# ==================================================================================
# Copyright (c) 2020 Nokia
# Copyright (c) 2020 AT&T Intellectual Property.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==================================================================================
"""
Framework for python xapps
Framework here means Xapp classes that can be subclassed
"""
import queue
from threading import Thread
from ricxappframe import xapp_rmr
from ricxappframe.rmr import rmr
from ricxappframe.xapp_sdl import SDLWrapper
from mdclogpy import Logger
# constants
RIC_HEALTH_CHECK_REQ = 100
RIC_HEALTH_CHECK_RESP = 101
# Private base class; not for direct client use
class _BaseXapp:
"""
Base xapp; not for client use directly
"""
def __init__(self, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False, post_init=None):
"""
Init
Parameters
----------
rmr_port: int
port to listen on
rmr_wait_for_ready: bool (optional)
if this is True, then init waits until rmr is ready to send, which
includes having a valid routing file. This can be set to
False if the client only wants to *receive only*.
use_fake_sdl: bool (optional)
if this is True, it uses dbaas' "fake dict backend" instead
of Redis or other backends. Set this to true when developing
your xapp or during unit testing to completely avoid needing
a dbaas running or any network at all.
post_init: function (optional)
runs this user provided function after the base xapp is
initialized; its signature should be post_init(self)
"""
# PUBLIC, can be used by xapps using self.(name):
self.logger = Logger(name=__name__)
# Start rmr rcv thread
self._rmr_loop = xapp_rmr.RmrLoop(port=rmr_port, wait_for_ready=rmr_wait_for_ready)
self._mrc = self._rmr_loop.mrc # for convenience
# SDL
self._sdl = SDLWrapper(use_fake_sdl)
# run the optionally provided user post init
if post_init:
post_init(self)
# Public rmr methods
def rmr_get_messages(self):
"""
Returns a generator iterable over all items in the queue that
have not yet been read by the client xapp. Each item is a tuple
(S, sbuf) where S is a message summary dict and sbuf is the raw
message. The caller MUST call rmr.rmr_free_msg(sbuf) when
finished with each sbuf to prevent memory leaks!
"""
while not self._rmr_loop.rcv_queue.empty():
(summary, sbuf) = self._rmr_loop.rcv_queue.get()
yield (summary, sbuf)
def rmr_send(self, payload, mtype, retries=100):
"""
Allocates a buffer, sets payload and mtype, and sends
Parameters
----------
payload: bytes
payload to set
mtype: int
message type
retries: int (optional)
Number of times to retry at the application level before excepting RMRFailure
Returns
-------
bool
whether or not the send worked after retries attempts
"""
sbuf = rmr.rmr_alloc_msg(vctx=self._mrc, size=len(payload), payload=payload, gen_transaction_id=True, mtype=mtype)
for _ in range(retries):
sbuf = rmr.rmr_send_msg(self._mrc, sbuf)
if sbuf.contents.state == 0:
self.rmr_free(sbuf)
return True
self.rmr_free(sbuf)
return False
def rmr_rts(self, sbuf, new_payload=None, new_mtype=None, retries=100):
"""
Allows the xapp to return to sender, possibly adjusting the
payload and message type before doing so. This does NOT free
the sbuf for the caller as the caller may wish to perform
multiple rts per buffer. The client needs to free.
Parameters
----------
sbuf: ctypes c_void_p
Pointer to an rmr message buffer
new_payload: bytes (optional)
New payload to set
new_mtype: int (optional)
New message type (replaces the received message)
retries: int (optional)
Number of times to retry at the application level before
throwing exception RMRFailure
Returns
-------
bool
whether or not the send worked after retries attempts
"""
for _ in range(retries):
sbuf = rmr.rmr_rts_msg(self._mrc, sbuf, payload=new_payload, mtype=new_mtype)
if sbuf.contents.state == 0:
return True
self.logger.info("RTS Failed! Summary: {}".format(rmr.message_summary(sbuf)))
return False
def rmr_free(self, sbuf):
"""
Frees an rmr message buffer after use
Note: this does not need to be a class method, self is not
used. However if we break it out as a function we need a home
for it.
Parameters
----------
sbuf: ctypes c_void_p
Pointer to an rmr message buffer
"""
rmr.rmr_free_msg(sbuf)
# SDL
# NOTE, even though these are passthroughs, the separate SDL wrapper
# is useful for other applications like A1. Therefore, we don't
# embed that SDLWrapper functionality here so that it can be
# instantiated on its own.
def sdl_set(self, ns, key, value, usemsgpack=True):
"""
Stores a key-value pair,
optionally serializing the value to bytes using msgpack.
