Tor Norbye | 3a2425a5 | 2013-11-04 10:16:08 -0800 | [diff] [blame] | 1 | # -*- Mode: Python; tab-width: 4 -*- |
| 2 | # Id: asynchat.py,v 2.26 2000/09/07 22:29:26 rushing Exp |
| 3 | # Author: Sam Rushing <rushing@nightmare.com> |
| 4 | |
| 5 | # ====================================================================== |
| 6 | # Copyright 1996 by Sam Rushing |
| 7 | # |
| 8 | # All Rights Reserved |
| 9 | # |
| 10 | # Permission to use, copy, modify, and distribute this software and |
| 11 | # its documentation for any purpose and without fee is hereby |
| 12 | # granted, provided that the above copyright notice appear in all |
| 13 | # copies and that both that copyright notice and this permission |
| 14 | # notice appear in supporting documentation, and that the name of Sam |
| 15 | # Rushing not be used in advertising or publicity pertaining to |
| 16 | # distribution of the software without specific, written prior |
| 17 | # permission. |
| 18 | # |
| 19 | # SAM RUSHING DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, |
| 20 | # INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN |
| 21 | # NO EVENT SHALL SAM RUSHING BE LIABLE FOR ANY SPECIAL, INDIRECT OR |
| 22 | # CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS |
| 23 | # OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, |
| 24 | # NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
| 25 | # CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| 26 | # ====================================================================== |
| 27 | |
| 28 | r"""A class supporting chat-style (command/response) protocols. |
| 29 | |
| 30 | This class adds support for 'chat' style protocols - where one side |
| 31 | sends a 'command', and the other sends a response (examples would be |
| 32 | the common internet protocols - smtp, nntp, ftp, etc..). |
| 33 | |
| 34 | The handle_read() method looks at the input stream for the current |
| 35 | 'terminator' (usually '\r\n' for single-line responses, '\r\n.\r\n' |
| 36 | for multi-line output), calling self.found_terminator() on its |
| 37 | receipt. |
| 38 | |
| 39 | for example: |
| 40 | Say you build an async nntp client using this class. At the start |
| 41 | of the connection, you'll have self.terminator set to '\r\n', in |
| 42 | order to process the single-line greeting. Just before issuing a |
| 43 | 'LIST' command you'll set it to '\r\n.\r\n'. The output of the LIST |
| 44 | command will be accumulated (using your own 'collect_incoming_data' |
| 45 | method) up to the terminator, and then control will be returned to |
| 46 | you - by calling your self.found_terminator() method. |
| 47 | """ |
| 48 | |
| 49 | import socket |
| 50 | import asyncore |
| 51 | from collections import deque |
| 52 | |
| 53 | class async_chat (asyncore.dispatcher): |
| 54 | """This is an abstract class. You must derive from this class, and add |
| 55 | the two methods collect_incoming_data() and found_terminator()""" |
| 56 | |
| 57 | # these are overridable defaults |
| 58 | |
| 59 | ac_in_buffer_size = 4096 |
| 60 | ac_out_buffer_size = 4096 |
| 61 | |
| 62 | def __init__ (self, conn=None): |
| 63 | self.ac_in_buffer = '' |
| 64 | self.ac_out_buffer = '' |
| 65 | self.producer_fifo = fifo() |
| 66 | asyncore.dispatcher.__init__ (self, conn) |
| 67 | |
| 68 | def collect_incoming_data(self, data): |
| 69 | raise NotImplementedError, "must be implemented in subclass" |
| 70 | |
| 71 | def found_terminator(self): |
| 72 | raise NotImplementedError, "must be implemented in subclass" |
| 73 | |
| 74 | def set_terminator (self, term): |
| 75 | "Set the input delimiter. Can be a fixed string of any length, an integer, or None" |
| 76 | self.terminator = term |
| 77 | |
| 78 | def get_terminator (self): |
| 79 | return self.terminator |
| 80 | |
| 81 | # grab some more data from the socket, |
| 82 | # throw it to the collector method, |
| 83 | # check for the terminator, |
| 84 | # if found, transition to the next state. |
| 85 | |
| 86 | def handle_read (self): |
| 87 | |
| 88 | try: |
| 89 | data = self.recv (self.ac_in_buffer_size) |
| 90 | except socket.error, why: |
| 91 | self.handle_error() |
| 92 | return |
| 93 | |
| 94 | self.ac_in_buffer = self.ac_in_buffer + data |
| 95 | |
| 96 | # Continue to search for self.terminator in self.ac_in_buffer, |
| 97 | # while calling self.collect_incoming_data. The while loop |
| 98 | # is necessary because we might read several data+terminator |
| 99 | # combos with a single recv(1024). |
| 100 | |
| 101 | while self.ac_in_buffer: |
| 102 | lb = len(self.ac_in_buffer) |
| 103 | terminator = self.get_terminator() |
| 104 | if not terminator: |
| 105 | # no terminator, collect it all |
| 106 | self.collect_incoming_data (self.ac_in_buffer) |
| 107 | self.ac_in_buffer = '' |
| 108 | elif isinstance(terminator, int) or isinstance(terminator, long): |
| 109 | # numeric terminator |
| 110 | n = terminator |
| 111 | if lb < n: |
| 112 | self.collect_incoming_data (self.ac_in_buffer) |
| 113 | self.ac_in_buffer = '' |
| 114 | self.terminator = self.terminator - lb |
| 115 | else: |
| 116 | self.collect_incoming_data (self.ac_in_buffer[:n]) |
| 117 | self.ac_in_buffer = self.ac_in_buffer[n:] |
| 118 | self.terminator = 0 |
| 119 | self.found_terminator() |
| 120 | else: |
| 121 | # 3 cases: |
| 122 | # 1) end of buffer matches terminator exactly: |
| 123 | # collect data, transition |
| 124 | # 2) end of buffer matches some prefix: |
| 125 | # collect data to the prefix |
| 126 | # 3) end of buffer does not match any prefix: |
| 127 | # collect data |
| 128 | terminator_len = len(terminator) |
| 129 | index = self.ac_in_buffer.find(terminator) |
| 130 | if index != -1: |
| 131 | # we found the terminator |
| 132 | if index > 0: |
| 133 | # don't bother reporting the empty string (source of subtle bugs) |
| 134 | self.collect_incoming_data (self.ac_in_buffer[:index]) |
| 135 | self.ac_in_buffer = self.ac_in_buffer[index+terminator_len:] |
| 136 | # This does the Right Thing if the terminator is changed here. |
| 137 | self.found_terminator() |
| 138 | else: |
| 139 | # check for a prefix of the terminator |
| 140 | index = find_prefix_at_end (self.ac_in_buffer, terminator) |
| 141 | if index: |
| 142 | if index != lb: |
| 143 | # we found a prefix, collect up to the prefix |
| 144 | self.collect_incoming_data (self.ac_in_buffer[:-index]) |
| 145 | self.ac_in_buffer = self.ac_in_buffer[-index:] |
| 146 | break |
| 147 | else: |
| 148 | # no prefix, collect it all |
| 149 | self.collect_incoming_data (self.ac_in_buffer) |
| 150 | self.ac_in_buffer = '' |
| 151 | |
| 152 | def handle_write (self): |
| 153 | self.initiate_send () |
| 154 | |
| 155 | def handle_close (self): |
| 156 | self.close() |
| 157 | |
| 158 | def push (self, data): |
| 159 | self.producer_fifo.push (simple_producer (data)) |
| 160 | self.initiate_send() |
| 161 | |
| 162 | def push_with_producer (self, producer): |
| 163 | self.producer_fifo.push (producer) |
| 164 | self.initiate_send() |
| 165 | |
| 166 | def readable (self): |
| 167 | "predicate for inclusion in the readable for select()" |
| 168 | return (len(self.ac_in_buffer) <= self.ac_in_buffer_size) |
| 169 | |
| 170 | def writable (self): |
| 171 | "predicate for inclusion in the writable for select()" |
| 172 | # return len(self.ac_out_buffer) or len(self.producer_fifo) or (not self.connected) |
| 173 | # this is about twice as fast, though not as clear. |
| 174 | return not ( |
| 175 | (self.ac_out_buffer == '') and |
