Fix #24: can the add() method return a boolean indicating a 'fresh' insert

[thomascharbonnel]

No description provided.

[alexandrnikitin]

Hi Thomas, Thank you for the PR. I left few comments.

[alexandrnikitin]

still return Unit

[thomascharbonnel]

Ooops

[alexandrnikitin]

It's an additional read op that I really want to avoid. It can be done inside UnsafeBitArray but still.
What if it will be a separate method for AddAndGet semantic (needs better name for sure). WDYT?

[thomascharbonnel]

Why not for the separate method, addAndGet is not that bad (that's my way of saying that I can't think of anything clearer).
Do you think it's better to go the naive way

def addAndGet(x: T): Boolean = {
  val was_set = mightContain(x)
  add(x)
  !was_set
}

or C&P?

[alexandrnikitin]

I think the best way is a separate method in BloomFilter class and another one in UnsafeBitArray (it has the read operation there already)

UnsafeBitArray{
  def setAndGet?(index: Long): Boolean = {
    val offset = ptr + (index >>> 6) * 8L
    val long = unsafe.getLong(offset)
    if (bit not set in long) {
        unsafe.putLong(offset, long | (1L << index))
        true
    } else false
  }
}