The new Installability Tester (IT) module replaces the remaining C-parts. Unlike C-implementation, it does not give up and emit an "AIEEE" half-way through. In order to determine installability, it uses two sets "musts" and "never". As the names suggest, the sets represents the packages that must be (co-)installable with the package being tested and those that can never be co-installable. For a package to be installable, "musts" and "never" have remain disjoint. These sets are also used to reduce the number of alternatives that are available to satisfy a given dependency. When these sets are unable to remove the choice completely, the new IT defers the choice to later. This occasionally reduces backtracking as a later package may conflict or unconditionally depend on one of the remaining alternatives. Signed-off-by: Niels Thykier <niels@thykier.net>debian
Niels Thykier
13 years ago
parent
cf84bcfa58
commit
7051d5b0e9
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# -*- 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 contextlib import contextmanager
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from britney_util import ifilter_except, iter_except
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from installability.tester import InstallabilityTester
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class _RelationBuilder(object):
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"""Private helper class to "build" relations"""
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def __init__(self, itbuilder, binary):
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self._itbuilder = itbuilder
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self._binary = binary
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binary_data = itbuilder._package_table[binary]
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self._new_deps = set(binary_data[0])
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self._new_breaks = set(binary_data[1])
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def add_dependency_clause(self, or_clause):
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"""Add a dependency clause
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The clause must be a sequence of (name, version, architecture)
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tuples. The clause is an OR clause, i.e. any tuple in the
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sequence can satisfy the relation. It is irrelevant if the
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dependency is from the "Depends" or the "Pre-Depends" field.
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Note that is the sequence is empty, the dependency is assumed
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to be unsatisfiable.
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The binaries in the clause are not required to have been added
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to the InstallabilityTesterBuilder when this method is called.
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However, they must be added before the "build()" method is
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called.
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"""
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clause = self._itbuilder._intern_set(or_clause)
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binary = self._binary
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itbuilder = self._itbuilder
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package_table = itbuilder._package_table
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reverse_package_table = itbuilder._reverse_package_table
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okay = False
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for dep_tuple in clause:
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okay = True
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reverse_relations = itbuilder._reverse_relations(dep_tuple)
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reverse_relations[0].add(binary)
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self._new_deps.add(clause)
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if not okay:
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self._itbuilder._broken.add(binary)
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def add_breaks(self, broken_binary):
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"""Add a Breaks-clause
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Marks the given binary as being broken by the current
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package. That is, the given package satisfies a relation
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in either the "Breaks" or the "Conflicts" field. The binary
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given must be a (name, version, architecture)-tuple.
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The binary is not required to have been added to the
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InstallabilityTesterBuilder when this method is called. However,
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it must be added before the "build()" method is called.
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"""
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itbuilder = self._itbuilder
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self._new_breaks.add(broken_binary)
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reverse_relations = itbuilder._reverse_relations(broken_binary)
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reverse_relations[1].add(self._binary)
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def _commit(self):
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itbuilder = self._itbuilder
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data = (itbuilder._intern_set(self._new_deps),
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itbuilder._intern_set(self._new_breaks))
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itbuilder._package_table[self._binary] = data
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class InstallabilityTesterBuilder(object):
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"""Builder to create instances of InstallabilityTester"""
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def __init__(self):
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self._package_table = {}
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self._reverse_package_table = {}
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self._essentials = set()
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self._testing = set()
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self._internmap = {}
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self._broken = set()
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def add_binary(self, binary, essential=False, in_testing=False,
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frozenset=frozenset):
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"""Add a new binary package
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Adds a new binary package. The binary must be given as a
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(name, version, architecture)-tuple. Returns True if this
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binary is new (i.e. has never been added before) or False
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otherwise.
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Keyword arguments:
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* essential - Whether this package is "Essential: yes".
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* in_testing - Whether this package is in testing.
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The frozenset argument is a private optimisation.
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Cave-at: arch:all packages should be "re-mapped" to given
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architecture. That is, (pkg, version, "all") should be
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added as:
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for arch in architectures:
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binary = (pkg, version, arch)
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it.add_binary(binary)
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The resulting InstallabilityTester relies on this for
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correctness!
