# -*- Mode: Python -*- # Id: asyncore.py,v 2.51 2000/09/07 22:29:26 rushing Exp # Author: Sam Rushing # ====================================================================== # 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. """ # randomise object order for bandwidth balancing import random 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, \ ECONNREFUSED, EHOSTUNREACH, \ errorcode try: from errno import WSAEWOULDBLOCK except: pass from ssl import SSLError, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE _DISCONNECTED = frozenset((ECONNRESET, ENOTCONN, ESHUTDOWN, ECONNABORTED, EPIPE, EBADF, ECONNREFUSED, EHOSTUNREACH)) OP_READ = 1 OP_WRITE = 2 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) maxDownloadRate = 0 downloadTimestamp = 0 downloadBucket = 0 receivedBytes = 0 maxUploadRate = 0 uploadTimestamp = 0 uploadBucket = 0 sentBytes = 0 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 set_rates(download, upload): global maxDownloadRate, maxUploadRate, downloadBucket, uploadBucket, downloadTimestamp, uploadTimestamp maxDownloadRate = float(download) maxUploadRate = float(upload) downloadBucket = maxDownloadRate uploadBucket = maxUploadRate downloadTimestamp = time.time() uploadTimestamp = time.time() def update_received(download=0): global receivedBytes, maxDownloadRate, downloadBucket, downloadTimestamp currentTimestamp = time.time() receivedBytes += download if maxDownloadRate > 0: bucketIncrease = int(maxDownloadRate * (currentTimestamp - downloadTimestamp)) downloadBucket += bucketIncrease if downloadBucket > maxDownloadRate: downloadBucket = int(maxDownloadRate) downloadBucket -= download downloadTimestamp = currentTimestamp def update_sent(upload=0): global sentBytes, maxUploadRate, uploadBucket, uploadTimestamp currentTimestamp = time.time() sentBytes += upload if maxUploadRate > 0: bucketIncrease = int(maxUploadRate * (currentTimestamp - uploadTimestamp)) uploadBucket += bucketIncrease if uploadBucket > maxUploadRate: uploadBucket = int(maxUploadRate) uploadBucket -= upload uploadTimestamp = currentTimestamp 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 _DISCONNECTED: obj.handle_error() else: obj.handle_close() except _reraised_exceptions: raise except: obj.handle_error() def select_poller(timeout=0.0, map=None): """A poller which uses select(), available on most platforms.""" 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 try: r, w, e = select.select(r, w, e, timeout) except KeyboardInterrupt: return for fd in random.sample(r, len(r)): obj = map.get(fd) if obj is None: continue read(obj) for fd in random.sample(w, len(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 poll_poller(timeout=0.0, map=None): """A poller which uses poll(), available on most UNIXen.""" if map is None: map = socket_map if timeout is not None: # timeout is in milliseconds timeout = int(timeout*1000) try: poll_poller.pollster except AttributeError: poll_poller.pollster = select.poll() if map: for fd, obj in list(map.items()): flags = newflags = 0 if obj.readable(): flags |= select.POLLIN | select.POLLPRI newflags |= OP_READ else: newflags &= ~ OP_READ # accepting sockets should not be writable if obj.writable() and not obj.accepting: flags |= select.POLLOUT newflags |= OP_WRITE else: newflags &= ~ OP_WRITE if newflags != obj.flags: obj.flags = newflags if obj.poller_registered: poll_poller.pollster.modify(fd, flags) else: poll_poller.pollster.register(fd, flags) obj.poller_registered = True try: r = poll_poller.pollster.poll(timeout) except KeyboardInterrupt: r = [] for fd, flags in random.sample(r, len(r)): obj = map.get(fd) if obj is None: continue readwrite(obj, flags) # Aliases for backward compatibility poll = select_poller poll2 = poll3 = poll_poller def epoll_poller(timeout=0.0, map=None): """A poller which uses epoll(), supported on Linux 2.5.44 and newer.""" if map is None: map = socket_map try: epoll_poller.pollster except AttributeError: epoll_poller.pollster = select.epoll() if map: for fd, obj in map.items(): flags = newflags = 0 if obj.readable(): flags |= select.POLLIN | select.POLLPRI newflags |= OP_READ else: newflags &= ~ OP_READ # accepting sockets should not be writable if obj.writable() and not obj.accepting: flags |= select.POLLOUT newflags |= OP_WRITE else: newflags &= ~ OP_WRITE if newflags != obj.flags: obj.flags = newflags # Only check for exceptions if object was either readable # or writable. flags |= select.POLLERR | select.POLLHUP | select.POLLNVAL if obj.poller_registered: epoll_poller.pollster.modify(fd, flags) else: epoll_poller.pollster.register(fd, flags) obj.poller_registered = True try: r = epoll_poller.pollster.poll(timeout) except select.error, err: if err.args[0] != EINTR: raise r = [] for fd, flags in random.sample(r, len(r)): obj = map.get(fd) if obj is None: continue readwrite(obj, flags) def kqueue_poller(timeout=0.0, map=None): """A poller which uses kqueue(), BSD specific.""" if map is None: map = socket_map if map: kqueue = select.kqueue() flags = select.KQ_EV_ADD | select.KQ_EV_ENABLE selectables = 0 for fd, obj in map.items(): filter = 0 if obj.readable(): filter |= select.KQ_FILTER_READ if obj.writable(): filter |= select.KQ_FILTER_WRITE if filter: ev = select.kevent(fd, filter=filter, flags=flags) kqueue.control([ev], 0) selectables += 1 events = kqueue.control(None, selectables, timeout) for event in random.sample(events, len(events)): fd = event.ident obj = map.get(fd) if obj is None: continue if event.filter == select.KQ_FILTER_READ: read(obj) if event.filter == select.KQ_FILTER_WRITE: write(obj) kqueue.close() def loop(timeout=30.0, use_poll=False, map=None, count=None, poller=select_poller): if map is None: map = socket_map # code which grants backward compatibility with "use_poll" # argument which should no longer be used in favor of # "poller" if hasattr(select, 'epoll'): poller = epoll_poller elif hasattr(select, 'kqueue'): poller = kqueue_poller elif hasattr(select, 'poll'): poller = poll_poller elif hasattr(select, 'select'): poller = select_poller poller = select_poller # print "Poll loop using %s" % (poller.__name__) if count is None: while map: # fill buckets first update_sent() update_received() # then poll poller(timeout, map) else: timeout /= count while map and count > 0: # fill buckets first update_sent() update_received() poller(timeout, map) # then poll count = count - 1 class dispatcher: debug = False connected = False accepting = False connecting = False closing = False addr = None ignore_log_types = frozenset(['warning']) poller_registered = False flags = 0 # don't do network IO with a smaller bucket than this minTx = 1500 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] 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 try: epoll_poller.pollster.unregister(fd) except (AttributeError, KeyError, TypeError): # no epoll used, or not registered pass try: poll_poller.pollster.unregister(fd) except (AttributeError, KeyError, TypeError): # no poll used, or not registered pass 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 socket.error: pass # ================================================== # predicates for select() # these are used as filters for the lists of sockets # to pass to select(). # ================================================== def readable(self): if maxDownloadRate > 0: return downloadBucket > dispatcher.minTx return True def writable(self): if maxUploadRate > 0: return uploadBucket > dispatcher.minTx 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, ENOTCONN): return None else: raise else: return conn, addr def send(self, data): try: result = self.socket.send(data) return result except SSLError as err: if err.errno == SSL_ERROR_WANT_WRITE: return 0 else: raise except socket.error as why: if why.args[0] in (EAGAIN, EWOULDBLOCK) or \ (sys.platform.startswith('win') and \ err.errno == WSAEWOULDBLOCK): 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 SSLError as err: if err.errno == SSL_ERROR_WANT_READ: return b'' else: raise except socket.error as why: # winsock sometimes raises ENOTCONN if why.args[0] in (EAGAIN, EWOULDBLOCK) or \ (sys.platform.startswith('win') and \ err.errno == WSAEWOULDBLOCK): return b'' 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() 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): 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): 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[: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) 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): 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()