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 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(namespace, key, value, usemsgpack)
217 def sdl_get(self, namespace, 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(namespace, key, usemsgpack)
242 def sdl_find_and_get(self, namespace, 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(namespace, prefix, usemsgpack)
270 def sdl_delete(self, namespace, key):
272 Deletes the key-value pair with the specified key in the specified namespace.
281 self._sdl.delete(namespace, 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., the Xapp
336 only performs an action when a message is received. Clients should
337 invoke the run method, which has a loop that waits for RMR messages
338 and calls the appropriate client-registered consume callback on each.
340 If environment variable CONFIG_FILE is defined, and that variable
341 contains a path to an existing file, this class polls a watcher
342 defined on that file to detect file-write events, and invokes a
343 configuration-change handler on each event. The handler is also
344 invoked at startup. If no handler function is supplied to the
345 constructor, this class defines a default handler that only logs a
350 default_handler: function
351 A function with the signature (summary, sbuf) to be called when a
352 message type is received for which no other handler is registered.
353 default_handler argument summary: dict
354 The RMR message summary, a dict of key-value pairs
355 default_handler argument sbuf: ctypes c_void_p
356 Pointer to an RMR message buffer. The user must call free on this when done.
357 config_handler: function (optional, default is documented above)
358 A function with the signature (json) to be called at startup and each time
359 a configuration-file change event is detected. The JSON object is read from
360 the configuration file, if the prerequisites are met.
361 config_handler argument json: dict
362 The contents of the configuration file, parsed as JSON.
363 rmr_port: integer (optional, default is 4562)
364 Initialize RMR to listen on this port
365 rmr_wait_for_ready: boolean (optional, default is True)
366 Wait for RMR to signal ready before starting the dispatch loop
367 use_fake_sdl: boolean (optional, default is False)
368 Use an in-memory store instead of the real SDL service
369 post_init: function (optional, default None)
370 Run this function after the app initializes and before the dispatch loop starts;
371 its signature should be post_init(self)
374 def __init__(self, default_handler, config_handler=None, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False, post_init=None):
380 rmr_port=rmr_port, rmr_wait_for_ready=rmr_wait_for_ready, use_fake_sdl=use_fake_sdl, post_init=post_init
384 self._default_handler = default_handler
385 self._config_handler = config_handler
388 # used for thread control
389 self._keep_going = True
391 # register a default healthcheck handler
392 # this default checks that rmr is working and SDL is working
393 # the user can override this and register their own handler
394 # if they wish since the "last registered callback wins".
395 def handle_healthcheck(self, summary, sbuf):
396 healthy = self.healthcheck()
397 payload = b"OK\n" if healthy else b"ERROR [RMR or SDL is unhealthy]\n"
398 self.rmr_rts(sbuf, new_payload=payload, new_mtype=RIC_HEALTH_CHECK_RESP)
401 self.register_callback(handle_healthcheck, RIC_HEALTH_CHECK_REQ)
403 # define a default configuration-change handler if none was provided.
404 if not config_handler:
405 def handle_config_change(self, config):
406 self.logger.debug("xapp_frame: default config handler invoked")
407 self._config_handler = handle_config_change
409 # call the config handler at startup if prereqs were met
411 with open(self._config_path) as json_file:
412 data = json.load(json_file)
413 self.logger.debug("run: invoking config handler at start")
414 self._config_handler(self, data)
416 def register_callback(self, handler, message_type):
418 registers this xapp to call handler(summary, buf) when an rmr message is received of type message_type
423 a function with the signature (summary, sbuf) to be called
424 when a message of type message_type is received
426 the rmr message summary
427 sbuf: ctypes c_void_p
428 Pointer to an rmr message buffer. The user must call free on this when done.
431 the message type to look for
433 Note if this method is called multiple times for a single message type, the "last one wins".
435 self._dispatch[message_type] = handler
437 def run(self, thread=False, rmr_timeout=5, inotify_timeout=0):
439 This function should be called when the reactive Xapp is ready to start.
440 After start, the Xapp's handlers will be called on received messages.
444 thread: bool (optional, default is False)
445 If False, execution is not returned and the framework loops forever.
446 If True, a thread is started to run the queue read/dispatch loop
447 and execution is returned to caller; the thread can be stopped
448 by calling the .stop() method.
450 rmr_timeout: integer (optional, default is 5 seconds)
451 Length of time to wait for an RMR message to arrive.
453 inotify_timeout: integer (optional, default is 0 seconds)
454 Length of time to wait for an inotify event to arrive.
458 while self._keep_going:
462 (summary, sbuf) = self._rmr_loop.rcv_queue.get(block=True, timeout=rmr_timeout)
464 func = self._dispatch.get(summary[rmr.RMR_MS_MSG_TYPE], None)
466 func = self._default_handler
467 self.logger.debug("run: invoking msg handler on type {}".format(summary[rmr.RMR_MS_MSG_TYPE]))
468 func(self, summary, sbuf)
473 # poll configuration file watcher
475 events = self.config_check(timeout=inotify_timeout)
477 with open(self._config_path) as json_file:
478 data = json.load(json_file)
479 self.logger.debug("run: invoking config handler on change event {}".format(event))
480 self._config_handler(self, data)
481 except Exception as error:
482 self.logger.error("run: configuration handler failed: {}".format(error))
485 Thread(target=loop).start()
491 Sets the flag to end the dispatch loop.
494 self.logger.debug("Setting flag to end framework work loop.")
495 self._keep_going = False
498 class Xapp(_BaseXapp):
500 Represents a generic Xapp where the client provides a single function
501 for the framework to call at startup time (instead of providing callback
502 functions by message type). The Xapp writer must implement and provide a
503 function with a loop-forever construct similar to the `run` function in
504 the `RMRXapp` class. That function should poll to retrieve RMR messages
505 and dispatch them appropriately, poll for configuration changes, etc.
510 This function is called when the Xapp class's run method is invoked.
511 The function signature must be just function(self)
512 rmr_port: integer (optional, default is 4562)
513 Initialize RMR to listen on this port
514 rmr_wait_for_ready: boolean (optional, default is True)
515 Wait for RMR to signal ready before starting the dispatch loop
516 use_fake_sdl: boolean (optional, default is False)
517 Use an in-memory store instead of the real SDL service
520 def __init__(self, entrypoint, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False):
525 For the other parameters, see class _BaseXapp.
528 super().__init__(rmr_port=rmr_port, rmr_wait_for_ready=rmr_wait_for_ready, use_fake_sdl=use_fake_sdl)
529 self._entrypoint = entrypoint
533 This function should be called when the general Xapp is ready to start.
535 self._entrypoint(self)
537 # there is no need for stop currently here (base has, and nothing
538 # special to do here)