549 lines
16 KiB
Python
549 lines
16 KiB
Python
# -*- Mode: Python -*-
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# Id: asyncore.py,v 2.51 2000/09/07 22:29:26 rushing Exp
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# Author: Sam Rushing <rushing@nightmare.com>
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# ======================================================================
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# Copyright 1996 by Sam Rushing
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#
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# All Rights Reserved
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#
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# Permission to use, copy, modify, and distribute this software and
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# its documentation for any purpose and without fee is hereby
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# granted, provided that the above copyright notice appear in all
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# copies and that both that copyright notice and this permission
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# notice appear in supporting documentation, and that the name of Sam
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# Rushing not be used in advertising or publicity pertaining to
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# distribution of the software without specific, written prior
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# permission.
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#
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# SAM RUSHING DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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# INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
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# NO EVENT SHALL SAM RUSHING BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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# CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
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# OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
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# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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# CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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# ======================================================================
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"""Basic infrastructure for asynchronous socket service clients and servers.
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There are only two ways to have a program on a single processor do "more
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than one thing at a time". Multi-threaded programming is the simplest and
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most popular way to do it, but there is another very different technique,
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that lets you have nearly all the advantages of multi-threading, without
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actually using multiple threads. it's really only practical if your program
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is largely I/O bound. If your program is CPU bound, then pre-emptive
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scheduled threads are probably what you really need. Network servers are
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rarely CPU-bound, however.
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If your operating system supports the select() system call in its I/O
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library (and nearly all do), then you can use it to juggle multiple
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communication channels at once; doing other work while your I/O is taking
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place in the "background." Although this strategy can seem strange and
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complex, especially at first, it is in many ways easier to understand and
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control than multi-threaded programming. The module documented here solves
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many of the difficult problems for you, making the task of building
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sophisticated high-performance network servers and clients a snap.
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"""
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import exceptions
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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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import os
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from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, \
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ENOTCONN, ESHUTDOWN, EINTR, EISCONN
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try:
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socket_map
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except NameError:
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socket_map = {}
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class ExitNow(exceptions.Exception):
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pass
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def read(obj):
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try:
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obj.handle_read_event()
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except ExitNow:
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raise
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except:
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obj.handle_error()
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def write(obj):
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try:
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obj.handle_write_event()
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except ExitNow:
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raise
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except:
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obj.handle_error()
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def readwrite(obj, flags):
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try:
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if flags & select.POLLIN:
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obj.handle_read_event()
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if flags & select.POLLOUT:
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obj.handle_write_event()
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except ExitNow:
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raise
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except:
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obj.handle_error()
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def poll(timeout=0.0, map=None):
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if map is None:
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map = socket_map
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if map:
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r = []; w = []; e = []
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for fd, obj in map.items():
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if obj.readable():
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r.append(fd)
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if obj.writable():
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w.append(fd)
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if [] == r == w == e:
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time.sleep(timeout)
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else:
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try:
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r, w, e = select.select(r, w, e, timeout)
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except select.error, err:
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if err[0] != EINTR:
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raise
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else:
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return
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for fd in r:
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obj = map.get(fd)
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if obj is None:
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continue
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read(obj)
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for fd in w:
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obj = map.get(fd)
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if obj is None:
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continue
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write(obj)
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def poll2(timeout=0.0, map=None):
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import poll
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if map is None:
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map = socket_map
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if timeout is not None:
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# timeout is in milliseconds
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timeout = int(timeout*1000)
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if map:
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l = []
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for fd, obj in map.items():
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flags = 0
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if obj.readable():
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flags = poll.POLLIN
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if obj.writable():
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flags = flags | poll.POLLOUT
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if flags:
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l.append((fd, flags))
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r = poll.poll(l, timeout)
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for fd, flags in r:
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obj = map.get(fd)
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if obj is None:
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continue
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readwrite(obj, flags)
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def poll3(timeout=0.0, map=None):
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# Use the poll() support added to the select module in Python 2.0
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if map is None:
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map = socket_map
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if timeout is not None:
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# timeout is in milliseconds
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timeout = int(timeout*1000)
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pollster = select.poll()
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if map:
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for fd, obj in map.items():
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flags = 0
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if obj.readable():
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flags = select.POLLIN
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if obj.writable():
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flags = flags | select.POLLOUT
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if flags:
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pollster.register(fd, flags)
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try:
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r = pollster.poll(timeout)
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except select.error, err:
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if err[0] != EINTR:
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raise
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r = []
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for fd, flags in r:
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obj = map.get(fd)
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if obj is None:
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continue
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readwrite(obj, flags)
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def loop(timeout=30.0, use_poll=0, map=None):
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if map is None:
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map = socket_map
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if use_poll:
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if hasattr(select, 'poll'):
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poll_fun = poll3
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else:
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poll_fun = poll2
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else:
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poll_fun = poll
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while map:
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poll_fun(timeout, map)
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class dispatcher:
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debug = 0
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connected = 0
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accepting = 0
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closing = 0
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addr = None
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def __init__(self, sock=None, map=None):
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if sock:
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self.set_socket(sock, map)
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# I think it should inherit this anyway
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self.socket.setblocking(0)
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self.connected = 1
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# XXX Does the constructor require that the socket passed
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# be connected?
