From a4219b47157101bd7ae0165d4fd86c307ffb2c6f Mon Sep 17 00:00:00 2001
From: Zac Medico <zmedico@gentoo.org>
Date: Wed, 11 Mar 2009 06:11:21 +0000
Subject: [PATCH] Use a lock to ensure that threaded code doesn't cause
 problems with proxy registration and unregistration. (trunk r12683)

svn path=/main/branches/2.1.6/; revision=12943
---
 pym/portage/proxy/lazyimport.py | 51 +++++++++++++++++++++++----------
 1 file changed, 36 insertions(+), 15 deletions(-)

diff --git a/pym/portage/proxy/lazyimport.py b/pym/portage/proxy/lazyimport.py
index 954b29d74..1a4a246ef 100644
--- a/pym/portage/proxy/lazyimport.py
+++ b/pym/portage/proxy/lazyimport.py
@@ -6,16 +6,27 @@ __all__ = ['lazyimport']
 
 import sys
 import types
+
+try:
+	import threading
+except ImportError:
+	import dummy_threading as threading
+
 from portage.proxy.objectproxy import ObjectProxy
 
 _module_proxies = {}
+_module_proxies_lock = threading.RLock()
 
 def _register_module_proxy(name, proxy):
-	proxy_list = _module_proxies.get(name)
-	if proxy_list is None:
-		proxy_list = []
-		_module_proxies[name] = proxy_list
-	proxy_list.append(proxy)
+	_module_proxies_lock.acquire()
+	try:
+		proxy_list = _module_proxies.get(name)
+		if proxy_list is None:
+			proxy_list = []
+			_module_proxies[name] = proxy_list
+		proxy_list.append(proxy)
+	finally:
+		_module_proxies_lock.release()
 
 def _unregister_module_proxy(name):
 	"""
@@ -24,20 +35,30 @@ def _unregister_module_proxy(name):
 	destroy those proxies too. This way, destruction of a single proxy
 	can trigger destruction of all the rest.
 	"""
-	proxy_list = _module_proxies.get(name)
-	if proxy_list is not None:
-		del _module_proxies[name]
-		for proxy in proxy_list:
-			object.__getattribute__(proxy, '_get_target')()
-
-		modules = sys.modules
-		for name, proxy_list in list(_module_proxies.iteritems()):
-			if name not in modules:
-				continue
+	_module_proxies_lock.acquire()
+	try:
+		proxy_list = _module_proxies.get(name)
+		if proxy_list is not None:
+			# First delete this name from the dict so that
+			# if this same thread reenters below, it won't
+			# enter this path again.
 			del _module_proxies[name]
 			for proxy in proxy_list:
 				object.__getattribute__(proxy, '_get_target')()
 
+			modules = sys.modules
+			for name, proxy_list in list(_module_proxies.iteritems()):
+				if name not in modules:
+					continue
+				# First delete this name from the dict so that
+				# if this same thread reenters below, it won't
+				# enter this path again.
+				del _module_proxies[name]
+				for proxy in proxy_list:
+					object.__getattribute__(proxy, '_get_target')()
+	finally:
+		_module_proxies_lock.release()
+
 class _LazyImport(ObjectProxy):
 
 	__slots__ = ('_scope', '_alias', '_name', '_target')
-- 
2.26.2