benchmark/io_copy_stream_write_socket.yml


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prelude: |
  # The goal of this is to use a synthetic (non-IO) reader
  # to trigger the read/write loop of IO.copy_stream,
  # bypassing in-kernel mechanisms like sendfile for zero copy,
  # so we wrap the /dev/zero IO object:
benchmark:
  io_copy_stream_write_socket: |
    class Zero
      def initialize
        @n = 100000
        @in = File.open('/dev/zero', 'rb')
      end

      def read(len, buf)
        return if (@n -= 1) == 0
        @in.read(len, buf)
      end
    end

    begin
      require 'socket'
      src = Zero.new
      rd, wr = UNIXSocket.pair
      pid = fork do
        wr.close
        buf = String.new
        while rd.read(16384, buf)
        end
      end
      rd.close
      IO.copy_stream(src, wr)
    rescue Errno::ENOENT, NotImplementedError, NameError
      # not *nix: missing /dev/zero, fork, or UNIXSocket
    rescue LoadError # no socket?
    ensure
      wr.close if wr
      Process.waitpid(pid) if pid
    end if IO.respond_to?(:copy_stream)
loop_count: 1