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"""
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# Note, even with a dup, we need to do these
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if in_testing:
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self._testing.add(binary)
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if essential:
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self._essentials.add(binary)
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if binary not in self._package_table:
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# Allow binaries to be added multiple times (happens
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# when sid and testing have the same version)
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self._package_table[binary] = (frozenset(), frozenset())
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return True
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return False
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@contextmanager
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def relation_builder(self, binary):
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"""Returns a _RelationBuilder for a given binary [context]
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This method returns a context-managed _RelationBuilder for a
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given binary. So it should be used in a "with"-statment,
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like:
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with it.relation_builder(binary) as rel:
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rel.add_dependency_clause(dependency_clause)
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rel.add_breaks(pkgtuple)
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...
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The binary given must be a (name, version, architecture)-tuple.
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Note, this method is optimised to be called at most once per
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binary.
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"""
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if binary not in self._package_table:
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raise ValueError("Binary %s/%s/%s does not exist" % binary)
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rel = _RelationBuilder(self, binary)
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yield rel
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rel._commit()
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def _intern_set(self, s, frozenset=frozenset):
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"""Freeze and intern a given sequence (set variant of intern())
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Given a sequence, create a frozenset copy (if it is not
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already a frozenset) and intern that frozen set. Returns the
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interned set.
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At first glance, interning sets may seem absurd. However,
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it does enable memory savings of up to 600MB when applied
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to the "inner" sets of the dependency clauses and all the
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conflicts relations as well.
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"""
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if type(s) == frozenset:
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fset = s
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else:
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fset = frozenset(s)
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if fset in self._internmap:
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return self._internmap[fset]
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self._internmap[fset] = fset
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return fset
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def _reverse_relations(self, binary, set=set):
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"""Return the reverse relations for a binary
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Fetch the reverse relations for a given binary, which are
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created lazily.
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"""
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if binary in self._reverse_package_table:
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return self._reverse_package_table[binary]
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rel = [set(), set()]
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self._reverse_package_table[binary] = rel
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return rel
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def build(self):
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# Merge reverse conflicts with conflicts - this saves some
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# operations in _check_loop since we only have to check one
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# set (instead of two) and we remove a few duplicates here
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# and there.
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package_table = self._package_table
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reverse_package_table = self._reverse_package_table
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intern_set = self._intern_set
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safe_set = set()
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broken = self._broken
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not_broken = ifilter_except(broken)
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check = set(broken)
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def safe_set_satisfies(t):
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"""Check if t's dependencies can be satisfied by the safe set"""
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if not package_table[t][0]:
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# If it has no dependencies at all, then it is safe. :)
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return True
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for depgroup in package_table[t][0]:
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if not any(dep for dep in depgroup if dep in safe_set):
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return False
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return True
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for pkg in reverse_package_table:
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if pkg not in package_table:
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raise RuntimeError("%s/%s/%s referenced but not added!" % pkg)
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if not reverse_package_table[pkg][1]:
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# no rconflicts - ignore
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continue
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deps, con = package_table[pkg]
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if not con:
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con = intern_set(reverse_package_table[pkg][1])
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else:
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con = intern_set(con | reverse_package_table[pkg][1])
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package_table[pkg] = (deps, con)
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# Check if we can expand broken.
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for t in not_broken(iter_except(check.pop, KeyError)):
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# This package is not known to be broken... but it might be now
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isb = False
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for depgroup in package_table[t][0]:
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if not any(not_broken(depgroup)):
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# A single clause is unsatisfiable, the
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# package can never be installed - add it to
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# broken.
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isb = True
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break
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if not isb:
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continue
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broken.add(t)
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if t not in reverse_package_table:
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continue
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check.update(reverse_package_table[t][0] - broken)
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if broken:
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# Since a broken package will never be installable, nothing that depends on it
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# will ever be installable. Thus, there is no point in keeping relations on
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# the broken package.
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seen = set()
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empty_set = frozenset()
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null_data = (frozenset([empty_set]), empty_set)
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for b in (x for x in broken if x in reverse_package_table):
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for rdep in (r for r in not_broken(reverse_package_table[b][0])
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if r not in seen):
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ndep = intern_set((x - broken) for x in package_table[rdep][0])
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package_table[rdep] = (ndep, package_table[rdep][1] - broken)
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seen.add(rdep)
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# Since they won't affect the installability of any other package, we might as
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# as well null their data. This memory for these packages, but likely there
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# will only be a handful of these "at best" (fsvo of "best")
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for b in broken:
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package_table[b] = null_data
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if b in reverse_package_table:
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del reverse_package_table[b]
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# Now find an initial safe set (if any)
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check = set()
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for pkg in package_table:
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if package_table[pkg][1]:
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# has (reverse) conflicts - not safe
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continue
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if not safe_set_satisfies(pkg):
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continue
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safe_set.add(pkg)
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if pkg in reverse_package_table:
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# add all rdeps (except those already in the safe_set)
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check.update(reverse_package_table[pkg][0] - safe_set)
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# Check if we can expand the initial safe set
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for pkg in iter_except(check.pop, KeyError):
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if package_table[pkg][1]:
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# has (reverse) conflicts - not safe
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continue
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if safe_set_satisfies(pkg):
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safe_set.add(pkg)
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if pkg in reverse_package_table:
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# add all rdeps (except those already in the safe_set)
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check.update(reverse_package_table[pkg][0] - safe_set)
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return InstallabilityTester(package_table,
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frozenset(reverse_package_table),
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self._testing, self._broken,
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self._essentials, safe_set)
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@ -0,0 +1,464 @@
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# -*- 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 ifilter, ifilterfalse
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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):
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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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# 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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tcopy = [x for x in self._testing]
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for t in ifilterfalse(cache_inst.__contains__, tcopy):
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if t in cbroken:
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continue
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check_inst(t)
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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:
|
||||
# This is a recursive call, where there is no "never" so far.
|
||||
# We know t satisfies at least one of the remaining choices.
|
||||
# If it satisfies all remaining choices, we can use the cache
|
||||
# in this case (since never is empty).
|
||||
#
|
||||
# Otherwise, a later choice may be incompatible with t.
|
||||
for choice in choices:
|
||||
if t in choice:
|
||||
continue
|
||||
cache = False
|
||||
break
|
||||
if cache:
|
||||
return True
|
||||
|
||||
|
||||
universe = self._universe
|
||||
testing = self._testing
|
||||
cbroken = self._cache_broken
|
||||
safe_set = self._safe_set
|
||||
|
||||
# Our installability verdict - start with "yes" and change if
|
||||
# prove otherwise.
|
||||
verdict = True
|
||||
|
||||
# set of packages that must be installed with this package
|
||||
if musts is None:
|
||||
musts = set()
|
||||
musts.add(t)
|
||||
# set of packages we can *never* choose (e.g. due to conflicts)
|
||||
if never is None:
|
||||
never = set()
|
||||
# set of relations were we have a choice, but where we have not
|
||||
# committed ourselves yet. Hopefully some choices may be taken
|
||||
# for us (if one of the alternatives appear in "musts")
|
||||
if choices is None:
|
||||
choices = set()
|
||||
|
||||
# The subset of musts we haven't checked yet.
|
||||
check = set([t])
|
||||
|
||||
if len(musts) == 1:
|
||||
# Include the essential packages in testing as a starting point.
|
||||
if t[2] not in self._cache_ess:
|
||||
# The minimal essential set cache is not present -
|
||||
# compute it now.
|
||||
(start, ess_never) = self._get_min_pseudo_ess_set(t[2])
|
||||
else:
|
||||
(start, ess_never) = self._cache_ess[t[2]]
|
||||
|
||||
if t in ess_never:
|
||||
# t conflicts with something in the essential set or the essential
|
||||
# set conflicts with t - either way, t is f***ed
|
||||
cbroken.add(t)
|
||||
testing.remove(t)
|
||||
return False
|
||||
musts.update(start)
|
||||
never.update(ess_never)
|
||||
|
||||
# curry check_loop
|
||||
check_loop = partial(self._check_loop, universe, testing, musts,
|
||||
never, choices, cbroken)
