root / ncclient / operations / rpc.py @ 11bab021
History | View | Annotate | Download (12.2 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 |
|
18 |
from ncclient.xml_ import * |
19 |
from ncclient.transport import SessionListener |
20 |
|
21 |
from errors import OperationError, TimeoutExpiredError, MissingCapabilityError |
22 |
|
23 |
import logging |
24 |
logger = logging.getLogger("ncclient.operations.rpc")
|
25 |
|
26 |
|
27 |
class RPCReply: |
28 |
|
29 |
"""Represents an *<rpc-reply>*. Only concerns itself with whether the
|
30 |
operation was successful.
|
31 |
|
32 |
.. note::
|
33 |
If the reply has not yet been parsed there is an implicit, one-time
|
34 |
parsing overhead to accessing the attributes defined by this class and
|
35 |
any subclasses.
|
36 |
"""
|
37 |
|
38 |
def __init__(self, raw): |
39 |
self._raw = raw
|
40 |
self._parsed = False |
41 |
self._root = None |
42 |
self._errors = []
|
43 |
|
44 |
def __repr__(self): |
45 |
return self._raw |
46 |
|
47 |
def _parsing_hook(self, root): |
48 |
"""Subclass can implement.
|
49 |
|
50 |
:type root: :class:`~xml.etree.ElementTree.Element`
|
51 |
"""
|
52 |
pass
|
53 |
|
54 |
def parse(self): |
55 |
"""Parse the *<rpc-reply>*"""
|
56 |
if self._parsed: |
57 |
return
|
58 |
root = self._root = to_ele(self._raw) # The <rpc-reply> element |
59 |
# Per RFC 4741 an <ok/> tag is sent when there are no errors or warnings
|
60 |
ok = root.find(qualify("ok"))
|
61 |
if ok is None: |
62 |
# Create RPCError objects from <rpc-error> elements
|
63 |
error = root.find(qualify("rpc-error"))
|
64 |
if error is not None: |
65 |
for err in root.getiterator(error.tag): |
66 |
# Process a particular <rpc-error>
|
67 |
self._errors.append(RPCError(err))
|
68 |
self._parsing_hook(root)
|
69 |
self._parsed = True |
70 |
|
71 |
@property
|
72 |
def xml(self): |
73 |
"*<rpc-reply>* as returned"
|
74 |
return self._raw |
75 |
|
76 |
@property
|
77 |
def ok(self): |
78 |
"Boolean value indicating if there were no errors."
|
79 |
if not self._parsed: |
80 |
self.parse()
|
81 |
return not self._errors # empty list => false |
82 |
|
83 |
@property
|
84 |
def error(self): |
85 |
"""Short for :attr:`errors` [0]; :const:`None` if there were no errors.
|
86 |
"""
|
87 |
if not self._parsed: |
88 |
self.parse()
|
89 |
if self._errors: |
90 |
return self._errors[0] |
91 |
else:
|
92 |
return None |
93 |
|
94 |
@property
|
95 |
def errors(self): |
96 |
"""`list` of :class:`RPCError` objects. Will be empty if there were no
|
97 |
*<rpc-error>* elements in reply.
|
98 |
"""
|
99 |
if not self._parsed: |
100 |
self.parse()
|
101 |
return self._errors |
102 |
|
103 |
|
104 |
class RPCError(OperationError): |
105 |
|
106 |
"""Represents an *<rpc-error>*. It is a type of :exc:`OperationError`
|
107 |
and can be raised like any other exception."""
|
108 |
|
109 |
tag_to_attr = { |
110 |
qualify("error-type"): "_type", |
111 |
qualify("error-tag"): "_tag", |
112 |
qualify("error-severity"): "_severity", |
113 |
qualify("error-info"): "_info", |
114 |
qualify("error-path"): "_path", |
115 |
qualify("error-message"): "_message" |
116 |
} |
117 |
|
118 |
def __init__(self, err): |
119 |
for attr in tag_to_attr.values(): |
120 |
setattr(self, attr, None) |
121 |
for subele in err: |
122 |
attr = tag_to_attr.get(subele.tag, None)
|
123 |
if attr is not None: |
124 |
setattr(self, attr, subele.text) |
125 |
if self.message is not None: |
126 |
OperationError.__init__(self, self.message) |
127 |
else:
|
128 |
OperationError.__init__(self, self.to_dict()) |
129 |
|
130 |
def to_dict(self): |
131 |
return dict([ (attr[1:], gettattr(self, attr)) for attr in tag_to_attr.values() ]) |
132 |
|
133 |
@property
|
134 |
def type(self): |
135 |
"`string` representing text of *error-type* element"
|
136 |
return self._type |
137 |
|
138 |
@property
|
139 |
def tag(self): |
140 |
"`string` representing text of *error-tag* element"
|
141 |
return self._tag |
142 |
|
143 |
@property
|
144 |
def severity(self): |
145 |
"`string` representing text of *error-severity* element"
|
146 |
return self._severity |
147 |
|
148 |
@property
|
149 |
def path(self): |
150 |
"`string` or :const:`None`; representing text of *error-path* element"
|
151 |
return self._path |
152 |
|
153 |
@property
|
154 |
def message(self): |
155 |
"`string` or :const:`None`; representing text of *error-message* element"
|
156 |
return self._message |
157 |
|
158 |
@property
|
159 |
def info(self): |
160 |
"`string` (XML) or :const:`None`, representing *error-info* element"
