# -*- coding: utf-8 -*- # Copyright (C) 2012 Niels Thykier # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. from collections import defaultdict from functools import partial from itertools import chain, filterfalse from britney_util import iter_except class InstallabilityTester(object): def __init__(self, universe, revuniverse, testing, broken, essentials, safe_set, eqv_table): """Create a new installability tester universe is a dict mapping package ids to their dependencies and conflicts. revuniverse is a table containing all packages with reverse relations mapping them to their reverse relations. testing is a (mutable) set of package ids that determines which of the packages in universe are currently in testing. broken is a (mutable) set of package ids that are known to be uninstallable. essentials is a set of packages with "Essential: yes". safe_set is a set of all packages which have no conflicts and either have no dependencies or only depends on other "safe" packages. Package id: (pkg_name, pkg_version, pkg_arch) - NB: arch:all packages are "re-mapped" to given architecture. (simplifies caches and dependency checking) """ self._universe = universe self._testing = testing self._broken = broken self._essentials = essentials self._revuniverse = revuniverse self._safe_set = safe_set self._eqv_table = eqv_table self._stats = InstallabilityStats() # Cache of packages known to be broken - we deliberately do not # include "broken" in it. See _optimize for more info. self._cache_broken = set() # Cache of packages known to be installable self._cache_inst = set() # Per "arch" cache of the "minimal" (possibly incomplete) # pseudo-essential set. This includes all the packages that # are essential and packages that will always follow. # # It may not be a complete essential set, since alternatives # are not always resolved. Noticably cases like "awk" may be # left out (since it could be either gawk, mawk or # original-awk) unless something in this sets depends strictly # on one of them self._cache_ess = {} def compute_testing_installability(self): """Computes the installability of packages in testing This method computes the installability of all packages in testing and caches the result. This has the advantage of making "is_installable" queries very fast for all packages in testing. """ check_inst = self._check_inst cbroken = self._cache_broken cache_inst = self._cache_inst eqv_table = self._eqv_table testing = self._testing tcopy = [x for x in testing] for t in filterfalse(cache_inst.__contains__, tcopy): if t in cbroken: continue res = check_inst(t) if t in eqv_table: eqv = (x for x in eqv_table[t] if x in testing) if res: cache_inst.update(eqv) else: eqv_set = frozenset(eqv) testing -= eqv_set cbroken |= eqv_set @property def stats(self): return self._stats def are_equivalent(self, p1, p2): """Test if p1 and p2 are equivalent Returns True if p1 and p2 have the same "signature" in the package dependency graph (i.e. relations can not tell them apart semantically except for their name) """ eqv_table = self._eqv_table return p1 in eqv_table and p2 in eqv_table[p1] def reverse_dependencies_of(self, pkg_id): """Returns the set of reverse dependencies of a given package :param pkg_id: The package id as defined in the constructor. :return: A set containing the package ids all of the reverse dependencies of the input package. The result is suite agnostic. """ revuniverse = self._revuniverse if pkg_id not in revuniverse: return frozenset() return revuniverse[pkg_id][0] def negative_dependencies_of(self, pkg_id): """Returns the set of negative dependencies of a given package Note that there is no "reverse_negative_dependencies_of" method, since negative dependencies have no "direction" unlike positive dependencies. :param pkg_id: The package id as defined in the constructor. :return: A set containing the package ids all of the negative dependencies of the input package. The result is suite agnostic. """ return self._universe[pkg_id][1] def dependencies_of(self, pkg_id): """Returns the set of dependencies of a given package :param pkg_id: The package id as defined in the constructor. :return: A set containing the package ids all of the dependencies of the input package. The result is suite agnostic. """ return self._universe[pkg_id][0] def any_of_these_are_in_testing(self, pkgs): """Test if at least one package of a given set is in testing :param pkgs: A set of package ids (as defined in the constructor) :return: True if any of the packages in pkgs are currently in testing """ return not self._testing.isdisjoint(pkgs) def add_testing_binary(self, pkg_id): """Add a binary package to "testing" If the package is not known, this method will throw an KeyError. """ if pkg_id not in self._universe: raise KeyError(str(pkg_id)) if pkg_id in self._broken: self._testing.add(pkg_id) elif pkg_id not in self._testing: self._testing.add(pkg_id) if self._cache_inst: self._stats.cache_drops += 1 self._cache_inst = set() if self._cache_broken: # Re-add broken packages as some of them may now be installable self._testing |= self._cache_broken self._cache_broken = set() if pkg_id in self._essentials and pkg_id[2] in