diff options
Diffstat (limited to 'Lib/asynchat.py')
| -rw-r--r-- | Lib/asynchat.py | 315 |
1 files changed, 315 insertions, 0 deletions
diff --git a/Lib/asynchat.py b/Lib/asynchat.py new file mode 100644 index 0000000..de26ffa --- /dev/null +++ b/Lib/asynchat.py @@ -0,0 +1,315 @@ +# -*- Mode: Python; tab-width: 4 -*- +# Id: asynchat.py,v 2.26 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. +# ====================================================================== + +r"""A class supporting chat-style (command/response) protocols. + +This class adds support for 'chat' style protocols - where one side +sends a 'command', and the other sends a response (examples would be +the common internet protocols - smtp, nntp, ftp, etc..). + +The handle_read() method looks at the input stream for the current +'terminator' (usually '\r\n' for single-line responses, '\r\n.\r\n' +for multi-line output), calling self.found_terminator() on its +receipt. + +for example: +Say you build an async nntp client using this class. At the start +of the connection, you'll have self.terminator set to '\r\n', in +order to process the single-line greeting. Just before issuing a +'LIST' command you'll set it to '\r\n.\r\n'. The output of the LIST +command will be accumulated (using your own 'collect_incoming_data' +method) up to the terminator, and then control will be returned to +you - by calling your self.found_terminator() method. +""" +import asyncore +from collections import deque + +from warnings import warn +warn( + 'The asynchat module is deprecated. ' + 'The recommended replacement is asyncio', + DeprecationWarning, + stacklevel=2) + + + +class async_chat(asyncore.dispatcher): + """This is an abstract class. You must derive from this class, and add + the two methods collect_incoming_data() and found_terminator()""" + + # these are overridable defaults + + ac_in_buffer_size = 65536 + ac_out_buffer_size = 65536 + + # we don't want to enable the use of encoding by default, because that is a + # sign of an application bug that we don't want to pass silently + + use_encoding = 0 + encoding = 'latin-1' + + def __init__(self, sock=None, map=None): + # for string terminator matching + self.ac_in_buffer = b'' + + # we use a list here rather than io.BytesIO for a few reasons... + # del lst[:] is faster than bio.truncate(0) + # lst = [] is faster than bio.truncate(0) + self.incoming = [] + + # we toss the use of the "simple producer" and replace it with + # a pure deque, which the original fifo was a wrapping of + self.producer_fifo = deque() + asyncore.dispatcher.__init__(self, sock, map) + + def collect_incoming_data(self, data): + raise NotImplementedError("must be implemented in subclass") + + def _collect_incoming_data(self, data): + self.incoming.append(data) + + def _get_data(self): + d = b''.join(self.incoming) + del self.incoming[:] + return d + + def found_terminator(self): + raise NotImplementedError("must be implemented in subclass") + + def set_terminator(self, term): + """Set the input delimiter. + + Can be a fixed string of any length, an integer, or None. + """ + if isinstance(term, str) and self.use_encoding: + term = bytes(term, self.encoding) + elif isinstance(term, int) and term < 0: + raise ValueError('the number of received bytes must be positive') + self.terminator = term + + def get_terminator(self): + return self.terminator + + # grab some more data from the socket, + # throw it to the collector method, + # check for the terminator, + # if found, transition to the next state. + + def handle_read(self): + + try: + data = self.recv(self.ac_in_buffer_size) + except BlockingIOError: + return + except OSError: + self.handle_error() + return + + if isinstance(data, str) and self.use_encoding: + data = bytes(str, self.encoding) + self.ac_in_buffer = self.ac_in_buffer + data + + # Continue to search for self.terminator in self.ac_in_buffer, + # while calling self.collect_incoming_data. The while loop + # is necessary because we might read several data+terminator + # combos with a single recv(4096). + + while self.ac_in_buffer: + lb = len(self.ac_in_buffer) + terminator = self.get_terminator() + if not terminator: + # no terminator, collect it all + self.collect_incoming_data(self.ac_in_buffer) + self.ac_in_buffer = b'' + elif isinstance(terminator, int): + # numeric terminator + n = terminator + if lb < n: + self.collect_incoming_data(self.ac_in_buffer) + self.ac_in_buffer = b'' + self.terminator = self.terminator - lb + else: + self.collect_incoming_data(self.ac_in_buffer[:n]) + self.ac_in_buffer = self.ac_in_buffer[n:] + self.terminator = 0 + self.found_terminator() + else: + # 3 cases: + # 1) end of buffer matches terminator exactly: + # collect data, transition + # 2) end of buffer matches some prefix: + # collect data to the prefix + # 3) end of buffer does not match any prefix: + # collect data + terminator_len = len(terminator) + index = self.ac_in_buffer.find(terminator) + if index != -1: + # we found the terminator + if index > 0: + # don't bother reporting the empty string + # (source of subtle bugs) + self.collect_incoming_data(self.ac_in_buffer[:index]) + self.ac_in_buffer = self.ac_in_buffer[index+terminator_len:] + # This does the Right Thing if the terminator + # is changed here. + self.found_terminator() + else: + # check for a prefix of the terminator + index = find_prefix_at_end(self.ac_in_buffer, terminator) + if index: + if index != lb: + # we found a prefix, collect up to the prefix + self.collect_incoming_data(self.ac_in_buffer[:-index]) + self.ac_in_buffer = self.ac_in_buffer[-index:] + break + else: + # no prefix, collect it all + self.collect_incoming_data(self.ac_in_buffer) + self.ac_in_buffer = b'' + + def handle_write(self): + self.initiate_send() + + def handle_close(self): + self.close() + + def push(self, data): + if not isinstance(data, (bytes, bytearray, memoryview)): + raise TypeError('data argument must be byte-ish (%r)', + type(data)) + sabs = self.ac_out_buffer_size + if len(data) > sabs: + for i in range(0, len(data), sabs): + self.producer_fifo.append(data[i:i+sabs]) + else: + self.producer_fifo.append(data) + self.initiate_send() + + def push_with_producer(self, producer): + self.producer_fifo.append(producer) + self.initiate_send() + + def readable(self): + "predicate for inclusion in the readable for select()" + # cannot use the old predicate, it violates the claim of the + # set_terminator method. + + # return (len(self.ac_in_buffer) <= self.ac_in_buffer_size) + return 1 + + def writable(self): + "predicate for inclusion in the writable for select()" + return self.producer_fifo or (not self.connected) + + def close_when_done(self): + "automatically close this channel once the outgoing queue is empty" + self.producer_fifo.append(None) + + def initiate_send(self): + while self.producer_fifo and self.connected: + first = self.producer_fifo[0] + # handle empty string/buffer or None entry + if not first: + del self.producer_fifo[0] + if first is None: + self.handle_close() + return + + # handle classic producer behavior + obs = self.ac_out_buffer_size + try: + data = first[:obs] + except TypeError: + data = first.more() + if data: + self.producer_fifo.appendleft(data) + else: + del self.producer_fifo[0] + continue + + if isinstance(data, str) and self.use_encoding: + data = bytes(data, self.encoding) + + # send the data + try: + num_sent = self.send(data) + except OSError: + self.handle_error() + return + + if num_sent: + if num_sent < len(data) or obs < len(first): + self.producer_fifo[0] = first[num_sent:] + else: + del self.producer_fifo[0] + # we tried to send some actual data + return + + def discard_buffers(self): + # Emergencies only! + self.ac_in_buffer = b'' + del self.incoming[:] + self.producer_fifo.clear() + + +class simple_producer: + + def __init__(self, data, buffer_size=512): + self.data = data + self.buffer_size = buffer_size + + def more(self): + if len(self.data) > self.buffer_size: + result = self.data[:self.buffer_size] + self.data = self.data[self.buffer_size:] + return result + else: + result = self.data + self.data = b'' + return result + + +# Given 'haystack', see if any prefix of 'needle' is at its end. This +# assumes an exact match has already been checked. Return the number of +# characters matched. +# for example: +# f_p_a_e("qwerty\r", "\r\n") => 1 +# f_p_a_e("qwertydkjf", "\r\n") => 0 +# f_p_a_e("qwerty\r\n", "\r\n") => <undefined> + +# this could maybe be made faster with a computed regex? +# [answer: no; circa Python-2.0, Jan 2001] +# new python: 28961/s +# old python: 18307/s +# re: 12820/s +# regex: 14035/s + +def find_prefix_at_end(haystack, needle): + l = len(needle) - 1 + while l and not haystack.endswith(needle[:l]): + l -= 1 + return l |