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
|
# Copyright (C) 2008 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
import collections
from cStringIO import StringIO
from bzrlib import (
debug,
errors,
)
from bzrlib.trace import mutter
class MessageHandler(object):
"""Base class for handling messages received via the smart protocol.
As parts of a message are received, the corresponding PART_received method
will be called.
"""
def __init__(self):
self.headers = None
def headers_received(self, headers):
"""Called when message headers are received.
This default implementation just stores them in self.headers.
"""
self.headers = headers
def byte_part_received(self, byte):
"""Called when a 'byte' part is received.
Note that a 'byte' part is a message part consisting of exactly one
byte.
"""
raise NotImplementedError(self.byte_received)
def bytes_part_received(self, bytes):
"""Called when a 'bytes' part is received.
A 'bytes' message part can contain any number of bytes. It should not
be confused with a 'byte' part, which is always a single byte.
"""
raise NotImplementedError(self.bytes_received)
def structure_part_received(self, structure):
"""Called when a 'structure' part is received.
:param structure: some structured data, which will be some combination
of list, dict, int, and str objects.
"""
raise NotImplementedError(self.bytes_received)
def protocol_error(self, exception):
"""Called when there is a protocol decoding error.
The default implementation just re-raises the exception.
"""
raise
def end_received(self):
"""Called when the end of the message is received."""
# No-op by default.
pass
class ConventionalRequestHandler(MessageHandler):
"""A message handler for "conventional" requests.
"Conventional" is used in the sense described in
doc/developers/network-protocol.txt: a simple message with arguments and an
optional body.
Possible states:
* args: expecting args
* body: expecting body (terminated by receiving a post-body status)
* error: expecting post-body error
* end: expecting end of message
* nothing: finished
"""
def __init__(self, request_handler, responder):
MessageHandler.__init__(self)
self.request_handler = request_handler
self.responder = responder
self.expecting = 'args'
self._should_finish_body = False
self._response_sent = False
def protocol_error(self, exception):
if self.responder.response_sent:
# We can only send one response to a request, no matter how many
# errors happen while processing it.
return
self.responder.send_error(exception)
def byte_part_received(self, byte):
if self.expecting == 'body':
if byte == 'S':
# Success. Nothing more to come except the end of message.
self.expecting = 'end'
elif byte == 'E':
# Error. Expect an error structure.
self.expecting = 'error'
else:
raise errors.SmartProtocolError(
'Non-success status byte in request body: %r' % (byte,))
else:
raise errors.SmartProtocolError(
'Unexpected message part: byte(%r)' % (byte,))
def structure_part_received(self, structure):
if self.expecting == 'args':
self._args_received(structure)
elif self.expecting == 'error':
self._error_received(structure)
else:
raise errors.SmartProtocolError(
'Unexpected message part: structure(%r)' % (structure,))
def _args_received(self, args):
self.expecting = 'body'
self.request_handler.dispatch_command(args[0], args[1:])
if self.request_handler.finished_reading:
self._response_sent = True
self.responder.send_response(self.request_handler.response)
self.expecting = 'end'
def _error_received(self, error_args):
self.expecting = 'end'
self.request_handler.post_body_error_received(error_args)
def bytes_part_received(self, bytes):
if self.expecting == 'body':
self._should_finish_body = True
self.request_handler.accept_body(bytes)
else:
raise errors.SmartProtocolError(
'Unexpected message part: bytes(%r)' % (bytes,))
def end_received(self):
if self.expecting not in ['body', 'end']:
raise errors.SmartProtocolError(
'End of message received prematurely (while expecting %s)'
% (self.expecting,))
self.expecting = 'nothing'
self.request_handler.end_received()
if not self.request_handler.finished_reading:
raise errors.SmartProtocolError(
"Complete conventional request was received, but request "
"handler has not finished reading.")
if not self._response_sent:
self.responder.send_response(self.request_handler.response)
class ResponseHandler(object):
"""Abstract base class for an object that handles a smart response."""
def read_response_tuple(self, expect_body=False):
"""Reads and returns the response tuple for the current request.
:keyword expect_body: a boolean indicating if a body is expected in the
response. Some protocol versions needs this information to know
when a response is finished. If False, read_body_bytes should
*not* be called afterwards. Defaults to False.
:returns: tuple of response arguments.
"""
raise NotImplementedError(self.read_response_tuple)
def read_body_bytes(self, count=-1):
"""Read and return some bytes from the body.
:param count: if specified, read up to this many bytes. By default,
reads the entire body.
:returns: str of bytes from the response body.
"""
raise NotImplementedError(self.read_body_bytes)
def read_streamed_body(self):
"""Returns an iterable that reads and returns a series of body chunks.
"""
raise NotImplementedError(self.read_streamed_body)
def cancel_read_body(self):
"""Stop expecting a body for this response.
If expect_body was passed to read_response_tuple, this cancels that
expectation (and thus finishes reading the response, allowing a new
request to be issued). This is useful if a response turns out to be an
error rather than a normal result with a body.
