Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!gatech!hubcap!ncrcae!ncr-sd!crash!ford
From: ford@crash.CTS.COM (Michael Ditto)
Newsgroups: comp.sys.amiga
Subject: Re: MCC pipes, and what do SysV named pipes really do?
Message-ID: <1218@crash.CTS.COM>
Date: Sat, 13-Jun-87 00:11:02 EDT
Article-I.D.: crash.1218
Posted: Sat Jun 13 00:11:02 1987
Date-Received: Sat, 20-Jun-87 20:08:49 EDT
References: <1174@crash.CTS.COM> <279@louie.udel.EDU> <3872@jade.BERKELEY.EDU> <149@sugar.UUCP>
Reply-To: ford@crash.CTS.COM (Michael Ditto)
Organization: Crash TS, El Cajon, CA
Lines: 16
Keywords: usg System V named pipes fifos
Summary: not very useful

In article <149@sugar.UUCP> peter@sugar.UUCP (Peter DaSilva) writes:
>Similarly a writer doesn't hang: it can just write its bytes and get out of
>there without waiting for a reader to show up. You also don't hang on close
>...

Actually, you do hang if the pipe is full.  This makes System V named pipes
essentially useless in my opinion.  The main application I see for them is something
like a spooler queue.  But if the server reading the pipe is busy, and several
clients append their requests to the pipe, it becomes full, and the next attempt
to queue a request will block.  It's too bad there is no way to have a 'FIFO file',
where the full file system capabilities are available (unlimited and variable length
files), but where the act of reading some bytes causes them to be 'deleted'.

An interesting aspect of System V named pipes, though, is that their contents are
maintained across reboots.  It's just the size limit (usually 5K) that makes them
useless.