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The bundled selectors library which is used by the local and ssh connection plugins had a bug which caused a traceback in a cornercase. If selectors were in use and a syscall was interrupted, selectors would attempt to restart the syscall after the interrupt was processed. if the attempt determined that the timeout for running the syscall had already expired, the code attempted to raise OSError. The raise was using a Python3-ism and needed to be ported to work on Python2. Fixes #41630
654 lines
23 KiB
Python
654 lines
23 KiB
Python
# This file is from the selectors2.py package. It backports the PSF Licensed
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# selectors module from the Python-3.5 stdlib to older versions of Python.
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# The author, Seth Michael Larson, dual licenses his modifications under the
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# PSF License and MIT License:
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# https://github.com/SethMichaelLarson/selectors2#license
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#
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# Copyright (c) 2016 Seth Michael Larson
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#
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# PSF License (see licenses/PSF-license.txt or https://opensource.org/licenses/Python-2.0)
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# MIT License (see licenses/MIT-license.txt or https://opensource.org/licenses/MIT)
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#
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# Backport of selectors.py from Python 3.5+ to support Python < 3.4
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# Also has the behavior specified in PEP 475 which is to retry syscalls
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# in the case of an EINTR error. This module is required because selectors34
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# does not follow this behavior and instead returns that no dile descriptor
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# events have occurred rather than retry the syscall. The decision to drop
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# support for select.devpoll is made to maintain 100% test coverage.
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import errno
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import math
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import select
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import socket
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import sys
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import time
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from collections import namedtuple, Mapping
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try:
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monotonic = time.monotonic
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except (AttributeError, ImportError): # Python 3.3<
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monotonic = time.time
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__author__ = 'Seth Michael Larson'
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__email__ = 'sethmichaellarson@protonmail.com'
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__version__ = '1.1.0'
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__license__ = 'MIT'
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__all__ = [
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'EVENT_READ',
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'EVENT_WRITE',
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'SelectorError',
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'SelectorKey',
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'DefaultSelector'
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]
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EVENT_READ = (1 << 0)
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EVENT_WRITE = (1 << 1)
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HAS_SELECT = True # Variable that shows whether the platform has a selector.
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_SYSCALL_SENTINEL = object() # Sentinel in case a system call returns None.
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class SelectorError(Exception):
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def __init__(self, errcode):
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super(SelectorError, self).__init__()
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self.errno = errcode
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def __repr__(self):
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return "<SelectorError errno={0}>".format(self.errno)
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def __str__(self):
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return self.__repr__()
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def _fileobj_to_fd(fileobj):
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""" Return a file descriptor from a file object. If
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given an integer will simply return that integer back. """
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if isinstance(fileobj, int):
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fd = fileobj
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else:
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try:
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fd = int(fileobj.fileno())
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except (AttributeError, TypeError, ValueError):
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raise ValueError("Invalid file object: {0!r}".format(fileobj))
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if fd < 0:
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raise ValueError("Invalid file descriptor: {0}".format(fd))
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return fd
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# Python 3.5 uses a more direct route to wrap system calls to increase speed.
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if sys.version_info >= (3, 5):
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def _syscall_wrapper(func, _, *args, **kwargs):
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""" This is the short-circuit version of the below logic
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because in Python 3.5+ all selectors restart system calls. """
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try:
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return func(*args, **kwargs)
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except (OSError, IOError, select.error) as e:
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errcode = None
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if hasattr(e, "errno"):
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errcode = e.errno
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elif hasattr(e, "args"):
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errcode = e.args[0]
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raise SelectorError(errcode)
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else:
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def _syscall_wrapper(func, recalc_timeout, *args, **kwargs):
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""" Wrapper function for syscalls that could fail due to EINTR.
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All functions should be retried if there is time left in the timeout
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in accordance with PEP 475. """
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timeout = kwargs.get("timeout", None)
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if timeout is None:
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expires = None
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recalc_timeout = False
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else:
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timeout = float(timeout)
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if timeout < 0.0: # Timeout less than 0 treated as no timeout.
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expires = None
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else:
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expires = monotonic() + timeout
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args = list(args)
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if recalc_timeout and "timeout" not in kwargs:
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raise ValueError(
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"Timeout must be in args or kwargs to be recalculated")
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result = _SYSCALL_SENTINEL
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while result is _SYSCALL_SENTINEL:
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try:
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result = func(*args, **kwargs)
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# OSError is thrown by select.select
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# IOError is thrown by select.epoll.poll
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# select.error is thrown by select.poll.poll
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# Aren't we thankful for Python 3.x rework for exceptions?
