Count of buffered items

[Evan Ireland]

	I am interested in the practical application of functions that
return the number of buffered items on an input or output stream, e.g. the
number of characters in a keyboard typeahead buffer, or the number of
messages (not message sizes) in a message queue.

	I realise that it is often useful to know whether this number is
non-zero, in order to prevent blocking I/O calls, but would like to hear
from anyone who has found information about the actual number of buffered
items useful at the application level (not at the level of the buffering
mechanisms, since obviously they need to detect buffer-full conditions
etc.)

	Please reply directly by email, to E.Ireland at massey.ac.nz.