module LittleGhost::CodeMode::Protocol

Length-prefixed JSON framing shared by code-mode parent and child hosts. Frames are bounded before allocation and parsing.

Constants

Error: Raised for malformed or oversized frames.
MAX_FRAME_BYTES: Largest encoded JSON payload accepted by the protocol.

Public Instance Methods

dump (value)

Source

# File lib/little_ghost/code_mode/protocol.rb, line 37
def dump(value)
  payload = JSON.generate(value)
  raise Error, "Code-mode frame exceeds the size limit" if payload.bytesize > MAX_FRAME_BYTES

  [payload.bytesize].pack("N") << payload.b
rescue JSON::GeneratorError, EncodingError => error
  raise Error, "Code-mode frame cannot be encoded as JSON: #{error.message}"
end

Returns one encoded frame for value.

extract! (buffer)

Source

# File lib/little_ghost/code_mode/protocol.rb, line 48
def extract!(buffer)
  return if buffer.bytesize < 4

  length = buffer.unpack1("N")
  raise Error, "Code-mode frame exceeds the size limit" if length > MAX_FRAME_BYTES
  return if buffer.bytesize < length + 4

  payload = buffer.byteslice(4, length)
  buffer.slice!(0, length + 4)
  JSON.parse(payload)
rescue JSON::ParserError, EncodingError => error
  raise Error, "Code-mode frame is not valid JSON: #{error.message}"
end

Removes and returns one complete frame from buffer, or returns nil while more bytes are required.

read (io)

Source

# File lib/little_ghost/code_mode/protocol.rb, line 18
def read(io)
  header = read_exactly(io, 4)
  return if header.nil?

  length = header.unpack1("N")
  raise Error, "Code-mode frame exceeds the size limit" if length > MAX_FRAME_BYTES

  JSON.parse(read_exactly(io, length) || raise(EOFError, "Code-mode frame ended early"))
rescue JSON::ParserError, EncodingError => error
  raise Error, "Code-mode frame is not valid JSON: #{error.message}"
end

Reads one complete frame from io, or returns nil at clean EOF.

write (io, value)

Source

# File lib/little_ghost/code_mode/protocol.rb, line 31
def write(io, value)
  io.write(dump(value))
  io.flush if io.respond_to?(:flush)
end

Encodes value and writes one complete frame to io.