Don't load many times the same publisher

This change save some resources usage by loading only once each
publisher.

Change-Id: Ibc0fd399ca0668937f53ac3a2e68938a0a24cb87

ceilometer/pipeline.py

@@ -59,6 +59,7 @@ OPTS = [
                ),
 ]
 
+
 LOG = log.getLogger(__name__)
 
 
@@ -360,7 +361,7 @@ class Sink(object):
     passed data directly from the sink which are published unchanged.
     """
 
-    def __init__(self, conf, cfg, transformer_manager):
+    def __init__(self, conf, cfg, transformer_manager, publisher_manager):
         self.conf = conf
         self.cfg = cfg
 
@@ -380,9 +381,9 @@ class Sink(object):
             if '://' not in p:
                 # Support old format without URL
                 p = p + "://"
+
             try:
-                self.publishers.append(publisher.get_publisher(
-                    self.conf, p, self.NAMESPACE))
+                self.publishers.append(publisher_manager.get(p))
             except Exception:
                 LOG.error(_LE("Unable to load publisher %s"), p,
                           exc_info=True)
@@ -415,7 +416,7 @@ class Sink(object):
 
 class EventSink(Sink):
 
-    NAMESPACE = 'ceilometer.event.publisher'
+    PUBLISHER_PURPOSE = 'event'
 
     def publish_events(self, events):
         if events:
@@ -439,7 +440,7 @@ class EventSink(Sink):
 
 class SampleSink(Sink):
 
-    NAMESPACE = 'ceilometer.publisher'
+    PUBLISHER_PURPOSE = 'sample'
 
     def _transform_sample(self, start, sample):
         try:
@@ -610,11 +611,13 @@ class SamplePipeline(Pipeline):
         self.sink.publish_samples(supported)
 
 
-SAMPLE_TYPE = {'pipeline': SamplePipeline,
+SAMPLE_TYPE = {'name': 'sample',
+               'pipeline': SamplePipeline,
                'source': SampleSource,
                'sink': SampleSink}
 
-EVENT_TYPE = {'pipeline': EventPipeline,
+EVENT_TYPE = {'name': 'event',
+              'pipeline': EventPipeline,
               'source': EventSource,
               'sink': EventSink}
 
@@ -670,6 +673,21 @@ class ConfigManagerBase(object):
         return False
 
 
+class PublisherManager(object):
+    def __init__(self, conf, purpose):
+        self._loaded_publishers = {}
+        self._conf = conf
+        self._purpose = purpose
+
+    def get(self, url):
+        if url not in self._loaded_publishers:
+            p = publisher.get_publisher(
+                self._conf, url,
+                'ceilometer.%s.publisher' % self._purpose)
+            self._loaded_publishers[url] = p
+        return self._loaded_publishers[url]
+
+
 class PipelineManager(ConfigManagerBase):
     """Pipeline Manager
 
@@ -754,6 +772,7 @@ class PipelineManager(ConfigManagerBase):
             raise PipelineException("Both sources & sinks are required",
                                     cfg)
         LOG.info(_LI('detected decoupled pipeline config format'))
+        publisher_manager = PublisherManager(self.conf, p_type['name'])
 
         unique_names = set()
         sources = []
@@ -776,7 +795,8 @@ class PipelineManager(ConfigManagerBase):
             else:
                 unique_names.add(name)
                 sinks[s['name']] = p_type['sink'](self.conf, s,
-                                                  transformer_manager)
+                                                  transformer_manager,
+                                                  publisher_manager)
         unique_names.clear()
 
         for source in sources:

ceilometer/publisher/__init__.py

@@ -22,7 +22,7 @@ import six
 from stevedore import driver
 
 
-def get_publisher(conf, url, namespace='ceilometer.publisher'):
+def get_publisher(conf, url, namespace):
     """Get publisher driver and load it.
 
     :param URL: URL for the publisher

setup.cfg

@@ -226,7 +226,7 @@ ceilometer.transformer =
     aggregator = ceilometer.transformer.conversions:AggregatorTransformer
     arithmetic = ceilometer.transformer.arithmetic:ArithmeticTransformer
 
-ceilometer.publisher =
+ceilometer.sample.publisher =
     test = ceilometer.publisher.test:TestPublisher
     notifier = ceilometer.publisher.messaging:SampleNotifierPublisher
     udp = ceilometer.publisher.udp:UDPPublisher