root / ncclient / operations / rpc.py @ 0b7d3b31
History | View | Annotate | Download (12.7 kB)
1 |
# Copyright 2009 Shikhar Bhushan
|
---|---|
2 |
#
|
3 |
# Licensed under the Apache License, Version 2.0 (the "License");
|
4 |
# you may not use this file except in compliance with the License.
|
5 |
# You may obtain a copy of the License at
|
6 |
#
|
7 |
# http://www.apache.org/licenses/LICENSE-2.0
|
8 |
#
|
9 |
# Unless required by applicable law or agreed to in writing, software
|
10 |
# distributed under the License is distributed on an "AS IS" BASIS,
|
11 |
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
12 |
# See the License for the specific language governing permissions and
|
13 |
# limitations under the License.
|
14 |
|
15 |
from threading import Event, Lock |
16 |
from uuid import uuid1 |
17 |
from weakref import WeakValueDictionary |
18 |
|
19 |
from ncclient import content |
20 |
from ncclient.transport import SessionListener |
21 |
|
22 |
from errors import OperationError, TimeoutExpiredError, MissingCapabilityError |
23 |
|
24 |
import logging |
25 |
logger = logging.getLogger('ncclient.operations.rpc')
|
26 |
|
27 |
|
28 |
class RPCReply: |
29 |
|
30 |
"""Represents an *<rpc-reply>*. Only concerns itself with whether the
|
31 |
operation was successful.
|
32 |
|
33 |
.. note::
|
34 |
If the reply has not yet been parsed there is an implicit, one-time
|
35 |
parsing overhead to accessing the attributes defined by this class and
|
36 |
any subclasses.
|
37 |
"""
|
38 |
|
39 |
def __init__(self, raw): |
40 |
self._raw = raw
|
41 |
self._parsed = False |
42 |
self._root = None |
43 |
self._errors = []
|
44 |
|
45 |
def __repr__(self): |
46 |
return self._raw |
47 |
|
48 |
def _parsing_hook(self, root): |
49 |
"""Subclass can implement.
|
50 |
|
51 |
:type root: :class:`~xml.etree.ElementTree.Element`
|
52 |
"""
|
53 |
pass
|
54 |
|
55 |
def parse(self): |
56 |
"""Parse the *<rpc-reply>*"""
|
57 |
if self._parsed: |
58 |
return
|
59 |
root = self._root = content.xml2ele(self._raw) # <rpc-reply> element |
60 |
# per rfc 4741 an <ok/> tag is sent when there are no errors or warnings
|
61 |
ok = content.find(root, 'data', nslist=[content.BASE_NS, content.CISCO_BS])
|
62 |
if ok is not None: |
63 |
logger.debug('parsed [%s]' % ok.tag)
|
64 |
else: # create RPCError objects from <rpc-error> elements |
65 |
error = content.find(root, 'data', nslist=[content.BASE_NS, content.CISCO_BS])
|
66 |
if error is not None: |
67 |
logger.debug('parsed [%s]' % error.tag)
|
68 |
for err in root.getiterator(error.tag): |
69 |
# process a particular <rpc-error>
|
70 |
d = {} |
71 |
for err_detail in err.getchildren(): # <error-type> etc.. |
72 |
tag = content.unqualify(err_detail.tag) |
73 |
if tag != 'error-info': |
74 |
d[tag] = err_detail.text.strip() |
75 |
else:
|
76 |
d[tag] = content.ele2xml(err_detail) |
77 |
self._errors.append(RPCError(d))
|
78 |
self._parsing_hook(root)
|
79 |
self._parsed = True |
80 |
|
81 |
@property
|
82 |
def xml(self): |
83 |
"*<rpc-reply>* as returned"
|
84 |
return self._raw |
85 |
|
86 |
@property
|
87 |
def ok(self): |
88 |
"Boolean value indicating if there were no errors."
|
89 |
if not self._parsed: |
90 |
self.parse()
|
91 |
return not self._errors # empty list => false |
92 |
|
93 |
@property
|
94 |
def error(self): |
95 |
"""Short for :attr:`errors` [0]; :const:`None` if there were no errors.
