33502
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""" Back-ported, durable, and portable selectors """ |
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# MIT License |
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# |
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# Copyright (c) 2017 Seth Michael Larson |
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# |
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# Permission is hereby granted, free of charge, to any person obtaining a copy |
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# of this software and associated documentation files (the "Software"), to deal |
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# in the Software without restriction, including without limitation the rights |
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
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# copies of the Software, and to permit persons to whom the Software is |
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# furnished to do so, subject to the following conditions: |
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# |
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# The above copyright notice and this permission notice shall be included in all |
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# copies or substantial portions of the Software. |
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# |
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
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# SOFTWARE. |
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# no-check-code |
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from __future__ import absolute_import |
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import collections |
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import errno |
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import math |
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import platform |
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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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|
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namedtuple = collections.namedtuple |
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Mapping = collections.Mapping |
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|
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try: |
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monotonic = time.monotonic |
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except AttributeError: |
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monotonic = time.time |
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|
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__author__ = 'Seth Michael Larson' |
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__email__ = 'sethmichaellarson@protonmail.com' |
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__version__ = '2.0.0' |
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__license__ = 'MIT' |
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__url__ = 'https://www.github.com/SethMichaelLarson/selectors2' |
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|
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__all__ = ['EVENT_READ', |
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'EVENT_WRITE', |
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'SelectorKey', |
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'DefaultSelector', |
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'BaseSelector'] |
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|
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EVENT_READ = (1 << 0) |
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EVENT_WRITE = (1 << 1) |
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_DEFAULT_SELECTOR = None |
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_SYSCALL_SENTINEL = object() # Sentinel in case a system call returns None. |
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_ERROR_TYPES = (OSError, IOError, socket.error) |
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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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|
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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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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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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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|
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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, *_): |
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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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|
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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._wrap_select, True, self._readers, |
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self._writers, 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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|
