improved the epoll implementation lookup

eventlet/hubs/epolls.py

@@ -1,15 +1,27 @@
 from eventlet import patcher
 time = patcher.original('time')
-try:
-    # shoot for epoll module first
-    from epoll import poll as epoll
-except ImportError, e:
-    # if we can't import that, hope we're on 2.6
-    select = patcher.original('select')
-    try:
+select = patcher.original("select")
+if hasattr(select, 'epoll'):
     epoll = select.epoll
-    except AttributeError:
-        raise ImportError("No epoll on select module")
+else:
+    try:
+        # http://pypi.python.org/pypi/select26/
+        from select26 import epoll
+    except ImportError:
+        try:
+            import epoll as _epoll_mod
+        except ImportError:
+            raise ImportError(
+                "No epoll implementation found in select module or PYTHONPATH")
+        else:
+            if hasattr(_epoll_mod, 'poll'):
+                epoll = _epoll_mod.poll
+            else:
+                raise ImportError(
+                    "You have an old, buggy epoll module in PYTHONPATH."
+                    " Install http://pypi.python.org/pypi/python-epoll/"
+                    " NOT http://pypi.python.org/pypi/pyepoll/. "
+                    " easy_install pyepoll installs the wrong version.")
 
 from eventlet.hubs.hub import BaseHub
 from eventlet.hubs import poll