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 should
19 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"
39 # Private base class; not for direct client use
44 This base class initializes RMR by starting a thread that checks for
45 incoming messages, and provisions an SDL object.
47 If environment variable CONFIG_FILE_ENV is defined, and that value is a
48 path to an existing file, a watcher is defined to monitor modifications
49 (writes) to that file using the Linux kernel's inotify feature, and the
50 configuration-change handler function is invoked. The watcher can be
51 polled by calling method config_check().
58 rmr_wait_for_ready: bool (optional)
59 If this is True, then init waits until rmr is ready to send, which
60 includes having a valid routing file. This can be set to
61 False if the client only wants to *receive only*.
63 use_fake_sdl: bool (optional)
64 if this is True, it uses the dbaas "fake dict backend" instead
65 of Redis or other backends. Set this to true when developing
66 an xapp or during unit testing to eliminate the need for DBAAS.
68 post_init: function (optional)
69 Runs this user-provided function after the base xapp is
70 initialized; its signature should be post_init(self)
73 def __init__(self, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False, post_init=None):
75 Documented in the class comment.
77 # PUBLIC, can be used by xapps using self.(name):
78 self.logger = Logger(name=__name__)
80 # Start rmr rcv thread
81 self._rmr_loop = xapp_rmr.RmrLoop(port=rmr_port, wait_for_ready=rmr_wait_for_ready)
82 self._mrc = self._rmr_loop.mrc # for convenience
85 self._sdl = SDLWrapper(use_fake_sdl)
88 # The environment variable specifies the path to the Xapp config file
89 self._config_path = os.environ.get(CONFIG_FILE_ENV, None)
90 if self._config_path and os.path.isfile(self._config_path):
91 self._inotify = inotify_simple.INotify()
92 self._inotify.add_watch(self._config_path, inotify_simple.flags.MODIFY)
93 self.logger.debug("__init__: watching config file {}".format(self._config_path))
96 self.logger.warning("__init__: NOT watching any config file")
98 # run the optionally provided user post init
104 def rmr_get_messages(self):
106 Returns a generator iterable over all items in the queue that
107 have not yet been read by the client xapp. Each item is a tuple
108 (S, sbuf) where S is a message summary dict and sbuf is the raw
109 message. The caller MUST call rmr.rmr_free_msg(sbuf) when
110 finished with each sbuf to prevent memory leaks!
112 while not self._rmr_loop.rcv_queue.empty():
113 (summary, sbuf) = self._rmr_loop.rcv_queue.get()
114 yield (summary, sbuf)
116 def rmr_send(self, payload, mtype, retries=100):
118 Allocates a buffer, sets payload and mtype, and sends
126 retries: int (optional)
127 Number of times to retry at the application level before excepting RMRFailure
132 whether or not the send worked after retries attempts
134 sbuf = rmr.rmr_alloc_msg(vctx=self._mrc, size=len(payload), payload=payload, gen_transaction_id=True, mtype=mtype)
136 for _ in range(retries):
137 sbuf = rmr.rmr_send_msg(self._mrc, sbuf)
138 if sbuf.contents.state == 0:
145 def rmr_rts(self, sbuf, new_payload=None, new_mtype=None, retries=100):
147 Allows the xapp to return to sender, possibly adjusting the
148 payload and message type before doing so. This does NOT free
149 the sbuf for the caller as the caller may wish to perform
150 multiple rts per buffer. The client needs to free.
154 sbuf: ctypes c_void_p
155 Pointer to an rmr message buffer
156 new_payload: bytes (optional)
158 new_mtype: int (optional)
159 New message type (replaces the received message)
160 retries: int (optional)
161 Number of times to retry at the application level before
162 throwing exception RMRFailure
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, ns, key, value, usemsgpack=True):
196 Stores a key-value pair to SDL, optionally serializing the value
197 to bytes using msgpack.
206 Object or byte array to store. See the `usemsgpack` parameter.
207 usemsgpack: boolean (optional, default is True)
208 Determines whether the value is serialized using msgpack before storing.
209 If usemsgpack is True, the msgpack function `packb` is invoked
210 on the value to yield a byte array that is then sent to SDL.
211 Stated differently, if usemsgpack is True, the value can be anything
212 that is serializable by msgpack.
213 If usemsgpack is False, the value must be bytes.
215 self._sdl.set(ns, key, value, usemsgpack)
217 def sdl_get(self, ns, key, usemsgpack=True):
219 Gets the value for the specified namespace and key from SDL,
220 optionally deserializing stored bytes using msgpack.
