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551 lines
21 KiB
551 lines
21 KiB
# -*- coding: utf-8 -*-
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# Copyright (C) 2012 Niels Thykier <niels@thykier.net>
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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from functools import partial
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from itertools import filterfalse
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from britney_util import iter_except
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class InstallabilityTester(object):
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def __init__(self, universe, revuniverse, testing, broken, essentials,
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safe_set, eqv_table):
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"""Create a new installability tester
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universe is a dict mapping package tuples to their
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dependencies and conflicts.
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revuniverse is a set of all packages with reverse relations
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testing is a (mutable) set of package tuples that determines
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which of the packages in universe are currently in testing.
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broken is a (mutable) set of package tuples that are known to
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be uninstallable.
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essentials is a set of packages with "Essential: yes".
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safe_set is a set of all packages which have no conflicts and
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either have no dependencies or only depends on other "safe"
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packages.
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Package tuple: (pkg_name, pkg_version, pkg_arch)
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- NB: arch:all packages are "re-mapped" to given architecture.
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(simplifies caches and dependency checking)
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"""
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self._universe = universe
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self._testing = testing
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self._broken = broken
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self._essentials = essentials
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self._revuniverse = revuniverse
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self._safe_set = safe_set
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self._eqv_table = eqv_table
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# Cache of packages known to be broken - we deliberately do not
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# include "broken" in it. See _optimize for more info.
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self._cache_broken = set()
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# Cache of packages known to be installable
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self._cache_inst = set()
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# Per "arch" cache of the "minimal" (possibly incomplete)
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# pseudo-essential set. This includes all the packages that
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# are essential and packages that will always follow.
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#
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# It may not be a complete essential set, since alternatives
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# are not always resolved. Noticably cases like "awk" may be
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# left out (since it could be either gawk, mawk or
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# original-awk) unless something in this sets depends strictly
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# on one of them
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self._cache_ess = {}
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def compute_testing_installability(self):
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"""Computes the installability of packages in testing
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This method computes the installability of all packages in
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testing and caches the result. This has the advantage of
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making "is_installable" queries very fast for all packages
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in testing.
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"""
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check_inst = self._check_inst
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cbroken = self._cache_broken
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cache_inst = self._cache_inst
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eqv_table = self._eqv_table
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testing = self._testing
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tcopy = [x for x in testing]
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for t in filterfalse(cache_inst.__contains__, tcopy):
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if t in cbroken:
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continue
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res = check_inst(t)
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if t in eqv_table:
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eqv = (x for x in eqv_table[t] if x in testing)
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if res:
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cache_inst.update(eqv)
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else:
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eqv_set = frozenset(eqv)
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testing -= eqv_set
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cbroken |= eqv_set
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def are_equivalent(self, p1, p2):
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"""Test if p1 and p2 are equivalent
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Returns True if p1 and p2 have the same "signature" in
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the package dependency graph (i.e. relations can not tell
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them appart sematically except for their name)
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"""
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eqv_table = self._eqv_table
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return p1 in eqv_table and p2 in eqv_table[p1]
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def add_testing_binary(self, pkg_name, pkg_version, pkg_arch):
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"""Add a binary package to "testing"
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If the package is not known, this method will throw an
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Keyrror.
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"""
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t = (pkg_name, pkg_version, pkg_arch)
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if t not in self._universe:
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raise KeyError(str(t))
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if t in self._broken:
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self._testing.add(t)
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elif t not in self._testing:
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self._testing.add(t)
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self._cache_inst = set()
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if self._cache_broken:
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# Re-add broken packages as some of them may now be installable
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self._testing |= self._cache_broken
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self._cache_broken = set()
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if t in self._essentials and t[2] in self._cache_ess:
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# Adds new essential => "pseudo-essential" set needs to be
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# recomputed
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del self._cache_ess[t[2]]
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return True
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def remove_testing_binary(self, pkg_name, pkg_version, pkg_arch):
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"""Remove a binary from "testing"
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If the package is not known, this method will throw an
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Keyrror.