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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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|
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def _wrap_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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|
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__all__.append('SelectSelector') |
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|
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# Jython has a different implementation of .fileno() for socket objects. |
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if platform.system() == 'Java': |
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class _JythonSelectorMapping(object): |
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""" This is an implementation of _SelectorMapping that is built |
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for use specifically with Jython, which does not provide a hashable |
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value from socket.socket.fileno(). """ |
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|
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def __init__(self, selector): |
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assert isinstance(selector, JythonSelectSelector) |
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self._selector = selector |
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def __len__(self): |
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return len(self._selector._sockets) |
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|
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def __getitem__(self, fileobj): |
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for sock, key in self._selector._sockets: |
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if sock is fileobj: |
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return key |
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else: |
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raise KeyError("{0!r} is not registered.".format(fileobj)) |
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|
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class JythonSelectSelector(SelectSelector): |
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""" This is an implementation of SelectSelector that is for Jython |
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which works around that Jython's socket.socket.fileno() does not |
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return an integer fd value. All SelectorKey.fd will be equal to -1 |
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and should not be used. This instead uses object id to compare fileobj |
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and will only use select.select as it's the only selector that allows |
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directly passing in socket objects rather than registering fds. |
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See: http://bugs.jython.org/issue1678 |
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https://wiki.python.org/jython/NewSocketModule#socket.fileno.28.29_does_not_return_an_integer |
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""" |
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|
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def __init__(self): |
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super(JythonSelectSelector, self).__init__() |
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|
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self._sockets = [] # Uses a list of tuples instead of dictionary. |
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self._map = _JythonSelectorMapping(self) |
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self._readers = [] |
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self._writers = [] |
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|
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# Jython has a select.cpython_compatible_select function in older versions. |
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self._select_func = getattr(select, 'cpython_compatible_select', select.select) |
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|
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def register(self, fileobj, events, data=None): |
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for sock, _ in self._sockets: |
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if sock is fileobj: |
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raise KeyError("{0!r} is already registered" |
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.format(fileobj, sock)) |
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|
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key = SelectorKey(fileobj, -1, events, data) |
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self._sockets.append((fileobj, key)) |
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|
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if events & EVENT_READ: |