self._cache_ess: # Adds new essential => "pseudo-essential" set needs to be # recomputed del self._cache_ess[pkg_id[2]] return True def remove_testing_binary(self, pkg_id): """Remove a binary from "testing" If the package is not known, this method will throw an Keyrror. """ if pkg_id not in self._universe: raise KeyError(str(pkg_id)) self._cache_broken.discard(pkg_id) if pkg_id in self._testing: self._testing.remove(pkg_id) if pkg_id[2] in self._cache_ess and pkg_id in self._cache_ess[pkg_id[2]][0]: # Removes a package from the "pseudo-essential set" del self._cache_ess[pkg_id[2]] if pkg_id not in self._revuniverse: # no reverse relations - safe return True if pkg_id not in self._broken and pkg_id in self._cache_inst: # It is in our cache (and not guaranteed to be broken) - throw out the cache self._cache_inst = set() self._stats.cache_drops += 1 return True def is_installable(self, pkg_id): """Test if a package is installable in this package set The package is assumed to be in "testing" and only packages in "testing" can be used to satisfy relations. Returns True iff the package is installable. Returns False otherwise. """ self._stats.is_installable_calls += 1 if pkg_id not in self._universe: raise KeyError(str(pkg_id)) if pkg_id not in self._testing or pkg_id in self._broken: self._stats.cache_hits += 1 return False if pkg_id in self._cache_inst: self._stats.cache_hits += 1 return True self._stats.cache_misses += 1 return self._check_inst(pkg_id) def _check_inst(self, t, musts=None, never=None, choices=None): # See the explanation of musts, never and choices below. cache_inst = self._cache_inst stats = self._stats if musts and t in cache_inst and not never: # use the inst cache only for direct queries/simple queries. cache = True 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 eqv_table = self._eqv_table # 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) stats.conflicts_essential += 1 return False musts.update(start) never.update(ess_never) # curry check_loop check_loop = partial(self._check_loop, universe, testing, eqv_table, stats, musts, never, 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 disjointed # 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, set=set, len=len): """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 literals # in the choice, so the choice is gone for choice in filter(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 len(remain) > 1 and not remain.isdisjoint(safe_set): first = None for r in filter(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) stats.choice_resolved_using_safe_set += 1 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) stats.choice_presolved += 1 continue if not remain: # all alternatives would violate the conflicts or are uninstallable # => package is not installable stats.choice_presolved += 1 return None # 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_tmp = set() choices_tmp = set() check_tmp = set([p]) if not self._check_loop(universe, testing, eqv_table, stats, musts_copy, never_tmp, cbroken, choices_tmp, check_tmp): # p cannot be chosen/is broken (unlikely, but ...) continue # Test if we can pick p without any consequences. # - when we can, we avoid a backtrack point. if never_tmp <= never and choices_tmp <= rebuild: # we can pick p without picking up new conflicts # or unresolved choices. Therefore we commit to # using p. # # NB: Optimally, we would go to the start of this # routine, but to conserve stack-space, we return # and expect to be called again later. musts.update(musts_copy) stats.choice_resolved_without_restore_point += 1 return False if not musts.isdisjoint(never_tmp): # If we pick p, we will definitely end up making # t uninstallable, so p is a no-go. continue stats.backtrace_restore_point_created += 1 # We are not sure that p is safe, setup a backtrack # point and recurse. never_tmp |= never choices_tmp |= rebuild if self._check_inst(p, musts_copy, never_tmp, choices_tmp): # Success, p was a valid choice and made it all # installable 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) stats.backtrace_restore_point_used += 1 # 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) stats.backtrace_last_option += 1 return False # END _pick_choice while check: if not check_loop(choices, 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) stats.solved_installable += 1 else: stats.solved_uninstallable += 1 return verdict def _check_loop(self, universe, testing, eqv_table, stats, musts, never, cbroken, choices, check, len=len, frozenset=frozenset): """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... not_satisfied = partial(filter, 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 satisfied 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 = (depgroup & testing) - never if not candidates: # 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 len(candidates) == 1: # only one possible solution to this choice and we # haven't seen it before check.update(candidates) musts.update(candidates) else: possible_eqv = set(x for x in candidates if x in eqv_table) if len(possible_eqv) > 1: # Exploit equivalency to reduce the number of # candidates if possible. Basically, this # code maps "similar" candidates into a single # candidate that will give a identical result # to any other candidate it eliminates. # # See InstallabilityTesterBuilder's # _build_eqv_packages_table method for more # information on how this works. new_cand = set(x for x in candidates if x not in possible_eqv) stats.eqv_table_times_used += 1 for chosen in iter_except(possible_eqv.pop, KeyError): new_cand.add(chosen) possible_eqv -= eqv_table[chosen] stats.eqv_table_total_number_of_alternatives_eliminated += len(candidates) - len(new_cand) if len(new_cand) == 1: check.update(new_cand) musts.update(new_cand) stats.eqv_table_reduced_to_one += 1 continue elif len(candidates) == len(new_cand): stats.eqv_table_reduced_by_zero += 1 candidates = frozenset(new_cand) else: # Candidates have to be a frozenset to be added to choices candidates = frozenset(candidates) # 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 eqv_table = self._eqv_table cbroken = self._cache_broken universe = self._universe stats = self._stats 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(filter, start.isdisjoint) while ess_base: self._check_loop(universe, testing, eqv_table, stats, start, ess_never, cbroken, ess_choices, 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] def compute_stats(self): universe = self._universe eqv_table = self._eqv_table graph_stats = defaultdict(ArchStats) seen_eqv = defaultdict(set) for pkg in universe: (pkg_name, pkg_version, pkg_arch) = pkg deps, con = universe[pkg] arch_stats = graph_stats[pkg_arch] arch_stats.nodes += 1 if pkg in eqv_table and pkg not in seen_eqv[pkg_arch]: eqv = [e for e in eqv_table[pkg] if e[2] == pkg_arch] arch_stats.eqv_nodes += len(eqv) arch_stats.add_dep_edges(deps) arch_stats.add_con_edges(con) for stat in graph_stats.values(): stat.compute_all() return graph_stats class InstallabilityStats(object): def __init__(self): self.cache_hits = 0 self.cache_misses = 0 self.cache_drops = 0 self.backtrace_restore_point_created = 0 self.backtrace_restore_point_used = 0 self.backtrace_last_option = 0 self.choice_presolved = 0 self.choice_resolved_using_safe_set = 0 self.choice_resolved_without_restore_point = 0 self.is_installable_calls = 0 self.solved_installable = 0 self.solved_uninstallable = 0 self.conflicts_essential = 0 self.eqv_table_times_used = 0 self.eqv_table_reduced_to_one = 0 self.eqv_table_reduced_by_zero = 0 self.eqv_table_total_number_of_alternatives_eliminated = 0 def stats(self): formats = [ "Requests - is_installable: {is_installable_calls}", "Cache - hits: {cache_hits}, misses: {cache_misses}, drops: {cache_drops}", "Choices - pre-solved: {choice_presolved}, safe-set: {choice_resolved_using_safe_set}, No RP: {choice_resolved_without_restore_point}", "Backtrace - RP created: {backtrace_restore_point_created}, RP used: {backtrace_restore_point_used}, reached last option: {backtrace_last_option}", "Solved - installable: {solved_installable}, uninstallable: {solved_uninstallable}, conflicts essential: {conflicts_essential}", "Eqv - times used: {eqv_table_times_used}, perfect reductions: {eqv_table_reduced_to_one}, failed reductions: {eqv_table_reduced_by_zero}, total no. of alternatives pruned: {eqv_table_total_number_of_alternatives_eliminated}", ] return [x.format(**self.__dict__) for x in formats] class ArchStats(object): def __init__(self): self.nodes = 0 self.eqv_nodes = 0 self.dep_edges = [] self.con_edges = [] self.stats = defaultdict(lambda: defaultdict(int)) def stat(self, statname): return self.stats[statname] def stat_summary(self): text = [] for statname in ['nodes', 'dependency-clauses', 'dependency-clause-alternatives', 'negative-dependency-clauses']: stat = self.stats[statname] if statname != 'nodes': format_str = "%s, max: %d, min: %d, median: %d, average: %f (%d/%d)" values = [statname, stat['max'], stat['min'], stat['median'], stat['average'], stat['sum'], stat['size']] if 'average-per-node' in stat: format_str += ", average-per-node: %f" values.append(stat['average-per-node']) else: format_str = "nodes: %d, eqv-nodes: %d" values = (self.nodes, self.eqv_nodes) text.append(format_str % tuple(values)) return text def add_dep_edges(self, edges): self.dep_edges.append(edges) def add_con_edges(self, edges): self.con_edges.append(edges) def _list_stats(self, stat_name, sorted_list, average_per_node=False): if sorted_list: stats = self.stats[stat_name] stats['max'] = sorted_list[-1] stats['min'] = sorted_list[0] stats['sum'] = sum(sorted_list) stats['size'] = len(sorted_list) stats['average'] = float(stats['sum'])/len(sorted_list) stats['median'] = sorted_list[len(sorted_list)//2] if average_per_node: stats['average-per-node'] = float(stats['sum'])/self.nodes def compute_all(self): dep_edges = self.dep_edges con_edges = self.con_edges sorted_no_dep_edges = sorted(len(x) for x in dep_edges) sorted_size_dep_edges = sorted(len(x) for x in chain.from_iterable(dep_edges)) sorted_no_con_edges = sorted(len(x) for x in con_edges) self._list_stats('dependency-clauses', sorted_no_dep_edges) self._list_stats('dependency-clause-alternatives', sorted_size_dep_edges, average_per_node=True) self._list_stats('negative-dependency-clauses', sorted_no_con_edges)