f098ca1 Feb 8, 2015
77 lines (64 sloc) 2.57 KB
#!/usr/bin/env python
#
# Copyright 2012 Facebook
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Select-based IOLoop implementation.
Used as a fallback for systems that don't support epoll or kqueue.
"""
from __future__ import absolute_import, division, print_function, with_statement
import select
from tornado.ioloop import IOLoop, PollIOLoop
class _Select(object):
"""A simple, select()-based IOLoop implementation for non-Linux systems"""
def __init__(self):
self.read_fds = set()
self.write_fds = set()
self.error_fds = set()
self.fd_sets = (self.read_fds, self.write_fds, self.error_fds)
def close(self):
pass
def register(self, fd, events):
if fd in self.read_fds or fd in self.write_fds or fd in self.error_fds:
raise IOError("fd %s already registered" % fd)
if events & IOLoop.READ:
self.read_fds.add(fd)
if events & IOLoop.WRITE:
self.write_fds.add(fd)
if events & IOLoop.ERROR:
self.error_fds.add(fd)
# Closed connections are reported as errors by epoll and kqueue,
# but as zero-byte reads by select, so when errors are requested
# we need to listen for both read and error.
# self.read_fds.add(fd)
def modify(self, fd, events):
self.unregister(fd)
self.register(fd, events)
def unregister(self, fd):
self.read_fds.discard(fd)
self.write_fds.discard(fd)
self.error_fds.discard(fd)
def poll(self, timeout):
readable, writeable, errors = select.select(
self.read_fds, self.write_fds, self.error_fds, timeout)
events = {}
for fd in readable:
events[fd] = events.get(fd, 0) | IOLoop.READ
for fd in writeable:
events[fd] = events.get(fd, 0) | IOLoop.WRITE
for fd in errors:
events[fd] = events.get(fd, 0) | IOLoop.ERROR
return events.items()
class SelectIOLoop(PollIOLoop):
def initialize(self, **kwargs):
super(SelectIOLoop, self).initialize(impl=_Select(), **kwargs)