From 8867ef0cf96b5354f87da9e0ee0d7cfc30ad95d2 Mon Sep 17 00:00:00 2001
From: Niels Thykier <niels@thykier.net>
Date: Thu, 1 Nov 2018 06:43:23 +0000
Subject: [PATCH] Let the BinaryPackageUniverse track essential packages

Signed-off-by: Niels Thykier <niels@thykier.net>
---
 britney2/installability/builder.py  |  3 +--
 britney2/installability/tester.py   |  9 +++------
 britney2/installability/universe.py | 12 +++++++++++-
 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/britney2/installability/builder.py b/britney2/installability/builder.py
index 2eab495..e094d4a 100644
--- a/britney2/installability/builder.py
+++ b/britney2/installability/builder.py
@@ -308,12 +308,11 @@ class InstallabilityTesterBuilder(object):
 
         relations, eqv_table = self._build_eqv_packages_table(package_table, reverse_package_table)
 
-        universe = BinaryPackageUniverse(relations)
+        universe = BinaryPackageUniverse(relations, intern_set(self._essentials))
 
         solver = InstallabilityTester(universe,
                                       self._testing,
                                       self._broken,
-                                      self._essentials,
                                       eqv_table)
 
         return universe, solver
diff --git a/britney2/installability/tester.py b/britney2/installability/tester.py
index 055a403..3c2d29b 100644
--- a/britney2/installability/tester.py
+++ b/britney2/installability/tester.py
@@ -22,7 +22,7 @@ from britney2.utils import iter_except
 
 class InstallabilityTester(object):
 
-    def __init__(self, universe, testing, broken, essentials, eqv_table):
+    def __init__(self, universe, testing, broken, eqv_table):
         """Create a new installability tester
 
         universe is a BinaryPackageUniverse
@@ -33,8 +33,6 @@ class InstallabilityTester(object):
         broken is a (mutable) set of package ids that are known to
         be uninstallable.
 
-        essentials is a set of packages with "Essential: yes".
-
         Package id: (pkg_name, pkg_version, pkg_arch)
           - NB: arch:all packages are "re-mapped" to given architecture.
             (simplifies caches and dependency checking)
@@ -43,7 +41,6 @@ class InstallabilityTester(object):
         self._universe = universe
         self._testing = testing
         self._broken = broken
-        self._essentials = essentials
         self._eqv_table = eqv_table
         self._stats = InstallabilityStats()
         logger_name = ".".join((self.__class__.__module__, self.__class__.__name__))
@@ -136,7 +133,7 @@ class InstallabilityTester(object):
                 # 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.architecture in self._cache_ess:
+            if pkg_id in self._universe.essential_packages and pkg_id.architecture in self._cache_ess:
                 # Adds new essential => "pseudo-essential" set needs to be
                 # recomputed
                 del self._cache_ess[pkg_id.architecture]
@@ -519,7 +516,7 @@ class InstallabilityTester(object):
             universe = self._universe
             stats = self._stats
 
-            ess_base = [x for x in self._essentials if x.architecture == arch and x in testing]
+            ess_base = [x for x in self._universe.essential_packages if x.architecture == arch and x in testing]
             start = set(ess_base)
             ess_never = set()
             ess_choices = set()
diff --git a/britney2/installability/universe.py b/britney2/installability/universe.py
index 12d304b..8f08b76 100644
--- a/britney2/installability/universe.py
+++ b/britney2/installability/universe.py
@@ -38,8 +38,9 @@ class BinaryPackageUniverse(object):
     in that suite?".
     """
 
-    def __init__(self, relations):
+    def __init__(self, relations, essential_packages):
         self._relations = relations
+        self._essential_packages = essential_packages
 
     def dependencies_of(self, pkg_id):
         """Returns the set of dependencies of a given package
@@ -109,6 +110,15 @@ class BinaryPackageUniverse(object):
         """
         return self._relations[pkg_id]
 
+    @property
+    def essential_packages(self):
+        """A frozenset of all "Essential: yes" binaries in the universe
+
+        :return A frozenset of BinaryPackageIds of all binaries that are
+        marked as essential.
+        """
+        return self._essential_packages
+
     def __contains__(self, pkg_id):
         return pkg_id in self._relations