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self._readers.append(fileobj) |
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if events & EVENT_WRITE: |
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self._writers.append(fileobj) |
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return key |
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|
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def unregister(self, fileobj): |
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for i, (sock, key) in enumerate(self._sockets): |
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if sock is fileobj: |
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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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354 |
|
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if key.events & EVENT_READ: |
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self._readers.remove(fileobj) |
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if key.events & EVENT_WRITE: |
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self._writers.remove(fileobj) |
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359 |
|
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del self._sockets[i] |
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return key |
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362 |
|
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def _wrap_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 self._select_func(r, w, [], timeout) |
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366 |
|
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__all__.append('JythonSelectSelector') |
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SelectSelector = JythonSelectSelector # Override so the wrong selector isn't used. |
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|
|
370 |
|
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if hasattr(select, "poll"): |
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class PollSelector(BaseSelector): |
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""" Poll-based selector """ |
|
374 |
def __init__(self): |
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super(PollSelector, self).__init__() |
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376 |
self._poll = select.poll() |
|
377 |
|
|
378 |
def register(self, fileobj, events, data=None): |
|
379 |
key = super(PollSelector, self).register(fileobj, events, data) |
|
380 |
event_mask = 0 |
|
381 |
if events & EVENT_READ: |
|
382 |
event_mask |= select.POLLIN |
|
383 |
if events & EVENT_WRITE: |
|
384 |
event_mask |= select.POLLOUT |
|
385 |
self._poll.register(key.fd, event_mask) |
|
386 |
return key |
|
387 |
|
|
388 |
def unregister(self, fileobj): |
|
389 |
key = super(PollSelector, self).unregister(fileobj) |
|
390 |
self._poll.unregister(key.fd) |
|
391 |
return key |
|
392 |
|
|
393 |
def _wrap_poll(self, timeout=None): |
|
394 |
""" Wrapper function for select.poll.poll() so that |
|
395 |
_syscall_wrapper can work with only seconds. """ |
|
396 |
if timeout is not None: |
|
397 |
if timeout <= 0: |
|
398 |
timeout = 0 |
|
399 |
else: |
|
400 |
# select.poll.poll() has a resolution of 1 millisecond, |
|
401 |
# round away from zero to wait *at least* timeout seconds. |
|
402 |
timeout = math.ceil(timeout * 1000) |
|
403 |
|
|
404 |
result = self._poll.poll(timeout) |
|
405 |
return result |
|
406 |
|
|
407 |
def select(self, timeout=None): |
|
408 |
ready = [] |
|
409 |
fd_events = _syscall_wrapper(self._wrap_poll, True, timeout=timeout) |
|
410 |
for fd, event_mask in fd_events: |
|
411 |
events = 0 |
|
412 |
if event_mask & ~select.POLLIN: |
|
413 |
events |= EVENT_WRITE |
|
414 |
if event_mask & ~select.POLLOUT: |
|
415 |
events |= EVENT_READ |
|
416 |
|
|
417 |
key = self._key_from_fd(fd) |
|
418 |
if key: |
|
419 |
ready.append((key, events & key.events)) |
|
420 |
|
|
421 |
return ready |
|
422 |
|
|
423 |
__all__.append('PollSelector') |
|
424 |
|
|
425 |
if hasattr(select, "epoll"): |
|
426 |
class EpollSelector(BaseSelector): |
|
427 |
""" Epoll-based selector """ |
|
428 |
def __init__(self): |
|
429 |
super(EpollSelector, self).__init__() |
|
430 |
self._epoll = select.epoll() |
|
431 |
|
|
432 |
def fileno(self): |
|
433 |
return self._epoll.fileno() |
|
434 |
|
|
435 |
def register(self, fileobj, events, data=None): |
|
436 |
key = super(EpollSelector, self).register(fileobj, events, data) |
|
437 |
events_mask = 0 |
|
438 |
if events & EVENT_READ: |
|
439 |
events_mask |= select.EPOLLIN |
|
440 |
if events & EVENT_WRITE: |
|
441 |
events_mask |= select.EPOLLOUT |
|
442 |
_syscall_wrapper(self._epoll.register, False, key.fd, events_mask) |
|
443 |
return key |
|
444 |
|
|
445 |
def unregister(self, fileobj): |
|
446 |
key = super(EpollSelector, self).unregister(fileobj) |
|
447 |
try: |
|
448 |
_syscall_wrapper(self._epoll.unregister, False, key.fd) |
|
449 |
except _ERROR_TYPES: |
|
450 |
# This can occur when the fd was closed since registry. |
|
451 |
pass |
|
452 |
return key |
|
453 |
|
|
454 |
def select(self, timeout=None): |
|
455 |
if timeout is not None: |
|
456 |
if timeout <= 0: |
|
457 |
timeout = 0.0 |
|
458 |
else: |
|
459 |