|
161 |
return self._info |
162 |
|
163 |
|
164 |
class RPCReplyListener(SessionListener): # internal use |
165 |
|
166 |
creation_lock = Lock() |
167 |
|
168 |
# one instance per session -- maybe there is a better way??
|
169 |
def __new__(cls, session): |
170 |
with creation_lock:
|
171 |
instance = session.get_listener_instance(cls) |
172 |
if instance is None: |
173 |
instance = object.__new__(cls)
|
174 |
instance._lock = Lock() |
175 |
instance._id2rpc = {} |
176 |
#instance._pipelined = session.can_pipeline
|
177 |
session.add_listener(instance) |
178 |
return instance
|
179 |
|
180 |
def register(self, id, rpc): |
181 |
with self._lock: |
182 |
self._id2rpc[id] = rpc |
183 |
|
184 |
def callback(self, root, raw): |
185 |
tag, attrs = root |
186 |
if tag != qualify("rpc-reply"): |
187 |
return
|
188 |
for key in attrs: # in the <rpc-reply> attributes |
189 |
if key == "message-id": # if we found msgid attr |
190 |
id = attrs[key] # get the msgid
|
191 |
with self._lock: |
192 |
try:
|
193 |
rpc = self._id2rpc[id] # the corresponding rpc |
194 |
logger.debug("Delivering to %r" % rpc)
|
195 |
rpc.deliver_reply(raw) |
196 |
except KeyError: |
197 |
raise OperationError("Unknown 'message-id': %s", id) |
198 |
# no catching other exceptions, fail loudly if must
|
199 |
else:
|
200 |
# if no error delivering, can del the reference to the RPC
|
201 |
del self._id2rpc[id] |
202 |
break
|
203 |
else:
|
204 |
raise OperationError("Could not find 'message-id' attribute in <rpc-reply>") |
205 |
|
206 |
def errback(self, err): |
207 |
try:
|
208 |
for rpc in self._id2rpc.values(): |
209 |
rpc.deliver_error(err) |
210 |
finally:
|
211 |
self._id2rpc.clear()
|
212 |
|
213 |
|
214 |
class RPC(object): |
215 |
|
216 |
"""Base class for all operations.
|
217 |
|
218 |
Directly corresponds to *<rpc>* requests. Handles making the request, and
|
219 |
taking delivery of the reply.
|
220 |
"""
|
221 |
|
222 |
#: Subclasses can specify their dependencies on capabilities. List of URI's
|
223 |
# or abbreviated names, e.g. ':writable-running'. These are verified at the
|
224 |
# time of object creation. If the capability is not available, a
|
225 |
# :exc:`MissingCapabilityError` is raised.
|
226 |
DEPENDS = [] |
227 |
|
228 |
#: Subclasses can specify a different reply class, but it must be a
|
229 |
# subclass of :class:`RPCReply`.
|
230 |
REPLY_CLS = RPCReply |
231 |
|
232 |
def __init__(self, session, async=False, timeout=None, raise_mode="none"): |
233 |
self._session = session
|
234 |
try:
|
235 |
for cap in self.DEPENDS: |
236 |
self._assert(cap)
|
237 |
except AttributeError: |
238 |
pass
|
239 |
self._async = async
|
240 |
self._timeout = timeout
|
241 |
self._raise_mode = raise_mode
|
242 |
self._id = uuid1().urn # Keeps things simple instead of having a class attr that has to be locked |
243 |
self._listener = RPCReplyListener(session)
|
244 |
self._listener.register(self._id, self) |
245 |
self._reply = None |
246 |
self._error = None |
247 |
self._event = Event()
|
248 |
|
249 |
def _build(self, subele): |
250 |
# internal
|
251 |
ele = new_ele("rpc", {"message-id": self._id}, xmlns=BASE_NS_1_0) |
252 |
ele.append(subele) |
253 |
return to_xml(ele)
|
254 |
|
255 |
def _request(self, op): |
256 |
"""Subclasses call this method to make the RPC request.
