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v0.8.1
https://github.com/python/cpython
Tip revision: 1da43e5e916949c8e849e656d9d05fa4b9d6836c authored by Benjamin Peterson on 26 June 2009, 13:21:52 UTC
rearrange the sections of the README, so they'll hopefully be more in the order people will interested in
rearrange the sections of the README, so they'll hopefully be more in the order people will interested in
Tip revision: 1da43e5
asyncore.py
# -*- Mode: Python -*-
# Id: asyncore.py,v 2.51 2000/09/07 22:29:26 rushing Exp
# 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 select
import socket
import sys
import time
import os
from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, \
ENOTCONN, ESHUTDOWN, EINTR, EISCONN, EBADF, ECONNABORTED, errorcode
try:
socket_map
except NameError:
socket_map = {}
def _strerror(err):
res = os.strerror(err)
if res == 'Unknown error':
res = errorcode[err]
return res
class ExitNow(Exception):
pass
_reraised_exceptions = (ExitNow, KeyboardInterrupt, SystemExit)
def read(obj):
try:
obj.handle_read_event()
except _reraised_exceptions:
raise
except:
obj.handle_error()
def write(obj):
try:
obj.handle_write_event()
except _reraised_exceptions:
raise
except:
obj.handle_error()
def _exception(obj):
try:
obj.handle_expt_event()
except _reraised_exceptions:
raise
except:
obj.handle_error()
def readwrite(obj, flags):
try:
if flags & select.POLLIN:
obj.handle_read_event()
if flags & select.POLLOUT:
obj.handle_write_event()
if flags & select.POLLPRI:
obj.handle_expt_event()
if flags & (select.POLLHUP | select.POLLERR | select.POLLNVAL):
obj.handle_close()
except socket.error as e:
if e.args[0] not in (EBADF, ECONNRESET, ENOTCONN, ESHUTDOWN, ECONNABORTED):
obj.handle_error()
else:
obj.handle_close()
except _reraised_exceptions:
raise
except:
obj.handle_error()
def poll(timeout=0.0, map=None):
if map is None:
map = socket_map
if map:
r = []; w = []; e = []
for fd, obj in list(map.items()):
is_r = obj.readable()
is_w = obj.writable()
if is_r:
r.append(fd)
if is_w:
w.append(fd)
if is_r or is_w:
e.append(fd)
if [] == r == w == e:
time.sleep(timeout)
return
try:
r, w, e = select.select(r, w, e, timeout)
except select.error as err:
if err.args[0] != EINTR:
raise
else:
return
for fd in r:
obj = map.get(fd)
if obj is None:
continue
read(obj)
for fd in w:
obj = map.get(fd)
if obj is None:
continue
write(obj)
for fd in e:
obj = map.get(fd)
if obj is None:
continue
_exception(obj)
def poll2(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
if timeout is not None:
# timeout is in milliseconds
timeout = int(timeout*1000)
pollster = select.poll()
if map:
for fd, obj in list(map.items()):
flags = 0
if obj.readable():
flags |= select.POLLIN | select.POLLPRI
if obj.writable():
flags |= select.POLLOUT
if flags:
# Only check for exceptions if object was either readable
# or writable.
flags |= select.POLLERR | select.POLLHUP | select.POLLNVAL
pollster.register(fd, flags)
try:
r = pollster.poll(timeout)
except select.error as err:
if err.args[0] != EINTR:
raise
r = []
for fd, flags in r:
obj = map.get(fd)
if obj is None:
continue
readwrite(obj, flags)
poll3 = poll2 # Alias for backward compatibility
def loop(timeout=30.0, use_poll=False, map=None, count=None):
if map is None:
map = socket_map
if use_poll and hasattr(select, 'poll'):
poll_fun = poll2
else:
poll_fun = poll
if count is None:
while map:
poll_fun(timeout, map)
else:
while map and count > 0:
poll_fun(timeout, map)
count = count - 1
class dispatcher:
debug = False
connected = False
accepting = False
closing = False
addr = None
ignore_log_types = frozenset(['warning'])
def __init__(self, sock=None, map=None):
if map is None:
self._map = socket_map
else:
self._map = map
self._fileno = None
if sock:
# Set to nonblocking just to make sure for cases where we
# get a socket from a blocking source.
sock.setblocking(0)
self.set_socket(sock, map)
self.connected = True
# The constructor no longer requires that the socket
# passed be connected.
try:
self.addr = sock.getpeername()
except socket.error as err:
if err.args[0] == ENOTCONN:
# To handle the case where we got an unconnected
# socket.
self.connected = False
else:
# The socket is broken in some unknown way, alert
# the user and remove it from the map (to prevent
# polling of broken sockets).
self.del_channel(map)
raise
else:
self.socket = None
def __repr__(self):
status = [self.__class__.__module__+"."+self.__class__.__name__]
if self.accepting and self.addr:
status.append('listening')
elif self.connected:
status.append('connected')
if self.addr is not None:
try:
status.append('%s:%d' % self.addr)
except TypeError:
status.append(repr(self.addr))
return '<%s at %#x>' % (' '.join(status), id(self))
def add_channel(self, map=None):
#self.log_info('adding channel %s' % self)
if map is None:
map = self._map
map[self._fileno] = self
def del_channel(self, map=None):
fd = self._fileno
if map is None:
map = self._map
if fd in map:
#self.log_info('closing channel %d:%s' % (fd, self))
del map[fd]
self._fileno = None
def create_socket(self, family, type):
self.family_and_type = family, type
sock = socket.socket(family, type)
sock.setblocking(0)
self.set_socket(sock)
def set_socket(self, sock, map=None):
