Avoid re-using the same timeout for further watcher ops

Instead of re-using the same timeout that is passed into the
'run_watchers' function we should adjust that timeout after
each fetch so that the expected timeout the user gives to this
function is observed.

Change-Id: I5d171b1ac8b207213224f4e0f3909625de7275db
(cherry picked from commit e38a29f67180cb40a0b7915305bec62ed9527229)

1 files changed, 13 insertions, 1 deletions

diff --git a/tooz/drivers/redis.py b/tooz/drivers/redis.py
index 76b29f4..f52d36a 100644
--- a/tooz/drivers/redis.py
+++ b/tooz/drivers/redis.py
@@ -20,6 +20,11 @@ import contextlib
 from distutils import version
 import logging
 
+try:
+    from time import monotonic as _now  # noqa
+except ImportError:
+    from time import time as _now  # noqa
+
 from concurrent import futures
 from oslo_utils import strutils
 import redis
@@ -664,10 +669,17 @@ class RedisDriver(coordination.CoordinationDriver):
         raise tooz.NotImplemented
 
     def run_watchers(self, timeout=None):
+        if timeout is not None:
+            started_at = _now()
         result = []
         for group_id in self.get_groups().get(timeout=timeout):
+            leftover_timeout = None
+            if timeout is not None:
+                elapsed = max(0.0, _now() - started_at)
+                leftover_timeout = timeout - elapsed
             try:
-                group_members = self.get_members(group_id).get(timeout=timeout)
+                group_members = self.get_members(group_id).get(
+                    timeout=leftover_timeout)
             except coordination.GroupNotCreated:
                 group_members = set()
             else: