[Aptitude-devel] Resolver tiering complete.

[Daniel Burrows]

  The initial implementation of tiering in aptitude's dependency solver
is complete.

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daniel at emurlahn:~/programming/aptitude/head$ ./src/aptitude -s full-upgrade
[snip]
The following actions will resolve these dependencies:

Keep the following packages at their current version:
libauthen-dechpwd-perl [2.002-4 (unstable, now)]
libauthen-passphrase-perl [0.005-3 (now)]
nvidia-glx [173.14.09-5 (now)]
nvidia-glx-dev [173.14.09-5 (now)]

Tier: Safe actions (10000)

Accept this solution? [Y/n/q/?] n
The following actions will resolve these dependencies:

Remove the following packages:
libglu1-mesa-dev
libsdl-gfx1.2-dev
libsdl-image1.2-dev
libsdl-mixer1.2-dev
libsdl-net1.2-dev
libsdl-ttf2.0-dev
libsdl1.2-dev
libsmpeg-dev
nvidia-glx-dev

Keep the following packages at their current version:
libauthen-dechpwd-perl [2.002-4 (unstable, now)]
libauthen-passphrase-perl [0.005-3 (now)]
nvidia-glx [173.14.09-5 (now)]

Tier: Remove packages (30000)

Accept this solution? [Y/n/q/?] 
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  There's a serious lingering problem with the resolver, though.  After
implementing all this stuff, I noticed that the GUI upgrade calculator
was massively slow on my computer (in fact, I thought at first that it
was failing to terminate).  "safe-upgrade" worked fine.

  I thought at first that this might be a problem with how it sets up
the scores, or with the code to reason about a hypothetical state.
That led me to find several subtle bugs in how aptitude scores
solutions, but not the cause.  Then I realized that there's one more
difference between the two upgrade calculators: the GUI one doesn't
remove unused packages before it calculates the upgrade.  I tried
disabling this in "safe-upgrade" (by setting Aptitude::Delete-Unused to
"false") and WOW did safe-upgrade get slow.  It looks like there's a
fairly serious issue here, but I haven't been able to characterize it
yet.  I'm also not 100% sure that this is the only problem; it seems
like even taking this into account, the GUI upgrade calculator is a lot
slower than the command-line one.

  I'll look at this more tomorrow.

  Daniel