close

Closes the queue. A closed queue cannot be re-opened.

After the call to close completes, the following are true:

• closed? will return true

• close will be ignored.

• calling enq/push/<< will return nil.

• when empty? is false, calling deq/pop/shift will return an object from the queue as usual.

ClosedQueueError is inherited from StopIteration, so that you can break loop block.

Example:

    q = Queue.new
    Thread.new{
      while e = q.deq # wait for nil to break loop
        # ...
      end
    }
    q.close