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except (OSError, IOError, select.error) as e:
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# select.error wasn't a subclass of OSError in the past.
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errcode = None
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if hasattr(e, "errno"):
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errcode = e.errno
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elif hasattr(e, "args"):
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errcode = e.args[0]
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# Also test for the Windows equivalent of EINTR.
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is_interrupt = (errcode == errno.EINTR or (hasattr(errno, "WSAEINTR") and
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errcode == errno.WSAEINTR))
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if is_interrupt:
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if expires is not None:
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current_time = monotonic()
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if current_time > expires:
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raise OSError(errno.ETIMEDOUT)
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if recalc_timeout:
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if "timeout" in kwargs:
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kwargs["timeout"] = expires - current_time
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continue
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if errcode:
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raise SelectorError(errcode)
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else:
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raise
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return result
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SelectorKey = namedtuple('SelectorKey', ['fileobj', 'fd', 'events', 'data'])
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class _SelectorMapping(Mapping):
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""" Mapping of file objects to selector keys """
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def __init__(self, selector):
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self._selector = selector
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def __len__(self):
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return len(self._selector._fd_to_key)
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def __getitem__(self, fileobj):
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try:
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fd = self._selector._fileobj_lookup(fileobj)
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return self._selector._fd_to_key[fd]
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except KeyError:
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raise KeyError("{0!r} is not registered.".format(fileobj))
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def __iter__(self):
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return iter(self._selector._fd_to_key)
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class BaseSelector(object):
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""" Abstract Selector class
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A selector supports registering file objects to be monitored
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for specific I/O events.
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A file object is a file descriptor or any object with a
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`fileno()` method. An arbitrary object can be attached to the
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file object which can be used for example to store context info,
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a callback, etc.
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A selector can use various implementations (select(), poll(), epoll(),
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and kqueue()) depending on the platform. The 'DefaultSelector' class uses
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the most efficient implementation for the current platform.
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"""
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def __init__(self):
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# Maps file descriptors to keys.
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self._fd_to_key = {}
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# Read-only mapping returned by get_map()
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self._map = _SelectorMapping(self)
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def _fileobj_lookup(self, fileobj):
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""" Return a file descriptor from a file object.
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This wraps _fileobj_to_fd() to do an exhaustive
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search in case the object is invalid but we still
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have it in our map. Used by unregister() so we can
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unregister an object that was previously registered
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even if it is closed. It is also used by _SelectorMapping
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"""
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try:
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return _fileobj_to_fd(fileobj)
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except ValueError:
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# Search through all our mapped keys.
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for key in self._fd_to_key.values():
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if key.fileobj is fileobj:
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return key.fd
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# Raise ValueError after all.
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raise
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def register(self, fileobj, events, data=None):
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""" Register a file object for a set of events to monitor. """
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if (not events) or (events & ~(EVENT_READ | EVENT_WRITE)):
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raise ValueError("Invalid events: {0!r}".format(events))
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key = SelectorKey(fileobj, self._fileobj_lookup(fileobj), events, data)
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if key.fd in self._fd_to_key:
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raise KeyError("{0!r} (FD {1}) is already registered"
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.format(fileobj, key.fd))
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self._fd_to_key[key.fd] = key
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return key
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def unregister(self, fileobj):
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""" Unregister a file object from being monitored. """
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try:
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key = self._fd_to_key.pop(self._fileobj_lookup(fileobj))
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except KeyError:
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raise KeyError("{0!r} is not registered".format(fileobj))
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# Getting the fileno of a closed socket on Windows errors with EBADF.
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except socket.error as err:
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if err.errno != errno.EBADF:
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raise
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else:
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for key in self._fd_to_key.values():
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if key.fileobj is fileobj:
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self._fd_to_key.pop(key.fd)
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break
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else:
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raise KeyError("{0!r} is not registered".format(fileobj))
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return key
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def modify(self, fileobj, events, data=None):
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""" Change a registered file object monitored events and data. """
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# NOTE: Some subclasses optimize this operation even further.