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"""
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t = (pkg_name, pkg_version, pkg_arch)
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if t not in self._universe:
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raise KeyError(str(t))
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self._cache_broken.discard(t)
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if t in self._testing:
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self._testing.remove(t)
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if t[2] in self._cache_ess and t in self._cache_ess[t[2]][0]:
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# Removes a package from the "pseudo-essential set"
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del self._cache_ess[t[2]]
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if t not in self._revuniverse:
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# no reverse relations - safe
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return True
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if t not in self._broken and t in self._cache_inst:
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# It is in our cache (and not guaranteed to be broken) - throw out the cache
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self._cache_inst = set()
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return True
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def is_installable(self, pkg_name, pkg_version, pkg_arch):
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"""Test if a package is installable in this package set
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The package is assumed to be in "testing" and only packages in
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"testing" can be used to satisfy relations.
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Returns True iff the package is installable.
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Returns False otherwise.
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"""
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t = (pkg_name, pkg_version, pkg_arch)
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if t not in self._universe:
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raise KeyError(str(t))
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if t not in self._testing or t in self._broken:
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return False
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if t in self._cache_inst:
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return True
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return self._check_inst(t)
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def _check_inst(self, t, musts=None, never=None, choices=None):
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# See the explanation of musts, never and choices below.
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cache_inst = self._cache_inst
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if t in cache_inst and not never:
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# use the inst cache only for direct queries/simple queries.
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cache = True
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if choices:
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# This is a recursive call, where there is no "never" so far.
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# We know t satisfies at least one of the remaining choices.
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# If it satisfies all remaining choices, we can use the cache
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# in this case (since never is empty).
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#
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# Otherwise, a later choice may be incompatible with t.
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for choice in choices:
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if t in choice:
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continue
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cache = False
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break
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if cache:
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return True
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universe = self._universe
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testing = self._testing
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cbroken = self._cache_broken
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safe_set = self._safe_set
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eqv_table = self._eqv_table
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# Our installability verdict - start with "yes" and change if
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# prove otherwise.
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verdict = True
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# set of packages that must be installed with this package
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if musts is None:
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musts = set()
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musts.add(t)
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# set of packages we can *never* choose (e.g. due to conflicts)
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if never is None:
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never = set()
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# set of relations were we have a choice, but where we have not
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# committed ourselves yet. Hopefully some choices may be taken
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# for us (if one of the alternatives appear in "musts")
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if choices is None:
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choices = set()
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# The subset of musts we haven't checked yet.
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check = set([t])
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if len(musts) == 1:
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# Include the essential packages in testing as a starting point.
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if t[2] not in self._cache_ess:
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# The minimal essential set cache is not present -
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# compute it now.
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(start, ess_never) = self._get_min_pseudo_ess_set(t[2])
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else:
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(start, ess_never) = self._cache_ess[t[2]]
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if t in ess_never:
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# t conflicts with something in the essential set or the essential
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# set conflicts with t - either way, t is f***ed
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cbroken.add(t)
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testing.remove(t)
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return False
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musts.update(start)
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never.update(ess_never)
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# curry check_loop
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check_loop = partial(self._check_loop, universe, testing,
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eqv_table, musts, never, choices,
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cbroken)
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# Useful things to remember:
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#
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# * musts and never are disjointed at all times
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# - if not, t cannot be installable. Either t, or one of
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# its dependencies conflict with t or one of its (other)
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# dependencies.
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#
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# * choices should generally be avoided as much as possible.
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# - picking a bad choice requires backtracking
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# - sometimes musts/never will eventually "solve" the choice.
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#
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# * check never includes choices (these are always in choices)
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#
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# * A package is installable if never and musts are disjoined
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# and both check and choices are empty.
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# - exception: _pick_choice may determine the installability
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# of t via recursion (calls _check_inst). In this case
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# check and choices are not (always) empty.
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def _pick_choice(rebuild, set=set, len=len):
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"""Picks a choice from choices and updates rebuild.
