merge lp:nova and resolve conflicts

3 files changed, 67 insertions, 3 deletions

diff --git a/nova/flags.py b/nova/flags.py
index 8cf199b2f..213d4d4e1 100644
--- a/nova/flags.py
+++ b/nova/flags.py
@@ -321,6 +321,8 @@ DEFINE_integer('auth_token_ttl', 3600, 'Seconds for auth tokens to linger')
 
 DEFINE_string('state_path', os.path.join(os.path.dirname(__file__), '../'),
               "Top-level directory for maintaining nova's state")
+DEFINE_string('lock_path', os.path.join(os.path.dirname(__file__), '../'),
+              "Directory for lock files")
 DEFINE_string('logdir', None, 'output to a per-service log file in named '
                               'directory')
 
diff --git a/nova/tests/test_misc.py b/nova/tests/test_misc.py
index e6da6112a..a658e4978 100644
--- a/nova/tests/test_misc.py
+++ b/nova/tests/test_misc.py
@@ -14,10 +14,12 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import errno
 import os
+import select
 
 from nova import test
-from nova.utils import parse_mailmap, str_dict_replace
+from nova.utils import parse_mailmap, str_dict_replace, synchronized
 
 
 class ProjectTestCase(test.TestCase):
@@ -55,3 +57,47 @@ class ProjectTestCase(test.TestCase):
                                 '%r not listed in Authors' % missing)
             finally:
                 tree.unlock()
+
+
+class LockTestCase(test.TestCase):
+    def test_synchronized_wrapped_function_metadata(self):
+        @synchronized('whatever')
+        def foo():
+            """Bar"""
+            pass
+        self.assertEquals(foo.__doc__, 'Bar', "Wrapped function's docstring "
+                                              "got lost")
+        self.assertEquals(foo.__name__, 'foo', "Wrapped function's name "
+                                               "got mangled")
+
+    def test_synchronized(self):
+        rpipe1, wpipe1 = os.pipe()
+        rpipe2, wpipe2 = os.pipe()
+
+        @synchronized('testlock')
+        def f(rpipe, wpipe):
+            try:
+                os.write(wpipe, "foo")
+            except OSError, e:
+                self.assertEquals(e.errno, errno.EPIPE)
+                return
+
+            rfds, _, __ = select.select([rpipe], [], [], 1)
+            self.assertEquals(len(rfds), 0, "The other process, which was"
+                                            " supposed to be locked, "
+                                            "wrote on its end of the "
+                                            "pipe")
+            os.close(rpipe)
+
+        pid = os.fork()
+        if pid > 0:
+            os.close(wpipe1)
+            os.close(rpipe2)
+
+            f(rpipe1, wpipe2)
+        else:
+            os.close(rpipe1)
+            os.close(wpipe2)
+
+            f(rpipe2, wpipe1)
+            os._exit(0)
diff --git a/nova/utils.py b/nova/utils.py
index 02b71900c..3007bf19d 100644
--- a/nova/utils.py
+++ b/nova/utils.py
@@ -23,10 +23,14 @@ System-level utilities and helper functions.
 
 import base64
 import datetime
+import functools
 import inspect
 import json
+import lockfile
+import netaddr
 import os
 import random
+import re
 import socket
 import string
 import struct
@@ -34,8 +38,6 @@ import sys
 import time
 import types
 from xml.sax import saxutils
-import re
-import netaddr
 
 from eventlet import event
 from eventlet import greenthread
@@ -43,11 +45,13 @@ from eventlet.green import subprocess
 
 from nova import exception
 from nova.exception import ProcessExecutionError
+from nova import flags
 from nova import log as logging
 
 
 LOG = logging.getLogger("nova.utils")
 TIME_FORMAT = "%Y-%m-%dT%H:%M:%SZ"
+FLAGS = flags.FLAGS
 
 
 def import_class(import_str):
@@ -491,6 +495,18 @@ def loads(s):
     return json.loads(s)
 
 
+def synchronized(name):
+    def wrap(f):
+        @functools.wraps(f)
+        def inner(*args, **kwargs):
+            lock = lockfile.FileLock(os.path.join(FLAGS.lock_path,
+                                                  'nova-%s.lock' % name))
+            with lock:
+                return f(*args, **kwargs)
+        return inner
+    return wrap
+
+
 def get_from_path(items, path):
     """ Returns a list of items matching the specified path.  Takes an
     XPath-like expression e.g. prop1/prop2/prop3, and for each item in items,