Re: [Help-stow] major stow upgrade

[Paulo J. Matos]

Only now noticed this email.. are you the new stow maintainer or you
are branching stow?

Cheers,

Paulo Matos

On Thu, Aug 9, 2007 at 1:14 AM, Kahlil Hodgson
<address@hidden> wrote:
> Hi Guys,
>
>  I've been working on a major upgrade of the "most excellent" stow
>  package -- we use this extensively for the CS&IT school's shared servers.
>
>  I thought I should let you know where I've got up to and perhaps
>  elicit some feedback :-) You can get a tarball of my current efforts from
>
>       http://goanna.cs.rmit.edu.au/~kal/stow-2.0.1.tar.gz
>
>  and I've attached a copy of the contained CHANGES file/
>
>  Haven't got around to writing much documentation yet --
>  running a bit low on spare time :-(
>
>  Kind Regards,
>
>  Kal
>  --
>  Kahlil (Kal) Hodgson
>  Senior Systems Programmer
>  SET IT Unix Team
>  RMIT University, Victoria Australia
>  Phone: +61 3 992 53208
>  Office: 10.10.17
>
>  "All parts should go together without forcing.  You must remember that
>  the parts you are reassembling were disassembled by you.  Therefore,
>  if you can't get them together again, there must be a reason.  By all
>  means, do not use a hammer."  -- IBM maintenance manual, 1925
>
>
>
>
> I have not yet patched the documentation nor set up the module installation
>  properly because I wanted to wait until a few more people to test the new
>  version and to see if you wanted to incorporate the new code into the
> existing
>  package.
>
>  Tested on an upgrade cycle here at CS&IT Should have more testing before it
>  goes public.
>
>  * Implement a test suite and support code.  This was built before
> implementing
>   any of the extra features so I could more easily check for equivalent
>   functionality.  The initial code base had to be refactored substantially
>   to allow for testing.  The test suite is not exhaustive, but it should
>   provide enough to check for regressions.
>
>  * Defer operations until all potential conflicts have been assessed.
>   We do this by traversing the installation image(s) and recording
>   the actions that need to be performed.  Redundant actions are factored
>   out, e.g., we don't want to create a link that we will later remove in
> order
>   to create a directory.  Benefits of this approach
>   1. Get to see _all_ the conflicts that are blocking an installation: you
>      don't have to deal with them one at a time.
>   2. No operations are be performed if _any_ conflicts are detected:
>      a failed stow will not leave you with a partially installed package.
>   3. Minimises the set of operations that need to be performed.
>   4. Operations are executed as a batch which is much faster
>      This can be an advantage when upgrading packages on a live system
>      where you want to minimise the amount of time when the package is
>      unavailable.
>
>  * The above implementation fixes the false conflict problem mentioned in
> the
>   info file. It also fixes the two bugs mentioned in the man page.
>
>  * Multiple stow directories now cooperate in folding/unfolding.
>
>  * Conflict messages are more uniform and informative. Verbosity and tracing
>   is more extensive and uniform ...
>
>  * Implemented option parsing via Getopt::Long
>
>  * Default command line arguments can be set via '.stowrc' and '~/.stowrc'
> files
>   (contents are parsed as they occurred on the command line).
>
>  * Support multiple actions per invocation, e.g., to update an installation
> of
>   emacs you can now do
>
>         stow -D emacs-21.3 -S emacs-21.4a
>
>   which will replace  emacs-21.3 with emacs-21.4a.
>   You can mix and match any number of actions, e.g.,
>
>         stow -S p1 p2 -D p3 p4 -S p5 -R p6
>
>   will unstow p3, p4 and p6, then stow p1, p2, p5 and p6.
>
>  * The above required a new (optional) command line arg -S to indicate
> explicitly
>   that the following pkg names should be stowed.
>
>  * New (repeatable) command line arg
>
>         --ignore='<regex>'
>
>   to suppress operating on a file matching the regex (suffix), e.g.,
>
>         --ignore='~' --ignore='\.#.*'
>
>   will ignore emacs and CVS backup files (suitable for ~/.stowrc file).
>   I opted for Perl regular expressions because they are more powerful and
>   easier to implement.
>
>  * New (repeatable) command line arg
>
>         --defer='<regex>'
>
>   will defer stowing a file matching the regex (prefix) if that file is
> already
>   stowed to a different package, e.g.,
>
>         --defer='man' --defer='info'
>
>   will cause stow to skip over pre-existing man and info pages.
>
>   Equivalently, you could use
>
>         --defer='man|info'
>
>   since the argument is just a Perl regex.
>
>  * New (repeatable) command line arg
>
>         --override='<regex>'
>
>   will force a file matching the regex (prefix) to stow even if the file is
>   already stowed to a different package, e.g.,
>
>         --override='man' --override='info'
>
>   will unstow any pre-existing man and info pages that would conflict
>   with the file we are trying to stow.
>
>   Equivalently, you could use
>
>         --override='man|info'
>
>   since the argument is just a Perl regex.
>
>  * The last two options give us a facility to manage packages with common
>   content, e.g., man pages from CPAN packages.  Using multiple stow
> directories
>   and .stowrc files can also simplify things.  In our setup we have the
>   standard /usr/local/stow directory for packages to be installed in
>   /usr/local.  Since we install a large number of extra Perl packages (195)
>   we use an additional stow directory: /usr/local/stow/perl-5.8.8-extras.
>   Both stow directories contain a '.stow' file so that they collaborate
>   appropriately.  I then use the following .stowrc file in
>   /usr/local/stow/perl-5.8.8-extras
>
>         --dir=/usr/local/stow/perl-5.8.8-extras
>         --target=/usr/local
>         --override=bin
>         --override=man
>         --ignore='perllocal.pod'
>         --ignore='\.packlist'
>         --ignore='.bs'
>
>   When I stow packages from here they automatically override any man pages
>   and binaries that may already have been stowed by another package or by
> the
>   core perl-5.8.8 installation.  For example if you want to upgrade
>   the Test-Simple package you need to override all the man pages that would
>   have been installed by the core package.  If you are upgrading CPAN, you
>   will also have to override the pre-existing cpan executable.
>
>  * By default, be less aggressive about searching for invalid symlinks when
>   unstowing.  That is, we only search for bad symlinks in the directories
>   explicitly mentioned in the installation image, and do not dig down into
>   other subdirs.  Digging down into other directories can be very time
>   consuming if you have a really big tree (like with a couple of Oracle
>   installations lying around). In general the old behaviour is only
> necessary
>   when you have really stuffed up your installation by deleting a directory
>   that has already been stowed.  Doing that on a live system is somewhat
> crazy
>   and hopefully rare.  Provide an option '-p|--compat' to enable the old
>   behaviour for those needing to patch up mistakes.
>
>
>
>
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>
>



-- 
Paulo Jorge Matos - pocm at soton.ac.uk
http://www.personal.soton.ac.uk/pocm
PhD Student @ ECS
University of Southampton, UK
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