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britney.py: Handle version-ranged dependencies a bit smarter

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Avoid creating two dependency clauses for dependencies emulating a
"version range" a la:

  Depends: pkg-a (>= 2), pkg-a (<< 3~)

Previously this would create two clauses a la:

 - (pkg-a, 2, arch), (pkg-a, 3, arch)
 - (pkg-a, 1, arch), (pkg-a, 2, arch)

However, it is plain to see that only (pkg-a, 2, arch) is a valid
solution and the other options are just noise.  This patch makes
Britney merge these two claues into a single clause containing exactly
(pkg-a, 2, arch).

Signed-off-by: Niels Thykier <niels@thykier.net>
This commit is contained in:
Niels Thykier 2014-08-04 20:19:49 +02:00
parent 3817e9bae8
commit 6a19e254de
1 changed files with 35 additions and 1 deletions
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36
britney.py
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@ -431,10 +431,12 @@ class Britney(object):
depends = []
conflicts = []
possible_dep_ranges = {}
# We do not differ between depends and pre-depends
if pkgdata[DEPENDS]:
depends.extend(apt_pkg.parse_depends(pkgdata[DEPENDS], False))
if pkgdata[CONFLICTS]:
conflicts = apt_pkg.parse_depends(pkgdata[CONFLICTS], False)
@ -442,8 +444,10 @@ class Britney(object):
for (al, dep) in [(depends, True), \
(conflicts, False)]:
for block in al:
sat = set()
for dep_dist in binaries:
(_, pkgs) = solvers(block, arch, dep_dist)
for p in pkgs:
@ -460,7 +464,37 @@ class Britney(object):
# is using §7.6.2
relations.add_breaks(pt)
if dep:
relations.add_dependency_clause(sat)
if len(block) != 1:
relations.add_dependency_clause(sat)
else:
# This dependency might be a part
# of a version-range a la:
#
# Depends: pkg-a (>= 1),
# pkg-a (<< 2~)
#
# In such a case we want to reduce
# that to a single clause for
# efficiency.
#
# In theory, it could also happen
# with "non-minimal" dependencies
# a la:
#
# Depends: pkg-a, pkg-a (>= 1)
#
# But dpkg is known to fix that up
# at build time, so we will
# probably only see "ranges" here.
key = block[0][0]
if key in possible_dep_ranges:
possible_dep_ranges[key] &= sat
else:
possible_dep_ranges[key] = sat
if dep:
for clause in possible_dep_ranges.itervalues():
relations.add_dependency_clause(clause)
self._inst_tester = builder.build()