From 492fd109ed92f15e421ebbdbd4fba5a9129eef17 Mon Sep 17 00:00:00 2001
From: Nate Johnston <iam@natejohnston.info>
Date: Tue, 26 May 2020 12:29:18 -0400
Subject: [PATCH] Migrate timecost decorator to neutron-lib

There are a few functions in neutron-lib where timecost profiling would
be beneficial, so that means it is a good time to transition this
library to neutron-lib.

Change-Id: I7c84a83a2f836493f63b220f7ff0cbcc823374f2
---
 neutron_lib/utils/helpers.py                  | 21 +++++++++++++++++++
 .../rehome-timecost-90dcfc8c7f7280f5.yaml     |  6 ++++++
 2 files changed, 27 insertions(+)
 create mode 100644 releasenotes/notes/rehome-timecost-90dcfc8c7f7280f5.yaml

diff --git a/neutron_lib/utils/helpers.py b/neutron_lib/utils/helpers.py
index cbc23bf33..ffc7a7a20 100644
--- a/neutron_lib/utils/helpers.py
+++ b/neutron_lib/utils/helpers.py
@@ -16,9 +16,16 @@ import decimal
 import random
 import weakref
 
+from oslo_log import log as logging
+from oslo_utils import timeutils
+from oslo_utils import uuidutils
+
 from neutron_lib._i18n import _
 
 
+LOG = logging.getLogger(__name__)
+
+
 def parse_mappings(mapping_list, unique_values=True, unique_keys=True):
     """Parse a list of mapping strings into a dictionary.
 
@@ -198,3 +205,17 @@ def resolve_ref(ref):
     if isinstance(ref, weakref.ref):
         ref = ref()
     return ref
+
+
+def timecost(f):
+    call_id = uuidutils.generate_uuid()
+    message_base = ("Time-cost: call %(call_id)s function %(fname)s ") % {
+                    "call_id": call_id, "fname": f.__name__}
+    end_message = (message_base + "took %(seconds).3fs seconds to run")
+
+    @timeutils.time_it(LOG, message=end_message, min_duration=None)
+    def wrapper(*args, **kwargs):
+        LOG.debug(message_base + "start")
+        ret = f(*args, **kwargs)
+        return ret
+    return wrapper
diff --git a/releasenotes/notes/rehome-timecost-90dcfc8c7f7280f5.yaml b/releasenotes/notes/rehome-timecost-90dcfc8c7f7280f5.yaml
new file mode 100644
index 000000000..8cc886f0d
--- /dev/null
+++ b/releasenotes/notes/rehome-timecost-90dcfc8c7f7280f5.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    The ``timecost`` decorator is available in ``neutron_lib.utils.helpers``
+    now.  This permits functions to be decorated with functionality that will
+    emit a debug log with the time it took to execute the function.