"""
raise NotImplementedError(self.cancel_read_body)
class ConventionalResponseHandler(MessageHandler, ResponseHandler):
def __init__(self):
MessageHandler.__init__(self)
self.status = None
self.args = None
self._bytes_parts = collections.deque()
self._body_started = False
self._body_stream_status = None
self._body = None
self._body_error_args = None
self.finished_reading = False
def setProtoAndMediumRequest(self, protocol_decoder, medium_request):
self._protocol_decoder = protocol_decoder
self._medium_request = medium_request
def byte_part_received(self, byte):
if byte not in ['E', 'S']:
raise errors.SmartProtocolError(
'Unknown response status: %r' % (byte,))
if self._body_started:
if self._body_stream_status is not None:
raise errors.SmartProtocolError(
'Unexpected byte part received: %r' % (byte,))
self._body_stream_status = byte
else:
if self.status is not None:
raise errors.SmartProtocolError(
'Unexpected byte part received: %r' % (byte,))
self.status = byte
def bytes_part_received(self, bytes):
self._body_started = True
self._bytes_parts.append(bytes)
def structure_part_received(self, structure):
if type(structure) is not tuple:
raise errors.SmartProtocolError(
'Args structure is not a sequence: %r' % (structure,))
if not self._body_started:
if self.args is not None:
raise errors.SmartProtocolError(
'Unexpected structure received: %r (already got %r)'
% (structure, self.args))
self.args = structure
else:
if self._body_stream_status != 'E':
raise errors.SmartProtocolError(
'Unexpected structure received after body: %r'
% (structure,))
self._body_error_args = structure
def _wait_for_response_args(self):
while self.args is None and not self.finished_reading:
self._read_more()
def _wait_for_response_end(self):
while not self.finished_reading:
self._read_more()
def _read_more(self):
next_read_size = self._protocol_decoder.next_read_size()
if next_read_size == 0:
# a complete request has been read.
self.finished_reading = True
self._medium_request.finished_reading()
return
bytes = self._medium_request.read_bytes(next_read_size)
if bytes == '':
# end of file encountered reading from server
if 'hpss' in debug.debug_flags:
mutter(
'decoder state: buf[:10]=%r, state_accept=%s',
self._protocol_decoder._get_in_buffer()[:10],
self._protocol_decoder.state_accept.__name__)
raise errors.ConnectionReset(
"please check connectivity and permissions")
self._protocol_decoder.accept_bytes(bytes)
def protocol_error(self, exception):
# Whatever the error is, we're done with this request.
self.finished_reading = True
self._medium_request.finished_reading()
raise
def read_response_tuple(self, expect_body=False):
"""Read a response tuple from the wire."""
self._wait_for_response_args()
if not expect_body:
self._wait_for_response_end()
if 'hpss' in debug.debug_flags:
mutter(' result: %r', self.args)
if self.status == 'E':
self._wait_for_response_end()
_translate_error(self.args)
return tuple(self.args)
def read_body_bytes(self, count=-1):
"""Read bytes from the body, decoding into a byte stream.
We read all bytes at once to ensure we've checked the trailer for
errors, and then feed the buffer back as read_body_bytes is called.
Like the builtin file.read in Python, a count of -1 (the default) means
read the entire body.
"""
# TODO: we don't necessarily need to buffer the full request if count
# != -1. (2008/04/30, Andrew Bennetts)
if self._body is None:
self._wait_for_response_end()
body_bytes = ''.join(self._bytes_parts)
if 'hpss' in debug.debug_flags:
mutter(' %d body bytes read', len(body_bytes))
self._body = StringIO(body_bytes)
self._bytes_parts = None
return self._body.read(count)
def read_streamed_body(self):
while not self.finished_reading:
while self._bytes_parts:
bytes_part = self._bytes_parts.popleft()
if 'hpss' in debug.debug_flags:
mutter(' %d byte part read', len(bytes_part))
yield bytes_part
self._read_more()
if self._body_stream_status == 'E':
_translate_error(self._body_error_args)
def cancel_read_body(self):
self._wait_for_response_end()
def _translate_error(error_tuple):
# Many exceptions need some state from the requestor to be properly
# translated (e.g. they need a branch object). So this only translates a
# few errors, and the rest are turned into a generic ErrorFromSmartServer.
error_name = error_tuple[0]
error_args = error_tuple[1:]
if error_name == 'UnknownMethod':
raise errors.UnknownSmartMethod(error_args[0])
if error_name == 'LockContention':
raise errors.LockContention('(remote lock)')
elif error_name == 'LockFailed':
raise errors.LockFailed(*error_args[:2])
elif error_name == 'FileExists':
raise errors.FileExists(error_args[0])
elif error_name == 'NoSuchFile':
raise errors.NoSuchFile(error_args[0])
else:
raise errors.ErrorFromSmartServer(error_tuple)
|