# select.epoll.poll() has a resolution of 1 millisecond |
|
460 |
# but luckily takes seconds so we don't need a wrapper |
|
461 |
# like PollSelector. Just for better rounding. |
|
462 |
timeout = math.ceil(timeout * 1000) * 0.001 |
|
463 |
timeout = float(timeout) |
|
464 |
else: |
|
465 |
timeout = -1.0 # epoll.poll() must have a float. |
|
466 |
|
|
467 |
# We always want at least 1 to ensure that select can be called |
|
468 |
# with no file descriptors registered. Otherwise will fail. |
|
469 |
max_events = max(len(self._fd_to_key), 1) |
|
470 |
|
|
471 |
ready = [] |
|
472 |
fd_events = _syscall_wrapper(self._epoll.poll, True, |
|
473 |
timeout=timeout, |
|
474 |
maxevents=max_events) |
|
475 |
for fd, event_mask in fd_events: |
|
476 |
events = 0 |
|
477 |
if event_mask & ~select.EPOLLIN: |
|
478 |
events |= EVENT_WRITE |
|
479 |
if event_mask & ~select.EPOLLOUT: |
|
480 |
events |= EVENT_READ |
|
481 |
|
|
482 |
key = self._key_from_fd(fd) |
|
483 |
if key: |
|
484 |
ready.append((key, events & key.events)) |
|
485 |
return ready |
|
486 |
|
|
487 |
def close(self): |
|
488 |
self._epoll.close() |
|
489 |
super(EpollSelector, self).close() |
|
490 |
|
|
491 |
__all__.append('EpollSelector') |
|
492 |
|
|
493 |
|
|
494 |
if hasattr(select, "devpoll"): |
|
495 |
class DevpollSelector(BaseSelector): |
|
496 |
"""Solaris /dev/poll selector.""" |
|
497 |
|
|
498 |
def __init__(self): |
|
499 |
super(DevpollSelector, self).__init__() |
|
500 |
self._devpoll = select.devpoll() |
|
501 |
|
|
502 |
def fileno(self): |
|
503 |
return self._devpoll.fileno() |
|
504 |
|
|
505 |
def register(self, fileobj, events, data=None): |
|
506 |
key = super(DevpollSelector, self).register(fileobj, events, data) |
|
507 |
poll_events = 0 |
|
508 |
if events & EVENT_READ: |
|
509 |
poll_events |= select.POLLIN |
|
510 |
if events & EVENT_WRITE: |
|
511 |
poll_events |= select.POLLOUT |
|
512 |
self._devpoll.register(key.fd, poll_events) |
|
513 |
return key |
|
514 |
|
|
515 |
def unregister(self, fileobj): |
|
516 |
key = super(DevpollSelector, self).unregister(fileobj) |
|
517 |
self._devpoll.unregister(key.fd) |
|
518 |
return key |
|
519 |
|
|
520 |
def _wrap_poll(self, timeout=None): |
|
521 |
""" Wrapper function for select.poll.poll() so that |
|
522 |
_syscall_wrapper can work with only seconds. """ |
|
523 |
if timeout is not None: |
|
524 |
if timeout <= 0: |
|
525 |
timeout = 0 |
|
526 |
else: |
|
527 |
# select.devpoll.poll() has a resolution of 1 millisecond, |
|
528 |
# round away from zero to wait *at least* timeout seconds. |
|
529 |
timeout = math.ceil(timeout * 1000) |
|
530 |
|
|
531 |
result = self._devpoll.poll(timeout) |
|
532 |
return result |
|
533 |
|
|
534 |
def select(self, timeout=None): |
|
535 |
ready = [] |
|
536 |
fd_events = _syscall_wrapper(self._wrap_poll, True, timeout=timeout) |
|
537 |
for fd, event_mask in fd_events: |
|
538 |
events = 0 |
|
539 |
if event_mask & ~select.POLLIN: |
|
540 |
events |= EVENT_WRITE |
|
541 |
if event_mask & ~select.POLLOUT: |
|
542 |
events |= EVENT_READ |
|
543 |
|
|
544 |
key = self._key_from_fd(fd) |
|
545 |
if key: |
|
546 |
ready.append((key, events & key.events)) |
|
547 |
|
|
548 |
return ready |
|
549 |
|
|
550 |
def close(self): |
|
551 |
self._devpoll.close() |
|
552 |
super(DevpollSelector, self).close() |
|
553 |
|
|
554 |
__all__.append('DevpollSelector') |
|
555 |
|
|
556 |
|
|
557 |
if hasattr(select, "kqueue"): |
|
558 |
class KqueueSelector(BaseSelector): |
|
559 |
""" Kqueue / Kevent-based selector """ |
|
560 |
def __init__(self): |
|
561 |
super(KqueueSelector, self).__init__() |
|
562 |
self._kqueue = select.kqueue() |
|
563 |
|
|
564 |
def fileno(self): |
|
565 |
return self._kqueue.fileno() |
|
566 |
|
|
567 |
def register(self, fileobj, events, data=None): |
|
568 |
key = super(KqueueSelector, self).register(fileobj, events, data) |
|
569 |
if events & EVENT_READ: |
|
570 |
kevent = select.kevent(key.fd, |
|
571 |
select.KQ_FILTER_READ, |
|
572 |
select.KQ_EV_ADD) |
|
573 |
|
|
574 |
_syscall_wrapper(self._kqueue.control, False, [kevent], 0, 0) |
|
575 |
|
|
576 |
if events & EVENT_WRITE: |
|
577 |
kevent = select.kevent(key.fd, |
|
578 |
select.KQ_FILTER_WRITE, |
|
579 |
select.KQ_EV_ADD) |
|
580 |
|
|
581 |
_syscall_wrapper(self._kqueue.control, False, [kevent], 0, 0) |
|
582 |
|
|
583 |
return key |
|
584 |
|
|
585 |
def unregister(self, fileobj): |
|
586 |
key = super(KqueueSelector, self).unregister(fileobj) |
|
587 |
if key.events & EVENT_READ: |
|
588 |
kevent = select.kevent(key.fd, |
|
589 |
select.KQ_FILTER_READ, |
|
590 |
select.KQ_EV_DELETE) |
|
591 |
try: |
|
592 |
_syscall_wrapper(self._kqueue.control, False, [kevent], 0, 0) |
|
593 |
except _ERROR_TYPES: |
|
594 |
pass |
|
595 |
if key.events & EVENT_WRITE: |
|
596 |
kevent = select.kevent(key.fd, |
|
597 |
select.KQ_FILTER_WRITE, |
|
598 |
select.KQ_EV_DELETE) |
|
599 |
try: |
|
600 |
_syscall_wrapper(self._kqueue.control, False, [kevent], 0, 0) |
|
601 |
except _ERROR_TYPES: |
|
602 |
pass |
|
603 |
|
|
604 |
return key |
|
605 |
|
|
606 |
def select(self, timeout=None): |
|
607 |
if timeout is not None: |
|
608 |
timeout = max(timeout, 0) |
|
609 |
|
|
610 |
max_events = len(self._fd_to_key) * 2 |
|
611 |
ready_fds = {} |
|
612 |
