }
    .getOrElse {
      (markers.head._1, markers.head._2, new Markers(markers.tail, mmap + (mf -> fn)))
    }
  }
}

var markers: Markers = new Markers(List((fn1, classOf[Marker1]), (fn2, classOf[Marker2], (fn3, classOf[Marker3], ...))
val mutex = new Object

class MarkerRecord[T](val fn: Fn, cls: Class[_])

implicit def getMarker[T:Manifest]: MarkerRecord[T] = {
  mutuex.synchronized {
    val (fn, cls, markers) = markers.get[T]
    new MarkerRecord[T](fn, cls)
  }
}

// Now do: implicitly[MarkerRecord[T]] and you will get the unique value for this type T.
// This prevents type erasure from fucking up Kryo.