Let the BinaryPackageUnvierse track broken packages

Signed-off-by: Niels Thykier <niels@thykier.net>

britney2/installability/builder.py

@@ -308,11 +308,10 @@ class InstallabilityTesterBuilder(object):
 
         relations, eqv_table = self._build_eqv_packages_table(package_table, reverse_package_table)
 
-        universe = BinaryPackageUniverse(relations, intern_set(self._essentials))
+        universe = BinaryPackageUniverse(relations, intern_set(self._essentials), intern_set(broken))
 
         solver = InstallabilityTester(universe,
                                       self._testing,
-                                      self._broken,
                                       eqv_table)
 
         return universe, solver

britney2/installability/tester.py

@@ -22,7 +22,7 @@ from britney2.utils import iter_except
 
 class InstallabilityTester(object):
 
-    def __init__(self, universe, testing, broken, eqv_table):
+    def __init__(self, universe, testing, eqv_table):
         """Create a new installability tester
 
         universe is a BinaryPackageUniverse
@@ -30,9 +30,6 @@ class InstallabilityTester(object):
         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.
-
         Package id: (pkg_name, pkg_version, pkg_arch)
           - NB: arch:all packages are "re-mapped" to given architecture.
             (simplifies caches and dependency checking)
@@ -40,7 +37,6 @@ class InstallabilityTester(object):
 
         self._universe = universe
         self._testing = testing
-        self._broken = broken
         self._eqv_table = eqv_table
         self._stats = InstallabilityStats()
         logger_name = ".".join((self.__class__.__module__, self.__class__.__name__))
@@ -122,7 +118,7 @@ class InstallabilityTester(object):
         if pkg_id not in self._universe:  # pragma: no cover
             raise KeyError(str(pkg_id))
 
-        if pkg_id in self._broken:
+        if pkg_id in self._universe.broken_packages:
             self._testing.add(pkg_id)
         elif pkg_id not in self._testing:
             self._testing.add(pkg_id)
@@ -162,7 +158,7 @@ class InstallabilityTester(object):
             if not self._universe.reverse_dependencies_of(pkg_id):
                 # no reverse relations - safe
                 return True
-            if pkg_id not in self._broken and pkg_id in self._cache_inst:
+            if pkg_id not in self._universe.broken_packages 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
@@ -185,7 +181,7 @@ class InstallabilityTester(object):
         if pkg_id not in self._universe:  # pragma: no cover
             raise KeyError(str(pkg_id))
 
-        if pkg_id not in self._testing or pkg_id in self._broken:
+        if pkg_id not in self._testing or pkg_id in self._universe.broken_packages:
             self._stats.cache_hits += 1
             return False
 

britney2/installability/universe.py

@@ -36,11 +36,25 @@ class BinaryPackageUniverse(object):
     Being immutable, the universe does *not* track stateful data such
     as "which package is in what suite?" nor "is this package installable
     in that suite?".
+
+    The universe also includes some packages that are considered "broken".
+    These packages have been identified to always be uninstallability
+    regardless of the selection of package available (e.g. the depend
+    on a non-existent package or has a relation that is impossible to
+    satisfy).
+
+    For these packages, the universe only tracks that they
+    exist and that they are broken.  This implies that their relations
+    have been nulled into empty sets and they have been removed from
+    the relations of other packages.  This optimizes analysis of the
+    universe on packages that is/can be installable at the expense
+    of a "minor" lie about the "broken" packages.
     """
 
-    def __init__(self, relations, essential_packages):
+    def __init__(self, relations, essential_packages, broken_packages):
         self._relations = relations
         self._essential_packages = essential_packages
+        self._broken_packages = broken_packages
 
     def dependencies_of(self, pkg_id):
         """Returns the set of dependencies of a given package
@@ -96,8 +110,7 @@ class BinaryPackageUniverse(object):
 
         :param pkg_id: The BinaryPackageId of a binary package.
         :return: A frozenset of all package ids that are equivalent to the
-        input package.  Note that this set always includes the input
-        package assuming it is a known package.
+        input package.
         """
         return self._relations[pkg_id].pkg_ids
 
@@ -119,6 +132,15 @@ class BinaryPackageUniverse(object):
         """
         return self._essential_packages
 
+    @property
+    def broken_packages(self):
+        """A frozenset of all broken binaries in the universe
+
+        :return A frozenset of BinaryPackageIds of all binaries that are
+        considered "broken" and had their relations nulled.
+        """
+        return self._broken_packages
+
     def __contains__(self, pkg_id):
         return pkg_id in self._relations