class Fluent::Plugin::TailInput::TailWatcher::FIFO

def <<(chunk)
  # Although "chunk" is most likely transient besides String#force_encoding itself
  # won't affect the actual content of it, it is also probable that "chunk" is
  # a reused buffer and changing its encoding causes some problems on the caller side.
  #
  # Actually, the caller here is specific and "chunk" comes from IO#partial with
  # the second argument, which the function always returns as a return value.
  #
  # Feeding a string that has its encoding attribute set to any double-byte or
  # quad-byte encoding to IO#readpartial as the second arguments results in an
  # assertion failure on Ruby < 2.4.0 for unknown reasons.
  orig_encoding = chunk.encoding
  chunk.force_encoding(from_encoding)
  @buffer << chunk
  # Thus the encoding needs to be reverted back here
  chunk.force_encoding(orig_encoding)
end