Debians commandline package manager https://git.kalnischkies.de/apt/atom?h=3.1.15 2026-01-31T16:57:06Z 2026-01-31T16:57:06Z Julian Andres Klode jak@debian.org 2026-01-31T16:57:06Z urn:sha1:c794ce0992466ab9bd45562f2c59798a10ba594f 2026-01-31T16:51:50Z Julian Andres Klode jak@debian.org 2026-01-31T16:51:50Z urn:sha1:f2ca127212bcde9921cfc31245dc44d5b3c975eb solver3: Use classical watchers and minor refactorings See merge request apt-team/apt!548 2026-01-31T16:30:20Z Julian Andres Klode jak@debian.org 2025-12-29T17:47:15Z urn:sha1:1fbb857b6b2cbddcea9e8b03aa0c766c72e91f34 Instead of tracking dependencies and reverse dependencies, install classical watchers. This vastly streamlines the propagation code and allows us to easily switch to literals in the next step. This implementation watches _all_ solutions rather than using the modern 2-watched literals scheme or the intermediate head/tail watchers. Ultimately a more effective watcher scheme would be interesting but not a significant priority seeing as most of the solver runtime is spent not in propagation but in problem translation. decision trees -------------- The new watchers produce slightly different decision trees, sometimes subtly changing solutions. Notably in various observed examples in Ubuntu 25.04, courier was installed as an MTA instead of postfix: The old decision tree was: apcupsd:amd64 -> mailutils:amd64=1:3.18-1 -> mailutils:amd64 -> postfix:amd64=3.9.1-10ubuntu1 The new decision tree is: lsb:amd64 -> lsb-core:amd64 -> courier-mta:amd64=1.3.13-1 The difference here being that lsb-core declares a mail-transport-agent dependency whereas mailutils depends on `default-mta | mail-transport-agency`; but both are effectively subject to selection at similar time. Further work is needed to optimize selection. A notable choice may also be to deal with broken packages like lsb-core that declare dependencies solely on a virtual package by reconstructing the default provider for that package utilizing default-* dependencies or similar notions. Likewise in the test suite, explanations are different in some uninstallable cases. backtracking ~~~~~~~~~~~~ The following major changes were observed in the 25.04 test suite: -tmp/regression-remove/07f0a068-36c2-11f0-b7c1-fa163e171f02:18 +tmp/regression-remove/07f0a068-36c2-11f0-b7c1-fa163e171f02:3 -tmp/regression-remove/32078f70-3734-11f0-a75a-fa163ec8ca8c:64 +tmp/regression-remove/32078f70-3734-11f0-a75a-fa163ec8ca8c:19 Other test cases showed little deviation, +/- 1, generally the same amount of backtracking. performance ~~~~~~~~~~~ Running Ubuntu's regression test suite resulted in no significant performance difference being observable. Before: 290s user time; 16.66% solver After: 299s user time; 17.36% solver Tests where run with make -j 8 and solver performance extracted perf report --symbol-filter=ResolveExternal --stdio 2026-01-31T14:10:14Z Julian Andres Klode jak@debian.org 2025-12-29T21:20:29Z urn:sha1:267fd0117a057afd88bc15bfb4f4d688804a9ab4 2026-01-31T14:08:29Z Julian Andres Klode jak@debian.org 2026-01-06T10:45:16Z urn:sha1:ceca5e8d0f9e1a1c5297ed79f00ca76c61e2140c Quite a convenient way since we need exactly lifted bool semantics 2026-01-23T20:03:36Z Julian Andres Klode jak@debian.org 2026-01-23T20:03:36Z urn:sha1:0a37f95b2d9582c5cad95725302abaf0635ee8a3 2026-01-23T11:33:54Z Julian Andres Klode jak@debian.org 2026-01-23T11:33:54Z urn:sha1:8fe21178b305c31c082489c0469dbb13cf10fe49 variants: Do not report unsupported variants in repositories See merge request apt-team/apt!546 2026-01-23T11:04:31Z Julian Andres Klode jak@debian.org 2026-01-23T11:03:04Z urn:sha1:49e80c2d9061372e0ec697be43bcba4c451b7752 We configure all variants the CPU supports as active, but repositories usually do not provide all of them, so let's not be noisy. 2026-01-20T13:57:33Z Julian Andres Klode jak@debian.org 2026-01-20T13:57:33Z urn:sha1:9cb74f8992db1d21b091147ca3791531b3c43a73 why: Render info about all providers on virtual packages See merge request apt-team/apt!545 2026-01-20T13:07:15Z Julian Andres Klode jak@debian.org 2026-01-20T13:04:20Z urn:sha1:34876ed2e5cdf504e2a4f9721486d279ae5f3be6 Refactor code into a doOne helper lambda, and then add loop over the providers to use it. This fixes a crash seen by Benjamin in a nice way than just failing :) Reported-by: Benjamin Drung