librelist archives

Re: [homebrew] Proposed: keg-only brews are exempt from "cleanup"

From:

Max Howell

Date:

2011-03-13 @ 13:46

I proposed something like this several times. We sort of plan it.

But adding CURRENT to the keg is a no go. Too much stuff depends on kegs 
in racks only being viable versions, not dupes or symlinks.

But we can stick that symlink somewhere else.
On Sunday, 13 March 2011 at 00:33, Camillo wrote: 
> On 11/mar/2011, at 05.53, Adam Vandenberg wrote:
> 
> > While waiting for a more comprehensive solution for updating keg-only
> > brews (and I'm not convinced that the refactor branch solves all the
> > issues here), I propose that keg-only brews be exempt from "brew
> > cleanup".
> > 
> > So if I have readline 6.0, 6.1, and 6.2 all installed, "brew cleanup"
> > will NOT try to remove older ones, since it is keg-only, and things I
> > have installed will be linking directly to a versioned cellar path.
> > 
> > This change will let us accept some keg-only stuff that could stand to
> > be updated (readline, gettext) without causing people to have to
> > rebrew a ton of stuff all of a sudden, as happened with Readline 6.1
> > was merged in.
> > 
> > Thoughts?
> 
> We should do this instead:
> 
> Let's say you're installing formula xyz version 1.2. Ordinarily you'd 
make the installation prefix Cellar/xyz/1.2, but for keg-only formulas 
that's a problem, because then dependencies refer to that version-specific
path. So, instead, we create the directory Cellar/xyz/1.2 and a symlink 
Cellar/xyz/current -> 1.2; then we install xyz with prefix 
Cellar/xyz/current. This way, the install names of the libraries, together
with any other paths that may be saved during installation (eg paths to 
configuration files) all refer to the version-agnostic path 
Cellar/xyz/current.
> 
> When we build formula zyx, which depends on xyz, we add 
Cellar/xyz/current to the appropriate paths (instead of Cellar/xyz/1.2), 
so we are sure that zyx also points to the version-agnostic path (thus 
covering things other than libraries).
> When xyz 1.3 is released, we simply create the empty directory 
Cellar/xyz/1.3, point the symlink Cellar/xyz/current to 1.3, and again 
install with prefix Cellar/xyz/current. Since zyx was linking to 
Cellar/zyx/current/lib/libxyz.dylib and the new version of the library is 
still available at that path, everything keeps working.
> 
> Camillo
> 

On 13 March 2011 13:46, Max Howell <max@methylblue.com> wrote:
> I proposed something like this several times. We sort of plan it.
> But adding CURRENT to the keg is a no go. Too much stuff depends on kegs in
> racks only being viable versions, not dupes or symlinks.
> But we can stick that symlink somewhere else.

I'd rather we try and exhaust the install_name_tool options first
before hacking around with symlinks. This is exactly what
install_name_tool is designed for and if we run it on all executables
there shouldn't be any of these keg-only problems any more and we get
to keep our current elegant layout.

-- 
Mike McQuaid
http://mikemcquaid.com

On 13/mar/2011, at 14.46, Max Howell wrote:

> I proposed something like this several times. We sort of plan it.
> 
> But adding CURRENT to the keg is a no go. Too much stuff depends on kegs
in racks only being viable versions, not dupes or symlinks.
> 
> But we can stick that symlink somewhere else.

Good! Let's do it, then. Last time I suggested this (jan. 1) I was 
thinking of $prefix/share/homebrew/keg_only/xyz as an alternate location 
for the symlink (I assume a location inside Cellar has the same problems 
as one inside the keg). Would that work?

As an aside, if changing the directory layout of kegs requires changes in 
more than one place, that means the code could use a bit of refactoring. 
There should be a single place that tells homebrew what versions of a keg 
are installed, which one is active, and so on. That would also allow 
formulas to check for known incompatible versions of dependencies, and 
present the user with advice (something I've wanted to do before).

Camillo

How about: /usr/local/Cellar/PrivateReserve <- link the current
keg-onlys in to new folders under there.

On Sun, Mar 13, 2011 at 11:12 AM, Camillo <camillo.lists@gmail.com> wrote:
> On 13/mar/2011, at 14.46, Max Howell wrote:
>
>> I proposed something like this several times. We sort of plan it.
>>
>> But adding CURRENT to the keg is a no go. Too much stuff depends on 
kegs in racks only being viable versions, not dupes or symlinks.
>>
>> But we can stick that symlink somewhere else.
>
> Good! Let's do it, then. Last time I suggested this (jan. 1) I was 
thinking of $prefix/share/homebrew/keg_only/xyz as an alternate location 
for the symlink (I assume a location inside Cellar has the same problems 
as one inside the keg). Would that work?
>
> As an aside, if changing the directory layout of kegs requires changes 
in more than one place, that means the code could use a bit of 
refactoring. There should be a single place that tells homebrew what 
versions of a keg are installed, which one is active, and so on. That 
would also allow formulas to check for known incompatible versions of 
dependencies, and present the user with advice (something I've wanted to 
do before).
>
> Camillo
>

On Sun, Mar 13, 2011 at 11:16 AM, Adam Vandenberg <flangy@gmail.com> wrote:

> How about: /usr/local/Cellar/PrivateReserve <- link the current
> keg-onlys in to new folders under there.


I like the name, but would it cause problems having a directory in Cellar
that is not a keg?  Lots of Homebrew assumes that `ls /usr/local/Cellar`
returns a list of kegs and nothing but kegs.