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try:
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key = self._fd_to_key[self._fileobj_lookup(fileobj)]
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except KeyError:
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raise KeyError("{0!r} is not registered".format(fileobj))
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if events != key.events:
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self.unregister(fileobj)
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key = self.register(fileobj, events, data)
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elif data != key.data:
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# Use a shortcut to update the data.
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key = key._replace(data=data)
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self._fd_to_key[key.fd] = key
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return key
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def select(self, timeout=None):
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""" Perform the actual selection until some monitored file objects
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are ready or the timeout expires. """
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raise NotImplementedError()
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def close(self):
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""" Close the selector. This must be called to ensure that all
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underlying resources are freed. """
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self._fd_to_key.clear()
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self._map = None
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def get_key(self, fileobj):
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""" Return the key associated with a registered file object. """
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mapping = self.get_map()
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if mapping is None:
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raise RuntimeError("Selector is closed")
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try:
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return mapping[fileobj]
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except KeyError:
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raise KeyError("{0!r} is not registered".format(fileobj))
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def get_map(self):
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""" Return a mapping of file objects to selector keys """
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return self._map
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def _key_from_fd(self, fd):
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""" Return the key associated to a given file descriptor
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Return None if it is not found. """
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try:
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return self._fd_to_key[fd]
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except KeyError:
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return None
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def __enter__(self):
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return self
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def __exit__(self, *args):
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self.close()
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# Almost all platforms have select.select()
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if hasattr(select, "select"):
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class SelectSelector(BaseSelector):
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""" Select-based selector. """
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def __init__(self):
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super(SelectSelector, self).__init__()
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self._readers = set()
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self._writers = set()
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def register(self, fileobj, events, data=None):
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key = super(SelectSelector, self).register(fileobj, events, data)
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if events & EVENT_READ:
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self._readers.add(key.fd)
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if events & EVENT_WRITE:
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self._writers.add(key.fd)
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return key
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def unregister(self, fileobj):
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key = super(SelectSelector, self).unregister(fileobj)
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self._readers.discard(key.fd)
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self._writers.discard(key.fd)
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return key
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def _select(self, r, w, timeout=None):
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""" Wrapper for select.select because timeout is a positional arg """
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return select.select(r, w, [], timeout)
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def select(self, timeout=None):
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# Selecting on empty lists on Windows errors out.
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if not len(self._readers) and not len(self._writers):
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return []
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timeout = None if timeout is None else max(timeout, 0.0)
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ready = []
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r, w, _ = _syscall_wrapper(self._select, True, self._readers,
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self._writers, timeout=timeout)
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r = set(r)
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w = set(w)
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for fd in r | w:
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events = 0
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if fd in r:
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events |= EVENT_READ
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if fd in w:
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events |= EVENT_WRITE
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key = self._key_from_fd(fd)
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if key:
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ready.append((key, events & key.events))
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return ready
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__all__.append('SelectSelector')
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if hasattr(select, "poll"):
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class PollSelector(BaseSelector):
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""" Poll-based selector """
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def __init__(self):
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super(PollSelector, self).__init__()
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self._poll = select.poll()
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def register(self, fileobj, events, data=None):
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key = super(PollSelector, self).register(fileobj, events, data)
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event_mask = 0
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if events & EVENT_READ:
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event_mask |= select.POLLIN
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if events & EVENT_WRITE:
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event_mask |= select.POLLOUT
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self._poll.register(key.fd, event_mask)
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return key
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def unregister(self, fileobj):
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key = super(PollSelector, self).unregister(fileobj)
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self._poll.unregister(key.fd)
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return key
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def _wrap_poll(self, timeout=None):
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""" Wrapper function for select.poll.poll() so that
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_syscall_wrapper can work with only seconds. """
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if timeout is not None:
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if timeout <= 0:
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timeout = 0
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else:
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# select.poll.poll() has a resolution of 1 millisecond,
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# round away from zero to wait *at least* timeout seconds.