|
||||
|
||||
|
||||
# Useful things to remember:
|
||||
#
|
||||
# * musts and never are disjointed at all times
|
||||
# - if not, t cannot be installable. Either t, or one of
|
||||
# its dependencies conflict with t or one of its (other)
|
||||
# dependencies.
|
||||
#
|
||||
# * choices should generally be avoided as much as possible.
|
||||
# - picking a bad choice requires backtracking
|
||||
# - sometimes musts/never will eventually "solve" the choice.
|
||||
#
|
||||
# * check never includes choices (these are always in choices)
|
||||
#
|
||||
# * A package is installable if never and musts are disjoined
|
||||
# and both check and choices are empty.
|
||||
# - exception: _pick_choice may determine the installability
|
||||
# of t via recursion (calls _check_inst). In this case
|
||||
# check and choices are not (always) empty.
|
||||
|
||||
def _pick_choice(rebuild):
|
||||
"""Picks a choice from choices and updates rebuild.
|
||||
|
||||
Prunes the choices and updates "rebuild" to reflect the
|
||||
pruned choices.
|
||||
|
||||
Returns True if t is installable (determined via recursion).
|
||||
Returns False if a choice was picked and added to check.
|
||||
Returns None if t is uninstallable (no choice can be picked).
|
||||
|
||||
NB: If this returns False, choices should be replaced by
|
||||
rebuild.
|
||||
"""
|
||||
|
||||
# We already satisfied/chosen at least one of the litterals
|
||||
# in the choice, so the choice is gone
|
||||
for choice in ifilter(musts.isdisjoint, choices):
|
||||
# cbroken is needed here because (in theory) it could
|
||||
# have changed since the choice was discovered and it
|
||||
# is smaller than testing (so presumably faster)
|
||||
remain = choice - never - cbroken
|
||||
|
||||
if not remain:
|
||||
# all alternatives would violate the conflicts => package is not installable
|
||||
return None
|
||||
|
||||
if len(remain) > 1 and not remain.isdisjoint(safe_set):
|
||||
first = None
|
||||
for r in ifilter(safe_set.__contains__, remain):
|
||||
# don't bother giving extra arguments to _check_inst. "safe" packages are
|
||||
# usually trivial to satisfy on their own and will not involve conflicts
|
||||
# (so never will not help)
|
||||
if r in cache_inst or self._check_inst(r):
|
||||
first = r
|
||||
break
|
||||
if first:
|
||||
musts.add(first)
|
||||
check.add(first)
|
||||
continue
|
||||
# None of the safe set choices are installable, so drop them
|
||||
remain -= safe_set
|
||||
|
||||
if len(remain) == 1:
|
||||
# the choice was reduced to one package we haven't checked - check that
|
||||
check.update(remain)
|
||||
musts.update(remain)
|
||||
continue
|
||||
# The choice is still deferred
|
||||
rebuild.add(frozenset(remain))
|
||||
|
||||
if check or not rebuild:
|
||||
return False
|
||||
|
||||
choice = iter(rebuild.pop())
|
||||
last = next(choice) # pick one to go last
|
||||
for p in choice:
|
||||
musts_copy = musts.copy()
|
||||
never_copy = never.copy()
|
||||
choices_copy = choices.copy()
|
||||
if self._check_inst(p, musts_copy, never_copy, choices_copy):
|
||||
return True
|
||||
# If we get here, we failed to find something that would satisfy choice (without breaking
|
||||
# the installability of t). This means p cannot be used to satisfy the dependencies, so
|
||||
# pretend to conflict with it - hopefully it will reduce future choices.
|
||||
never.add(p)
|
||||
|
||||
# Optimization for the last case; avoid the recursive call and just
|
||||
# assume the last will lead to a solution. If it doesn't there is
|
||||
# no solution and if it does, we don't have to back-track anyway.
|
||||
check.add(last)
|
||||
musts.add(last)
|
||||
return False
|
||||
# END _pick_choice
|
||||
|
||||
while check:
|
||||
if not check_loop(check):
|
||||
verdict = False
|
||||
break
|
||||
|
||||
if choices:
|
||||
rebuild = set()
|
||||
# We have to "guess" now, which is always fun, but not cheap
|
||||
r = _pick_choice(rebuild)
|
||||
if r is None:
|
||||
verdict = False
|
||||
break
|
||||
if r:
