1 # ==================================================================================
2 # Copyright (c) 2020 Nokia
3 # Copyright (c) 2020 AT&T Intellectual Property.
5 # Licensed under the Apache License, Version 2.0 (the "License");
6 # you may not use this file except in compliance with the License.
7 # You may obtain a copy of the License at
9 # http://www.apache.org/licenses/LICENSE-2.0
11 # Unless required by applicable law or agreed to in writing, software
12 # distributed under the License is distributed on an "AS IS" BASIS,
13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 # See the License for the specific language governing permissions and
15 # limitations under the License.
16 # ==================================================================================
18 This framework for Python Xapps provides classes that Xapp writers
19 should instantiate and/or subclass depending on their needs.
25 from threading import Thread
27 from mdclogpy import Logger
28 from ricxappframe import xapp_rmr
29 from ricxappframe.rmr import rmr
30 from ricxappframe.xapp_sdl import SDLWrapper
32 # message-type constants
33 RIC_HEALTH_CHECK_REQ = 100
34 RIC_HEALTH_CHECK_RESP = 101
36 # environment variable with path to configuration file
37 CONFIG_FILE_ENV = "CONFIG_FILE"
42 This class initializes RMR, starts a thread that checks for incoming
43 messages, provisions an SDL object and optionally creates a
44 config-file watcher. This private base class should not be
45 instantiated by clients directly, but it defines many public methods
46 that may be used by clients.
48 If environment variable CONFIG_FILE is defined, and that variable
49 contains a path to an existing file, a watcher is defined to monitor
50 modifications (writes) to that file using the Linux kernel's inotify
51 feature. The watcher must be polled by calling method
56 rmr_port: int (optional, default is 4562)
57 Port on which the RMR library listens for incoming messages.
59 rmr_wait_for_ready: bool (optional, default is True)
60 If this is True, then init waits until RMR is ready to send,
61 which includes having a valid routing file. This can be set
62 to False if the client wants to *receive only*.
64 use_fake_sdl: bool (optional, default is False)
65 if this is True, it uses the DBaaS "fake dict backend" instead
66 of Redis or other backends. Set this to True when developing
67 an xapp or during unit testing to eliminate the need for DBaaS.
69 post_init: function (optional, default is None)
70 Runs this user-provided function at the end of the init method;
71 its signature should be post_init(self)
74 def __init__(self, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False, post_init=None):
76 Documented in the class comment.
78 # PUBLIC, can be used by xapps using self.(name):
79 self.logger = Logger(name=__name__)
81 # Start rmr rcv thread
82 self._rmr_loop = xapp_rmr.RmrLoop(port=rmr_port, wait_for_ready=rmr_wait_for_ready)
83 self._mrc = self._rmr_loop.mrc # for convenience
86 self.sdl = SDLWrapper(use_fake_sdl)
89 # The environment variable specifies the path to the Xapp config file
90 self._config_path = os.environ.get(CONFIG_FILE_ENV, None)
91 if self._config_path and os.path.isfile(self._config_path):
92 self._inotify = inotify_simple.INotify()
93 self._inotify.add_watch(self._config_path, inotify_simple.flags.MODIFY)
94 self.logger.debug("__init__: watching config file {}".format(self._config_path))
97 self.logger.warning("__init__: NOT watching any config file")
99 # run the optionally provided user post init
105 def rmr_get_messages(self):
107 Returns a generator iterable over all items in the queue that
108 have not yet been read by the client xapp. Each item is a tuple
109 (S, sbuf) where S is a message summary dict and sbuf is the raw
110 message. The caller MUST call rmr.rmr_free_msg(sbuf) when
111 finished with each sbuf to prevent memory leaks!
