cpython/Lib/asyncore.py at 3.5 · python/cpython · GitHub

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# -*- Mode: Python -*-

# Id: asyncore.py,v 2.51 2000/09/07 22:29:26 rushing Exp

# Author: Sam Rushing <rushing@nightmare.com>

# ======================================================================

# 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 warnings

import os

from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, EINVAL, \

ENOTCONN, ESHUTDOWN, EISCONN, EBADF, ECONNABORTED, EPIPE, EAGAIN, \

errorcode

_DISCONNECTED = frozenset({ECONNRESET, ENOTCONN, ESHUTDOWN, ECONNABORTED, EPIPE,

EBADF})

try:

socket_map

except NameError:

socket_map = {}

def _strerror(err):

try:

return os.strerror(err)

except (ValueError, OverflowError, NameError):

if err in errorcode:

return errorcode[err]

return "Unknown error %s" %err

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 OSError as e:

if e.args[0] not in _DISCONNECTED:

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)

# accepting sockets should not be writable

if is_w and not obj.accepting:

w.append(fd)

if is_r or is_w:

e.append(fd)

if [] == r == w == e:

time.sleep(timeout)

return

r, w, e = select.select(r, w, e, timeout)

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

# accepting sockets should not be writable

if obj.writable() and not obj.accepting:

flags |= select.POLLOUT

if flags:

pollster.register(fd, flags)

r = pollster.poll(timeout)

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

connecting = 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 OSError as err:

if err.args[0] in (ENOTCONN, EINVAL):

# 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__.__qualname__]

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))

__str__ = __repr__

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=socket.AF_INET, type=socket.SOCK_STREAM):

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 OSError:

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

self.connecting = True

err = self.socket.connect_ex(address)

if err in (EINPROGRESS, EALREADY, EWOULDBLOCK) \

or err == EINVAL and os.name in ('nt', 'ce'):

self.addr = address

return

if err in (0, EISCONN):

self.addr = address

self.handle_connect_event()

else:

raise OSError(err, errorcode[err])

def accept(self):

# XXX can return either an address pair or None

try:

conn, addr = self.socket.accept()

except TypeError:

return None

except OSError as why:

if why.args[0] in (EWOULDBLOCK, ECONNABORTED, EAGAIN):

return None

else:

raise

else:

return conn, addr

def send(self, data):

try:

result = self.socket.send(data)

return result

except OSError as why:

if why.args[0] == EWOULDBLOCK:

return 0

elif why.args[0] in _DISCONNECTED:

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 OSError as why:

# winsock sometimes raises ENOTCONN

if why.args[0] in _DISCONNECTED:

self.handle_close()

return b''

else:

raise

def close(self):

self.connected = False

self.accepting = False

self.connecting = False

self.del_channel()

if self.socket is not None:

try:

self.socket.close()

except OSError as why:

if why.args[0] not in (ENOTCONN, EBADF):

raise

# 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:

if self.connecting:

self.handle_connect_event()

self.handle_read()

else:

self.handle_read()

def handle_connect_event(self):

err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)

if err != 0:

raise OSError(err, _strerror(err))

self.handle_connect()

self.connected = True

self.connecting = False

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:

if self.connecting:

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,

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):

pair = self.accept()

if pair is not None:

self.handle_accepted(*pair)

def handle_accepted(self, sock, addr):

sock.close()

self.log_info('unhandled accepted 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[:65536])

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':

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 __del__(self):

if self.fd >= 0:

warnings.warn("unclosed file %r" % self, ResourceWarning)

self.close()

def recv(self, *args):

return os.read(self.fd, *args)

def send(self, *args):

return os.write(self.fd, *args)

def getsockopt(self, level, optname, buflen=None):

if (level == socket.SOL_SOCKET and

optname == socket.SO_ERROR and

not buflen):

return 0

raise NotImplementedError("Only asyncore specific behaviour "

"implemented.")

read = recv

write = send

def close(self):

if self.fd < 0:

return

os.close(self.fd)

self.fd = -1

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

os.set_blocking(fd, False)

def set_file(self, fd):

self.socket = file_wrapper(fd)

self._fileno = self.socket.fileno()

self.add_channel()

cpython/Lib/asyncore.py at 3.5 · python/cpython · GitHub

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