# -*- Mode: Python; tab-width: 4 -*-
# $Id: asyncore.py 299 2005-06-09 17:32:28Z heikki $
# Author: Sam Rushing <rushing@nightmare.com>
# ======================================================================
# Copyright 1996 by Sam Rushing
#
# All Rights Reserved
#
# Permission to use, copy, modify, and distribute this software and
# its documentation for any purpose and without fee is hereby
# granted, provided that the above copyright notice appear in all
# copies and that both that copyright notice and this permission
# notice appear in supporting documentation, and that the name of Sam
# Rushing not be used in advertising or publicity pertaining to
# distribution of the software without specific, written prior
# permission.
#
# SAM RUSHING DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
# INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
# NO EVENT SHALL SAM RUSHING BE LIABLE FOR ANY SPECIAL, INDIRECT OR
# CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
# OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
# CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
# ======================================================================
"""Basic infrastructure for asynchronous socket service clients and servers.
There are only two ways to have a program on a single processor do "more
than one thing at a time". Multi-threaded programming is the simplest and
most popular way to do it, but there is another very different technique,
that lets you have nearly all the advantages of multi-threading, without
actually using multiple threads. it's really only practical if your program
is largely I/O bound. If your program is CPU bound, then pre-emptive
scheduled threads are probably what you really need. Network servers are
rarely CPU-bound, however.
If your operating system supports the select() system call in its I/O
library (and nearly all do), then you can use it to juggle multiple
communication channels at once; doing other work while your I/O is taking
place in the "background." Although this strategy can seem strange and
complex, especially at first, it is in many ways easier to understand and
control than multi-threaded programming. The module documented here solves
many of the difficult problems for you, making the task of building
sophisticated high-performance network servers and clients a snap.
"""
import exceptions
import select
import socket
import string
import sys
import os
if os.name == 'nt':
EWOULDBLOCK = 10035
EINPROGRESS = 10036
EALREADY = 10037
ECONNRESET = 10054
ENOTCONN = 10057
ESHUTDOWN = 10058
else:
from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, ENOTCONN, ESHUTDOWN
try:
socket_map
except NameError:
socket_map = {}
class ExitNow (exceptions.Exception):
pass
DEBUG = 0
def poll (timeout=0.0, map=None):
global DEBUG
if map is None:
map = socket_map
if map:
r = []; w = []; e = []
for fd, obj in map.items():
if obj.readable():
r.append (fd)
if obj.writable():
w.append (fd)
r,w,e = select.select (r,w,e, timeout)
if DEBUG:
print r,w,e
for fd in r:
try:
obj = map[fd]
try:
obj.handle_read_event()
except ExitNow:
raise ExitNow
except:
obj.handle_error()
except KeyError:
pass
for fd in w:
try:
obj = map[fd]
try:
obj.handle_write_event()
except ExitNow:
raise ExitNow
except:
obj.handle_error()
except KeyError:
pass
def poll2 (timeout=0.0, map=None):
import poll
if map is None:
map=socket_map
# timeout is in milliseconds
timeout = int(timeout*1000)
if map:
l = []
for fd, obj in map.items():
flags = 0
if obj.readable():
flags = poll.POLLIN
if obj.writable():
flags = flags | poll.POLLOUT
if flags:
l.append ((fd, flags))
r = poll.poll (l, timeout)
for fd, flags in r:
try:
obj = map[fd]
try:
if (flags & poll.POLLIN):
obj.handle_read_event()
if (flags & poll.POLLOUT):
obj.handle_write_event()
except ExitNow:
raise ExitNow
except:
obj.handle_error()
except KeyError:
pass
def poll3 (timeout=0.0, map=None):
# Use the poll() support added to the select module in Python 2.0
if map is None:
map=socket_map
# timeout is in milliseconds
timeout = int(timeout*1000)
pollster = select.poll()
if map:
l = []
for fd, obj in map.items():
flags = 0
if obj.readable():
flags = select.POLLIN
if obj.writable():
flags = flags | select.POLLOUT
if flags:
pollster.register(fd, flags)
r = pollster.poll (timeout)
for fd, flags in r:
try:
obj = map[fd]
try:
if (flags & select.POLLIN):
obj.handle_read_event()
if (flags & select.POLLOUT):
obj.handle_write_event()
except ExitNow:
raise ExitNow
except:
obj.handle_error()
except KeyError:
pass
def loop (timeout=30.0, use_poll=0, map=None):
if use_poll:
if hasattr (select, 'poll'):
poll_fun = poll3
else:
poll_fun = poll2
else:
poll_fun = poll
if map is None:
map=socket_map
while map:
poll_fun (timeout, map)
class dispatcher:
debug = 0
connected = 0
accepting = 0
closing = 0
addr = None
def __init__ (self, sock=None, map=None):
if sock:
self.set_socket (sock, map)
# I think it should inherit this anyway
self.socket.setblocking (0)
self.connected = 1
def __repr__ (self):
try:
status = []
if self.accepting and self.addr:
status.append ('listening')
elif self.connected:
status.append ('connected')
if self.addr:
status.append ('%s:%d' % self.addr)
return '<%s %s at %x>' % (
self.__class__.__name__,
string.join (status, ' '),
id(self)
)
except:
try:
ar = repr(self.addr)
except:
ar = 'no self.addr!'
