Use python's epoll wrapper

Custom ctypes wrapper for epoll is not needed with python 2.6+.
Also, do not retry upon temporary error: it is valid to handle no packet,
and retrying the poll call would increase overall timeout without easy fix.
Also, remove meaningless frozensets (leftovers from an old bug's symptoms).

neo/lib/epoll.py

-#
-# Copyright (C) 2006-2010  Nexedi SA
-#
-# This program is free software; you can redistribute it and/or
-# modify it under the terms of the GNU General Public License
-# as published by the Free Software Foundation; either version 2
-# of the License, or (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program; if not, write to the Free Software
-# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
-
-"""This is an epoll(4) interface available in Linux 2.6."""
-
-from ctypes import CDLL, get_errno, Union, Structure
-from ctypes import c_void_p, c_int, byref, c_uint32, c_uint64
-from os import close
-from errno import EINTR, EAGAIN
-
-libc = CDLL('libc.so.6', use_errno=True)
-epoll_create = libc.epoll_create
-epoll_wait = libc.epoll_wait
-epoll_ctl = libc.epoll_ctl
-
-EPOLLIN = 0x001
-EPOLLPRI = 0x002
-EPOLLOUT = 0x004
-EPOLLRDNORM = 0x040
-EPOLLRDBAND = 0x080
-EPOLLWRNORM = 0x100
-EPOLLWRBAND = 0x200
-EPOLLMSG = 0x400
-EPOLLERR = 0x008
-EPOLLHUP = 0x010
-EPOLLONESHOT = (1 << 30)
-EPOLLET = (1 << 31)
-
-EPOLL_CTL_ADD = 1
-EPOLL_CTL_DEL = 2
-EPOLL_CTL_MOD = 3
-
-class EpollData(Union):
-    _fields_ = [("ptr", c_void_p),
-                ("fd", c_int),
-                ("u32", c_uint32),
-                ("u64", c_uint64)]
-
-class EpollEvent(Structure):
-    _fields_ = [("events", c_uint32),
-                ("data", EpollData)]
-    _pack_ = 1
-
-class Epoll(object):
-    efd = -1
-
-    def __init__(self):
-        self.efd = epoll_create(10)
-        if self.efd == -1:
-            raise OSError(get_errno(), 'epoll_create failed')
-
-        self.maxevents = 1024 # XXX arbitrary
-        epoll_event_array = EpollEvent * self.maxevents
-        self.events = epoll_event_array()
-
-    def poll(self, timeout=1):
-        if timeout is None:
-            timeout = -1
-        else:
-            timeout *= 1000
-            timeout = int(timeout)
-        while True:
-            n = epoll_wait(self.efd, byref(self.events), self.maxevents,
-                           timeout)
-            if n == -1:
-                e = get_errno()
-                # XXX: Why 0 ?
-                if e in (0, EINTR, EAGAIN):
-                    continue
-                else:
-                    raise OSError(e, 'epoll_wait failed')
-            else:
-                readable_fd_list = []
-                writable_fd_list = []
-                error_fd_list = []
-                for i in xrange(n):
-                    ev = self.events[i]
-                    fd = int(ev.data.fd)
-                    if ev.events & EPOLLIN:
-                        readable_fd_list.append(fd)
-                    if ev.events & EPOLLOUT:
-                        writable_fd_list.append(fd)
-                    if ev.events & (EPOLLERR | EPOLLHUP):
-                        error_fd_list.append(fd)
-                return readable_fd_list, writable_fd_list, error_fd_list
-
-    def register(self, fd):
-        ev = EpollEvent()
-        ev.data.fd = fd
-        ret = epoll_ctl(self.efd, EPOLL_CTL_ADD, fd, byref(ev))
-        if ret == -1:
-            raise OSError(get_errno(), 'epoll_ctl failed')
-
-    def modify(self, fd, readable, writable):
-        ev = EpollEvent()
-        ev.data.fd = fd
-        events = 0
-        if readable:
-            events |= EPOLLIN
-        if writable:
-            events |= EPOLLOUT
-        ev.events = events
-        ret = epoll_ctl(self.efd, EPOLL_CTL_MOD, fd, byref(ev))
-        if ret == -1:
-            raise OSError(get_errno(), 'epoll_ctl failed')
-
-    def unregister(self, fd):
-        ev = EpollEvent()
-        ret = epoll_ctl(self.efd, EPOLL_CTL_DEL, fd, byref(ev))
-        if ret == -1:
-            raise OSError(get_errno(), 'epoll_ctl failed')
-
-    def __del__(self):
-        efd = self.efd
-        if efd >= 0:
-            del self.efd
-            close(efd)
-    close = __del__

neo/lib/event.py

@@ -17,7 +17,8 @@
 
 from time import time
 import neo.lib
-from .epoll import Epoll
+from select import epoll, EPOLLIN, EPOLLOUT, EPOLLERR, EPOLLHUP
+from errno import EINTR, EAGAIN
 from .profiling import profiler_decorator
 
 class EpollEventManager(object):
@@ -27,7 +28,7 @@ class EpollEventManager(object):
         self.connection_dict = {}
         self.reader_set = set([])
         self.writer_set = set([])
-        self.epoll = Epoll()
+        self.epoll = epoll()
         self._pending_processing = []
 
