Simple buffer which accumulates items until buf size is met or max time exceeded since last flush

buffer.rb

class Buffer
  attr_reader :min_buf_size, :min_buf_interval, :last_flushed
  def initialize(min_buf_size = 8, min_buf_interval = 1.0, &block)
    @min_buf_size = min_buf_size
    @min_buf_interval = min_buf_interval

    @buf = []
    @last_flushed = now
    @block = block
  end

  # Add item to buf. Flush buffer if either
  #   * min_buf_interval has passed since last flush OR
  #   * buffer size >= min_buf_size
  def add(item)
    @buf << item

    if flush?
      _flush
    end
  end

  # Override this if you want to use OOP-style inheritance for flushing buf
  def flush(buf)
    # no-op
  end

  # call finish when you want to stop buffering to flush
  # possibly remaining items
  def finish
    _flush if !empty?
  end

  def empty?
    @buf.empty?
  end

  private

  def _flush
    if @block
      @block.call(@buf.dup)
    else
      flush(@buf.dup)
    end

    @buf.clear
    @last_flushed = now
  end

  def flush?
    !empty? && (time_to_flush? || buf_full?)
  end

  def buf_full?
    @buf.size >= @min_buf_size
  end

  def time_to_flush?
    now - @last_flushed >= min_buf_interval
  end

  def now
    Time.now
  end
end