From d48bba18a7cebc57e63f5b2c5a1e939654de0883 Mon Sep 17 00:00:00 2001
From: Dan Smith <dansmith@redhat.com>
Date: Wed, 9 Aug 2017 10:53:53 -0700
Subject: [PATCH] Mark Chance and Caching schedulers as deprecated

FilterScheduler with Placement should replace both of these. Mark them
as deprecated now so the timer starts.

Change-Id: Ia7ff98ff28b7265058845e46b277317a2bfc96d2
---
 nova/conf/scheduler.py                                   | 4 ++--
 nova/scheduler/caching_scheduler.py                      | 6 ++++++
 nova/scheduler/chance.py                                 | 8 ++++++++
 .../notes/scheduler-deprecation-20d035193c7392e4.yaml    | 9 +++++++++
 4 files changed, 25 insertions(+), 2 deletions(-)
 create mode 100644 releasenotes/notes/scheduler-deprecation-20d035193c7392e4.yaml

diff --git a/nova/conf/scheduler.py b/nova/conf/scheduler.py
index 3aefed75bd1f..7d3c628e39f0 100644
--- a/nova/conf/scheduler.py
+++ b/nova/conf/scheduler.py
@@ -46,8 +46,8 @@ Other options are:
 
 * 'caching_scheduler' which aggressively caches the system state for better
   individual scheduler performance at the risk of more retries when running
-  multiple schedulers.
-* 'chance_scheduler' which simply picks a host at random.
+  multiple schedulers. [DEPRECATED]
+* 'chance_scheduler' which simply picks a host at random. [DEPRECATED]
 * 'fake_scheduler' which is used for testing.
 
 Possible values:
diff --git a/nova/scheduler/caching_scheduler.py b/nova/scheduler/caching_scheduler.py
index 52cab73cc9cf..e53c42e777fa 100644
--- a/nova/scheduler/caching_scheduler.py
+++ b/nova/scheduler/caching_scheduler.py
@@ -16,8 +16,12 @@
 import collections
 import itertools
 
+from oslo_log import log as logging
+
 from nova.scheduler import filter_scheduler
 
+LOG = logging.getLogger(__name__)
+
 
 class CachingScheduler(filter_scheduler.FilterScheduler):
     """Scheduler to test aggressive caching of the host list.
@@ -58,6 +62,8 @@ class CachingScheduler(filter_scheduler.FilterScheduler):
     def __init__(self, *args, **kwargs):
         super(CachingScheduler, self).__init__(*args, **kwargs)
         self.all_host_states = None
+        LOG.warning('CachingScheduler is deprecated in Pike and will be '
+                    'removed in a subsequent release.')
 
     def run_periodic_tasks(self, context):
         """Called from a periodic tasks in the manager."""
diff --git a/nova/scheduler/chance.py b/nova/scheduler/chance.py
index 44d9c746836e..1be05be8f807 100644
--- a/nova/scheduler/chance.py
+++ b/nova/scheduler/chance.py
@@ -21,6 +21,8 @@ Chance (Random) Scheduler implementation
 
 import random
 
+from oslo_log import log as logging
+
 from nova.compute import rpcapi as compute_rpcapi
 import nova.conf
 from nova import exception
@@ -28,6 +30,7 @@ from nova.i18n import _
 from nova.scheduler import driver
 
 CONF = nova.conf.CONF
+LOG = logging.getLogger(__name__)
 
 
 class ChanceScheduler(driver.Scheduler):
@@ -35,6 +38,11 @@ class ChanceScheduler(driver.Scheduler):
 
     USES_ALLOCATION_CANDIDATES = False
 
+    def __init__(self, *args, **kwargs):
+        super(ChanceScheduler, self).__init__(*args, **kwargs)
+        LOG.warning('ChanceScheduler is deprecated in Pike and will be '
+                    'removed in a subsequent release.')
+
     def _filter_hosts(self, hosts, spec_obj):
         """Filter a list of hosts based on RequestSpec."""
 
diff --git a/releasenotes/notes/scheduler-deprecation-20d035193c7392e4.yaml b/releasenotes/notes/scheduler-deprecation-20d035193c7392e4.yaml
new file mode 100644
index 000000000000..ce604db46a14
--- /dev/null
+++ b/releasenotes/notes/scheduler-deprecation-20d035193c7392e4.yaml
@@ -0,0 +1,9 @@
+---
+deprecations:
+  - |
+    The CachingScheduler and ChanceScheduler drivers are deprecated in Pike.
+    These are not integrated with the placement service, and their primary
+    purpose (speed over correctness) should be addressed by the default
+    FilterScheduler going forward. If ChanceScheduler behavior is desired
+    (i.e. speed trumps correctness) then configuring the FilterScheduler with
+    no enabled filters should approximate that behavior.