Make for-yields parallel

[wyozi]

For instance the futures at

cyan/app/controllers/admin/prod/Products.scala

Lines 42 to 45 in e328ea7

	prodOpt <- productsDAO.findById(prodId)
	devLicense <- productConfigDAO.getValue(prodId, "devlicense")
	recentNewLicenses <- plpDAO.findRecentNewLicenses(prodOpt.get, 15, devLicense)
	recentPings <- pingsDAO.findRecentForProduct(prodOpt.get, 15, devLicense)

will be completed sequentially instead of in parallel.

(http://stackoverflow.com/a/19046133)

[wyozi]

One solution would be changing

for {
  x <- fut1()
  y <- fut2()
  z <- fut3()
} yield (x, y, z)

to

(
  fut1() zip
  fut2() zip
  fut3()
) map {
  case (x, y, z) => (x, y, z)
}

[wyozi]

Also possible to define utility functions, i.e.

def par_tuple[E1, E2](e1: =>E1, e2: =>E2): Future[(E1, E2)] = {
  val f = future { e1 }
  val g = future { e2 }
  val h: Future[(E1, E2)] = for {
    x <- f
    y <- g
  } yield (x, y)
  h
}

(https://stackoverflow.com/questions/12923429/easy-parallel-evaluation-of-tuples-in-scala)