[Zope3-checkins] CVS: Zope3/src/persistence - cache.py:1.6

[Tim Peters]

Update of /cvs-repository/Zope3/src/persistence
In directory cvs.zope.org:/tmp/cvs-serv18615/src/persistence

Modified Files:
	cache.py 
Log Message:
Cache.incrgc():  If garbage collection happens to occur while iterating
over __active, weakrefs can cause __active to change size.  This in turn
could cause a mysterious "Transaction failed during second phase
of two-phase commit" TransactionError.  The cure is to use .items()
instead of .iteritems().


=== Zope3/src/persistence/cache.py 1.5 => 1.6 ===
--- Zope3/src/persistence/cache.py:1.5	Tue Mar 11 17:09:06 2003
+++ Zope3/src/persistence/cache.py	Mon Mar 17 14:44:01 2003
@@ -90,12 +90,14 @@
         now = int(time() % 86400)
 
         # Implement a trivial LRU cache by sorting the items by access
-        # time and trundling over the list until we've reached out
+        # time and trundling over the list until we've reached our
         # target size.  The number of objects in the cache should be
         # relatively small (thousands) so the memory for the list is
-        # pretty minimal.
+        # pretty minimal.  Caution:  Don't use iteritems().  Because of
+        # weakrefs, if garbage collection happens to occur, __active
+        # can change size.
         L = []
-        for oid, ob in self.__active.iteritems():
+        for oid, ob in self.__active.items():
             if ob is not None:
                 ob = ob()
             # The _p_atime field is seconds since the start of the day.