     def close(self):
@@ -111,8 +112,19 @@ class EpollEventManager(object):
             self._poll(timeout=0)
 
     def _poll(self, timeout=1):
-        rlist, wlist, elist = self.epoll.poll(timeout)
-        for fd in frozenset(rlist):
+        try:
+            event_list = self.epoll.poll(timeout)
+        except IOError, exc:
+            if exc.errno in (0, EAGAIN):
+                neo.lib.logging.info('epoll.poll triggered undocumented '
+                  'error %r', exc.errno)
+            elif exc.errno != EINTR:
+                raise
+            event_list = ()
+        wlist = []
+        elist = []
+        for fd, event in event_list:
+            if event & EPOLLIN:
                 conn = self.connection_dict[fd]
                 conn.lock()
                 try:
@@ -121,8 +133,12 @@ class EpollEventManager(object):
                     conn.unlock()
                 if conn.hasPendingMessages():
                     self._addPendingConnection(conn)
+            if event & EPOLLOUT:
+                wlist.append(fd)
+            if event & (EPOLLERR | EPOLLHUP):
+                elist.append(fd)
 
-        for fd in frozenset(wlist):
+        for fd in wlist:
             # This can fail, if a connection is closed in readable().
             try:
                 conn = self.connection_dict[fd]
@@ -135,7 +151,7 @@ class EpollEventManager(object):
                 finally:
                     conn.unlock()
 
-        for fd in frozenset(elist):
+        for fd in elist:
             # This can fail, if a connection is closed in previous calls to
             # readable() or writable().
             try:
@@ -165,7 +181,8 @@ class EpollEventManager(object):
         fd = connector.getDescriptor()
         if fd not in self.reader_set:
             self.reader_set.add(fd)
-            self.epoll.modify(fd, 1, fd in self.writer_set)
+            self.epoll.modify(fd, EPOLLIN | (
+                fd in self.writer_set and EPOLLOUT))
 
     def removeReader(self, conn):
         connector = conn.getConnector()
@@ -173,7 +190,7 @@ class EpollEventManager(object):
         fd = connector.getDescriptor()
         if fd in self.reader_set:
             self.reader_set.remove(fd)
-            self.epoll.modify(fd, 0, fd in self.writer_set)
+            self.epoll.modify(fd, fd in self.writer_set and EPOLLOUT)
 
     @profiler_decorator
     def addWriter(self, conn):
@@ -182,7 +199,8 @@ class EpollEventManager(object):
         fd = connector.getDescriptor()
         if fd not in self.writer_set:
             self.writer_set.add(fd)
-            self.epoll.modify(fd, fd in self.reader_set, 1)
+            self.epoll.modify(fd, EPOLLOUT | (
+                fd in self.reader_set and EPOLLIN))
 
     def removeWriter(self, conn):
         connector = conn.getConnector()
@@ -190,7 +208,7 @@ class EpollEventManager(object):
         fd = connector.getDescriptor()
         if fd in self.writer_set:
             self.writer_set.remove(fd)
-            self.epoll.modify(fd, fd in self.reader_set, 0)
+            self.epoll.modify(fd, fd in self.reader_set and EPOLLIN)
 
     def log(self):
         neo.lib.logging.info('Event Manager:')

neo/tests/testEvent.py

@@ -17,7 +17,7 @@
 import unittest
 from mock import Mock
 from . import NeoUnitTestBase
-from neo.lib.epoll import Epoll
+from select import epoll, EPOLLIN, EPOLLOUT
 from neo.lib.event import EpollEventManager
 
 class EventTests(NeoUnitTestBase):
@@ -28,7 +28,7 @@ class EventTests(NeoUnitTestBase):
         self.assertEqual(len(em.connection_dict), 0)
         self.assertEqual(len(em.reader_set), 0)
         self.assertEqual(len(em.writer_set), 0)
-        self.assertTrue(isinstance(em.epoll, Epoll))
+        self.assertTrue(isinstance(em.epoll, epoll))
         # use a mock object instead of epoll
         em.epoll = Mock()
         connector = self.getFakeConnector(descriptor=1014)
@@ -94,9 +94,8 @@ class EventTests(NeoUnitTestBase):
         w_conn = self.getFakeConnection(connector=w_connector)
         em.register(w_conn)
         em.epoll = Mock({"poll":(
-          (r_connector.getDescriptor(),),
-          (w_connector.getDescriptor(),),
-          (),
+          (r_connector.getDescriptor(), EPOLLIN),
+          (w_connector.getDescriptor(), EPOLLOUT),
         )})
         em.poll(timeout=10)
         # check it called poll on epoll

neo/tests/threaded/__init__.py

@@ -138,7 +138,7 @@ class SerializedEventManager(EventManager):
 
     def _poll(self, timeout=1):
         if self._pending_processing:
-            assert not timeout
+            assert timeout <= 0
         elif 0 == self._timeout == timeout == Serialized.pending == len(
             self.writer_set):
             return
@@ -324,7 +324,7 @@ class NeoCTL(neo.neoctl.app.NeoCTL):
     def __init__(self, cluster, address=(getVirtualIp('admin'), 0)):
         self._cluster = cluster
         super(NeoCTL, self).__init__(address)
-        self.em._timeout = None
+        self.em._timeout = -1
 
     server = property(lambda self: self._cluster.resolv(self._server),
                       lambda self, address: setattr(self, '_server', address))