|
257 |
|
258 |
In synchronous mode, waits until the reply is received and returns
|
259 |
:class:`RPCReply`.
|
260 |
|
261 |
In asynchronous mode, returns immediately, returning a reference to this
|
262 |
object. The :attr:`event` attribute will be set when the reply has been
|
263 |
received (see :attr:`reply`) or an error occured (see :attr:`error`).
|
264 |
|
265 |
:type opspec: :obj:`dict` or :obj:`string` or :class:`~xml.etree.ElementTree.Element`
|
266 |
:rtype: :class:`RPCReply` (sync) or :class:`RPC` (async)
|
267 |
"""
|
268 |
logger.info('Requesting %r' % self.__class__.__name__) |
269 |
req = self._build(op)
|
270 |
self._session.send(req)
|
271 |
if self._async: |
272 |
logger.debug('Async request, returning %r', self) |
273 |
return self |
274 |
else:
|
275 |
logger.debug('Sync request, will wait for timeout=%r' %
|
276 |
self._timeout)
|
277 |
self._event.wait(self._timeout) |
278 |
if self._event.isSet(): |
279 |
if self._error: |
280 |
# Error that prevented reply delivery
|
281 |
raise self._error |
282 |
self._reply.parse()
|
283 |
if self._reply.error is not None: |
284 |
# <rpc-error>'s [ RPCError ]
|
285 |
if self._raise_mode == "all": |
286 |
raise self._reply.error |
287 |
elif (self._raise_mode == "errors" and |
288 |
self._reply.error.type == "error"): |
289 |
raise self._reply.error |
290 |
return self._reply |
291 |
else:
|
292 |
raise TimeoutExpiredError
|
293 |
|
294 |
def request(self, *args, **kwds): |
295 |
"Subclasses implement this method."
|
296 |
return self._request(self.SPEC) |
297 |
|
298 |
def _assert(self, capability): |
299 |
"""Subclasses can use this method to verify that a capability is available
|
300 |
with the NETCONF server, before making a request that requires it. A
|
301 |
:exc:`MissingCapabilityError` will be raised if the capability is not
|
302 |
available."""
|
303 |
if capability not in self._session.server_capabilities: |
304 |
raise MissingCapabilityError('Server does not support [%s]' % |
305 |
capability) |
306 |
|
307 |
def deliver_reply(self, raw): |
308 |
# internal use
|
309 |
self._reply = self.REPLY_CLS(raw) |
310 |
self._event.set()
|
311 |
|
312 |
def deliver_error(self, err): |
313 |
# internal use
|
314 |
self._error = err
|
315 |
self._event.set()
|
316 |
|
317 |
@property
|
318 |
def reply(self): |
319 |
":class:`RPCReply` element if reply has been received or :const:`None`"
|
320 |
return self._reply |
321 |
|
322 |
@property
|
323 |
def error(self): |
324 |
""":exc:`Exception` type if an error occured or :const:`None`.
|
325 |
|
326 |
.. note::
|
327 |
This represents an error which prevented a reply from being
|
328 |
received. An *<rpc-error>* does not fall in that category -- see
|
329 |
:class:`RPCReply` for that.
|
330 |
"""
|
331 |
return self._error |
332 |
|
333 |
@property
|
334 |
def id(self): |
335 |
"The *message-id* for this RPC"
|
336 |
return self._id |
337 |
|
338 |
@property
|
339 |
def session(self): |
340 |
"""The :class:`~ncclient.transport.Session` object associated with this
|
341 |
RPC"""
|
342 |
return self._session |
343 |
|
344 |
@property
|
345 |
def event(self): |
346 |
""":class:`~threading.Event` that is set when reply has been received or
|
347 |
error occured."""
|
348 |
return self._event |
349 |
|
350 |
def set_async(self, async=True): |
351 |
"""Set asynchronous mode for this RPC."""
|
352 |
self._async = async
|
353 |
if async and not session.can_pipeline: |
354 |
raise UserWarning('Asynchronous mode not supported for this device/session') |
355 |
|
356 |
def set_raise_mode(self, mode): |
357 |
assert(choice in ("all", "errors", "none")) |
358 |
self._raise_mode = mode
|
359 |
|
360 |
def set_timeout(self, timeout): |
361 |
"""Set the timeout for synchronous waiting; defining how long the RPC
|
362 |
request will block on a reply before raising an error. Irrelevant for
|
363 |
asynchronous usage."""
|
364 |
self._timeout = timeout
|
365 |
|
366 |
#: Whether this RPC is asynchronous
|
367 |
is_async = property(fget=lambda self: self._async, fset=set_async) |
368 |
|
369 |
#: Timeout for synchronous waiting
|
370 |
timeout = property(fget=lambda self: self._timeout, fset=set_timeout) |