From fa12462d8926e36b95d2557f88708f6d89132b59 Mon Sep 17 00:00:00 2001
From: Ryan Williams <rdw@lindenlab.com>
Date: Tue, 15 Dec 2009 14:15:55 -0800
Subject: [PATCH] Added epoll support, should improve performance on systems
 that support it.

---
 eventlet/api.py         | 18 +++++++++++-------
 eventlet/hubs/epolls.py | 24 ++++++++++++++++++++++++
 eventlet/hubs/poll.py   | 18 ++++++++++++++----
 3 files changed, 49 insertions(+), 11 deletions(-)
 create mode 100644 eventlet/hubs/epolls.py

diff --git a/eventlet/api.py b/eventlet/api.py
index e88bcf8..0bc45b0 100644
--- a/eventlet/api.py
+++ b/eventlet/api.py
@@ -365,13 +365,17 @@ def get_default_hub():
         from eventlet.hubs import twistedr
         return twistedr
 
-    import select
-    if hasattr(select, 'poll'):
-        import eventlet.hubs.poll
-        return eventlet.hubs.poll
-    else:
-        import eventlet.hubs.selects
-        return eventlet.hubs.selects
+    try:
+        import eventlet.hubs.epolls
+        return eventlet.hubs.epolls
+    except ImportError:
+        import select
+        if hasattr(select, 'poll'):
+            import eventlet.hubs.poll
+            return eventlet.hubs.poll
+        else:
+            import eventlet.hubs.selects
+            return eventlet.hubs.selects
 
 
 def use_hub(mod=None):
diff --git a/eventlet/hubs/epolls.py b/eventlet/hubs/epolls.py
new file mode 100644
index 0000000..57f84d7
--- /dev/null
+++ b/eventlet/hubs/epolls.py
@@ -0,0 +1,24 @@
+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
+    from select import epoll
+
+import time
+from eventlet.hubs.hub import BaseHub
+from eventlet.hubs import poll
+
+# NOTE: we rely on the fact that the epoll flag constants
+# are identical in value to the poll constants
+
+class Hub(poll.Hub):
+    WAIT_MULTIPLIER = 1.0  # epoll.poll's timeout is measured in seconds
+    def __init__(self, clock=time.time):
+        BaseHub.__init__(self, clock)
+        self.poll = epoll()
+        try:
+            # modify is required by select.epoll
+            self.modify = self.poll.modify
+        except AttributeError:
+            self.modify = self.poll.register
diff --git a/eventlet/hubs/poll.py b/eventlet/hubs/poll.py
index c05a41c..f0a7340 100644
--- a/eventlet/hubs/poll.py
+++ b/eventlet/hubs/poll.py
@@ -11,9 +11,16 @@ READ_MASK = select.POLLIN | select.POLLPRI
 WRITE_MASK = select.POLLOUT
 
 class Hub(BaseHub):
+    WAIT_MULTIPLIER=1000.0 # poll.poll's timeout is measured in milliseconds
+
     def __init__(self, clock=time.time):
         super(Hub, self).__init__(clock)
         self.poll = select.poll()
+        # poll.modify is new to 2.6
+        try:
+            self.modify = self.poll.modify
+        except AttributeError:
+            self.modify = self.poll.register
 
     def add(self, evtype, fileno, cb):
         oldlisteners = self.listeners[evtype].get(fileno)
@@ -21,21 +28,24 @@ class Hub(BaseHub):
         listener = super(Hub, self).add(evtype, fileno, cb)
         if not oldlisteners:
             # Means we've added a new listener
-            self.register(fileno)
+            self.register(fileno, new=True)
         return listener
     
     def remove(self, listener):
         super(Hub, self).remove(listener)
         self.register(listener.fileno)
 
-    def register(self, fileno):
+    def register(self, fileno, new=False):
         mask = 0
         if self.listeners[READ].get(fileno):
             mask |= READ_MASK
         if self.listeners[WRITE].get(fileno):
             mask |= WRITE_MASK
         if mask:
-            self.poll.register(fileno, mask)
+            if new:
+                self.poll.register(fileno, mask)
+            else:
+                self.modify(fileno, mask)
         else: 
             try:
                 self.poll.unregister(fileno)
@@ -58,7 +68,7 @@ class Hub(BaseHub):
                 sleep(seconds)
             return
         try:
-            presult = self.poll.poll(seconds * 1000.0)
+            presult = self.poll.poll(seconds * self.WAIT_MULTIPLIER)
         except select.error, e:
             if e.args[0] == errno.EINTR:
                 return