|
|
613 |
kevent_list = _syscall_wrapper(self._kqueue.control, True, |
|
614 |
None, max_events, timeout) |
|
615 |
|
|
616 |
for kevent in kevent_list: |
|
617 |
fd = kevent.ident |
|
618 |
event_mask = kevent.filter |
|
619 |
events = 0 |
|
620 |
if event_mask == select.KQ_FILTER_READ: |
|
621 |
events |= EVENT_READ |
|
622 |
if event_mask == select.KQ_FILTER_WRITE: |
|
623 |
events |= EVENT_WRITE |
|
624 |
|
|
625 |
key = self._key_from_fd(fd) |
|
626 |
if key: |
|
627 |
if key.fd not in ready_fds: |
|
628 |
ready_fds[key.fd] = (key, events & key.events) |
|
629 |
else: |
|
630 |
old_events = ready_fds[key.fd][1] |
|
631 |
ready_fds[key.fd] = (key, (events | old_events) & key.events) |
|
632 |
|
|
633 |
return list(ready_fds.values()) |
|
634 |
|
|
635 |
def close(self): |
|
636 |
self._kqueue.close() |
|
637 |
super(KqueueSelector, self).close() |
|
638 |
|
|
639 |
__all__.append('KqueueSelector') |
|
640 |
|
|
641 |
|
|
642 |
def _can_allocate(struct): |
|
643 |
""" Checks that select structs can be allocated by the underlying |
|
644 |
operating system, not just advertised by the select module. We don't |
|
645 |
check select() because we'll be hopeful that most platforms that |
|
646 |
don't have it available will not advertise it. (ie: GAE) """ |
|
647 |
try: |
|
648 |
# select.poll() objects won't fail until used. |
|
649 |
if struct == 'poll': |
|
650 |
p = select.poll() |
|
651 |
p.poll(0) |
|
652 |
|
|
653 |
# All others will fail on allocation. |
|
654 |
else: |
|
655 |
getattr(select, struct)().close() |
|
656 |
return True |
|
657 |
except (OSError, AttributeError): |
|
658 |
return False |
|
659 |
|
|
660 |
|
|
661 |
# Python 3.5 uses a more direct route to wrap system calls to increase speed. |
|
662 |
if sys.version_info >= (3, 5): |
|
663 |
def _syscall_wrapper(func, _, *args, **kwargs): |
|
664 |
""" This is the short-circuit version of the below logic |
|
665 |
because in Python 3.5+ all selectors restart system calls. """ |
|
666 |
return func(*args, **kwargs) |
|
667 |
else: |
|
668 |
def _syscall_wrapper(func, recalc_timeout, *args, **kwargs): |
|
669 |
""" Wrapper function for syscalls that could fail due to EINTR. |
|
670 |
All functions should be retried if there is time left in the timeout |
|
671 |
in accordance with PEP 475. """ |
|
672 |
timeout = kwargs.get("timeout", None) |
|
673 |
if timeout is None: |
|
674 |
expires = None |
|
675 |
recalc_timeout = False |
|
676 |
else: |
|
677 |
timeout = float(timeout) |
|
678 |
if timeout < 0.0: # Timeout less than 0 treated as no timeout. |
|
679 |
expires = None |
|
680 |
else: |
|
681 |
expires = monotonic() + timeout |
|
682 |
|
|
683 |
args = list(args) |
|
684 |
if recalc_timeout and "timeout" not in kwargs: |
|
685 |
raise ValueError( |
|
686 |
"Timeout must be in args or kwargs to be recalculated") |
|
687 |
|
|
688 |
result = _SYSCALL_SENTINEL |
|
689 |
while result is _SYSCALL_SENTINEL: |
|
690 |
try: |
|
691 |
result = func(*args, **kwargs) |
|
692 |
# OSError is thrown by select.select |
|
693 |
# IOError is thrown by select.epoll.poll |
|
694 |
# select.error is thrown by select.poll.poll |
|
695 |
# Aren't we thankful for Python 3.x rework for exceptions? |
|
696 |
except (OSError, IOError, select.error) as e: |
|
697 |
# select.error wasn't a subclass of OSError in the past. |
|
698 |
errcode = None |
|
699 |
if hasattr(e, "errno"): |
|
700 |
errcode = e.errno |
|
701 |
elif hasattr(e, "args"): |
|
702 |
errcode = e.args[0] |
|
703 |
|
|
704 |
# Also test for the Windows equivalent of EINTR. |
|
705 |
is_interrupt = (errcode == errno.EINTR or (hasattr(errno, "WSAEINTR") and |
|
706 |
errcode == errno.WSAEINTR)) |
|
707 |
|
|
708 |
if is_interrupt: |
|
709 |
if expires is not None: |
|
710 |
current_time = monotonic() |
|
711 |
if current_time > expires: |
|
712 |
raise OSError(errno=errno.ETIMEDOUT) |
|
713 |
if recalc_timeout: |
|
714 |
if "timeout" in kwargs: |
|
715 |
kwargs["timeout"] = expires - current_time |
|
716 |
continue |
|
717 |
raise |
|
718 |
return result |
|
719 |
|
|
720 |
|
|
721 |
# Choose the best implementation, roughly: |
|
722 |
# kqueue == devpoll == epoll > poll > select |
|
723 |
# select() also can't accept a FD > FD_SETSIZE (usually around 1024) |
|
724 |
def DefaultSelector(): |
|
725 |
""" This function serves as a first call for DefaultSelector to |
|
726 |
detect if the select module is being monkey-patched incorrectly |
|
727 |
by eventlet, greenlet, and preserve proper behavior. """ |
|
728 |
global _DEFAULT_SELECTOR |
|
729 |
if _DEFAULT_SELECTOR is None: |
|
730 |
if platform.system() == 'Java': # Platform-specific: Jython |
|
731 |
_DEFAULT_SELECTOR = JythonSelectSelector |
|
732 |
elif _can_allocate('kqueue'): |
|
733 |
_DEFAULT_SELECTOR = KqueueSelector |
|
734 |
elif _can_allocate('devpoll'): |
|
735 |
_DEFAULT_SELECTOR = DevpollSelector |
|
736 |
elif _can_allocate('epoll'): |
|
737 |
_DEFAULT_SELECTOR = EpollSelector |
|
738 |
elif _can_allocate('poll'): |
|
739 |
_DEFAULT_SELECTOR = PollSelector |
|
740 |
elif hasattr(select, 'select'): |
|
741 |
_DEFAULT_SELECTOR = SelectSelector |
|
742 |
else: # Platform-specific: AppEngine |
|
743 |
raise RuntimeError('Platform does not have a selector.') |
|
744 |
return _DEFAULT_SELECTOR() |