X-Git-Url: http://xvm.mit.edu/gitweb/invirt/packages/invirt-base.git/blobdiff_plain/9bf898972c7dd0916a262626a082dc0d930c52ef..06a2334e33b03e38bd880411b4ef82183462d6f1:/files/usr/share/python-support/sipb-xen-base/invirt/common.py

diff --git a/files/usr/share/python-support/sipb-xen-base/invirt/common.py b/files/usr/share/python-support/sipb-xen-base/invirt/common.py
index 5f669ba..d986196 100644
--- a/files/usr/share/python-support/sipb-xen-base/invirt/common.py
+++ b/files/usr/share/python-support/sipb-xen-base/invirt/common.py
@@ -1,5 +1,5 @@
 import unittest
-from fcntl import flock, LOCK_EX, LOCK_UN
+from fcntl import flock, LOCK_EX, LOCK_SH, LOCK_UN
 
 class struct(object):
     'A simple namespace object.'
@@ -39,7 +39,7 @@ def with_closing(rsrc):
         finally: rsrc.close()
     return wrapper
 
-def with_lock_file(path):
+def with_lock_file(path, exclusive = True):
     """
     Context manager for lock files.  Example:
 
@@ -53,7 +53,9 @@ def with_lock_file(path):
     def wrapper(func):
         @with_closing(file(path, 'w'))
         def g(f):
-            flock(f, LOCK_EX)
+            if exclusive: locktype = LOCK_EX
+            else:         locktype = LOCK_SH
+            flock(f, locktype)
             try: return func()
             finally: flock(f, LOCK_UN)
         return g