| 176 | self.producer_fifo.is_empty() and |
| 177 | self.connected |
| 178 | ) |
| 179 | |
| 180 | def close_when_done (self): |
| 181 | "automatically close this channel once the outgoing queue is empty" |
| 182 | self.producer_fifo.push (None) |
| 183 | |
| 184 | # refill the outgoing buffer by calling the more() method |
| 185 | # of the first producer in the queue |
| 186 | def refill_buffer (self): |
| 187 | while 1: |
| 188 | if len(self.producer_fifo): |
| 189 | p = self.producer_fifo.first() |
| 190 | # a 'None' in the producer fifo is a sentinel, |
| 191 | # telling us to close the channel. |
| 192 | if p is None: |
| 193 | if not self.ac_out_buffer: |
| 194 | self.producer_fifo.pop() |
| 195 | self.close() |
| 196 | return |
| 197 | elif isinstance(p, str): |
| 198 | self.producer_fifo.pop() |
| 199 | self.ac_out_buffer = self.ac_out_buffer + p |
| 200 | return |
| 201 | data = p.more() |
| 202 | if data: |
| 203 | self.ac_out_buffer = self.ac_out_buffer + data |
| 204 | return |
| 205 | else: |
| 206 | self.producer_fifo.pop() |
| 207 | else: |
| 208 | return |
| 209 | |
| 210 | def initiate_send (self): |
| 211 | obs = self.ac_out_buffer_size |
| 212 | # try to refill the buffer |
| 213 | if (len (self.ac_out_buffer) < obs): |
| 214 | self.refill_buffer() |
| 215 | |
| 216 | if self.ac_out_buffer and self.connected: |
| 217 | # try to send the buffer |
| 218 | try: |
| 219 | num_sent = self.send (self.ac_out_buffer[:obs]) |
| 220 | if num_sent: |
| 221 | self.ac_out_buffer = self.ac_out_buffer[num_sent:] |
| 222 | |
| 223 | except socket.error, why: |
| 224 | self.handle_error() |
| 225 | return |
| 226 | |
| 227 | def discard_buffers (self): |
| 228 | # Emergencies only! |
| 229 | self.ac_in_buffer = '' |
| 230 | self.ac_out_buffer = '' |
| 231 | while self.producer_fifo: |
| 232 | self.producer_fifo.pop() |
| 233 | |
| 234 | |
| 235 | class simple_producer: |
| 236 | |
| 237 | def __init__ (self, data, buffer_size=512): |
| 238 | self.data = data |
| 239 | self.buffer_size = buffer_size |
| 240 | |
| 241 | def more (self): |
| 242 | if len (self.data) > self.buffer_size: |
| 243 | result = self.data[:self.buffer_size] |
| 244 | self.data = self.data[self.buffer_size:] |
| 245 | return result |
| 246 | else: |
| 247 | result = self.data |
| 248 | self.data = '' |
| 249 | return result |
| 250 | |
| 251 | class fifo: |
| 252 | def __init__ (self, list=None): |
| 253 | if not list: |
| 254 | self.list = deque() |
| 255 | else: |
| 256 | self.list = deque(list) |
| 257 | |
| 258 | def __len__ (self): |
| 259 | return len(self.list) |
| 260 | |
| 261 | def is_empty (self): |
| 262 | return not self.list |
| 263 | |
| 264 | def first (self): |
| 265 | return self.list[0] |
| 266 | |
| 267 | def push (self, data): |
| 268 | self.list.append(data) |
| 269 | |
| 270 | def pop (self): |
| 271 | if self.list: |
| 272 | return (1, self.list.popleft()) |
| 273 | else: |
| 274 | return (0, None) |
| 275 | |
| 276 | # Given 'haystack', see if any prefix of 'needle' is at its end. This |
| 277 | # assumes an exact match has already been checked. Return the number of |
| 278 | # characters matched. |
| 279 | # for example: |
| 280 | # f_p_a_e ("qwerty\r", "\r\n") => 1 |
| 281 | # f_p_a_e ("qwertydkjf", "\r\n") => 0 |
| 282 | # f_p_a_e ("qwerty\r\n", "\r\n") => <undefined> |
| 283 | |
| 284 | # this could maybe be made faster with a computed regex? |
| 285 | # [answer: no; circa Python-2.0, Jan 2001] |
| 286 | # new python: 28961/s |
| 287 | # old python: 18307/s |
| 288 | # re: 12820/s |
| 289 | # regex: 14035/s |
| 290 | |
| 291 | def find_prefix_at_end (haystack, needle): |
| 292 | l = len(needle) - 1 |
| 293 | while l and not haystack.endswith(needle[:l]): |
| 294 | l -= 1 |
| 295 | return l |