Source

cpython / Lib / asyncore.py

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
# -*- 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 exceptions
import select
import socket
import sys
import time

import os
from errno import EALREADY, EINPROGRESS, EWOULDBLOCK, ECONNRESET, \
     ENOTCONN, ESHUTDOWN, EINTR, EISCONN, errorcode

try:
    socket_map
except NameError:
    socket_map = {}

class ExitNow(exceptions.Exception):
    pass

def read(obj):
    try:
        obj.handle_read_event()
    except ExitNow:
        raise
    except:
        obj.handle_error()

def write(obj):
    try:
        obj.handle_write_event()
    except ExitNow:
        raise
    except:
        obj.handle_error()

def _exception (obj):
    try:
        obj.handle_expt_event()
    except ExitNow:
        raise
    except:
        obj.handle_error()

def readwrite(obj, flags):
    try:
        if flags & (select.POLLIN | select.POLLPRI):
            obj.handle_read_event()
        if flags & select.POLLOUT:
            obj.handle_write_event()
        if flags & (select.POLLERR | select.POLLHUP | select.POLLNVAL):
            obj.handle_expt_event()
    except ExitNow:
        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)
            if is_w:
                w.append(fd)
            if is_r or is_w:
                e.append(fd)
        if [] == r == w == e:
            time.sleep(timeout)
        else:
            try:
                r, w, e = select.select(r, w, e, timeout)
            except select.error, err:
                if err[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
            if obj.writable():
                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[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
    closing = False
    addr = None

    def __init__(self, sock=None, map=None):
        if map is None:
            self._map = socket_map
        else:
            self._map = map

        if sock:
            self.set_socket(sock, map)
            # I think it should inherit this anyway
            self.socket.setblocking(0)
            self.connected = True
            # XXX Does the constructor require that the socket passed
            # be connected?
            try:
                self.addr = sock.getpeername()
            except socket.error:
                # The addr isn't crucial
                pass
        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))

    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 map.has_key(fd):
            #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
        self.socket = socket.socket(family, type)
        self.socket.setblocking(0)
        self._fileno = self.socket.fileno()
        self.add_channel()

    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 = 1
        return self.socket.listen(num)

    def bind(self, addr):
        self.addr = addr
        return self.socket.bind(addr)

    def connect(self, address):
        self.connected = False
        err = self.socket.connect_ex(address)
        # XXX Should interpret Winsock return values
        if err in (EINPROGRESS, EALREADY, EWOULDBLOCK):
            return
        if err in (0, EISCONN):
            self.addr = address
            self.connected = True
            self.handle_connect()
        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()
            return conn, addr
        except socket.error, why:
            if why[0] == EWOULDBLOCK:
                pass
            else:
                raise

    def send(self, data):
        try:
            result = self.socket.send(data)
            return result
        except socket.error, why:
            if why[0] == EWOULDBLOCK:
                return 0
            else:
                raise
            return 0

    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 throws ENOTCONN
            if why[0] in [ECONNRESET, ENOTCONN, ESHUTDOWN]:
                self.handle_close()
                return ''
            else:
                raise

    def close(self):
        self.del_channel()
        self.socket.close()

    # cheap inheritance, used to pass all other attribute
    # references to the underlying socket object.
    def __getattr__(self, attr):
        return getattr(self.socket, attr)

    # 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 __debug__ or type != 'info':
            print '%s: %s' % (type, message)

    def handle_read_event(self):
        if self.accepting:
            # for an accepting socket, getting a read implies
            # that we are connected
            if not self.connected:
                self.connected = True
            self.handle_accept()
        elif not self.connected:
            self.handle_connect()
            self.connected = True
            self.handle_read()
        else:
            self.handle_read()

    def handle_write_event(self):
        # getting a write implies that we are connected
        if not self.connected:
            self.handle_connect()
            self.connected = True
        self.handle_write()

    def handle_expt_event(self):
        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.close()

    def handle_expt(self):
        self.log_info('unhandled exception', '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 = []
    assert tb # Must have a traceback
    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):
    if map is None:
        map = socket_map
    for x in map.values():
        x.socket.close()
    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.

        def __init__(self, fd):
            self.fd = fd

        def recv(self, *args):
            return os.read(self.fd, *args)

        def send(self, *args):
            return os.write(self.fd, *args)

        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
            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._fileno = fd
            self.socket = file_wrapper(fd)
            self.add_channel()
Tip: Filter by directory path e.g. /media app.js to search for public/media/app.js.
Tip: Use camelCasing e.g. ProjME to search for ProjectModifiedEvent.java.
Tip: Filter by extension type e.g. /repo .js to search for all .js files in the /repo directory.
Tip: Separate your search with spaces e.g. /ssh pom.xml to search for src/ssh/pom.xml.
Tip: Use ↑ and ↓ arrow keys to navigate and return to view the file.
Tip: You can also navigate files with Ctrl+j (next) and Ctrl+k (previous) and view the file with Ctrl+o.
Tip: You can also navigate files with Alt+j (next) and Alt+k (previous) and view the file with Alt+o.