Allows to change defaults opts

This change introduces to possibility for the consumer application
to change the default oslo.messaging config options.

Same API interface as oslo.db have been taken.
The first option is executor_thread_pool_size.

This option was called rpc_thread_pool_size, but because it's used by
notification and rpc 'executor_thread_pool_size' looks a better name.

Changing executor_thread_pool_size default will be useful for ceilometer
the default of 64 is really to small to consume many notifications at
once for batching them. When is clearly sufficient for rpc stuffs.

Change-Id: Iea0d7a72e38d27c600403c815258aa5eee0d0c8c

1 files changed, 20 insertions, 0 deletions

diff --git a/oslo_messaging/opts.py b/oslo_messaging/opts.py
index 1f065b5..267b7ec 100644
--- a/oslo_messaging/opts.py
+++ b/oslo_messaging/opts.py
@@ -76,3 +76,23 @@ def list_opts():
     :returns: a list of (group_name, opts) tuples
     """
     return [(g, copy.deepcopy(o)) for g, o in _opts]
+
+
+def set_defaults(conf, executor_thread_pool_size=None):
+    """Set defaults for configuration variables.
+
+    Overrides default options values.
+
+    :param conf: Config instance specified to set default options in it. Using
+     of instances instead of a global config object prevents conflicts between
+     options declaration.
+    :type conf: oslo.config.cfg.ConfigOpts instance.
+
+    :keyword executor_thread_pool_size: Size of executor thread pool.
+    :type executor_thread_pool_size: int
+    :default executor_thread_pool_size: None
+
+    """
+    if executor_thread_pool_size is not None:
+        conf.set_default('executor_thread_pool_size',
+                         executor_thread_pool_size)