interface.py revision 781d71db
1#!/usr/bin/env python
2#
3# Copyright 2011 Facebook
4#
5# Licensed under the Apache License, Version 2.0 (the "License"); you may
6# not use this file except in compliance with the License. You may obtain
7# a copy of the License at
8#
9#     http://www.apache.org/licenses/LICENSE-2.0
10#
11# Unless required by applicable law or agreed to in writing, software
12# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
13# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
14# License for the specific language governing permissions and limitations
15# under the License.
16
17"""Interfaces for platform-specific functionality.
18
19This module exists primarily for documentation purposes and as base classes
20for other tornado.platform modules.  Most code should import the appropriate
21implementation from `tornado.platform.auto`.
22"""
23
24from __future__ import absolute_import, division, print_function, with_statement
25
26
27def set_close_exec(fd):
28    """Sets the close-on-exec bit (``FD_CLOEXEC``)for a file descriptor."""
29    raise NotImplementedError()
30
31
32class Waker(object):
33    """A socket-like object that can wake another thread from ``select()``.
34
35    The `~tornado.ioloop.IOLoop` will add the Waker's `fileno()` to
36    its ``select`` (or ``epoll`` or ``kqueue``) calls.  When another
37    thread wants to wake up the loop, it calls `wake`.  Once it has woken
38    up, it will call `consume` to do any necessary per-wake cleanup.  When
39    the ``IOLoop`` is closed, it closes its waker too.
40    """
41    def fileno(self):
42        """Returns the read file descriptor for this waker.
43
44        Must be suitable for use with ``select()`` or equivalent on the
45        local platform.
46        """
47        raise NotImplementedError()
48
49    def write_fileno(self):
50        """Returns the write file descriptor for this waker."""
51        raise NotImplementedError()
52
53    def wake(self):
54        """Triggers activity on the waker's file descriptor."""
55        raise NotImplementedError()
56
57    def consume(self):
58        """Called after the listen has woken up to do any necessary cleanup."""
59        raise NotImplementedError()
60
61    def close(self):
62        """Closes the waker's file descriptor(s)."""
63        raise NotImplementedError()
64