|
||||
# The recursive call have already updated the
|
||||
# cache so there is not point in doing it again.
|
||||
return True
|
||||
choices = rebuild
|
||||
|
||||
if verdict:
|
||||
# if t is installable, then so are all packages in musts
|
||||
self._cache_inst.update(musts)
|
||||
|
||||
return verdict
|
||||
|
||||
|
||||
def _check_loop(self, universe, testing, musts, never,
|
||||
choices, cbroken, check):
|
||||
"""Finds all guaranteed dependencies via "check".
|
||||
|
||||
If it returns False, t is not installable. If it returns True
|
||||
then "check" is exhausted. If "choices" are empty and this
|
||||
returns True, then t is installable.
|
||||
"""
|
||||
# Local variables for faster access...
|
||||
l = len
|
||||
fset = frozenset
|
||||
not_satisfied = partial(ifilter, musts.isdisjoint)
|
||||
|
||||
# While we have guaranteed dependencies (in check), examine all
|
||||
# of them.
|
||||
for cur in iter_except(check.pop, KeyError):
|
||||
(deps, cons) = universe[cur]
|
||||
|
||||
if cons:
|
||||
# Conflicts?
|
||||
if cur in never:
|
||||
# cur adds a (reverse) conflict, so check if cur
|
||||
# is in never.
|
||||
#
|
||||
# - there is a window where two conflicting
|
||||
# packages can be in check. Example "A" depends
|
||||
# on "B" and "C". If "B" conflicts with "C",
|
||||
# then both "B" and "C" could end in "check".
|
||||
return False
|
||||
# We must install cur for the package to be installable,
|
||||
# so "obviously" we can never choose any of its conflicts
|
||||
never.update(cons & testing)
|
||||
|
||||
# depgroup can be satisifed by picking something that is
|
||||
# already in musts - lets pick that (again). :)
|
||||
for depgroup in not_satisfied(deps):
|
||||
|
||||
# Of all the packages listed in the relation remove those that
|
||||
# are either:
|
||||
# - not in testing
|
||||
# - known to be broken (by cache)
|
||||
# - in never
|
||||
candidates = fset((depgroup & testing) - never)
|
||||
|
||||
if l(candidates) == 0:
|
||||
# We got no candidates to satisfy it - this
|
||||
# package cannot be installed with the current
|
||||
# testing
|
||||
if cur not in cbroken and depgroup.isdisjoint(never):
|
||||
# cur's dependency cannot be satisfied even if never was empty.
|
||||
# This means that cur itself is broken (as well).
|
||||
cbroken.add(cur)
|
||||
testing.remove(cur)
|
||||
return False
|
||||
if l(candidates) == 1:
|
||||
# only one possible solution to this choice and we
|
||||
# haven't seen it before
|
||||
check.update(candidates)
|
||||
musts.update(candidates)
|
||||
else:
|
||||
# defer this choice till later
|
||||
choices.add(candidates)
|
||||
return True
|
||||
|
||||
def _get_min_pseudo_ess_set(self, arch):
|
||||
if arch not in self._cache_ess:
|
||||
# The minimal essential set cache is not present -
|
||||
# compute it now.
|
||||
testing = self._testing
|
||||
cbroken = self._cache_broken
|
||||
universe = self._universe
|
||||
safe_set = self._safe_set
|
||||
|
||||
ess_base = set(x for x in self._essentials if x[2] == arch and x in testing)
|
||||
start = set(ess_base)
|
||||
ess_never = set()
|
||||
ess_choices = set()
|
||||
not_satisified = partial(ifilter, start.isdisjoint)
|
||||
|
||||
while ess_base:
|
||||
self._check_loop(universe, testing, start, ess_never,\
|
||||
ess_choices, cbroken, ess_base)
|
||||
if ess_choices:
|
||||
# Try to break choices where possible
|
||||
nchoice = set()
|
||||
for choice in not_satisified(ess_choices):
|
||||
b = False
|
||||
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]
|
||||
|
||||
Loading…
Reference in new issue