[gentoo-commits] proj/portage:master commit in: pym/portage/util/_dyn_libs/

["Zac Medico" <zmedico@gentoo.org>]

commit:     48e1b835df5fefe49e2227e37c007d87fade1c55
Author:     Zac Medico <zmedico <AT> gentoo <DOT> org>
AuthorDate: Sat May  7 17:25:20 2011 +0000
Commit:     Zac Medico <zmedico <AT> gentoo <DOT> org>
CommitDate: Sat May  7 17:25:20 2011 +0000
URL:        http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=48e1b835

PreserveLibsRegistry: add lock/unlock assertions

Also, add comments to store() about unobvious interaction with
locking due to atomic replacement of the inode.

---
 .../util/_dyn_libs/PreservedLibsRegistry.py        |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/pym/portage/util/_dyn_libs/PreservedLibsRegistry.py b/pym/portage/util/_dyn_libs/PreservedLibsRegistry.py
index f3cbb33..3fb8120 100644
--- a/pym/portage/util/_dyn_libs/PreservedLibsRegistry.py
+++ b/pym/portage/util/_dyn_libs/PreservedLibsRegistry.py
@@ -36,11 +36,16 @@ class PreservedLibsRegistry(object):
 
 	def lock(self):
 		"""Grab an exclusive lock on the preserved libs registry."""
+		if self._lock is not None:
+			raise AssertionError("already locked")
 		self._lock = lockfile(self._filename)
 
 	def unlock(self):
 		"""Release our exclusive lock on the preserved libs registry."""
+		if self._lock is None:
+			raise AssertionError("not locked")
 		unlockfile(self._lock)
+		self._lock = None
 
 	def load(self):
 		""" Reload the registry data from file """
@@ -65,7 +70,13 @@ class PreservedLibsRegistry(object):
 		self.pruneNonExisting()
 
 	def store(self):
-		""" Store the registry data to file """
+		"""
+		Store the registry data to the file. The existing inode will be
+		replaced atomically, so if that inode is currently being used
+		for a lock then that lock will be rendered useless. Therefore,
+		it is important not to call this method until the current lock
+		is ready to be immediately released.
+		"""
 		if os.environ.get("SANDBOX_ON") == "1" or \
 			self._data == self._data_orig:
 			return