| 1 |
-----BEGIN PGP SIGNED MESSAGE----- |
| 2 |
Hash: SHA1 |
| 3 |
|
| 4 |
Hi everyone, |
| 5 |
|
| 6 |
Please consider a blocker syntax extension, for inclusion in EAPI 2, |
| 7 |
which will serve to indicate that conflicting packages may be |
| 8 |
temporarily installed simultaneously when upgrading or installing a |
| 9 |
series of packages. When temporary simultaneous installation of |
| 10 |
conflicting packages occurs, the installation of a newer package may |
| 11 |
overwrite any colliding files that belong to an older package which |
| 12 |
is explicitly blocked. When such a file collision occurs, the |
| 13 |
colliding files will cease to belong to the older package, and they |
| 14 |
will remain installed after the older package is eventually |
| 15 |
uninstalled. The older package will be uninstalled only after any |
| 16 |
newer blocking packages have been merged on top of it. I have |
| 17 |
written a blog entry [1] which shows some specific examples of this |
| 18 |
process in action. |
| 19 |
|
| 20 |
In EAPI 2, I suggest that we introduce a new !!atom syntax to |
| 21 |
indicate blockers for which temporary simultaneous installation with |
| 22 |
a blocked package is not allowed. This way we will be able to |
| 23 |
continue to use the existing !atom syntax, but slightly change it's |
| 24 |
existing meaning so it serves to indicate that temporary |
| 25 |
simultaneous installation with a blocked package will be allowed. By |
| 26 |
using this approach, we will be able to use the !atom syntax for the |
| 27 |
majority of blockers, and we'll only have to use the new !!atom |
| 28 |
syntax for special cases in which temporary simultaneous |
| 29 |
installation of blocking packages should not be allowed. |
| 30 |
|
| 31 |
With >=sys-apps/portage-2.1.5, temporary simultaneous installation |
| 32 |
of blocking packages is already allowed in some cases, but since the |
| 33 |
current blocker syntax does not express all of the needed |
| 34 |
information, it relies on heuristics in order to judge whether or |
| 35 |
not temporary simultaneous installation of conflicting packages will |
| 36 |
be allowed [2]. In practice, these heuristics appear to be |
| 37 |
sufficient in many cases. However, in some cases, such as bug 234886 |
| 38 |
[3], additional information is needed in order to confirm that |
| 39 |
simultaneous installation of conflicting packages should be allowed. |
| 40 |
|
| 41 |
As a workaround for bug 234886, I have temporarily removed e2fsprogs |
| 42 |
from the system set in order to force the blocker pass the heuristic |
| 43 |
test that is employed by >=sys-apps/portage-2.1.5. This workaround |
| 44 |
is possible since e2fsprogs is still pulled in as a dependency of |
| 45 |
util-linux (which is also a member of the system set) in the |
| 46 |
relevant profiles. Since removing e2fsprogs from the system set is |
| 47 |
clearly suboptimal, and workarounds like that won't necessarily be |
| 48 |
feasible in similar cases that arise, we need to extend blocker |
| 49 |
syntax to convey the information about when temporary simultaneous |
| 50 |
installation of conflicting packages should be allowed. |
| 51 |
|
| 52 |
Does the suggested blocker syntax extension seem like a good |
| 53 |
solution to the problem? Would anybody like to discuss any |
| 54 |
alternative approaches? |
| 55 |
|
| 56 |
[1] |
| 57 |
http://planet.gentoo.org/developers/zmedico/2008/05/09/blocking_package_file_collisions |
| 58 |
[2] |
| 59 |
http://dev.gentoo.org/~zmedico/portage/doc/portage.html#dependency-resolution-package-modeling-conflicts |
| 60 |
[3] http://bugs.gentoo.org/show_bug.cgi?id=234886 |
| 61 |
|
| 62 |
- -- |
| 63 |
Thanks, |
| 64 |
Zac |
| 65 |
-----BEGIN PGP SIGNATURE----- |
| 66 |
Version: GnuPG v2.0.9 (GNU/Linux) |
| 67 |
|
| 68 |
iEYEARECAAYFAki7HW4ACgkQ/ejvha5XGaMkUACfTVsOqv9mPUO0BULfoCwTerLF |
| 69 |
AAUAoKW2Firg7zw/BaoX+FTlRfWE6/zZ |
| 70 |
=TY+V |
| 71 |
-----END PGP SIGNATURE----- |
Archives