track embedded python distribution
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James Taylor
244
python/gevent/select.py
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244
python/gevent/select.py
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# Copyright (c) 2009-2011 Denis Bilenko. See LICENSE for details.
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"""
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Waiting for I/O completion.
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"""
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from __future__ import absolute_import
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import sys
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from gevent.event import Event
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from gevent.hub import get_hub
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from gevent.hub import sleep as _g_sleep
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from gevent._compat import integer_types
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from gevent._compat import iteritems
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from gevent._compat import itervalues
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from gevent._util import copy_globals
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from gevent._util import _NONE
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from errno import EINTR
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if sys.platform.startswith('win32'):
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def _original_select(_r, _w, _x, _t):
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# windows cant handle three empty lists, but we've always
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# accepted that, so don't try the compliance check on windows
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return ((), (), ())
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else:
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from select import select as _original_select
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try:
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from select import poll as original_poll
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from select import POLLIN, POLLOUT, POLLNVAL
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__implements__ = ['select', 'poll']
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except ImportError:
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original_poll = None
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__implements__ = ['select']
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__all__ = ['error'] + __implements__
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import select as __select__
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error = __select__.error
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__imports__ = copy_globals(__select__, globals(),
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names_to_ignore=__all__,
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dunder_names_to_keep=())
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_EV_READ = 1
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_EV_WRITE = 2
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def get_fileno(obj):
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try:
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fileno_f = obj.fileno
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except AttributeError:
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if not isinstance(obj, integer_types):
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raise TypeError('argument must be an int, or have a fileno() method: %r' % (obj,))
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return obj
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else:
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return fileno_f()
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class SelectResult(object):
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__slots__ = ('read', 'write', 'event')
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def __init__(self):
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self.read = []
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self.write = []
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self.event = Event()
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def add_read(self, socket):
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self.read.append(socket)
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self.event.set()
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add_read.event = _EV_READ
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def add_write(self, socket):
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self.write.append(socket)
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self.event.set()
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add_write.event = _EV_WRITE
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def __add_watchers(self, watchers, fdlist, callback, io, pri):
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for fd in fdlist:
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watcher = io(get_fileno(fd), callback.event)
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watcher.priority = pri
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watchers.append(watcher)
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watcher.start(callback, fd)
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def _make_watchers(self, watchers, rlist, wlist):
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loop = get_hub().loop
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io = loop.io
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MAXPRI = loop.MAXPRI
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try:
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self.__add_watchers(watchers, rlist, self.add_read, io, MAXPRI)
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self.__add_watchers(watchers, wlist, self.add_write, io, MAXPRI)
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except IOError as ex:
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raise error(*ex.args)
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def _closeall(self, watchers):
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for watcher in watchers:
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watcher.stop()
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del watchers[:]
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def select(self, rlist, wlist, timeout):
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watchers = []
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try:
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self._make_watchers(watchers, rlist, wlist)
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self.event.wait(timeout=timeout)
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return self.read, self.write, []
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finally:
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self._closeall(watchers)
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def select(rlist, wlist, xlist, timeout=None): # pylint:disable=unused-argument
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"""An implementation of :meth:`select.select` that blocks only the current greenlet.
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.. caution:: *xlist* is ignored.
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.. versionchanged:: 1.2a1
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Raise a :exc:`ValueError` if timeout is negative. This matches Python 3's
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behaviour (Python 2 would raise a ``select.error``). Previously gevent had
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undefined behaviour.
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.. versionchanged:: 1.2a1
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Raise an exception if any of the file descriptors are invalid.
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"""
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if timeout is not None and timeout < 0:
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# Raise an error like the real implementation; which error
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# depends on the version. Python 3, where select.error is OSError,
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# raises a ValueError (which makes sense). Older pythons raise
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# the error from the select syscall...but we don't actually get there.
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# We choose to just raise the ValueError as it makes more sense and is
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# forward compatible
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raise ValueError("timeout must be non-negative")
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# First, do a poll with the original select system call. This
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# is the most efficient way to check to see if any of the file descriptors
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# have previously been closed and raise the correct corresponding exception.
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# (Because libev tends to just return them as ready...)
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# We accept the *xlist* here even though we can't below because this is all about
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# error handling.
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sel_results = ((), (), ())
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try:
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sel_results = _original_select(rlist, wlist, xlist, 0)
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except error as e:
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enumber = getattr(e, 'errno', None) or e.args[0]
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if enumber != EINTR:
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# Ignore interrupted syscalls
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raise
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if sel_results[0] or sel_results[1] or sel_results[2]:
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# If we actually had stuff ready, go ahead and return it. No need
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# to go through the trouble of doing our own stuff.
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# However, because this is typically a place where scheduling switches
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# can occur, we need to make sure that's still the case; otherwise a single
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# consumer could monopolize the thread. (shows up in test_ftplib.)
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_g_sleep()
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return sel_results
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result = SelectResult()
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return result.select(rlist, wlist, timeout)
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if original_poll is not None:
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class PollResult(object):
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__slots__ = ('events', 'event')
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def __init__(self):
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self.events = set()
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self.event = Event()
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def add_event(self, events, fd):
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if events < 0:
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result_flags = POLLNVAL
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else:
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result_flags = 0
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if events & _EV_READ:
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result_flags = POLLIN
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if events & _EV_WRITE:
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result_flags |= POLLOUT
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self.events.add((fd, result_flags))
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self.event.set()
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class poll(object):
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"""
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An implementation of :class:`select.poll` that blocks only the current greenlet.
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.. caution:: ``POLLPRI`` data is not supported.
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.. versionadded:: 1.1b1
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"""
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def __init__(self):
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self.fds = {} # {int -> watcher}
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self.loop = get_hub().loop
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def register(self, fd, eventmask=_NONE):
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if eventmask is _NONE:
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flags = _EV_READ | _EV_WRITE
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else:
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flags = 0
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if eventmask & POLLIN:
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flags = _EV_READ
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if eventmask & POLLOUT:
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flags |= _EV_WRITE
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# If they ask for POLLPRI, we can't support
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# that. Should we raise an error?
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fileno = get_fileno(fd)
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watcher = self.loop.io(fileno, flags)
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watcher.priority = self.loop.MAXPRI
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self.fds[fileno] = watcher
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def modify(self, fd, eventmask):
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self.register(fd, eventmask)
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def poll(self, timeout=None):
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"""
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poll the registered fds.
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.. versionchanged:: 1.2a1
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File descriptors that are closed are reported with POLLNVAL.
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"""
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result = PollResult()
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try:
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for fd, watcher in iteritems(self.fds):
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watcher.start(result.add_event, fd, pass_events=True)
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if timeout is not None and timeout > -1:
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timeout /= 1000.0
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result.event.wait(timeout=timeout)
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return list(result.events)
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finally:
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for awatcher in itervalues(self.fds):
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awatcher.stop()
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def unregister(self, fd):
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"""
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Unregister the *fd*.
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.. versionchanged:: 1.2a1
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Raise a `KeyError` if *fd* was not registered, like the standard
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library. Previously gevent did nothing.
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"""
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fileno = get_fileno(fd)
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del self.fds[fileno]
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del original_poll
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