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e94d8fab56
blocked in select(), this will raise select.error with errno set to EINTR. The except clauses correctly ignores this error, but the rest of the logic will then call read() for all objects in select's *input* list of read file descriptors. Then when an object's read_handler() is naive, it will call recv() on its socket, which will raise an IOError, and then asyncore decides to close the socket. To fix this, we simply return in this case. Backport candidate.
548 lines
16 KiB
Python
548 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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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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