113 while not self._rmr_loop.rcv_queue.empty():
114 (summary, sbuf) = self._rmr_loop.rcv_queue.get()
115 yield (summary, sbuf)
117 def rmr_send(self, payload, mtype, retries=100):
119 Allocates a buffer, sets payload and mtype, and sends
127 retries: int (optional)
128 Number of times to retry at the application level before excepting RMRFailure
133 whether or not the send worked after retries attempts
135 sbuf = rmr.rmr_alloc_msg(vctx=self._mrc, size=len(payload), payload=payload, gen_transaction_id=True, mtype=mtype)
137 for _ in range(retries):
138 sbuf = rmr.rmr_send_msg(self._mrc, sbuf)
139 if sbuf.contents.state == 0:
146 def rmr_rts(self, sbuf, new_payload=None, new_mtype=None, retries=100):
148 Allows the xapp to return to sender, possibly adjusting the
149 payload and message type before doing so. This does NOT free
150 the sbuf for the caller as the caller may wish to perform
151 multiple rts per buffer. The client needs to free.
155 sbuf: ctypes c_void_p
156 Pointer to an rmr message buffer
157 new_payload: bytes (optional)
159 new_mtype: int (optional)
160 New message type (replaces the received message)
161 retries: int (optional, default 100)
162 Number of times to retry at the application level
167 whether or not the send worked after retries attempts
169 for _ in range(retries):
170 sbuf = rmr.rmr_rts_msg(self._mrc, sbuf, payload=new_payload, mtype=new_mtype)
171 if sbuf.contents.state == 0:
174 self.logger.warning("RTS Failed! Summary: {}".format(rmr.message_summary(sbuf)))
177 def rmr_free(self, sbuf):
179 Frees an rmr message buffer after use
181 Note: this does not need to be a class method, self is not
182 used. However if we break it out as a function we need a home
187 sbuf: ctypes c_void_p
188 Pointer to an rmr message buffer
190 rmr.rmr_free_msg(sbuf)
192 # Convenience (pass-thru) function for invoking SDL.
194 def sdl_set(self, namespace, key, value, usemsgpack=True):
196 ** Deprecate Warning **
197 ** Will be removed in a future function **
199 Stores a key-value pair to SDL, optionally serializing the value
200 to bytes using msgpack.
209 Object or byte array to store. See the `usemsgpack` parameter.
210 usemsgpack: boolean (optional, default is True)
211 Determines whether the value is serialized using msgpack before storing.
212 If usemsgpack is True, the msgpack function `packb` is invoked
213 on the value to yield a byte array that is then sent to SDL.
214 Stated differently, if usemsgpack is True, the value can be anything
215 that is serializable by msgpack.
216 If usemsgpack is False, the value must be bytes.
218 self.sdl.set(namespace, key, value, usemsgpack)
220 def sdl_get(self, namespace, key, usemsgpack=True):
222 ** Deprecate Warning **
223 ** Will be removed in a future function **
225 Gets the value for the specified namespace and key from SDL,
226 optionally deserializing stored bytes using msgpack.
234 usemsgpack: boolean (optional, default is True)
235 If usemsgpack is True, the byte array stored by SDL is deserialized
236 using msgpack to yield the original object that was stored.
237 If usemsgpack is False, the byte array stored by SDL is returned
238 without further processing.
243 See the usemsgpack parameter for an explanation of the returned value type.
244 Answers None if the key is not found.
246 return self.sdl.get(namespace, key, usemsgpack)
248 def sdl_find_and_get(self, namespace, prefix, usemsgpack=True):
250 ** Deprecate Warning **
251 ** Will be removed in a future function **
253 Gets all key-value pairs in the specified namespace
254 with keys that start with the specified prefix,
255 optionally deserializing stored bytes using msgpack.
263 usemsgpack: boolean (optional, default is True)
264 If usemsgpack is True, the byte array stored by SDL is deserialized
265 using msgpack to yield the original value that was stored.
266 If usemsgpack is False, the byte array stored by SDL is returned
267 without further processing.
271 Dictionary of key-value pairs
272 Each key has the specified prefix.
273 The value object (its type) depends on the usemsgpack parameter,
274 but is either a Python object or raw bytes as discussed above.