228 usemsgpack: boolean (optional, default is True)
229 If usemsgpack is True, the byte array stored by SDL is deserialized
230 using msgpack to yield the original object that was stored.
231 If usemsgpack is False, the byte array stored by SDL is returned
232 without further processing.
237 See the usemsgpack parameter for an explanation of the returned value type.
238 Answers None if the key is not found.
240 return self._sdl.get(ns, key, usemsgpack)
242 def sdl_find_and_get(self, ns, prefix, usemsgpack=True):
244 Gets all key-value pairs in the specified namespace
245 with keys that start with the specified prefix,
246 optionally deserializing stored bytes using msgpack.
254 usemsgpack: boolean (optional, default is True)
255 If usemsgpack is True, the byte array stored by SDL is deserialized
256 using msgpack to yield the original value that was stored.
257 If usemsgpack is False, the byte array stored by SDL is returned
258 without further processing.
262 Dictionary of key-value pairs
263 Each key has the specified prefix.
264 The value object (its type) depends on the usemsgpack parameter,
265 but is either a Python object or raw bytes as discussed above.
266 Answers an empty dictionary if no keys matched the prefix.
268 return self._sdl.find_and_get(ns, prefix, usemsgpack)
270 def sdl_delete(self, ns, key):
272 Deletes the key-value pair with the specified key in the specified namespace.
281 self._sdl.delete(ns, key)
285 def healthcheck(self):
287 this needs to be understood how this is supposed to work
289 return self._rmr_loop.healthcheck() and self._sdl.healthcheck()
291 # Convenience function for discovering config change events
293 def config_check(self, timeout=0):
295 Checks the watcher for configuration-file events. The watcher
296 prerequisites and event mask are documented in __init__().
300 timeout: int (optional)
301 Number of seconds to wait for a configuration-file event, default 0.
305 List of Events, possibly empty
306 An event is a tuple with objects wd, mask, cookie and name.
309 Event(wd=1, mask=1073742080, cookie=0, name='foo')
312 if not self._inotify:
314 events = self._inotify.read(timeout=timeout)
319 cleans up and stops the xapp rmr thread (currently). This is
320 critical for unit testing as pytest will never return if the
323 TODO: can we register a ctrl-c handler so this gets called on
324 ctrl-c? Because currently two ctrl-c are needed to stop.
326 self._rmr_loop.stop()
329 # Public classes that Xapp writers should instantiate or subclass
330 # to implement an Xapp.
333 class RMRXapp(_BaseXapp):
335 Represents an Xapp that reacts only to RMR messages; i.e., when
336 messages are received, the Xapp does something. When run is called,
337 the xapp framework waits for RMR messages, and calls the appropriate
338 client-registered consume callback on each.
340 If environment variable CONFIG_FILE_ENV is defined, and that value is a
341 path to an existing file, the configuration-change handler is invoked at
342 startup and on each configuration-file write event. If no handler is
343 supplied, this class defines a default handler that logs each invocation.
347 default_handler: function
348 A function with the signature (summary, sbuf) to be called
349 when a message type is received for which no other handler is registered.
350 default_handler argument summary: dict
351 The RMR message summary, a dict of key-value pairs
352 default_handler argument sbuf: ctypes c_void_p
353 Pointer to an RMR message buffer. The user must call free on this when done.
354 config_handler: function (optional, default is documented above)
355 A function with the signature (json) to be called at startup and each time
356 a configuration-file change event is detected. The JSON object is read from
357 the configuration file, if the prerequisites are met.
358 config_handler argument json: dict
359 The contents of the configuration file, parsed as JSON.
360 rmr_port: integer (optional, default is 4562)
361 Initialize RMR to listen on this port
362 rmr_wait_for_ready: boolean (optional, default is True)
363 Wait for RMR to signal ready before starting the dispatch loop
364 use_fake_sdl: boolean (optional, default is False)
365 Use an in-memory store instead of the real SDL service
366 post_init: function (optional, default None)
367 Run this function after the app initializes and before the dispatch loop starts;
368 its signature should be post_init(self)
371 def __init__(self, default_handler, config_handler=None, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False, post_init=None):
377 rmr_port=rmr_port, rmr_wait_for_ready=rmr_wait_for_ready, use_fake_sdl=use_fake_sdl, post_init=post_init
381 self._default_handler = default_handler
382 self._config_handler = config_handler
385 # used for thread control
386 self._keep_going = True
388 # register a default healthcheck handler
389 # this default checks that rmr is working and SDL is working
390 # the user can override this and register their own handler
391 # if they wish since the "last registered callback wins".
