[Kimchi-devel] [kimchi-devel][PATCH 3/5] Add utils to support file lock

[lvroyce at linux.vnet.ibm.com]

From: Royce Lv <lvroyce at linux.vnet.ibm.com>

Wrap posix file lock with contextlib so that file sections
can be protected by lock.

Signed-off-by: Royce Lv <lvroyce at linux.vnet.ibm.com>
---
 src/kimchi/model/utils.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/kimchi/model/utils.py b/src/kimchi/model/utils.py
index 9896289..1188b19 100644
--- a/src/kimchi/model/utils.py
+++ b/src/kimchi/model/utils.py
@@ -18,8 +18,10 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
 
 import libvirt
+import posixfile
 import socket
 import urlparse
+from contextlib import contextmanager
 from lxml import etree, objectify
 from lxml.builder import E, ElementMaker
 
@@ -161,3 +163,17 @@ def get_metadata_node(dom, tag, metadata_support, mode="current"):
         if node is not None:
             return etree.tostring(node)
     return ""
+
+
+ at contextmanager
+def flock(fp, pos, len):
+    fp.lock('w|', len, pos)
+    yield
+    fp.lock('u', len, pos)
+
+
+ at contextmanager
+def f_open(path, mod):
+    file = posixfile.open(path, mod)
+    yield file
+    file.close()
-- 
1.9.3