[gentoo-portage-dev] [PATCH v2] depgraph: prune unnecessary rebuilds for --autounmask-continue (bug 619626)

[Zac Medico]

When there are autounmask USE changes, avoid unnecessary rebuilds
by accepting binary packages that were rejected due to the preexisting
USE configuration. This reuses the prune_rebuilds backtracker support
which was added for bug 439688.

X-Gentoo-bug: 619626
X-Gentoo-bug-url: https://bugs.gentoo.org/show_bug.cgi?id=619626
---
[PATCH v2]
* Ensure that it won't try to prune rebuilds more than once.
* Simplify boolean logic at the beginning of the
  _ignored_binaries_autounmask_backtrack method, as suggested
  by Brian Dolbec.

 pym/_emerge/depgraph.py                            | 89 ++++++++++++++++++----
 .../tests/resolver/test_autounmask_binpkg_use.py   | 64 ++++++++++++++++
 2 files changed, 138 insertions(+), 15 deletions(-)
 create mode 100644 pym/portage/tests/resolver/test_autounmask_binpkg_use.py

diff --git a/pym/_emerge/depgraph.py b/pym/_emerge/depgraph.py
index 726835dd4..f47ce559c 100644
--- a/pym/_emerge/depgraph.py
+++ b/pym/_emerge/depgraph.py
@@ -5,6 +5,7 @@ from __future__ import division, print_function, unicode_literals
 
 import collections
 import errno
+import functools
 import io
 import logging
 import stat
@@ -856,17 +857,11 @@ class depgraph(object):
 				for parent in self._forced_rebuilds[root][child]:
 					writemsg_stdout("    %s\n" % (parent,), noiselevel=-1)
 
-	def _show_ignored_binaries(self):
+	def _eliminate_ignored_binaries(self):
 		"""
-		Show binaries that have been ignored because their USE didn't
-		match the user's config.
+		Eliminate any package from self._dynamic_config.ignored_binaries
+		for which a more optimal alternative exists.
 		"""
-		if not self._dynamic_config.ignored_binaries \
-			or '--quiet' in self._frozen_config.myopts:
-			return
-
-		ignored_binaries = {}
-
 		for pkg in list(self._dynamic_config.ignored_binaries):
 
 			for selected_pkg in self._dynamic_config._package_tracker.match(
@@ -885,10 +880,67 @@ class depgraph(object):
 					self._dynamic_config.ignored_binaries.pop(pkg)
 					break
 
-			else:
-				for reason, info in self._dynamic_config.\
-					ignored_binaries[pkg].items():
-					ignored_binaries.setdefault(reason, {})[pkg] = info
+	def _ignored_binaries_autounmask_backtrack(self):
+		"""
+		Check if there are ignored binaries that would have been
+		accepted with the current autounmask USE changes.
+
+		@rtype: bool
+		@return: True if there are unnecessary rebuilds that
+			can be avoided by backtracking
+		"""
+		if not all([
+			self._dynamic_config._allow_backtracking,
+			self._dynamic_config._needed_use_config_changes,
+			self._dynamic_config.ignored_binaries]):
+			return False
+
+		self._eliminate_ignored_binaries()
+
+		# _eliminate_ignored_binaries may have eliminated
+		# all of the ignored binaries
+		if not self._dynamic_config.ignored_binaries:
+			return False
+
+		use_changes = collections.defaultdict(
+			functools.partial(collections.defaultdict, dict))
+		for pkg, (new_use, changes) in self._dynamic_config._needed_use_config_changes.items():
+			if pkg in self._dynamic_config.digraph:
+				use_changes[pkg.root][pkg.slot_atom] = (pkg, new_use)
+
+		for pkg in self._dynamic_config.ignored_binaries:
+			selected_pkg, new_use = use_changes[pkg.root].get(
+				pkg.slot_atom, (None, None))
+			if new_use is None:
+				continue
+
+			if new_use != pkg.use.enabled:
+				continue
+
+			if selected_pkg > pkg:
+				continue
+
+			return True
+
+		return False
+
+	def _show_ignored_binaries(self):
+		"""
+		Show binaries that have been ignored because their USE didn't
+		match the user's config.
+		"""
+		if not self._dynamic_config.ignored_binaries \
+			or '--quiet' in self._frozen_config.myopts:
+			return
+
+		self._eliminate_ignored_binaries()
+
+		ignored_binaries = {}
+
+		for pkg in self._dynamic_config.ignored_binaries:
+			for reason, info in self._dynamic_config.\
+				ignored_binaries[pkg].items():
+				ignored_binaries.setdefault(reason, {})[pkg] = info
 