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Prunes the choices and updates "rebuild" to reflect the
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pruned choices.
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Returns True if t is installable (determined via recursion).
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Returns False if a choice was picked and added to check.
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Returns None if t is uninstallable (no choice can be picked).
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NB: If this returns False, choices should be replaced by
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rebuild.
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"""
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# We already satisfied/chosen at least one of the litterals
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# in the choice, so the choice is gone
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for choice in filter(musts.isdisjoint, choices):
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# cbroken is needed here because (in theory) it could
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# have changed since the choice was discovered and it
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# is smaller than testing (so presumably faster)
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remain = choice - never - cbroken
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if len(remain) > 1 and not remain.isdisjoint(safe_set):
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first = None
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for r in filter(safe_set.__contains__, remain):
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# don't bother giving extra arguments to _check_inst. "safe" packages are
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# usually trivial to satisfy on their own and will not involve conflicts
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# (so never will not help)
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if r in cache_inst or self._check_inst(r):
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first = r
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break
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if first:
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musts.add(first)
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check.add(first)
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continue
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# None of the safe set choices are installable, so drop them
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remain -= safe_set
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if len(remain) == 1:
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# the choice was reduced to one package we haven't checked - check that
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check.update(remain)
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musts.update(remain)
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continue
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if not remain:
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# all alternatives would violate the conflicts or are uninstallable
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# => package is not installable
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return None
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# The choice is still deferred
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rebuild.add(frozenset(remain))
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if check or not rebuild:
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return False
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choice = iter(rebuild.pop())
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last = next(choice) # pick one to go last
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for p in choice:
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musts_copy = musts.copy()
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never_tmp = set()
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choices_tmp = set()
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check_tmp = set([p])
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if not self._check_loop(universe, testing, eqv_table,
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musts_copy, never_tmp,
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choices_tmp, cbroken,
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check_tmp):
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# p cannot be chosen/is broken (unlikely, but ...)
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continue
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# Test if we can pick p without any consequences.
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# - when we can, we avoid a backtrack point.
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if never_tmp <= never and choices_tmp <= rebuild:
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# we can pick p without picking up new conflicts
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# or unresolved choices. Therefore we commit to
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# using p.
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#
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# NB: Optimally, we would go to the start of this
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# routine, but to conserve stack-space, we return
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# and expect to be called again later.
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musts.update(musts_copy)
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return False
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if not musts.isdisjoint(never_tmp):
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# If we pick p, we will definitely end up making
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# t uninstallable, so p is a no-go.
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continue
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# We are not sure that p is safe, setup a backtrack
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# point and recurse.
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never_tmp |= never
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choices_tmp |= rebuild
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if self._check_inst(p, musts_copy, never_tmp,
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choices_tmp):
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# Success, p was a valid choice and made it all
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# installable
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return True
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# If we get here, we failed to find something that
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# would satisfy choice (without breaking the
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# installability of t). This means p cannot be used
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# to satisfy the dependencies, so pretend to conflict
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# with it - hopefully it will reduce future choices.
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never.add(p)
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# Optimization for the last case; avoid the recursive call
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# and just assume the last will lead to a solution. If it
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# doesn't there is no solution and if it does, we don't
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# have to back-track anyway.
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check.add(last)
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musts.add(last)
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return False
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# END _pick_choice
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while check:
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if not check_loop(check):
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verdict = False
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break
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if choices:
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rebuild = set()
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# We have to "guess" now, which is always fun, but not cheap
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r = _pick_choice(rebuild)
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if r is None:
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verdict = False
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break
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if r:
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# The recursive call have already updated the
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# cache so there is not point in doing it again.
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return True
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choices = rebuild
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if verdict:
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# if t is installable, then so are all packages in musts
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self._cache_inst.update(musts)
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return verdict
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def _check_loop(self, universe, testing, eqv_table, musts, never,
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choices, cbroken, check, len=len,
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frozenset=frozenset):
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"""Finds all guaranteed dependencies via "check".