|
96 |
"""
|
97 |
if not self._parsed: |
98 |
self.parse()
|
99 |
if self._errors: |
100 |
return self._errors[0] |
101 |
else:
|
102 |
return None |
103 |
|
104 |
@property
|
105 |
def errors(self): |
106 |
"""`list` of :class:`RPCError` objects. Will be empty if there were no
|
107 |
*<rpc-error>* elements in reply.
|
108 |
"""
|
109 |
if not self._parsed: |
110 |
self.parse()
|
111 |
return self._errors |
112 |
|
113 |
|
114 |
class RPCError(OperationError): # raise it if you like |
115 |
|
116 |
"""Represents an *<rpc-error>*. It is an instance of :exc:`OperationError`
|
117 |
so it can be raised like any other exception."""
|
118 |
|
119 |
def __init__(self, err_dict): |
120 |
self._dict = err_dict
|
121 |
if self.message is not None: |
122 |
OperationError.__init__(self, self.message) |
123 |
else:
|
124 |
OperationError.__init__(self)
|
125 |
|
126 |
@property
|
127 |
def type(self): |
128 |
"`string` represeting *error-type* element"
|
129 |
return self.get('error-type', None) |
130 |
|
131 |
@property
|
132 |
def severity(self): |
133 |
"`string` represeting *error-severity* element"
|
134 |
return self.get('error-severity', None) |
135 |
|
136 |
@property
|
137 |
def tag(self): |
138 |
"`string` represeting *error-tag* element"
|
139 |
return self.get('error-tag', None) |
140 |
|
141 |
@property
|
142 |
def path(self): |
143 |
"`string` or :const:`None`; represeting *error-path* element"
|
144 |
return self.get('error-path', None) |
145 |
|
146 |
@property
|
147 |
def message(self): |
148 |
"`string` or :const:`None`; represeting *error-message* element"
|
149 |
return self.get('error-message', None) |
150 |
|
151 |
@property
|
152 |
def info(self): |
153 |
"`string` or :const:`None`, represeting *error-info* element"
|
154 |
return self.get('error-info', None) |
155 |
|
156 |
## dictionary interface
|
157 |
|
158 |
__getitem__ = lambda self, key: self._dict.__getitem__(key) |
159 |
|
160 |
__iter__ = lambda self: self._dict.__iter__() |
161 |
|
162 |
__contains__ = lambda self, key: self._dict.__contains__(key) |
163 |
|
164 |
keys = lambda self: self._dict.keys() |
165 |
|
166 |
get = lambda self, key, default: self._dict.get(key, default) |
167 |
|
168 |
iteritems = lambda self: self._dict.iteritems() |
169 |
|
170 |
iterkeys = lambda self: self._dict.iterkeys() |
171 |
|
172 |
itervalues = lambda self: self._dict.itervalues() |
173 |
|
174 |
values = lambda self: self._dict.values() |
175 |
|
176 |
items = lambda self: self._dict.items() |
177 |
|
178 |
__repr__ = lambda self: repr(self._dict) |
179 |
|
180 |
|
181 |
class RPCReplyListener(SessionListener): |
182 |
|
183 |
# internal use
|
184 |
|
185 |
# one instance per session
|
186 |
def __new__(cls, session): |
187 |
instance = session.get_listener_instance(cls) |
188 |
if instance is None: |
189 |
instance = object.__new__(cls)
|
190 |
instance._lock = Lock() |
191 |
instance._id2rpc = WeakValueDictionary() |
192 |
instance._pipelined = session.can_pipeline |
193 |
session.add_listener(instance) |
194 |
return instance
|
195 |
|
196 |
def register(self, id, rpc): |
197 |
with self._lock: |
198 |
self._id2rpc[id] = rpc |
199 |
|
200 |
def callback(self, root, raw): |
201 |
tag, attrs = root |
202 |
if content.unqualify(tag) != 'rpc-reply': |
203 |
return
|
204 |
rpc = None
|
205 |
for key in attrs: |
206 |
if content.unqualify(key) == 'message-id': |
207 |
id = attrs[key] |
208 |
try:
|
209 |
with self._lock: |
210 |
rpc = self._id2rpc.pop(id) |
211 |
except KeyError: |
212 |
logger.warning('no object registered for message-id: [%s]' % id) |
213 |
except Exception as e: |
214 |
logger.debug('error - %r' % e)
|
215 |
break
|
216 |
else:
|
217 |
if not self._pipelined: |
218 |
with self._lock: |
219 |
assert(len(self._id2rpc) == 1) |
220 |
rpc = self._id2rpc.values()[0] |
221 |
self._id2rpc.clear()
|
222 |
else:
|
223 |
logger.warning('<rpc-reply> without message-id received: %s' % raw)
|
224 |
logger.debug('delivering to %r' % rpc)
|
225 |
rpc.deliver_reply(raw) |
226 |
|
227 |
def errback(self, err): |
228 |
for rpc in self._id2rpc.values(): |
229 |
rpc.deliver_error(err) |
230 |
|
231 |
|
232 |
class RPC(object): |
233 |
|
234 |
"""Base class for all operations.
|
235 |
|
236 |
Directly corresponds to *<rpc>* requests. Handles making the request, and
|
237 |
taking delivery of the reply.
|
238 |
"""
|
239 |
|
240 |
# : Subclasses can specify their dependencies on capabilities. List of URI's
|
241 |
# or abbreviated names, e.g. ':writable-running'. These are verified at the
|
242 |
# time of object creation. If the capability is not available, a
|
243 |
# :exc:`MissingCapabilityError` is raised.
|
244 |
DEPENDS = [] |
245 |
|
246 |
# : Subclasses can specify a different reply class, but it must be a
|
247 |
# subclass of :class:`RPCReply`.
|
248 |
REPLY_CLS = RPCReply |
249 |
|
250 |
def __init__(self, session, async=False, timeout=None): |
251 |
self._session = session
|
252 |
try:
|
253 |
for cap in self.DEPENDS: |
254 |
self._assert(cap)
|
255 |
except AttributeError: |
256 |
pass
|
257 |
self._async = async
|
258 |
self._timeout = timeout
|
259 |
# keeps things simple instead of having a class attr that has to be locked
|
260 |
self._id = uuid1().urn
|
261 |
# RPCReplyListener itself makes sure there isn't more than one instance -- i.e. multiton
|
262 |
self._listener = RPCReplyListener(session)
|
263 |
self._listener.register(self._id, self) |
264 |
self._reply = None |
265 |
self._error = None |
266 |
self._event = Event()
|
267 |
|
268 |
def _build(self, opspec): |
269 |
# internal
|
270 |
spec = { |
271 |
'tag': content.qualify('rpc'), |
272 |
'attrib': {'message-id': self._id}, |
273 |
'subtree': [ opspec ]
|
274 |
} |
275 |
return content.dtree2xml(spec)
|
276 |
|
277 |
def _request(self, op): |
278 |
"""Subclasses call this method to make the RPC request.
|
279 |
|
280 |
In asynchronous mode, returns an :class:`~threading.Event` which is set
|
281 |
when the reply has been received or an error occured. It is prudent,
|
282 |
therefore, to check the :attr:`error` attribute before accesing
|
283 |
:attr:`reply`.
|
284 |
|
285 |
Otherwise, waits until the reply is received and returns
|
286 |
:class:`RPCReply`.
