class Hopper

# File lib/hopper.rb, line 6
def initialize(capacity: 10, timeout: 2, always: false, exact: true, &block)
  @capacity = capacity
  @timeout  = timeout
  @always   = always
  @exact    = exact

  @running = false
  @condvar = ConditionVariable.new
  @hopper_mutex = Mutex.new
  @signal_mutex = Mutex.new
  @hopper = Array.new
  @block = block
  @thread = nil
  
  start
end

# File lib/hopper.rb, line 62
def <<(item)
  if !@running
    raise "Hopper is not running."
  end
  @hopper_mutex.synchronize {
    @hopper << item
    if @hopper.size >= @capacity then
      @condvar.signal
      @condvar.wait(@hopper_mutex) if @exact
    end
  }
end

# File lib/hopper.rb, line 56
def size
  @hopper_mutex.synchronize {
    return @hopper.size
  }
end

# File lib/hopper.rb, line 23
def start
  @running = true
  @thread = Thread.new do
    while @running
      timed_out = false

      # wait for signal or timeout
      @signal_mutex.synchronize {
        if @condvar.wait(@signal_mutex, @timeout) then
          timed_out = false
        else
          timed_out = true
        end
      }

      # yield passed block
      @hopper_mutex.synchronize {
        if @always || @hopper.size > 0
          @block.call @hopper, timed_out if @block
        end
        @hopper = Array.new
        @condvar.signal if @exact
      }

    end
  end
end

# File lib/hopper.rb, line 51
def stop
  @running = false
  @thread.join
end