def _check_loop(self, universe, testing, eqv_table, musts, never,
choices, cbroken, 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(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 = frozenset((depgroup & testing) - never)
if len(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 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)
for chosen in iter_except(possible_eqv.pop, KeyError):
new_cand.add(chosen)
possible_eqv -= eqv_table[chosen]
if len(new_cand) == 1:
check.update(new_cand)
musts.update(new_cand)
continue
candidates = frozenset(new_cand)
# defer this choice till later
choices.add(candidates)
return True
def solve_groups(self, groups):
sat_in_testing = self._testing.isdisjoint
universe = self._universe
revuniverse = self._revuniverse
result = []
emitted = set()
check = set()
order = {}
ptable = {}
key2item = {}
going_out = set()
going_in = set()
debug_solver = 0
try:
debug_solver = int(os.environ.get('BRITNEY_DEBUG', '0'))
except:
pass
# Build the tables
for (item, adds, rms) in groups:
key = str(item)
key2item[key] = item
order[key] = {'before': set(), 'after': set()}
going_in.update(adds)
going_out.update(rms)
for a in adds:
ptable[a] = key
for r in rms:
ptable[r] = key
if debug_solver > 1:
self._dump_groups(groups)
# This large loop will add ordering constrains on each "item"
# that migrates based on various rules.
for (item, adds, rms) in groups:
key = str(item)
oldcons = set()
newcons = set()
for r in rms:
oldcons.update(universe[r][1])
for a in adds:
newcons.update(universe[a][1])
current = newcons & oldcons
oldcons -= current
newcons -= current
if oldcons:
# Some of the old binaries have "conflicts" that will
# be removed.
for o in ifilter_only(ptable, oldcons):
# "key" removes a conflict with one of
# "other"'s binaries, so it is probably a good
# idea to migrate "key" before "other"
other = ptable[o]
if other == key:
# "Self-conflicts" => ignore
continue
if debug_solver and other not in order[key]['before']:
print("N: Conflict induced order: %s before %s" % (key, other))
order[key]['before'].add(other)
order[other]['after'].add(key)
for r in ifilter_only(revuniverse, rms):
# The binaries have reverse dependencies in testing;
# check if we can/should migrate them first.
for rdep in revuniverse[r][0]:
for depgroup in universe[rdep][0]:
rigid = depgroup - going_out
if not sat_in_testing(rigid):
# (partly) satisfied by testing, assume it is okay
continue
if rdep in ptable:
other = ptable[rdep]
if other == key:
# "Self-dependency" => ignore
continue
if debug_solver and other not in order[key]['after']:
print("N: Removal induced order: %s before %s" % (key, other))
order[key]['after'].add(other)
order[other]['before'].add(key)
for a in adds:
# Check if this item should migrate before others
# (e.g. because they depend on a new [version of a]
# binary provided by this item).
for depgroup in universe[a][0]:
rigid = depgroup - going_out
if not sat_in_testing(rigid):
# (partly) satisfied by testing, assume it is okay
continue
# okay - we got three cases now.
# - "swap" (replace existing binary with a newer version)
# - "addition" (add new binary without removing any)
# - "removal" (remove binary without providing a new)
#
# The problem is that only the two latter requires
# an ordering. A "swap" (in itself) should not
# affect us.
other_adds = set()
other_rms = set()
for d in ifilter_only(ptable, depgroup):
if d in going_in:
# "other" provides something "key" needs,
# schedule accordingly.
other = ptable[d]
other_adds.add(other)
else:
# "other" removes something "key" needs,
# schedule accordingly.
other = ptable[d]
other_rms.add(other)
for other in (other_adds - other_rms):
if debug_solver and other != key and other not in order[key]['after']:
print("N: Dependency induced order (add): %s before %s" % (key, other))
order[key]['after'].add(other)
order[other]['before'].add(key)
for other in (other_rms - other_adds):
if debug_solver and other != key and other not in order[key]['before']:
print("N: Dependency induced order (remove): %s before %s" % (key, other))
order[key]['before'].add(other)
order[other]['after'].add(key)
### MILESTONE: Partial-order constrains computed ###
# At this point, we have computed all the partial-order
# constrains needed. Some of these may have created strongly
# connected components (SSC) [of size 2 or greater], which
# represents a group of items that (we believe) must migrate
# together.
#
# Each one of those components will become an "easy" hint.
comps = self._compute_scc(order, ptable)