return '<__repr__ (self) failed for object at %x (addr=%s)>' % (id(self),ar)
def add_channel (self, map=None):
#self.log_info ('adding channel %s' % self)
if map is None:
map=socket_map
map [self._fileno] = self
def del_channel (self, map=None):
fd = self._fileno
if map is None:
map=socket_map
if map.has_key (fd):
#self.log_info ('closing channel %d:%s' % (fd, self))
del map [fd]
def create_socket (self, family, type):
self.family_and_type = family, type
self.socket = socket.socket (family, type)
self.socket.setblocking(0)
self._fileno = self.socket.fileno()
self.add_channel()
def set_socket (self, sock, map=None):
self.__dict__['socket'] = sock
self._fileno = sock.fileno()
self.add_channel (map)
def set_reuse_addr (self):
# try to re-use a server port if possible
try:
self.socket.setsockopt (
socket.SOL_SOCKET, socket.SO_REUSEADDR,
self.socket.getsockopt (socket.SOL_SOCKET, socket.SO_REUSEADDR) | 1
)
except:
pass
# ==================================================
# predicates for select()
# these are used as filters for the lists of sockets
# to pass to select().
# ==================================================
def readable (self):
return 1
if os.name == 'mac':
# The macintosh will select a listening socket for
# write if you let it. What might this mean?
def writable (self):
return not self.accepting
else:
def writable (self):
return 1
# ==================================================
# socket object methods.
# ==================================================
def listen (self, num):
self.accepting = 1
if os.name == 'nt' and num > 5:
num = 1
return self.socket.listen (num)
def bind (self, addr):
self.addr = addr
return self.socket.bind (addr)
def connect (self, address):
self.connected = 0
try:
self.socket.connect (address)
except socket.error, why:
if why[0] in (EINPROGRESS, EALREADY, EWOULDBLOCK):
return
else:
raise socket.error, why
self.connected = 1
self.handle_connect()
def accept (self):
try:
conn, addr = self.socket.accept()
return conn, addr
except socket.error, why:
if why[0] == EWOULDBLOCK:
pass
else:
raise socket.error, why
def send (self, data):
try:
result = self.socket.send (data)
return result
except socket.error, why:
if why[0] == EWOULDBLOCK:
return 0
else:
raise socket.error, why
return 0
def recv (self, buffer_size):
try:
data = self.socket.recv (buffer_size)
if not data:
# a closed connection is indicated by signaling
# a read condition, and having recv() return 0.
self.handle_close()
return ''
else:
return data
except socket.error, why:
# winsock sometimes throws ENOTCONN
if why[0] in [ECONNRESET, ENOTCONN, ESHUTDOWN]:
self.handle_close()
return ''
else:
raise socket.error, why
def close (self):
self.del_channel()
self.socket.close()
# cheap inheritance, used to pass all other attribute
# references to the underlying socket object.
def __getattr__ (self, attr):
return getattr (self.socket, attr)
