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