merged = {}
scc = {}
# Now that we got the SSCs (in comps), we select on item from
# each SSC to represent the group and become an ID for that
# SSC.
# * ssc[ssc_id] => All the items in that SSC
# * merged[item] => The ID of the SSC to which the item belongs.
#
# We also "repair" the ordering, so we know in which order the
# hints should be emitted.
for com in comps:
scc_id = com[0]
scc[scc_id] = com
merged[scc_id] = scc_id
if len(com) > 1:
so_before = order[scc_id]['before']
so_after = order[scc_id]['after']
for n in com:
if n == scc_id:
continue
so_before.update(order[n]['before'])
so_after.update(order[n]['after'])
merged[n] = scc_id
del order[n]
if debug_solver:
print("N: SCC: %s -- %s" % (scc_id, str(sorted(com))))
for com in comps:
node = com[0]
nbefore = set(merged[b] for b in order[node]['before'])
nafter = set(merged[b] for b in order[node]['after'])
# Drop self-relations (usually caused by the merging)
nbefore.discard(node)
nafter.discard(node)
order[node]['before'] = nbefore
order[node]['after'] = nafter
if debug_solver:
print("N: -- PARTIAL ORDER --")
for com in sorted(order):
if debug_solver and order[com]['before']:
print("N: %s <= %s" % (com, str(sorted(order[com]['before']))))
if not order[com]['after']:
# This component can be scheduled immediately, add it
# to "check"
check.add(com)
elif debug_solver:
print("N: %s >= %s" % (com, str(sorted(order[com]['after']))))
if debug_solver:
print("N: -- END PARTIAL ORDER --")
print("N: -- LINEARIZED ORDER --")
for cur in iter_except(check.pop, KeyError):
if order[cur]['after'] <= emitted:
# This item is ready to be emitted right now
if debug_solver:
print("N: %s -- %s" % (cur, sorted(scc[cur])))
emitted.add(cur)
result.append([key2item[x] for x in scc[cur]])
if order[cur]['before']:
# There are components that come after this one.
# Add it to "check":
# - if it is ready, it will be emitted.
# - else, it will be dropped and re-added later.
check.update(order[cur]['before'] - emitted)
if debug_solver:
print("N: -- END LINEARIZED ORDER --")
return result
def build(self):
"""Compile the installability tester
This method will compile an installability tester from the
information given and (where possible) try to optimise a
few things.
"""
package_table = self._package_table
reverse_package_table = self._reverse_package_table
intern_set = self._intern_set
safe_set = set()
broken = self._broken
not_broken = ifilter_except(broken)
check = set(broken)
def safe_set_satisfies(t):
"""Check if t's dependencies can be satisfied by the safe set"""
if not package_table[t][0]:
# If it has no dependencies at all, then it is safe. :)
return True
for depgroup in package_table[t][0]:
if not any(dep for dep in depgroup if dep in safe_set):
return False
return True
# Merge reverse conflicts with conflicts - this saves some
# operations in _check_loop since we only have to check one
# set (instead of two) and we remove a few duplicates here
# and there.
#
# At the same time, intern the rdep sets
for pkg in reverse_package_table:
if pkg not in package_table:
raise RuntimeError("%s/%s/%s referenced but not added!" % pkg)
deps, con = package_table[pkg]
rdeps, rcon, rdep_relations = reverse_package_table[pkg]
if rcon:
if not con:
con = intern_set(rcon)
else:
con = intern_set(con | rcon)
package_table[pkg] = (deps, con)
reverse_package_table[pkg] = (intern_set(rdeps), con,
intern_set(rdep_relations))
# Check if we can expand broken.
for t in not_broken(iter_except(check.pop, KeyError)):
# This package is not known to be broken... but it might be now
isb = False
for depgroup in package_table[t][0]:
if not any(not_broken(depgroup)):
# A single clause is unsatisfiable, the
# package can never be installed - add it to
# broken.
isb = True
break
if not isb:
continue
broken.add(t)
if t not in reverse_package_table:
continue
check.update(reverse_package_table[t][0] - broken)
if broken:
# Since a broken package will never be installable, nothing that depends on it
# will ever be installable. Thus, there is no point in keeping relations on
# the broken package.
seen = set()
empty_set = frozenset()
null_data = (frozenset([empty_set]), empty_set)
for b in (x for x in broken if x in reverse_package_table):
for rdep in (r for r in not_broken(reverse_package_table[b][0])
if r not in seen):
ndep = intern_set((x - broken) for x in package_table[rdep][0])
package_table[rdep] = (ndep, package_table[rdep][1] - broken)
seen.add(rdep)
# Since they won't affect the installability of any other package, we might as
# as well null their data. This memory for these packages, but likely there
# will only be a handful of these "at best" (fsvo of "best")
for b in broken:
package_table[b] = null_data
if b in reverse_package_table:
del reverse_package_table[b]
# Now find an initial safe set (if any)
check = set()
for pkg in package_table:
if package_table[pkg][1]:
# has (reverse) conflicts - not safe
continue
if not safe_set_satisfies(pkg):
continue
safe_set.add(pkg)
if pkg in reverse_package_table:
# add all rdeps (except those already in the safe_set)
check.update(reverse_package_table[pkg][0] - safe_set)
# Check if we can expand the initial safe set
for pkg in iter_except(check.pop, KeyError):
if package_table[pkg][1]:
# has (reverse) conflicts - not safe
continue
if safe_set_satisfies(pkg):
safe_set.add(pkg)
if pkg in reverse_package_table:
# add all rdeps (except those already in the safe_set)
check.update(reverse_package_table[pkg][0] - safe_set)
eqv_table = self._build_eqv_packages_table(package_table,
reverse_package_table)
return InstallabilitySolver(package_table,
reverse_package_table,
self._testing, self._broken,
self._essentials, safe_set,
eqv_table)
