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Date:      Tue, 12 Dec 2000 13:06:56 -0800 (PST)
From:      John Baldwin <jhb@FreeBSD.ORG>
To:        Garrett Wollman <wollman@khavrinen.lcs.mit.edu>
Cc:        arch@FreeBSD.ORG
Subject:   Re: An opaque refcount type
Message-ID:  <XFMail.001212130656.jhb@FreeBSD.org>
In-Reply-To: <200012122100.QAA53113@khavrinen.lcs.mit.edu>

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On 12-Dec-00 Garrett Wollman wrote:
> In article <mit.lcs.mail.freebsd-arch/XFMail.001212122450.jhb@FreeBSD.org>
> you write:
>>an opaque refcount_t type.
> 
> By definition, C typedefs can never be opaque.  Only pointers to
> incomplete aggregates (i.e., `struct foo *' or `union bar *') are
> opaque in C.

It's opaque in the sense that a user doesn't know what it is inside it.  This
means we can freely change around the implementation.  For example, in the
INVARIANTS case it adds in lots of extra checks, but to ensure correctness, it
has to add in a mutex to use.

> In any event, I think requiring a functional interface to reference
> counts is probably a Bad Idea.

Would you prefer C macros to static inline's then?

> -GAWollman

-- 

John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.Baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/


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