# -*- 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()
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