275 Answers an empty dictionary if no keys matched the prefix.
277 return self.sdl.find_and_get(namespace, prefix, usemsgpack)
279 def sdl_delete(self, namespace, key):
281 ** Deprecate Warning **
282 ** Will be removed in a future function **
284 Deletes the key-value pair with the specified key in the specified namespace.
293 self.sdl.delete(namespace, key)
297 def healthcheck(self):
299 this needs to be understood how this is supposed to work
301 return self._rmr_loop.healthcheck() and self.sdl.healthcheck()
303 # Convenience function for discovering config change events
305 def config_check(self, timeout=0):
307 Checks the watcher for configuration-file events. The watcher
308 prerequisites and event mask are documented in __init__().
312 timeout: int (optional)
313 Number of seconds to wait for a configuration-file event, default 0.
317 List of Events, possibly empty
318 An event is a tuple with objects wd, mask, cookie and name.
321 Event(wd=1, mask=1073742080, cookie=0, name='foo')
324 if not self._inotify:
326 events = self._inotify.read(timeout=timeout)
331 cleans up and stops the xapp rmr thread (currently). This is
332 critical for unit testing as pytest will never return if the
335 TODO: can we register a ctrl-c handler so this gets called on
336 ctrl-c? Because currently two ctrl-c are needed to stop.
338 self._rmr_loop.stop()
341 # Public classes that Xapp writers should instantiate or subclass
342 # to implement an Xapp.
345 class RMRXapp(_BaseXapp):
347 Represents an Xapp that reacts only to RMR messages; i.e., the Xapp
348 only performs an action when a message is received. Clients should
349 invoke the run method, which has a loop that waits for RMR messages
350 and calls the appropriate client-registered consume callback on each.
352 If environment variable CONFIG_FILE is defined, and that variable
353 contains a path to an existing file, this class polls a watcher
354 defined on that file to detect file-write events, and invokes a
355 configuration-change handler on each event. The handler is also
356 invoked at startup. If no handler function is supplied to the
357 constructor, this class defines a default handler that only logs a
362 default_handler: function
363 A function with the signature (summary, sbuf) to be called when a
364 message type is received for which no other handler is registered.
365 default_handler argument summary: dict
366 The RMR message summary, a dict of key-value pairs
367 default_handler argument sbuf: ctypes c_void_p
368 Pointer to an RMR message buffer. The user must call free on this when done.
369 config_handler: function (optional, default is documented above)
370 A function with the signature (json) to be called at startup and each time
371 a configuration-file change event is detected. The JSON object is read from
372 the configuration file, if the prerequisites are met.
373 config_handler argument json: dict
374 The contents of the configuration file, parsed as JSON.
375 rmr_port: integer (optional, default is 4562)
376 Initialize RMR to listen on this port
377 rmr_wait_for_ready: boolean (optional, default is True)
378 Wait for RMR to signal ready before starting the dispatch loop
379 use_fake_sdl: boolean (optional, default is False)
380 Use an in-memory store instead of the real SDL service
381 post_init: function (optional, default None)
382 Run this function after the app initializes and before the dispatch loop starts;
383 its signature should be post_init(self)
386 def __init__(self, default_handler, config_handler=None, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False, post_init=None):
392 rmr_port=rmr_port, rmr_wait_for_ready=rmr_wait_for_ready, use_fake_sdl=use_fake_sdl, post_init=post_init
396 self._default_handler = default_handler
397 self._config_handler = config_handler
400 # used for thread control
401 self._keep_going = True
403 # register a default healthcheck handler
404 # this default checks that rmr is working and SDL is working
405 # the user can override this and register their own handler
406 # if they wish since the "last registered callback wins".
407 def handle_healthcheck(self, summary, sbuf):
408 healthy = self.healthcheck()
409 payload = b"OK\n" if healthy else b"ERROR [RMR or SDL is unhealthy]\n"
410 self.rmr_rts(sbuf, new_payload=payload, new_mtype=RIC_HEALTH_CHECK_RESP)
413 self.register_callback(handle_healthcheck, RIC_HEALTH_CHECK_REQ)
415 # define a default configuration-change handler if none was provided.
