open/4 option: flush(FlushType)
QP_stream: unsigned char flush_type
This field specifies whether or not the characters
buffered in an output stream can be written out immediately
as a partial record. It is not used for an input stream.
Characters written to an output stream are buffered until the current record
is terminated or the output buffer overflows.
When an output record is terminated, it is passed to the bottom
layer of the write function of the stream. The completed record
is either written to the associated device of the stream or
further buffered by the bottom layer write function.
If the output buffer overflows, or flush_output/1 is called,
buffered characters may be forced out through flushing
the output stream.
The possible values for flush_type are:
QP_FLUSH_ERROR
flush(error) in open/4.
It is an error to flush the output stream. Any call to flush_output/1
or QP_flush() is an error.
QP_FLUSH_FLUSH
flush(flush) in open/4.
Write out any characters in the output buffer to the associated device
of the stream. The host system must permit writing out of partial
records to support this option. The bottom layer flush function
must be supplied for the output stream.