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If it returns False, t is not installable. If it returns True
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then "check" is exhausted. If "choices" are empty and this
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returns True, then t is installable.
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"""
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# Local variables for faster access...
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not_satisfied = partial(filter, musts.isdisjoint)
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# While we have guaranteed dependencies (in check), examine all
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# of them.
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for cur in iter_except(check.pop, KeyError):
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(deps, cons) = universe[cur]
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if cons:
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# Conflicts?
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if cur in never:
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# cur adds a (reverse) conflict, so check if cur
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# is in never.
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#
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# - there is a window where two conflicting
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# packages can be in check. Example "A" depends
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# on "B" and "C". If "B" conflicts with "C",
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# then both "B" and "C" could end in "check".
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return False
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# We must install cur for the package to be installable,
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# so "obviously" we can never choose any of its conflicts
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never.update(cons & testing)
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# depgroup can be satisifed by picking something that is
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# already in musts - lets pick that (again). :)
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for depgroup in not_satisfied(deps):
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# Of all the packages listed in the relation remove those that
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# are either:
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# - not in testing
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# - known to be broken (by cache)
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# - in never
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candidates = frozenset((depgroup & testing) - never)
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if len(candidates) == 0:
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# We got no candidates to satisfy it - this
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# package cannot be installed with the current
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# testing
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if cur not in cbroken and depgroup.isdisjoint(never):
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# cur's dependency cannot be satisfied even if never was empty.
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# This means that cur itself is broken (as well).
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cbroken.add(cur)
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testing.remove(cur)
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return False
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if len(candidates) == 1:
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# only one possible solution to this choice and we
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# haven't seen it before
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check.update(candidates)
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musts.update(candidates)
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else:
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possible_eqv = set(x for x in candidates if x in eqv_table)
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if len(possible_eqv) > 1:
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# Exploit equivalency to reduce the number of
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# candidates if possible. Basically, this
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# code maps "similar" candidates into a single
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# candidate that will give a identical result
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# to any other candidate it eliminates.
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#
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# See InstallabilityTesterBuilder's
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# _build_eqv_packages_table method for more
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# information on how this works.
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new_cand = set(x for x in candidates if x not in possible_eqv)
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for chosen in iter_except(possible_eqv.pop, KeyError):
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new_cand.add(chosen)
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possible_eqv -= eqv_table[chosen]
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if len(new_cand) == 1:
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check.update(new_cand)
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musts.update(new_cand)
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continue
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candidates = frozenset(new_cand)
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# defer this choice till later
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choices.add(candidates)
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return True
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def _get_min_pseudo_ess_set(self, arch):
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if arch not in self._cache_ess:
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# The minimal essential set cache is not present -
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# compute it now.
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testing = self._testing
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eqv_table = self._eqv_table
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cbroken = self._cache_broken
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universe = self._universe
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safe_set = self._safe_set
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ess_base = set(x for x in self._essentials if x[2] == arch and x in testing)
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start = set(ess_base)
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ess_never = set()
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ess_choices = set()
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not_satisified = partial(filter, start.isdisjoint)
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while ess_base:
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self._check_loop(universe, testing, eqv_table,
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start, ess_never, ess_choices,
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cbroken, ess_base)
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if ess_choices:
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# Try to break choices where possible
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nchoice = set()
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for choice in not_satisified(ess_choices):
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b = False
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|
for c in choice:
|
|
if universe[c][1] <= ess_never and \
|
|
not any(not_satisified(universe[c][0])):
|
|
ess_base.add(c)
|
|
b = True
|
|
break
|
|
if not b:
|
|
nchoice.add(choice)
|
|
ess_choices = nchoice
|
|
else:
|
|
break
|
|
|
|
for x in start:
|
|
ess_never.update(universe[x][1])
|
|
self._cache_ess[arch] = (frozenset(start), frozenset(ess_never))
|
|
|
|
return self._cache_ess[arch]
|
|
|