|
287 |
|
288 |
:arg opspec: :ref:`dtree` for the operation
|
289 |
:type opspec: :obj:`dict` or :obj:`string` or :class:`~xml.etree.ElementTree.Element`
|
290 |
:rtype: :class:`~threading.Event` or :class:`RPCReply`
|
291 |
"""
|
292 |
logger.debug('request %r with opsepc=%r' % (self, op)) |
293 |
req = self._build(op)
|
294 |
self.session.send(req)
|
295 |
if self.async: |
296 |
logger.debug('async, returning event')
|
297 |
return self.event |
298 |
else:
|
299 |
logger.debug('sync, will wait for timeout=%r' % self.timeout) |
300 |
self.event.wait(self.timeout) |
301 |
if self.event.isSet(): |
302 |
if self.error: |
303 |
raise self._error |
304 |
self.reply.parse()
|
305 |
return self.reply |
306 |
else:
|
307 |
raise TimeoutExpiredError
|
308 |
|
309 |
def request(self, *args, **kwds): |
310 |
"""Subclasses implement this method. Here, the operation is constructed
|
311 |
in :ref:`dtree`, and the result of :meth:`_request` returned."""
|
312 |
raise NotImplementedError |
313 |
|
314 |
def _delivery_hook(self): |
315 |
"""Subclasses can implement this method. Will be called after
|
316 |
initialising the :attr:`reply` or :attr:`error` attribute and before
|
317 |
setting the :attr:`event`"""
|
318 |
pass
|
319 |
|
320 |
def _assert(self, capability): |
321 |
"""Subclasses can use this method to verify that a capability is available
|
322 |
with the NETCONF server, before making a request that requires it. A
|
323 |
:exc:`MissingCapabilityError` will be raised if the capability is not
|
324 |
available."""
|
325 |
if capability not in self._session.server_capabilities: |
326 |
raise MissingCapabilityError('Server does not support [%s]' % cap) |
327 |
|
328 |
def deliver_reply(self, raw): |
329 |
# internal use
|
330 |
self._reply = self.REPLY_CLS(raw) |
331 |
self._delivery_hook()
|
332 |
self._event.set()
|
333 |
|
334 |
def deliver_error(self, err): |
335 |
# internal use
|
336 |
self._error = err
|
337 |
self._delivery_hook()
|
338 |
self._event.set()
|
339 |
|
340 |
@property
|
341 |
def reply(self): |
342 |
":class:`RPCReply` element if reply has been received or :const:`None`"
|
343 |
return self._reply |
344 |
|
345 |
@property
|
346 |
def error(self): |
347 |
""":exc:`Exception` type if an error occured or :const:`None`.
|
348 |
|
349 |
This attribute should be checked if the request was made asynchronously,
|
350 |
so that it can be determined if :attr:`event` being set is because of a
|
351 |
reply or error.
|
352 |
|
353 |
.. note::
|
354 |
This represents an error which prevented a reply from being
|
355 |
received. An *<rpc-error>* does not fall in that category -- see
|
356 |
:class:`RPCReply` for that.
|
357 |
"""
|
358 |
return self._error |
359 |
|
360 |
@property
|
361 |
def id(self): |
362 |
"The *message-id* for this RPC"
|
363 |
return self._id |
364 |
|
365 |
@property
|
366 |
def session(self): |
367 |
"""The :class:`~ncclient.transport.Session` object associated with this
|
368 |
RPC"""
|
369 |
return self._session |
370 |
|
371 |
@property
|
372 |
def event(self): |
373 |
""":class:`~threading.Event` that is set when reply has been received or
|
374 |
error occured."""
|
375 |
return self._event |
376 |
|
377 |
def set_async(self, async=True): |
378 |
"""Set asynchronous mode for this RPC."""
|
379 |
self._async = async
|
380 |
if async and not session.can_pipeline: |
381 |
raise UserWarning('Asynchronous mode not supported for this device/session') |
382 |
|
383 |
def set_timeout(self, timeout): |
384 |
"""Set the timeout for synchronous waiting defining how long the RPC
|
385 |
request will block on a reply before raising an error."""
|
386 |
self._timeout = timeout
|
387 |
|
388 |
#: Whether this RPC is asynchronous
|
389 |
async = property(fget=lambda self: self._async, fset=set_async) |
390 |
|
391 |
#: Timeout for synchronous waiting
|
392 |
timeout = property(fget=lambda self: self._timeout, fset=set_timeout) |