 		if self._dynamic_config.myparams.get(
 			"binpkg_respect_use") in ("y", "n"):
@@ -4245,6 +4297,13 @@ class depgraph(object):
 				self._dynamic_config._skip_restart = True
 				return False, myfavorites
 
+		if (not self._dynamic_config._prune_rebuilds and
+			self._ignored_binaries_autounmask_backtrack()):
+			config = self._dynamic_config._backtrack_infos.setdefault("config", {})
+			config["prune_rebuilds"] = True
+			self._dynamic_config._need_restart = True
+			return False, myfavorites
+
 		# Any failures except those due to autounmask *alone* should return
 		# before this point, since the success_without_autounmask flag that's
 		# set below is reserved for cases where there are *zero* other
@@ -6224,10 +6283,10 @@ class depgraph(object):
 							iuses = pkg.iuse.all
 							old_use = self._pkg_use_enabled(pkg)
 							if myeb:
-								pkgsettings.setcpv(myeb)
+								now_use = self._pkg_use_enabled(myeb)
 							else:
 								pkgsettings.setcpv(pkg)
-							now_use = pkgsettings["PORTAGE_USE"].split()
+								now_use = pkgsettings["PORTAGE_USE"].split()
 							forced_flags = set()
 							forced_flags.update(pkgsettings.useforce)
 							forced_flags.update(pkgsettings.usemask)
diff --git a/pym/portage/tests/resolver/test_autounmask_binpkg_use.py b/pym/portage/tests/resolver/test_autounmask_binpkg_use.py
new file mode 100644
index 000000000..1ca4bf3d9
--- /dev/null
+++ b/pym/portage/tests/resolver/test_autounmask_binpkg_use.py
@@ -0,0 +1,64 @@
+# Copyright 2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+from portage.tests import TestCase
+from portage.tests.resolver.ResolverPlayground import ResolverPlayground, ResolverPlaygroundTestCase
+
+class AutounmaskBinpkgUseTestCase(TestCase):
+
+	def testAutounmaskBinpkgUse(self):
+		ebuilds = {
+			"dev-libs/A-1": {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/B[foo]",
+				"RDEPEND": "dev-libs/B[foo]",
+			},
+			"dev-libs/B-1": {
+				"EAPI": "6",
+				"IUSE": "foo",
+			},
+		}
+		binpkgs = {
+			"dev-libs/A-1": {
+				"EAPI": "6",
+				"DEPEND": "dev-libs/B[foo]",
+				"RDEPEND": "dev-libs/B[foo]",
+			},
+			"dev-libs/B-1": {
+				"EAPI": "6",
+				"IUSE": "foo",
+				"USE": "foo",
+			},
+		}
+		installed = {
+		}
+
+		test_cases = (
+			# Bug 619626: Test for unnecessary rebuild due
+			# to rejection of binary packages that would
+			# be acceptable after appplication of autounmask
+			# USE changes.
+			ResolverPlaygroundTestCase(
+				["dev-libs/A"],
+				all_permutations = True,
+				success = True,
+				options = {
+					"--usepkg": True,
+				},
+				mergelist = [
+				    "[binary]dev-libs/B-1",
+				    "[binary]dev-libs/A-1",
+				],
+				use_changes = {"dev-libs/B-1": {"foo": True}}
+			),
+		)
+
+		playground = ResolverPlayground(ebuilds=ebuilds,
+			binpkgs=binpkgs, installed=installed, debug=False)
+		try:
+			for test_case in test_cases:
+				playground.run_TestCase(test_case)
+				self.assertEqual(test_case.test_success, True, test_case.fail_msg)
+		finally:
+			playground.debug = False
+			playground.cleanup()
-- 
2.13.0