PackageUninstall: make async with MergeProcess

This fixes another ebuild-locks issue like the one fixed in commit
a81460175a441897282b0540cefff8060f2b92dc, but this time we use a
subprocess to ensure that the ebuild-locks for pkg_prerm and
pkg_postrm do not interfere with pkg_setup ebuild-locks held by
the main process.

1 files changed, 49 insertions, 8 deletions

diff --git a/pym/_emerge/PackageUninstall.py b/pym/_emerge/PackageUninstall.py
index 0e9130713..0829f50b7 100644
--- a/pym/_emerge/PackageUninstall.py
+++ b/pym/_emerge/PackageUninstall.py
@@ -4,17 +4,45 @@
 import logging
 import portage
 from portage import os
+from portage.dbapi._MergeProcess import MergeProcess
+from portage.exception import UnsupportedAPIException
+from _emerge.EbuildBuildDir import EbuildBuildDir
 from _emerge.emergelog import emergelog
 from _emerge.CompositeTask import CompositeTask
 from _emerge.unmerge import _unmerge_display
 
 class PackageUninstall(CompositeTask):
+	"""
+	Uninstall a package asynchronously in a subprocess. When
+	both parallel-install and ebuild-locks FEATURES are enabled,
+	it is essential for the ebuild-locks code to execute in a
+	subprocess, since the portage.locks module does not behave
+	as desired if we try to lock the same file multiple times
+	concurrently from the same process.
+	"""
 
 	__slots__ = ("world_atom", "ldpath_mtimes", "opts",
-			"pkg", "settings")
+			"pkg", "settings", "_builddir_lock")
 
 	def _start(self):
 
+		self.settings.setcpv(self.pkg)
+		vardb = self.pkg.root_config.trees["vartree"].dbapi
+		dbdir = vardb.getpath(self.pkg.cpv)
+		cat, pf = portage.catsplit(self.pkg.cpv)
+		myebuildpath = os.path.join(dbdir, pf + ".ebuild")
+
+		try:
+			portage.doebuild_environment(myebuildpath, "prerm",
+				settings=self.settings, db=vardb)
+		except UnsupportedAPIException:
+			# This is safe to ignore since this function is
+			# guaranteed to set PORTAGE_BUILDDIR even though
+			# it raises UnsupportedAPIException. The error
+			# will be logged when it prevents the pkg_prerm
+			# and pkg_postrm phases from executing.
+			pass
+
 		retval, pkgmap = _unmerge_display(self.pkg.root_config,
 			self.opts, "unmerge", [self.pkg.cpv], clean_delay=0,
 			writemsg_level=self._writemsg_level)
@@ -29,18 +57,31 @@ class PackageUninstall(CompositeTask):
 		self._emergelog("=== Unmerging... (%s)" % (self.pkg.cpv,))
 
 		cat, pf = portage.catsplit(self.pkg.cpv)
-		retval = portage.unmerge(cat, pf, settings=self.settings,
-			vartree=self.pkg.root_config.trees["vartree"],
-			ldpath_mtimes=self.ldpath_mtimes,
-			scheduler=self.scheduler)
 
-		if retval != os.EX_OK:
+		self._builddir_lock = EbuildBuildDir(
+			scheduler=self.scheduler, settings=self.settings)
+		self._builddir_lock.lock()
+
+		portage.prepare_build_dirs(
+			settings=self.settings, cleanup=True)
+
+		unmerge_task = MergeProcess(
+			mycat=cat, mypkg=pf, settings=self.settings,
+			treetype="vartree", vartree=self.pkg.root_config.trees["vartree"],
+			scheduler=self.scheduler, background=self.background,
+			mydbapi=self.pkg.root_config.trees["vartree"].dbapi,
+			prev_mtimes=self.ldpath_mtimes,
+			logfile=self.settings.get("PORTAGE_LOG_FILE"), unmerge=True)
+
+		self._start_task(unmerge_task, self._unmerge_exit)
+
+	def _unmerge_exit(self, unmerge_task):
+		if self._final_exit(unmerge_task) != os.EX_OK:
 			self._emergelog(" !!! unmerge FAILURE: %s" % (self.pkg.cpv,))
 		else:
 			self._emergelog(" >>> unmerge success: %s" % (self.pkg.cpv,))
 			self.world_atom(self.pkg)
-
-		self.returncode = retval
+		self._builddir_lock.unlock()
 		self.wait()
 
 	def _emergelog(self, msg):