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timeout = math.ceil(timeout * 1e3)
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result = self._poll.poll(timeout)
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return result
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def select(self, timeout=None):
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ready = []
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fd_events = _syscall_wrapper(self._wrap_poll, True, timeout=timeout)
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for fd, event_mask in fd_events:
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events = 0
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if event_mask & ~select.POLLIN:
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events |= EVENT_WRITE
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if event_mask & ~select.POLLOUT:
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events |= EVENT_READ
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key = self._key_from_fd(fd)
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if key:
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ready.append((key, events & key.events))
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return ready
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__all__.append('PollSelector')
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if hasattr(select, "epoll"):
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class EpollSelector(BaseSelector):
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""" Epoll-based selector """
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def __init__(self):
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super(EpollSelector, self).__init__()
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self._epoll = select.epoll()
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def fileno(self):
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return self._epoll.fileno()
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def register(self, fileobj, events, data=None):
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key = super(EpollSelector, self).register(fileobj, events, data)
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events_mask = 0
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if events & EVENT_READ:
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events_mask |= select.EPOLLIN
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if events & EVENT_WRITE:
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events_mask |= select.EPOLLOUT
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_syscall_wrapper(self._epoll.register, False, key.fd, events_mask)
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return key
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def unregister(self, fileobj):
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key = super(EpollSelector, self).unregister(fileobj)
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try:
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_syscall_wrapper(self._epoll.unregister, False, key.fd)
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except SelectorError:
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# This can occur when the fd was closed since registry.
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pass
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return key
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def select(self, timeout=None):
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if timeout is not None:
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if timeout <= 0:
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timeout = 0.0
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else:
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# select.epoll.poll() has a resolution of 1 millisecond
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# but luckily takes seconds so we don't need a wrapper
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# like PollSelector. Just for better rounding.
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timeout = math.ceil(timeout * 1e3) * 1e-3
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timeout = float(timeout)
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else:
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timeout = -1.0 # epoll.poll() must have a float.
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# We always want at least 1 to ensure that select can be called
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# with no file descriptors registered. Otherwise will fail.
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max_events = max(len(self._fd_to_key), 1)
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ready = []
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fd_events = _syscall_wrapper(self._epoll.poll, True,
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timeout=timeout,
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maxevents=max_events)
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for fd, event_mask in fd_events:
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events = 0
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if event_mask & ~select.EPOLLIN:
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events |= EVENT_WRITE
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if event_mask & ~select.EPOLLOUT:
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events |= EVENT_READ
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key = self._key_from_fd(fd)
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if key:
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ready.append((key, events & key.events))
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return ready
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def close(self):
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self._epoll.close()
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super(EpollSelector, self).close()
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__all__.append('EpollSelector')
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if hasattr(select, "devpoll"):
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class DevpollSelector(BaseSelector):
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"""Solaris /dev/poll selector."""
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def __init__(self):
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super(DevpollSelector, self).__init__()
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self._devpoll = select.devpoll()
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def fileno(self):
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return self._devpoll.fileno()
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def register(self, fileobj, events, data=None):
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key = super(DevpollSelector, self).register(fileobj, events, data)
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poll_events = 0
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if events & EVENT_READ:
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poll_events |= select.POLLIN
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if events & EVENT_WRITE:
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poll_events |= select.POLLOUT
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self._devpoll.register(key.fd, poll_events)
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return key
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def unregister(self, fileobj):
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key = super(DevpollSelector, self).unregister(fileobj)
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self._devpoll.unregister(key.fd)
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return key
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def _wrap_poll(self, timeout=None):
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""" Wrapper function for select.poll.poll() so that
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_syscall_wrapper can work with only seconds. """
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if timeout is not None:
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if timeout <= 0:
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timeout = 0
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else:
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# select.devpoll.poll() has a resolution of 1 millisecond,
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# round away from zero to wait *at least* timeout seconds.
