merged trunk

1 files changed, 50 insertions, 7 deletions

diff --git a/nova/utils.py b/nova/utils.py
index ef8405fc0..d18dd9843 100644
--- a/nova/utils.py
+++ b/nova/utils.py
@@ -33,12 +33,12 @@ from twisted.internet.threads import deferToThread
 
 from nova import exception
 from nova import flags
+from nova.exception import ProcessExecutionError
 
 
 FLAGS = flags.FLAGS
 TIME_FORMAT = "%Y-%m-%dT%H:%M:%SZ"
 
-
 def import_class(import_str):
     """Returns a class from a string including module and class"""
     mod_str, _sep, class_str = import_str.rpartition('.')
@@ -48,6 +48,14 @@ def import_class(import_str):
     except (ImportError, ValueError, AttributeError):
         raise exception.NotFound('Class %s cannot be found' % class_str)
 
+def import_object(import_str):
+    """Returns an object including a module or module and class"""
+    try:
+        __import__(import_str)
+        return sys.modules[import_str]
+    except ImportError:
+        cls = import_class(import_str)
+        return cls()
 
 def fetchfile(url, target):
     logging.debug("Fetching %s" % url)
@@ -61,6 +69,7 @@ def fetchfile(url, target):
     execute("curl --fail %s -o %s" % (url, target))
 
 def execute(cmd, process_input=None, addl_env=None, check_exit_code=True):
+    logging.debug("Running cmd: %s", cmd)
     env = os.environ.copy()
     if addl_env:
         env.update(addl_env)
@@ -75,8 +84,11 @@ def execute(cmd, process_input=None, addl_env=None, check_exit_code=True):
     if obj.returncode:
         logging.debug("Result was %s" % (obj.returncode))
         if check_exit_code and obj.returncode <> 0:
-            raise Exception(    "Unexpected exit code: %s.  result=%s" 
-                                % (obj.returncode, result))
+            (stdout, stderr) = result
+            raise ProcessExecutionError(exit_code=obj.returncode,
+                                        stdout=stdout,
+                                        stderr=stderr,
+                                        cmd=cmd)
     return result
 
 
@@ -107,8 +119,10 @@ def runthis(prompt, cmd, check_exit_code = True):
     exit_code = subprocess.call(cmd.split(" "))
     logging.debug(prompt % (exit_code))
     if check_exit_code and exit_code <> 0:
-        raise Exception(    "Unexpected exit code: %s from cmd: %s" 
-                            % (exit_code, cmd))
+        raise ProcessExecutionError(exit_code=exit_code,
+                                    stdout=None,
+                                    stderr=None,
+                                    cmd=cmd)
 
 
 def generate_uid(topic, size=8):
@@ -127,8 +141,7 @@ def last_octet(address):
 
 
 def get_my_ip():
-    ''' returns the actual ip of the local machine.
-    '''
+    """Returns the actual ip of the local machine."""
     if getattr(FLAGS, 'fake_tests', None):
         return '127.0.0.1'
     try:
@@ -152,6 +165,36 @@ def parse_isotime(timestr):
     return datetime.datetime.strptime(timestr, TIME_FORMAT)
 
 
+class LazyPluggable(object):
+    """A pluggable backend loaded lazily based on some value."""
+
+    def __init__(self, pivot, **backends):
+        self.__backends = backends
+        self.__pivot = pivot
+        self.__backend = None
+
+    def __get_backend(self):
+        if not self.__backend:
+            backend_name = self.__pivot.value
+            if backend_name not in self.__backends:
+                raise exception.Error('Invalid backend: %s' % backend_name)
+
+            backend = self.__backends[backend_name]
+            if type(backend) == type(tuple()):
+                name = backend[0]
+                fromlist = backend[1]
+            else:
+                name = backend
+                fromlist = backend
+
+            self.__backend = __import__(name, None, None, fromlist)
+            logging.info('backend %s', self.__backend)
+        return self.__backend
+
+    def __getattr__(self, key):
+        backend = self.__get_backend()
+        return getattr(backend, key)
+
 def deferredToThread(f):
     def g(*args, **kwargs):
         return deferToThread(f, *args, **kwargs)