392 def handle_healthcheck(self, summary, sbuf):
393 ok = self.healthcheck()
394 payload = b"OK\n" if ok else b"ERROR [RMR or SDL is unhealthy]\n"
395 self.rmr_rts(sbuf, new_payload=payload, new_mtype=RIC_HEALTH_CHECK_RESP)
398 self.register_callback(handle_healthcheck, RIC_HEALTH_CHECK_REQ)
400 # define a default configuration-change handler if none was provided.
401 if not config_handler:
402 def handle_config_change(self, config):
403 self.logger.debug("xapp_frame: default config handler invoked")
404 self._config_handler = handle_config_change
406 # call the config handler at startup if prereqs were met
408 with open(self._config_path) as json_file:
409 data = json.load(json_file)
410 self.logger.debug("run: invoking config handler at start")
411 self._config_handler(self, data)
413 def register_callback(self, handler, message_type):
415 registers this xapp to call handler(summary, buf) when an rmr message is received of type message_type
420 a function with the signature (summary, sbuf) to be called
421 when a message of type message_type is received
423 the rmr message summary
424 sbuf: ctypes c_void_p
425 Pointer to an rmr message buffer. The user must call free on this when done.
428 the message type to look for
430 Note if this method is called multiple times for a single message type, the "last one wins".
432 self._dispatch[message_type] = handler
434 def run(self, thread=False, rmr_timeout=5, inotify_timeout=0):
436 This function should be called when the reactive Xapp is ready to start.
437 After start, the Xapp's handlers will be called on received messages.
441 thread: bool (optional, default is False)
442 If False, execution is not returned and the framework loops forever.
443 If True, a thread is started to run the queue read/dispatch loop
444 and execution is returned to caller; the thread can be stopped
445 by calling the .stop() method.
447 rmr_timeout: integer (optional, default is 5 seconds)
448 Length of time to wait for an RMR message to arrive.
450 inotify_timeout: integer (optional, default is 0 seconds)
451 Length of time to wait for an inotify event to arrive.
455 while self._keep_going:
459 (summary, sbuf) = self._rmr_loop.rcv_queue.get(block=True, timeout=rmr_timeout)
461 func = self._dispatch.get(summary[rmr.RMR_MS_MSG_TYPE], None)
463 func = self._default_handler
464 self.logger.debug("run: invoking msg handler on type {}".format(summary[rmr.RMR_MS_MSG_TYPE]))
465 func(self, summary, sbuf)
470 # poll configuration file watcher
472 events = self.config_check(timeout=inotify_timeout)
474 with open(self._config_path) as json_file:
475 data = json.load(json_file)
476 self.logger.debug("run: invoking config handler on change event {}".format(event))
477 self._config_handler(self, data)
478 except Exception as error:
479 self.logger.error("run: configuration handler failed: {}".format(error))
482 Thread(target=loop).start()
488 Sets the flag to end the dispatch loop.
491 self.logger.debug("Setting flag to end framework work loop.")
492 self._keep_going = False
495 class Xapp(_BaseXapp):
497 Represents a generic Xapp where the client provides a single function
498 for the framework to call at startup time (instead of providing callback
499 functions by message type). The Xapp writer must implement and provide a
500 function with a loop-forever construct similar to the `run` function in
501 the `RMRXapp` class. That function should poll to retrieve RMR messages
502 and dispatch them appropriately, poll for configuration changes, etc.
507 This function is called when the Xapp class's run method is invoked.
508 The function signature must be just function(self)
509 rmr_port: integer (optional, default is 4562)
510 Initialize RMR to listen on this port
511 rmr_wait_for_ready: boolean (optional, default is True)
512 Wait for RMR to signal ready before starting the dispatch loop
513 use_fake_sdl: boolean (optional, default is False)
514 Use an in-memory store instead of the real SDL service
517 def __init__(self, entrypoint, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False):
522 For the other parameters, see class _BaseXapp.
525 super().__init__(rmr_port=rmr_port, rmr_wait_for_ready=rmr_wait_for_ready, use_fake_sdl=use_fake_sdl)
526 self._entrypoint = entrypoint
530 This function should be called when the general Xapp is ready to start.
532 self._entrypoint(self)
534 # there is no need for stop currently here (base has, and nothing
535 # special to do here)