[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [List Home]
Re: [p2-dev] Projector weight function

Hi Eckart,

Thanks for the bug report. We will take a closer look at your particular case.

The way the objective function is defined in p2 is described here:
http://www.cril.univ-artois.fr/spip/publications/lash2010.pdf

The behavior you observe might be expectable.

Suppose that you have package x version 1 and x version 2

Version 1 has no dependencies and version 2 has dependencies on y z u and v.

Suppose we have a minimal penalty of 1 for installing a package (to avoid installing a non necessary package).

In that case, if the penalty for installing an "old" package for x1 is 4 for instance, then the solver prefers to install x1 for a penalty of 4 instead of x2 for a penalty of 5 (1 for each x2, y,,z, u, v).

Note that with a bigger penalty for old versions, we could still install x2.

I will check in your bug report if this is really what happens in your case.

Cheers,

Daniel
Le 20 juil. 2011 à 13:22, Langhuth, Eckart a écrit :

> Hi,
>  
> As requested I created a p2 bug for this issue
> https://bugs.eclipse.org/bugs/show_bug.cgi?id=352560
>  
> Best regards,
> Eckart
>  
> From: p2-dev-bounces@xxxxxxxxxxx [mailto:p2-dev-bounces@xxxxxxxxxxx] On Behalf Of Pascal Rapicault
> Sent: Montag, 18. Juli 2011 18:52
> To: P2 developer discussions
> Subject: Re: [p2-dev] Projector weight function
>  
> For a new install (which is the case in a tycho build), the intent is for the resolver to return the highest version available.
> For addition on top of an install or update, the algorithm is a bit more complex but should favour the highest version of the things being in the transitive closure of what is being changed.
>  
> Could you please open a bug (https://bugs.eclipse.org/bugs/enter_bug.cgi?product=Equinox) with the necessary IUs to recreate the problem.
>  
> Thx
>  
> On 2011-07-14, at 4:46 PM, Langhuth, Eckart wrote:
> 
> 
> Hi,
>  
> while investigating a problem resulting in bug
> https://bugs.eclipse.org/bugs/show_bug.cgi?id=352081
> I stumbled over the behavior of org.eclipse.equinox.internal.p2.director.Projector.
>  
> Out of curiosity. Is there a description of the weight function used to determine a solution?
> In my example a feature includes a single plugin without a version constraint. (0.0.0)
> The search scope contains two version of the required plugin.
> The solution provided by the projector contains the plugin with the smaller version.
> My assumption would have been to prefer a solution with latest plugin version.
> The difference I see is that the higher version plugin defines more dependencies.
> Is it intended to prefer a small installation over a new one?
>  
> Best regards,
> Eckart
> _______________________________________________
> p2-dev mailing list
> p2-dev@xxxxxxxxxxx
> https://dev.eclipse.org/mailman/listinfo/p2-dev
>  
> _______________________________________________
> p2-dev mailing list
> p2-dev@xxxxxxxxxxx
> https://dev.eclipse.org/mailman/listinfo/p2-dev