_world_atom: avoid world set lock reentrance

This fixes a case with FEATURE=parallel-install, where a call from
_world_atom to the global event loop could result in reentrace and
lock interference.

2 files changed, 19 insertions, 6 deletions

diff --git a/pym/_emerge/Scheduler.py b/pym/_emerge/Scheduler.py
index 4b29c7110..5930550fa 100644
--- a/pym/_emerge/Scheduler.py
+++ b/pym/_emerge/Scheduler.py
@@ -1896,11 +1896,21 @@ class Scheduler(PollScheduler):
 		root_config = pkg.root_config
 		world_set = root_config.sets["selected"]
 		world_locked = False
-		if hasattr(world_set, "lock"):
-			world_set.lock()
-			world_locked = True
+		atom = None
+
+		if pkg.operation != "uninstall":
+			# Do this before acquiring the lock, since it queries the
+			# portdbapi which can call the global event loop, triggering
+			# a concurrent call to this method or something else that
+			# needs an exclusive (non-reentrant) lock on the world file.
+			atom = create_world_atom(pkg, args_set, root_config)
 
 		try:
+
+			if hasattr(world_set, "lock"):
+				world_set.lock()
+				world_locked = True
+
 			if hasattr(world_set, "load"):
 				world_set.load() # maybe it's changed on disk
 
@@ -1912,8 +1922,7 @@ class Scheduler(PollScheduler):
 					for s in pkg.root_config.setconfig.active:
 						world_set.remove(SETPREFIX+s)
 			else:
-				atom = create_world_atom(pkg, args_set, root_config)
-				if atom:
+				if atom is not None:
 					if hasattr(world_set, "add"):
 						self._status_msg(('Recording %s in "world" ' + \
 							'favorites file...') % atom)
diff --git a/pym/portage/_sets/files.py b/pym/portage/_sets/files.py
index b839582df..2fb64de87 100644
--- a/pym/portage/_sets/files.py
+++ b/pym/portage/_sets/files.py
@@ -1,4 +1,4 @@
-# Copyright 2007-2012 Gentoo Foundation
+# Copyright 2007-2013 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
 
 import errno
@@ -296,10 +296,14 @@ class WorldSelectedSet(EditablePackageSet):
 		ensure_dirs(os.path.dirname(self._filename), gid=portage_gid, mode=0o2750, mask=0o2)
 
 	def lock(self):
+		if self._lock is not None:
+			raise AssertionError("already locked")
 		self._ensure_dirs()
 		self._lock = lockfile(self._filename, wantnewlockfile=1)
 
 	def unlock(self):
+		if self._lock is None:
+			raise AssertionError("not locked")
 		unlockfile(self._lock)
 		self._lock = None