Path: utzoo!utgpu!watserv1!watdragon!lion!ccplumb
From: ccplumb@lion.waterloo.edu (Colin Plumb)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Semaphores
Keywords: Exec Semaphore
Message-ID: <20813@watdragon.waterloo.edu>
Date: 12 Feb 90 21:09:55 GMT
References: <00253.AA00253@miroc>
Sender: daemon@watdragon.waterloo.edu
Reply-To: ccplumb@lion.waterloo.edu (Colin Plumb)
Organization: U. of Waterloo, Ontario
Lines: 21

In article <00253.AA00253@miroc> caw@miroc.UUCP (Christopher A. Wichura) writes:
> I am about to start fooling with semaphores for a program I am working on
> and have run across something that bothers me.  There is no opposite to
> InitSemaphore() that I can find.  When my program wants to exit, which
> includes closing down the semaphore, what do I do?  Is it `safe' to simply
> drop the semaphore if all ObtainSemaphore()s have been matched by an equal
> number of ReleaseSemaphore()s?  This will be a private semaphore so I don't
> have to worry about removing it from the system lists, or at least so it
> would seem.

It is safe.  A semaphore is just a private data structure manipulated by
Exec which you have to allocate.  Exec only manipulates it on an explicit
call from you, so as long as no processes are dangling off it (which would
result in unrecoverable resources, as the processes would never run and
exit), if you can guarantee that nobody will ever again pass the semaphore
to one of the Exec routines (which is true in your case), you can deallocate
it like any other piece of memory.  InitSemaphore() just sets up the data
structure to the right value; there is no corresponding need to clear
memory before deallocating it.
-- 
	-Colin