1#
2# Analogue of `multiprocessing.connection` which uses queues instead of sockets
3#
4# multiprocessing/dummy/connection.py
5#
6# Copyright (c) 2006-2008, R Oudkerk
7# All rights reserved.
8#
9# Redistribution and use in source and binary forms, with or without
10# modification, are permitted provided that the following conditions
11# are met:
12#
13# 1. Redistributions of source code must retain the above copyright
14#    notice, this list of conditions and the following disclaimer.
15# 2. Redistributions in binary form must reproduce the above copyright
16#    notice, this list of conditions and the following disclaimer in the
17#    documentation and/or other materials provided with the distribution.
18# 3. Neither the name of author nor the names of any contributors may be
19#    used to endorse or promote products derived from this software
20#    without specific prior written permission.
21#
22# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
23# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
26# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32# SUCH DAMAGE.
33#
34
35__all__ = [ 'Client', 'Listener', 'Pipe' ]
36
37from queue import Queue
38
39
40families = [None]
41
42
43class Listener(object):
44
45    def __init__(self, address=None, family=None, backlog=1):
46        self._backlog_queue = Queue(backlog)
47
48    def accept(self):
49        return Connection(*self._backlog_queue.get())
50
51    def close(self):
52        self._backlog_queue = None
53
54    address = property(lambda self: self._backlog_queue)
55
56    def __enter__(self):
57        return self
58
59    def __exit__(self, exc_type, exc_value, exc_tb):
60        self.close()
61
62
63def Client(address):
64    _in, _out = Queue(), Queue()
65    address.put((_out, _in))
66    return Connection(_in, _out)
67
68
69def Pipe(duplex=True):
70    a, b = Queue(), Queue()
71    return Connection(a, b), Connection(b, a)
72
73
74class Connection(object):
75
76    def __init__(self, _in, _out):
77        self._out = _out
78        self._in = _in
79        self.send = self.send_bytes = _out.put
80        self.recv = self.recv_bytes = _in.get
81
82    def poll(self, timeout=0.0):
83        if self._in.qsize() > 0:
84            return True
85        if timeout <= 0.0:
86            return False
87        self._in.not_empty.acquire()
88        self._in.not_empty.wait(timeout)
89        self._in.not_empty.release()
90        return self._in.qsize() > 0
91
92    def close(self):
93        pass
94
95    def __enter__(self):
96        return self
97
98    def __exit__(self, exc_type, exc_value, exc_tb):
99        self.close()
100