class IntervalResponse::RackBodyWrapper

The Rack body wrapper is intended to be returned as the third element of the Rack response triplet. It supports the each method and will call to the IntervalResponse object given to it at instantiation, filling up a pre-allocated String object with the bytes to be served out. The String object will then be repeatedly yielded to the Rack webserver with the response data. Since Ruby strings are mutable, the String object will be sized to a certain capacity and reused across calls to save allocations.

Constants

CHUNK_SIZE

Default size of the chunk (String buffer) which is going to be yielded to the caller of the `each` method. Set toroughly one TCP kernel buffer

Public Class Methods

new(with_interval_response, chunk_size:) click to toggle source
# File lib/interval_response/rack_body_wrapper.rb, line 15
def initialize(with_interval_response, chunk_size:)
  @chunk_size = chunk_size
  @interval_response = with_interval_response
end

Public Instance Methods

each() { |read| ... } click to toggle source
# File lib/interval_response/rack_body_wrapper.rb, line 20
def each
  buf = String.new(capacity: @chunk_size)
  @interval_response.each do |segment, range_in_segment|
    case segment
    when IntervalResponse::LazyFile
      segment.with do |file_handle|
        with_each_chunk(range_in_segment) do |offset, read_n|
          file_handle.seek(offset, IO::SEEK_SET)
          yield file_handle.read(read_n, buf)
        end
      end
    when String
      with_each_chunk(range_in_segment) do |offset, read_n|
        yield segment.slice(offset, read_n)
      end
    when IO, Tempfile
      with_each_chunk(range_in_segment) do |offset, read_n|
        segment.seek(offset, IO::SEEK_SET)
        yield segment.read(read_n, buf)
      end
    else
      raise TypeError, "RackBodyWrapper only supports IOs or Strings"
    end
  end
ensure
  buf.clear
end

Private Instance Methods

with_each_chunk(range_in_segment) { |unit_offset, chunk_size| ... } click to toggle source
# File lib/interval_response/rack_body_wrapper.rb, line 50
def with_each_chunk(range_in_segment)
  range_size = range_in_segment.end - range_in_segment.begin + 1
  start_at_offset = range_in_segment.begin
  n_whole_segments, remainder = range_size.divmod(@chunk_size)

  n_whole_segments.times do |n|
    unit_offset = start_at_offset + (n * @chunk_size)
    yield unit_offset, @chunk_size
  end

  if remainder > 0
    unit_offset = start_at_offset + (n_whole_segments * @chunk_size)
    yield unit_offset, remainder
  end
end