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try:
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self.addr = sock.getpeername()
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except socket.error:
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# The addr isn't crucial
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pass
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else:
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self.socket = None
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def __repr__(self):
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status = [self.__class__.__module__+"."+self.__class__.__name__]
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if self.accepting and self.addr:
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status.append('listening')
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elif self.connected:
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status.append('connected')
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if self.addr is not None:
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try:
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status.append('%s:%d' % self.addr)
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except TypeError:
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status.append(repr(self.addr))
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return '<%s at %#x>' % (' '.join(status), id(self))
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def add_channel(self, map=None):
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#self.log_info('adding channel %s' % self)
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if map is None:
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map = socket_map
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map[self._fileno] = self
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def del_channel(self, map=None):
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fd = self._fileno
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if map is None:
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map = socket_map
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if map.has_key(fd):
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#self.log_info('closing channel %d:%s' % (fd, self))
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del map[fd]
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def create_socket(self, family, type):
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self.family_and_type = family, type
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self.socket = socket.socket(family, type)
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self.socket.setblocking(0)
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self._fileno = self.socket.fileno()
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self.add_channel()
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def set_socket(self, sock, map=None):
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self.socket = sock
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## self.__dict__['socket'] = sock
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self._fileno = sock.fileno()
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self.add_channel(map)
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def set_reuse_addr(self):
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# try to re-use a server port if possible
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try:
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self.socket.setsockopt(
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socket.SOL_SOCKET, socket.SO_REUSEADDR,
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self.socket.getsockopt(socket.SOL_SOCKET,
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socket.SO_REUSEADDR) | 1
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)
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except socket.error:
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pass
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# ==================================================
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# predicates for select()
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# these are used as filters for the lists of sockets
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# to pass to select().
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# ==================================================
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def readable(self):
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return True
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if os.name == 'mac':
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# The macintosh will select a listening socket for
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# write if you let it. What might this mean?
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def writable(self):
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return not self.accepting
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else:
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def writable(self):
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return True
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# ==================================================
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# socket object methods.
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# ==================================================
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def listen(self, num):
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self.accepting = 1
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if os.name == 'nt' and num > 5:
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num = 1
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return self.socket.listen(num)
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def bind(self, addr):
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self.addr = addr
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return self.socket.bind(addr)
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def connect(self, address):
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self.connected = 0
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err = self.socket.connect_ex(address)
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# XXX Should interpret Winsock return values
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if err in (EINPROGRESS, EALREADY, EWOULDBLOCK):
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return
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if err in (0, EISCONN):
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self.addr = address
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self.connected = 1
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self.handle_connect()
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else:
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raise socket.error, err
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def accept(self):
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# XXX can return either an address pair or None
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try:
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conn, addr = self.socket.accept()
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return conn, addr
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except socket.error, why:
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if why[0] == EWOULDBLOCK:
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pass
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else:
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raise socket.error, why
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def send(self, data):
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try:
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result = self.socket.send(data)
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return result
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except socket.error, why:
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if why[0] == EWOULDBLOCK:
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return 0
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else:
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raise socket.error, why
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return 0
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def recv(self, buffer_size):
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try:
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data = self.socket.recv(buffer_size)
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if not data:
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# a closed connection is indicated by signaling
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# a read condition, and having recv() return 0.
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self.handle_close()
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return ''
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else:
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return data
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except socket.error, why:
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# winsock sometimes throws ENOTCONN
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if why[0] in [ECONNRESET, ENOTCONN, ESHUTDOWN]:
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self.handle_close()
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return ''
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else:
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raise socket.error, why
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def close(self):
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self.del_channel()
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self.socket.close()
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# cheap inheritance, used to pass all other attribute
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# references to the underlying socket object.
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def __getattr__(self, attr):
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return getattr(self.socket, attr)
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# log and log_info maybe overriden to provide more sophisitcated
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# logging and warning methods. In general, log is for 'hit' logging
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# and 'log_info' is for informational, warning and error logging.
