New returns a reader that will asynchronously read from the supplied Reader into a number of buffers each of size BufferSize It will start reading from the input at once, maybe even before this function has returned.

BufferSize is the default size of the async buffer.

ErrorStreamAbandoned is returned when the input is closed before the end of the stream.

AsyncReader will do async read-ahead from the input reader and make the data available as an io.Reader.