From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin-developers@cygwin.com
Subject: Re: About the dll search algorithm of dlopen (patch-r3)
Date: Fri, 26 Aug 2016 11:18:00 -0000 [thread overview]
Message-ID: <20160826111824.GQ9783@calimero.vinschen.de> (raw)
In-Reply-To: <20160826105908.GO9783@calimero.vinschen.de>
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On Aug 26 12:59, Corinna Vinschen wrote:
> Hi Michael,
>
> On Aug 25 19:48, Michael Haubenwallner wrote:
> > Using tmp_pathbuf now, wrapped behind some trivial allocator - which
> > might fit better somewhere else than to dlfcn.cc?
> >
> > BTW: Is it really intended for tmp_pathbuf to have a single active
> > instance (per thread) at a time?
>
> Well, yes. tmp_pathbuf is meant to be initialized on function entry
> (more or less, depends). It's supposed to exist only once per frame.
> When the frame goes out of scope, the tmp_pathbuf usage counter is
> restored to the values of the parent frame.
>
> > + ATTENTION: Requesting memory from an instance of tmp_pathbuf breaks
> > + when another instance on a newer stack frame has provided memory. */
>
> I don't understand this comment, though. tmp_pathbuf can be used
> multiple times in the same thread stackm see other Cygwin functions.
> What you can't do is to call a function, instantiate tmp_pathbuf,
> allocate memory in the called function, and then use it in the caller.
> Well, you *can* do that, but if you do this more than once, the same
> memory region is reused.
> That's the whole idea of tmp_pathbuf.
> Temporary per-thread memory for the current frame and it's child frames
> is allocated. If a deeper frame using tmp_pathbuf goes out of scope,
> the memory is not free'd, but recycled next time temporary memory is
> needed. The buffers are either 32K or 64K to matches the maximum long
> path length. They are now used for any purpose where larger temporary
> per-thread memory is needed, but providing temporary long path buffers
> without killing the stack was their original purposes.
So I also don't quite understand splitting off tmp_pathbuf_allocator.
Why didn't you just include a tmp_pathbuf member into class pathfinder,
kind of like this:
/* pathfinder.h */
class pathfinder
{
tmp_pathbuf tp;
[...]
};
/* dlfcn.cc */
get_full_path_of_dll()
{
pathfinder finder (); /* Has a tmp_pathbuf member */
[...]
finder.add_basename (basename);
[...]
finder.add_searchdir (dir, ...);
return true; /* finder goes out of scope, so
its tmp_pathbuf goes out of scope
so tmp_pathbuf::~tmp_pathbuf is
called and all is well. */
}
?
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
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next prev parent reply other threads:[~2016-08-26 11:18 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-01 6:39 About the dll search algorithm of dlopen Michael Haubenwallner
2016-06-01 11:09 ` Corinna Vinschen
2016-06-01 14:25 ` Michael Haubenwallner
2016-06-01 20:18 ` Corinna Vinschen
2016-06-01 23:29 ` Yaakov Selkowitz
2016-08-19 16:37 ` Michael Haubenwallner
2016-08-19 16:39 ` Michael Haubenwallner
2016-08-20 19:32 ` Corinna Vinschen
2016-08-22 12:15 ` Michael Haubenwallner
2016-08-22 12:48 ` Peter Rosin
2016-08-22 13:01 ` Michael Haubenwallner
2016-08-22 16:02 ` About the dll search algorithm of dlopen (patch-r2) Michael Haubenwallner
2016-08-22 18:37 ` Corinna Vinschen
2016-08-23 8:16 ` Corinna Vinschen
2016-08-25 17:48 ` About the dll search algorithm of dlopen (patch-r3) Michael Haubenwallner
2016-08-26 10:59 ` Corinna Vinschen
2016-08-26 11:18 ` Corinna Vinschen [this message]
2016-08-26 11:49 ` Corinna Vinschen
2016-08-29 16:50 ` Michael Haubenwallner
2016-08-30 14:51 ` Corinna Vinschen
2016-08-30 15:57 ` Michael Haubenwallner
2016-08-31 18:48 ` Corinna Vinschen
2016-09-01 8:58 ` Michael Haubenwallner
2016-08-26 14:08 ` Michael Haubenwallner
2016-08-30 13:26 ` Corinna Vinschen
2016-08-26 12:04 ` Corinna Vinschen
2016-08-29 9:24 ` Michael Haubenwallner
2016-08-30 13:35 ` Corinna Vinschen
2016-08-30 16:41 ` Michael Haubenwallner
2016-08-31 18:43 ` Corinna Vinschen
2016-08-22 18:49 ` About the dll search algorithm of dlopen Corinna Vinschen
2016-08-23 8:55 ` Michael Haubenwallner
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