# log and log_info maybe overriden to provide more sophisitcated
# logging and warning methods. In general, log is for 'hit' logging
# and 'log_info' is for informational, warning and error logging.
def log (self, message):
sys.stderr.write ('log: %s\n' % str(message))
def log_info (self, message, type='info'):
if __debug__ or type != 'info':
print '%s: %s' % (type, message)
def handle_read_event (self):
if self.accepting:
# for an accepting socket, getting a read implies
# that we are connected
if not self.connected:
self.connected = 1
self.handle_accept()
elif not self.connected:
self.handle_connect()
self.connected = 1
self.handle_read()
else:
self.handle_read()
def handle_write_event (self):
# getting a write implies that we are connected
if not self.connected:
self.handle_connect()
self.connected = 1
self.handle_write()
def handle_expt_event (self):
self.handle_expt()
def handle_error (self):
(file,fun,line), t, v, tbinfo = compact_traceback()
# sometimes a user repr method will crash.
try:
self_repr = repr (self)
except:
self_repr = '<__repr__ (self) failed for object at %0x>' % id(self)
self.log_info (
'uncaptured python exception, closing channel %s (%s:%s %s)' % (
self_repr,
t,
v,
tbinfo
),
'error'
)
self.close()
def handle_expt (self):
self.log_info ('unhandled exception', 'warning')
def handle_read (self):
self.log_info ('unhandled read event', 'warning')
def handle_write (self):
self.log_info ('unhandled write event', 'warning')
def handle_connect (self):
self.log_info ('unhandled connect event', 'warning')
def handle_accept (self):
self.log_info ('unhandled accept event', 'warning')
def handle_close (self):
self.log_info ('unhandled close event', 'warning')
self.close()
# ---------------------------------------------------------------------------
# adds simple buffered output capability, useful for simple clients.
# [for more sophisticated usage use asynchat.async_chat]
# ---------------------------------------------------------------------------
class dispatcher_with_send (dispatcher):
def __init__ (self, sock=None):
dispatcher.__init__ (self, sock)
self.out_buffer = ''
def initiate_send (self):
num_sent = 0
num_sent = dispatcher.send (self, self.out_buffer[:512])
self.out_buffer = self.out_buffer[num_sent:]
def handle_write (self):
self.initiate_send()
def writable (self):
return (not self.connected) or len(self.out_buffer)
def send (self, data):
if self.debug:
self.log_info ('sending %s' % repr(data))
self.out_buffer = self.out_buffer + data
self.initiate_send()
# ---------------------------------------------------------------------------
# used for debugging.
# ---------------------------------------------------------------------------
def compact_traceback ():
t,v,tb = sys.exc_info()
tbinfo = []
while 1:
tbinfo.append ((
tb.tb_frame.f_code.co_filename,
tb.tb_frame.f_code.co_name,
str(tb.tb_lineno)
))
tb = tb.tb_next
if not tb:
break
# just to be safe
del tb
file, function, line = tbinfo[-1]
info = '[' + string.join (
map (
lambda x: string.join (x, '|'),
tbinfo
),
'] ['
) + ']'
return (file, function, line), t, v, info
def close_all (map=None):
if map is None:
map=socket_map
for x in map.values():
x.socket.close()
map.clear()
# Asynchronous File I/O:
#
# After a little research (reading man pages on various unixen, and
# digging through the linux kernel), I've determined that select()
# isn't meant for doing doing asynchronous file i/o.
# Heartening, though - reading linux/mm/filemap.c shows that linux
# supports asynchronous read-ahead. So _MOST_ of the time, the data
# will be sitting in memory for us already when we go to read it.
#
# What other OS's (besides NT) support async file i/o? [VMS?]
#
# Regardless, this is useful for pipes, and stdin/stdout...
import os
if os.name == 'posix':
import fcntl
import FCNTL
class file_wrapper:
# here we override just enough to make a file
# look like a socket for the purposes of asyncore.
def __init__ (self, fd):
self.fd = fd
def recv (self, *args):
return apply (os.read, (self.fd,)+args)
def send (self, *args):
return apply (os.write, (self.fd,)+args)
read = recv
write = send
def close (self):
return os.close (self.fd)
def fileno (self):
return self.fd
class file_dispatcher (dispatcher):
def __init__ (self, fd):
dispatcher.__init__ (self)
self.connected = 1
# set it to non-blocking mode
flags = fcntl.fcntl (fd, FCNTL.F_GETFL, 0)
flags = flags | FCNTL.O_NONBLOCK
fcntl.fcntl (fd, FCNTL.F_SETFL, flags)
self.set_file (fd)
def set_file (self, fd):
self._fileno = fd
self.socket = file_wrapper (fd)
self.add_channel()
