[Zope3-checkins] CVS: ZODB4/src/zodb/storage - base.py:1.29

[Jeremy Hylton]

Update of /cvs-repository/ZODB4/src/zodb/storage
In directory cvs.zope.org:/tmp/cvs-serv2080/storage

Modified Files:
	base.py 
Log Message:
Extend doc string to mention locking.


=== ZODB4/src/zodb/storage/base.py 1.28 => 1.29 ===
--- ZODB4/src/zodb/storage/base.py:1.28	Thu May  1 15:35:00 2003
+++ ZODB4/src/zodb/storage/base.py	Thu May 15 16:59:03 2003
@@ -86,6 +86,19 @@
 
     If the subclass wants to implement IVersionStorage, it must implement
     all the methods in that interface.
+
+    Each storage will have two locks that are accessed via lock
+    acquire and release methods bound to the instance.  (Yuck.)
+    _lock_acquire / _lock_release (reentrant)
+    _commit_lock_acquire / _commit_lock_release
+
+    The commit lock is acquired in tpcBegin() and released in
+    tpcAbort() and tpcFinish().  It is never acquired with the other
+    lock held.
+
+    The other lock appears to protect _oid and _transaction and
+    perhaps other things.  It is always held when load() is called, so
+    presumably the load() implementation should also acquire the lock.
     """
 
     _transaction = None # Transaction that is being committed