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timeout = math.ceil(timeout * 1e3)
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result = self._devpoll.poll(timeout)
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return result
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def select(self, timeout=None):
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ready = []
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fd_events = _syscall_wrapper(self._wrap_poll, True, timeout=timeout)
|
|
for fd, event_mask in fd_events:
|
|
events = 0
|
|
if event_mask & ~select.POLLIN:
|
|
events |= EVENT_WRITE
|
|
if event_mask & ~select.POLLOUT:
|
|
events |= EVENT_READ
|
|
|
|
key = self._key_from_fd(fd)
|
|
if key:
|
|
ready.append((key, events & key.events))
|
|
|
|
return ready
|
|
|
|
def close(self):
|
|
self._devpoll.close()
|
|
super(DevpollSelector, self).close()
|
|
|
|
__all__.append('DevpollSelector')
|
|
|
|
|
|
if hasattr(select, "kqueue"):
|
|
class KqueueSelector(BaseSelector):
|
|
""" Kqueue / Kevent-based selector """
|
|
def __init__(self):
|
|
super(KqueueSelector, self).__init__()
|
|
self._kqueue = select.kqueue()
|
|
|
|
def fileno(self):
|
|
return self._kqueue.fileno()
|
|
|
|
def register(self, fileobj, events, data=None):
|
|
key = super(KqueueSelector, self).register(fileobj, events, data)
|
|
if events & EVENT_READ:
|
|
kevent = select.kevent(key.fd,
|
|
select.KQ_FILTER_READ,
|
|
select.KQ_EV_ADD)
|
|
|
|
_syscall_wrapper(self._wrap_control, False, [kevent], 0, 0)
|
|
|
|
if events & EVENT_WRITE:
|
|
kevent = select.kevent(key.fd,
|
|
select.KQ_FILTER_WRITE,
|
|
select.KQ_EV_ADD)
|
|
|
|
_syscall_wrapper(self._wrap_control, False, [kevent], 0, 0)
|
|
|
|
return key
|
|
|
|
def unregister(self, fileobj):
|
|
key = super(KqueueSelector, self).unregister(fileobj)
|
|
if key.events & EVENT_READ:
|
|
kevent = select.kevent(key.fd,
|
|
select.KQ_FILTER_READ,
|
|
select.KQ_EV_DELETE)
|
|
try:
|
|
_syscall_wrapper(self._wrap_control, False, [kevent], 0, 0)
|
|
except SelectorError:
|
|
pass
|
|
if key.events & EVENT_WRITE:
|
|
kevent = select.kevent(key.fd,
|
|
select.KQ_FILTER_WRITE,
|
|
select.KQ_EV_DELETE)
|
|
try:
|
|
_syscall_wrapper(self._wrap_control, False, [kevent], 0, 0)
|
|
except SelectorError:
|
|
pass
|
|
|
|
return key
|
|
|
|
def select(self, timeout=None):
|
|
if timeout is not None:
|
|
timeout = max(timeout, 0)
|
|
|
|
max_events = len(self._fd_to_key) * 2
|
|
ready_fds = {}
|
|
|
|
kevent_list = _syscall_wrapper(self._wrap_control, True,
|
|
None, max_events, timeout=timeout)
|
|
|
|
for kevent in kevent_list:
|
|
fd = kevent.ident
|
|
event_mask = kevent.filter
|
|
events = 0
|
|
if event_mask == select.KQ_FILTER_READ:
|
|
events |= EVENT_READ
|
|
if event_mask == select.KQ_FILTER_WRITE:
|
|
events |= EVENT_WRITE
|
|
|
|
key = self._key_from_fd(fd)
|
|
if key:
|
|
if key.fd not in ready_fds:
|
|
ready_fds[key.fd] = (key, events & key.events)
|
|
else:
|
|
old_events = ready_fds[key.fd][1]
|
|
ready_fds[key.fd] = (key, (events | old_events) & key.events)
|
|
|
|
return list(ready_fds.values())
|
|
|
|
def close(self):
|
|
self._kqueue.close()
|
|
super(KqueueSelector, self).close()
|
|
|
|
def _wrap_control(self, changelist, max_events, timeout):
|
|
return self._kqueue.control(changelist, max_events, timeout)
|
|
|
|
__all__.append('KqueueSelector')
|
|
|
|
|
|
# Choose the best implementation, roughly:
|
|
# kqueue == epoll == devpoll > poll > select.
|
|
# select() also can't accept a FD > FD_SETSIZE (usually around 1024)
|
|
if 'KqueueSelector' in globals(): # Platform-specific: Mac OS and BSD
|
|
DefaultSelector = KqueueSelector
|
|
elif 'DevpollSelector' in globals():
|
|
DefaultSelector = DevpollSelector
|
|
elif 'EpollSelector' in globals(): # Platform-specific: Linux
|
|
DefaultSelector = EpollSelector
|
|
elif 'PollSelector' in globals(): # Platform-specific: Linux
|
|
DefaultSelector = PollSelector
|
|
elif 'SelectSelector' in globals(): # Platform-specific: Windows
|
|
DefaultSelector = SelectSelector
|
|
else: # Platform-specific: AppEngine
|
|
def no_selector(_):
|
|
raise ValueError("Platform does not have a selector")
|
|
DefaultSelector = no_selector
|
|
HAS_SELECT = False
|