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def log(self, message):
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sys.stderr.write('log: %s\n' % str(message))
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def log_info(self, message, type='info'):
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if __debug__ or type != 'info':
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print '%s: %s' % (type, message)
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def handle_read_event(self):
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if self.accepting:
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# for an accepting socket, getting a read implies
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# that we are connected
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if not self.connected:
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self.connected = 1
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self.handle_accept()
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elif not self.connected:
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self.handle_connect()
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self.connected = 1
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self.handle_read()
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else:
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self.handle_read()
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def handle_write_event(self):
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# getting a write implies that we are connected
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if not self.connected:
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self.handle_connect()
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self.connected = 1
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self.handle_write()
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def handle_expt_event(self):
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self.handle_expt()
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def handle_error(self):
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nil, t, v, tbinfo = compact_traceback()
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# sometimes a user repr method will crash.
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try:
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self_repr = repr(self)
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except:
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self_repr = '<__repr__(self) failed for object at %0x>' % id(self)
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self.log_info(
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'uncaptured python exception, closing channel %s (%s:%s %s)' % (
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self_repr,
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t,
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v,
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tbinfo
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),
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'error'
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)
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self.close()
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def handle_expt(self):
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self.log_info('unhandled exception', 'warning')
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def handle_read(self):
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self.log_info('unhandled read event', 'warning')
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def handle_write(self):
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self.log_info('unhandled write event', 'warning')
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def handle_connect(self):
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self.log_info('unhandled connect event', 'warning')
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def handle_accept(self):
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self.log_info('unhandled accept event', 'warning')
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def handle_close(self):
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self.log_info('unhandled close event', 'warning')
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self.close()
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# ---------------------------------------------------------------------------
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# adds simple buffered output capability, useful for simple clients.
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# [for more sophisticated usage use asynchat.async_chat]
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# ---------------------------------------------------------------------------
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class dispatcher_with_send(dispatcher):
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def __init__(self, sock=None):
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dispatcher.__init__(self, sock)
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self.out_buffer = ''
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def initiate_send(self):
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num_sent = 0
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num_sent = dispatcher.send(self, self.out_buffer[:512])
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self.out_buffer = self.out_buffer[num_sent:]
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def handle_write(self):
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self.initiate_send()
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def writable(self):
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return (not self.connected) or len(self.out_buffer)
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def send(self, data):
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if self.debug:
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self.log_info('sending %s' % repr(data))
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self.out_buffer = self.out_buffer + data
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self.initiate_send()
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# ---------------------------------------------------------------------------
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# used for debugging.
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# ---------------------------------------------------------------------------
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def compact_traceback():
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t, v, tb = sys.exc_info()
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tbinfo = []
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assert tb # Must have a traceback
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while tb:
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tbinfo.append((
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tb.tb_frame.f_code.co_filename,
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tb.tb_frame.f_code.co_name,
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str(tb.tb_lineno)
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))
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tb = tb.tb_next
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# just to be safe
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del tb
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file, function, line = tbinfo[-1]
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info = ' '.join(['[%s|%s|%s]' % x for x in tbinfo])
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return (file, function, line), t, v, info
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def close_all(map=None):
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if map is None:
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map = socket_map
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for x in map.values():
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x.socket.close()
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map.clear()
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# Asynchronous File I/O:
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#
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# After a little research (reading man pages on various unixen, and
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# digging through the linux kernel), I've determined that select()
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# isn't meant for doing doing asynchronous file i/o.
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# Heartening, though - reading linux/mm/filemap.c shows that linux
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# supports asynchronous read-ahead. So _MOST_ of the time, the data
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# will be sitting in memory for us already when we go to read it.
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#
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# What other OS's (besides NT) support async file i/o? [VMS?]
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#
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# Regardless, this is useful for pipes, and stdin/stdout...
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if os.name == 'posix':
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import fcntl
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class file_wrapper:
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# here we override just enough to make a file
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# look like a socket for the purposes of asyncore.
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def __init__(self, fd):
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self.fd = fd
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def recv(self, *args):
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return os.read(self.fd, *args)
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def send(self, *args):
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return os.write(self.fd, *args)
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read = recv
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write = send
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def close(self):
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return os.close(self.fd)
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def fileno(self):
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return self.fd
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class file_dispatcher(dispatcher):
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def __init__(self, fd):
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dispatcher.__init__(self)
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self.connected = 1
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# set it to non-blocking mode
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flags = fcntl.fcntl(fd, fcntl.F_GETFL, 0)
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flags = flags | os.O_NONBLOCK
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fcntl.fcntl(fd, fcntl.F_SETFL, flags)
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self.set_file(fd)
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def set_file(self, fd):
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self._fileno = fd
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self.socket = file_wrapper(fd)
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self.add_channel()
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