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From: libes@nbs-amrf.UUCP (Don Libes)
Newsgroups: net.unix-wizards
Subject: asynchronous timed I/O.  How?
Message-ID: <34@nbs-amrf.UUCP>
Date: Sat, 19-Oct-85 23:06:22 EDT
Article-I.D.: nbs-amrf.34
Posted: Sat Oct 19 23:06:22 1985
Date-Received: Tue, 22-Oct-85 06:22:58 EDT
Distribution: net
Organization: National Bureau of Standards
Lines: 21

I am familiar with asynchronous i/o via fcntl() & SIGIO and timed i/o
via timers & alarms.  Is it possible to get both at the same time (on 4.
2)?  I have a need for something like:  

/* fd is non-blocking */
timed_read(fd,buffer,length,timeout)

The only possibility (short of interrupting on every char - is that
really feasible?) I've considered is setting a timer and when it goes
off, checking via FIONCTL when the i/o would complete or not.  But
this means that all my reads will always take the max time allowed.

Any suggestions?

Also (if you've gotten this far), I need to catch an interrupt when
timeout occurs OR the read completes (and set a status).  So my final
version would look like:

timed_read(fd,buffer,length,timeout,&status,function)

Don Libes {seismo,umcp-cs}!nbs-amrf!libes