Edit File: 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 warnings import os from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, EINVAL, \ ENOTCONN, ESHUTDOWN, EINTR, 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 socket.error, 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 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 try: r, w, e = select.select(r, w, e, timeout) except select.error, 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 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: # 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, 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 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 socket.error, 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__.__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)) __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, 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 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 socket.error(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 socket.error 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 socket.error, 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 '' else: return data except socket.error, why: # winsock sometimes raises ENOTCONN if why.args[0] in _DISCONNECTED: self.handle_close() return '' else: raise def close(self): self.connected = False self.accepting = False self.connecting = False self.del_channel() try: self.socket.close() except socket.error, 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): try: retattr = getattr(self.socket, attr) except AttributeError: raise AttributeError("%s instance has no attribute '%s'" %(self.__class__.__name__, attr)) else: msg = "%(me)s.%(attr)s is deprecated. Use %(me)s.socket.%(attr)s " \ "instead." % {'me': self.__class__.__name__, 'attr':attr} warnings.warn(msg, DeprecationWarning, stacklevel=2) return retattr # 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 socket.error(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, 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 = '' 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 map.values(): try: x.close() except OSError, 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) 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 fd = self.fd self.fd = -1 os.close(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()