Change xenapi's wait_for_task to handle multiple simultaenous queries to fix lp:766404

1 files changed, 40 insertions, 46 deletions

diff --git a/nova/virt/xenapi_conn.py b/nova/virt/xenapi_conn.py
index 0cabccf08..5dc6b034f 100644
--- a/nova/virt/xenapi_conn.py
+++ b/nova/virt/xenapi_conn.py
@@ -326,7 +326,6 @@ class XenAPISession(object):
                             "(is the Dom0 disk full?)"))
         with timeout.Timeout(FLAGS.xenapi_login_timeout, exception):
             self._session.login_with_password(user, pw)
-        self.loop = None
 
     def get_imported_xenapi(self):
         """Stubout point. This can be replaced with a mock xenapi module."""
@@ -363,57 +362,52 @@ class XenAPISession(object):
 
     def wait_for_task(self, task, id=None):
         """Return the result of the given task. The task is polled
-        until it completes. Not re-entrant."""
+        until it completes."""
         done = event.Event()
-        self.loop = utils.LoopingCall(self._poll_task, id, task, done)
-        self.loop.start(FLAGS.xenapi_task_poll_interval, now=True)
-        rv = done.wait()
-        self.loop.stop()
-        return rv
-
-    def _stop_loop(self):
-        """Stop polling for task to finish."""
-        #NOTE(sandy-walsh) Had to break this call out to support unit tests.
-        if self.loop:
-            self.loop.stop()
+        loop = utils.LoopingCall(f=None)
+
+        def _poll_task():
+            """Poll the given XenAPI task, and return the result if the
+            action was completed successfully or not.
+            """
+            try:
+                name = self._session.xenapi.task.get_name_label(task)
+                status = self._session.xenapi.task.get_status(task)
+                if id:
+                    action = dict(
+                        instance_id=int(id),
+                        action=name[0:255],  # Ensure action is never > 255
+                        error=None)
+                if status == "pending":
+                    return
+                elif status == "success":
+                    result = self._session.xenapi.task.get_result(task)
+                    LOG.info(_("Task [%(name)s] %(task)s status:"
+                            " success    %(result)s") % locals())
+                    done.send(_parse_xmlrpc_value(result))
+                else:
+                    error_info = self._session.xenapi.task.get_error_info(task)
+                    action["error"] = str(error_info)
+                    LOG.warn(_("Task [%(name)s] %(task)s status:"
+                            " %(status)s    %(error_info)s") % locals())
+                    done.send_exception(self.XenAPI.Failure(error_info))
+
+                if id:
+                    db.instance_action_create(context.get_admin_context(),
+                            action)
+            except self.XenAPI.Failure, exc:
+                LOG.warn(exc)
+                done.send_exception(*sys.exc_info())
+            loop.stop()
+
+        loop.f = _poll_task
+        loop.start(FLAGS.xenapi_task_poll_interval, now=True)
+        return done.wait()
 
     def _create_session(self, url):
         """Stubout point. This can be replaced with a mock session."""
         return self.XenAPI.Session(url)
 
-    def _poll_task(self, id, task, done):
-        """Poll the given XenAPI task, and fire the given action if we
-        get a result.
-        """
-        try:
-            name = self._session.xenapi.task.get_name_label(task)
-            status = self._session.xenapi.task.get_status(task)
-            if id:
-                action = dict(
-                    instance_id=int(id),
-                    action=name[0:255],  # Ensure action is never > 255
-                    error=None)
-            if status == "pending":
-                return
-            elif status == "success":
-                result = self._session.xenapi.task.get_result(task)
-                LOG.info(_("Task [%(name)s] %(task)s status:"
-                        " success    %(result)s") % locals())
-                done.send(_parse_xmlrpc_value(result))
-            else:
-                error_info = self._session.xenapi.task.get_error_info(task)
-                action["error"] = str(error_info)
-                LOG.warn(_("Task [%(name)s] %(task)s status:"
-                        " %(status)s    %(error_info)s") % locals())
-                done.send_exception(self.XenAPI.Failure(error_info))
-
-            if id:
-                db.instance_action_create(context.get_admin_context(), action)
-        except self.XenAPI.Failure, exc:
-            LOG.warn(exc)
-            done.send_exception(*sys.exc_info())
-        self._stop_loop()
-
     def _unwrap_plugin_exceptions(self, func, *args, **kwargs):
         """Parse exception details"""
         try: