From: Guido van Rossum <guido@dropbox.com>
Date: Thu, 7 Nov 2013 16:39:28 +0000 (-0800)
Subject: Optimize BaseSelector.modify(). Patch by Arnaud Faure.
X-Git-Tag: v3.4.0b1~351
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d0786a1a5036c06770f1c958323387fd682e789e;p=thirdparty%2FPython%2Fcpython.git

Optimize BaseSelector.modify(). Patch by Arnaud Faure.
---

diff --git a/Lib/selectors.py b/Lib/selectors.py
index 3638e8544c64..3971502ef28a 100644
--- a/Lib/selectors.py
+++ b/Lib/selectors.py
@@ -138,11 +138,14 @@ class BaseSelector(metaclass=ABCMeta):
             key = self._fd_to_key[_fileobj_to_fd(fileobj)]
         except KeyError:
             raise KeyError("{!r} is not registered".format(fileobj)) from None
-        if events != key.events or data != key.data:
-            # TODO: If only the data changed, use a shortcut that only
-            # updates the data.
+        if events != key.events:
             self.unregister(fileobj)
             return self.register(fileobj, events, data)
+        elif data != key.data:
+            # Use a shortcut to update the data.
+            key = key._replace(data=data)
+            self._fd_to_key[key.fd] = key
+            return key
         else:
             return key
 
diff --git a/Lib/test/test_selectors.py b/Lib/test/test_selectors.py
index fd0481d83f51..c64c87aa3f7b 100644
--- a/Lib/test/test_selectors.py
+++ b/Lib/test/test_selectors.py
@@ -6,6 +6,7 @@ import socket
 from test import support
 from time import sleep
 import unittest
+import unittest.mock
 try:
     from time import monotonic as time
 except ImportError:
@@ -124,6 +125,15 @@ class BaseSelectorTestCase(unittest.TestCase):
         # modify unknown file obj
         self.assertRaises(KeyError, s.modify, 999999, selectors.EVENT_READ)
 
+        # modify use a shortcut
+        d3 = object()
+        s.register = unittest.mock.Mock()
+        s.unregister = unittest.mock.Mock()
+
+        s.modify(rd, selectors.EVENT_READ, d3)
+        self.assertFalse(s.register.called)
+        self.assertFalse(s.unregister.called)
+
     def test_close(self):
         s = self.SELECTOR()
         self.addCleanup(s.close)