Move watcher's LockFile function to utils

Reviewed-by: iustinp

daemons/ganeti-watcher

@@ -90,18 +90,6 @@ def DoCmd(cmd):
   return res
 
 
-def LockFile(fd):
-  """Locks a file using POSIX locks.
-
-  """
-  try:
-    fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
-  except IOError, err:
-    if err.errno == errno.EAGAIN:
-      raise errors.LockError("File already locked")
-    raise
-
-
 class WatcherState(object):
   """Interface to a state file recording restart attempts.
 
@@ -118,7 +106,7 @@ class WatcherState(object):
     fd = os.open(constants.WATCHER_STATEFILE, os.O_RDWR | os.O_CREAT)
     self.statefile = os.fdopen(fd, 'w+')
 
-    LockFile(self.statefile.fileno())
+    utils.LockFile(self.statefile.fileno())
 
     try:
       self._data = serializer.Load(self.statefile.read())
@@ -151,7 +139,7 @@ class WatcherState(object):
     # starting ganeti-watcher again at the same time will create a conflict.
     fd = utils.WriteFile(constants.WATCHER_STATEFILE,
                          data=serialized_form,
-                         prewrite=LockFile, close=False)
+                         prewrite=utils.LockFile, close=False)
     self.statefile = os.fdopen(fd, 'w+')
 
   def Close(self):

lib/utils.py

@@ -1082,3 +1082,15 @@ def LockedMethod(fn):
       lock.release()
     return result
   return wrapper
+
+
+def LockFile(fd):
+  """Locks a file using POSIX locks.
+
+  """
+  try:
+    fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
+  except IOError, err:
+    if err.errno == errno.EAGAIN:
+      raise errors.LockError("File already locked")
+    raise