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