416 if not config_handler:
417 def handle_config_change(self, config):
418 self.logger.debug("xapp_frame: default config handler invoked")
419 self._config_handler = handle_config_change
421 # call the config handler at startup if prereqs were met
423 with open(self._config_path) as json_file:
424 data = json.load(json_file)
425 self.logger.debug("run: invoking config handler at start")
426 self._config_handler(self, data)
428 def register_callback(self, handler, message_type):
430 registers this xapp to call handler(summary, buf) when an rmr message is received of type message_type
435 a function with the signature (summary, sbuf) to be called
436 when a message of type message_type is received
438 the rmr message summary
439 sbuf: ctypes c_void_p
440 Pointer to an rmr message buffer. The user must call free on this when done.
443 the message type to look for
445 Note if this method is called multiple times for a single message type, the "last one wins".
447 self._dispatch[message_type] = handler
449 def run(self, thread=False, rmr_timeout=5, inotify_timeout=0):
451 This function should be called when the reactive Xapp is ready to start.
452 After start, the Xapp's handlers will be called on received messages.
456 thread: bool (optional, default is False)
457 If False, execution is not returned and the framework loops forever.
458 If True, a thread is started to run the queue read/dispatch loop
459 and execution is returned to caller; the thread can be stopped
460 by calling the .stop() method.
462 rmr_timeout: integer (optional, default is 5 seconds)
463 Length of time to wait for an RMR message to arrive.
465 inotify_timeout: integer (optional, default is 0 seconds)
466 Length of time to wait for an inotify event to arrive.
470 while self._keep_going:
474 (summary, sbuf) = self._rmr_loop.rcv_queue.get(block=True, timeout=rmr_timeout)
476 func = self._dispatch.get(summary[rmr.RMR_MS_MSG_TYPE], None)
478 func = self._default_handler
479 self.logger.debug("run: invoking msg handler on type {}".format(summary[rmr.RMR_MS_MSG_TYPE]))
480 func(self, summary, sbuf)
485 # poll configuration file watcher
487 events = self.config_check(timeout=inotify_timeout)
489 with open(self._config_path) as json_file:
490 data = json.load(json_file)
491 self.logger.debug("run: invoking config handler on change event {}".format(event))
492 self._config_handler(self, data)
493 except Exception as error:
494 self.logger.error("run: configuration handler failed: {}".format(error))
497 Thread(target=loop).start()
503 Sets the flag to end the dispatch loop.
506 self.logger.debug("Setting flag to end framework work loop.")
507 self._keep_going = False
510 class Xapp(_BaseXapp):
512 Represents a generic Xapp where the client provides a single function
513 for the framework to call at startup time (instead of providing callback
514 functions by message type). The Xapp writer must implement and provide a
515 function with a loop-forever construct similar to the `run` function in
516 the `RMRXapp` class. That function should poll to retrieve RMR messages
517 and dispatch them appropriately, poll for configuration changes, etc.
522 This function is called when the Xapp class's run method is invoked.
523 The function signature must be just function(self)
524 rmr_port: integer (optional, default is 4562)
525 Initialize RMR to listen on this port
526 rmr_wait_for_ready: boolean (optional, default is True)
527 Wait for RMR to signal ready before starting the dispatch loop
528 use_fake_sdl: boolean (optional, default is False)
529 Use an in-memory store instead of the real SDL service
532 def __init__(self, entrypoint, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False):
537 For the other parameters, see class _BaseXapp.
540 super().__init__(rmr_port=rmr_port, rmr_wait_for_ready=rmr_wait_for_ready, use_fake_sdl=use_fake_sdl)
541 self._entrypoint = entrypoint
545 This function should be called when the general Xapp is ready to start.
547 self._entrypoint(self)
549 # there is no need for stop currently here (base has, and nothing
550 # special to do here)