From 2bb9b76c01019f3c82776429c07d34bd1c439f2b Mon Sep 17 00:00:00 2001
From: Chris McDonough <chrism@agendaless.com>
Date: Thu, 22 Jan 2009 08:03:37 +0000
Subject:   If no subscribers are registered via ``registerHandler`` or  
 ``registerSubscriptionAdapter``, ``notify`` is a noop for speed.

---
 CHANGES.txt                       | 10 +++++++---
 repoze/bfg/registry.py            | 22 +++++++++++++++++++---
 repoze/bfg/tests/test_registry.py | 33 ++++++++++++++++++++++++++-------
 3 files changed, 52 insertions(+), 13 deletions(-)

diff --git a/CHANGES.txt b/CHANGES.txt
index 8c6be8eb8..d2c31903f 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -14,10 +14,14 @@ Implementation Changes
 
 - Tease out an extra 4% performance boost by changing the Router;
   instead of using imported ZCA APIs, use the same APIs directly
-  against the registry that is an attribute of the Router.  As a
-  result, the registry used by BFG is now a subclass of
+  against the registry that is an attribute of the Router.
+
+- The registry used by BFG is now a subclass of
   ``zope.component.registry.Components`` (defined as
-  ``repoze.bfg.registry.Registry``); it has a ``notify`` method.
+  ``repoze.bfg.registry.Registry``); it has a ``notify`` method, a
+  ``registerSubscriptionAdapter`` and a ``registerHandler`` method.
+  If no subscribers are registered via ``registerHandler`` or
+  ``registerSubscriptionAdapter``, ``notify`` is a noop for speed.
 
 0.6.3 (2009-01-19)
 ==================
diff --git a/repoze/bfg/registry.py b/repoze/bfg/registry.py
index d1dff6744..b9a74d885 100644
--- a/repoze/bfg/registry.py
+++ b/repoze/bfg/registry.py
@@ -25,10 +25,26 @@ deprecated(
     )
 
 class Registry(Components):
+
+    # for optimization purposes, if no listeners are listening, don't try
+    # to notify them
+    _has_listeners = False
+
+    def registerSubscriptionAdapter(self, *arg, **kw):
+        result = Components.registerSubscriptionAdapter(self, *arg, **kw)
+        self._has_listeners = True
+        return result
+        
+    def registerHandler(self, *arg, **kw):
+        result = Components.registerHandler(self, *arg, **kw)
+        self._has_listeners = True
+        return result
+
     def notify(self, *events):
-        # iterating over subscribers assures they get executed
-        for ignored in self.subscribers(events, None):
-            pass
+        if self._has_listeners:
+            # iterating over subscribers assures they get executed
+            for ignored in self.subscribers(events, None):
+                pass
 
 class ThreadLocalRegistryManager(threading.local):
     def __init__(self):
diff --git a/repoze/bfg/tests/test_registry.py b/repoze/bfg/tests/test_registry.py
index 2c26d850e..f54ac934f 100644
--- a/repoze/bfg/tests/test_registry.py
+++ b/repoze/bfg/tests/test_registry.py
@@ -10,15 +10,34 @@ class TestRegistry(unittest.TestCase):
     def _makeOne(self):
         return self._getTargetClass()()
 
-    def test_notify(self):
+    def test_registerHandler_and_notify(self):
         registry = self._makeOne()
+        self.assertEqual(registry._has_listeners, False)
+        from zope.interface import Interface
+        from zope.interface import implements
+        class IFoo(Interface):
+            pass
+        class FooEvent(object):
+            implements(IFoo)
         L = []
-        def subscribers(events, *arg):
-            L.extend(events)
-            return ['abc']
-        registry.subscribers = subscribers
-        registry.notify('123')
-        self.assertEqual(L, ['123'])
+        def f(event):
+            L.append(event)
+        registry.registerHandler(f, [IFoo])
+        self.assertEqual(registry._has_listeners, True)
+        event = FooEvent()
+        registry.notify(event)
+        self.assertEqual(L, [event])
+
+    def test_registerSubscriptionAdapter_and_notify(self):
+        registry = self._makeOne()
+        self.assertEqual(registry._has_listeners, False)
+        from zope.interface import Interface
+        class EventHandler:
+            pass
+        class IFoo(Interface):
+            pass
+        registry.registerSubscriptionAdapter(EventHandler, [IFoo], Interface)
+        self.assertEqual(registry._has_listeners, True)
 
 class TestPopulateRegistry(unittest.TestCase):
     def setUp(self):
-- 
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