self.socket = sock
## 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 socket.error:
pass
# ==================================================
# predicates for select()
# these are used as filters for the lists of sockets
# to pass to select().
# ==================================================
def readable(self):
return True
def writable(self):
return True
# ==================================================
# socket object methods.
# ==================================================
def listen(self, num):
self.accepting = True
if os.name == 'nt' and num > 5:
num = 5
return self.socket.listen(num)
def bind(self, addr):
self.addr = addr
return self.socket.bind(addr)
def connect(self, address):
self.connected = False
err = self.socket.connect_ex(address)
# XXX Should interpret Winsock return values
if err in (EINPROGRESS, EALREADY, EWOULDBLOCK):
return
if err in (0, EISCONN):
self.addr = address
self.handle_connect_event()
else:
raise socket.error(err, errorcode[err])
def accept(self):
# XXX can return either an address pair or None
try:
conn, addr = self.socket.accept()
return conn, addr
except socket.error as why:
if why.args[0] == EWOULDBLOCK:
pass
else:
raise
def send(self, data):
try:
result = self.socket.send(data)
return result
except socket.error as why:
if why.args[0] == EWOULDBLOCK:
return 0
elif why.args[0] in (ECONNRESET, ENOTCONN, ESHUTDOWN, ECONNABORTED):
self.handle_close()
return 0
else:
raise
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 b''
else:
return data
except socket.error as why:
# winsock sometimes throws ENOTCONN
if why.args[0] in [ECONNRESET, ENOTCONN, ESHUTDOWN, ECONNABORTED]:
self.handle_close()
return b''
else:
raise
def close(self):
self.connected = False
self.accepting = False
self.del_channel()
try:
self.socket.close()
except socket.error as why:
if why.args[0] not in (ENOTCONN, EBADF):
raise
# 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 may be overridden to provide more sophisticated
# 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 type not in self.ignore_log_types:
print('%s: %s' % (type, message))
def handle_read_event(self):
if self.accepting:
# accepting sockets are never connected, they "spawn" new
# sockets that are connected
self.handle_accept()
elif not self.connected:
self.handle_connect_event()
self.handle_read()
else:
self.handle_read()
def handle_connect_event(self):
self.connected = True
self.handle_connect()
def handle_write_event(self):
if self.accepting:
# Accepting sockets shouldn't get a write event.
# We will pretend it didn't happen.
return
if not self.connected:
#check for errors
err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
if err != 0:
raise socket.error(err, _strerror(err))
self.handle_connect_event()
self.handle_write()
def handle_expt_event(self):
# handle_expt_event() is called if there might be an error on the
# socket, or if there is OOB data
# check for the error condition first
err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
if err != 0:
# we can get here when select.select() says that there is an
# exceptional condition on the socket
# since there is an error, we'll go ahead and close the socket
# like we would in a subclassed handle_read() that received no
# data
self.handle_close()
else:
self.handle_expt()
def handle_error(self):
nil, 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.handle_close()
def handle_expt(self):
self.log_info('unhandled incoming priority event', '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, map=None):
dispatcher.__init__(self, sock, map)
self.out_buffer = b''
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 = []
if not tb: # Must have a traceback
raise AssertionError("traceback does not exist")
while tb:
tbinfo.append((
tb.tb_frame.f_code.co_filename,
tb.tb_frame.f_code.co_name,
str(tb.tb_lineno)
))
tb = tb.tb_next
# just to be safe
del tb
file, function, line = tbinfo[-1]
info = ' '.join(['[%s|%s|%s]' % x for x in tbinfo])
return (file, function, line), t, v, info
def close_all(map=None, ignore_all=False):
if map is None:
map = socket_map
for x in list(map.values()):
try:
x.close()
except OSError as x:
if x.args[0] == EBADF:
pass
elif not ignore_all:
raise
except _reraised_exceptions:
raise
except:
if not ignore_all:
raise
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 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...
if os.name == 'posix':
import fcntl
class file_wrapper:
# Here we override just enough to make a file
# look like a socket for the purposes of asyncore.
# The passed fd is automatically os.dup()'d
def __init__(self, fd):
self.fd = os.dup(fd)
def recv(self, *args):
return os.read(self.fd, *args)
def send(self, *args):
return os.write(self.fd, *args)
read = recv
write = send
def close(self):
os.close(self.fd)
def fileno(self):
return self.fd
class file_dispatcher(dispatcher):
def __init__(self, fd, map=None):
dispatcher.__init__(self, None, map)
self.connected = True
try:
fd = fd.fileno()
except AttributeError:
pass
self.set_file(fd)
# set it to non-blocking mode
flags = fcntl.fcntl(fd, fcntl.F_GETFL, 0)
flags = flags | os.O_NONBLOCK
fcntl.fcntl(fd, fcntl.F_SETFL, flags)
def set_file(self, fd):
self.socket = file_wrapper(fd)
self._fileno = self.socket.fileno()
self.add_channel()