Re: File Locking
>>>>> "Christian" == Christian Schwarz <schwarz@monet.m.isar.de> writes:
Christian> Karl, thanks for the nice summary!
You're welcome. :-)
Christian> On 16 Jun 1997, Karl M. Hegbloom wrote:
>> ** Publib looks like it might already be the library needing to
>> be created that was mentioned earlier... or at least a very
>> good start.
Christian> Thanks for pointing that out! I just had a look at
Christian> "publib" and the "lockfile.c" is really very
Christian> concrete. (There is no documentation, though :-( )
No documentation? Sure there is. There's a manual page for every
function in the libc, and if you've got Emacs or XEmacs, and
`libc-mode', you can look up the docs in the TeXinfo with a few
keypushes. To read a manual page, just type {M-x man ENTER} and the
name of the manual you want. It defaults to the word the cursor was
on.
I wonder, should it utilize libuuid in some way? (I've a lot of
reading to do...) It seems that what should happen is that when a
lockfile is made, inside it should be the `sysid' of the computer
creating the lock, as well as the PID of the process on that computer.
I think the real way is for the `flock' structure, (through
<fcntl.h>) to contain a l_sysid field. With that, the kernel will
have a place to keep track of which machine holds the lock on a file.
It should be supported by the kernel-level nfs system, so that a
normal `flock', `fcntl', or `lockf' will work across nfs, without the
need for a dotfile kludge-hammer. I really need to read a lot more
about this type of thing. I've a feeling it will built into the next
major kernel release.
Christian> If we choose to go with "publib", someone would have to
Christian> change the static lib into a shared one, but this is
Christian> quite easy.
Ok.. Lars Wirzenius <liw@iki.fi> is the author and maintainer of
publib. Lars, are you reading us?
Christian> [snip]
>> Q: Who will do the work?
Christian> This is really a good question. Don't we have a
Christian> volunteer here on debian-devel?
>> I am doubtful of my own ability to be of much help... I'd like
>> to see what gets done by the programmer though.
Christian> If you are intrested in doing it, we don't care if you
Christian> have experience or not :-)
Ok, I'll try. I can learn as we go. I know how to use XEmacs and CVS
a little bit. (That's what I've been wasting my time on, instead of
doing math homework or ...)
Christian> I'd really like to have some people start working on
Christian> this. I don't have much experience on this but I would
Christian> try to get a first version running--unless noone else
Christian> volunteers.
Lars Wirzenius? What are your plans for publib?
I just saw the upload announcement for the latest `procmail' and
`smartlist' packages, and see that they have both just been GPL'd.
That means we can utilize the locking and `robustness' code from them,
methinks...
So, mainly, we need to put together a quick `liblockfile.so', and
then create a perl interface to it? Hmmm. I wonder if SWIG would do
that easily enough?
Well... I need to get out of the mailbox for a while, and spend the
day reading source code. (and I have a Scheme assignment to finish
today also.)
--
Karl M. Hegbloom <karlheg@inetarena.com>
http://www.inetarena.com/~karlheg
Portland, OR USA
Debian GNU 1.3 Linux 2.1.36 AMD K5 PR-133
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