Parameters
----------
ns: string
SDL namespace
key: string
SDL key
value:
Object or byte array to store. See the `usemsgpack` parameter.
usemsgpack: boolean (optional, default is True)
Determines whether the value is serialized using msgpack before storing.
If usemsgpack is True, the msgpack function `packb` is invoked
on the value to yield a byte array that is then sent to SDL.
Stated differently, if usemsgpack is True, the value can be anything
that is serializable by msgpack.
If usemsgpack is False, the value must be bytes.
"""
self._sdl.set(ns, key, value, usemsgpack)
def sdl_get(self, ns, key, usemsgpack=True):
"""
Gets the value for the specified namespace and key,
optionally deserializing stored bytes using msgpack.
Parameters
----------
ns: string
SDL namespace
key: string
SDL key
usemsgpack: boolean (optional, default is True)
If usemsgpack is True, the byte array stored by SDL is deserialized
using msgpack to yield the original object that was stored.
If usemsgpack is False, the byte array stored by SDL is returned
without further processing.
Returns
-------
Value
See the usemsgpack parameter for an explanation of the returned value type.
Answers None if the key is not found.
"""
return self._sdl.get(ns, key, usemsgpack)
def sdl_find_and_get(self, ns, prefix, usemsgpack=True):
"""
Gets all key-value pairs in the specified namespace
with keys that start with the specified prefix,
optionally deserializing stored bytes using msgpack.
Parameters
----------
ns: string
SDL namespace
prefix: string
the key prefix
usemsgpack: boolean (optional, default is True)
If usemsgpack is True, the byte array stored by SDL is deserialized
using msgpack to yield the original value that was stored.
If usemsgpack is False, the byte array stored by SDL is returned
without further processing.
Returns
-------
Dictionary of key-value pairs
Each key has the specified prefix.
The value object (its type) depends on the usemsgpack parameter,
but is either a Python object or raw bytes as discussed above.
Answers an empty dictionary if no keys matched the prefix.
"""
return self._sdl.find_and_get(ns, prefix, usemsgpack)
def sdl_delete(self, ns, key):
"""
Deletes the key-value pair with the specified key in the specified namespace.
Parameters
----------
ns: string
SDL namespace
key: string
SDL key
"""
self._sdl.delete(ns, key)
# Health
def healthcheck(self):
"""
this needs to be understood how this is supposed to work
"""
return self._rmr_loop.healthcheck() and self._sdl.healthcheck()
def stop(self):
"""
cleans up and stops the xapp rmr thread (currently). This is
critical for unit testing as pytest will never return if the
thread is running.
TODO: can we register a ctrl-c handler so this gets called on
ctrl-c? Because currently two ctrl-c are needed to stop.
"""
self._rmr_loop.stop()
# Public Classes to subclass (these subclass _BaseXapp)
[docs]class RMRXapp(_BaseXapp):
"""
Represents an Xapp that reacts only to RMR messages; i.e., when
messages are received, the Xapp does something. When run is called,
the xapp framework waits for RMR messages, and calls the appropriate
client-registered consume callback on each.
Parameters
----------
default_handler: function
A function with the signature (summary, sbuf) to be called
when a message type is received for which no other handler is registered.
default_handler argument summary: dict
The RMR message summary, a dict of key-value pairs
default_handler argument sbuf: ctypes c_void_p
Pointer to an RMR message buffer. The user must call free on this when done.
rmr_port: integer (optional, default is 4562)
Initialize RMR to listen on this port
rmr_wait_for_ready: boolean (optional, default is True)
Wait for RMR to signal ready before starting the dispatch loop
use_fake_sdl: boolean (optional, default is False)
Use an in-memory store instead of the real SDL service
post_init: function (optional, default None)
Run this function after the app initializes and before the dispatch loop starts;
its signature should be post_init(self)
"""
def __init__(self, default_handler, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False, post_init=None):
"""
Also see _BaseXapp
"""
# init base
super().__init__(
rmr_port=rmr_port, rmr_wait_for_ready=rmr_wait_for_ready, use_fake_sdl=use_fake_sdl, post_init=post_init
)
# setup callbacks
self._default_handler = default_handler
self._dispatch = {}
# used for thread control
self._keep_going = True
# register a default healthcheck handler
# this default checks that rmr is working and SDL is working
# the user can override this and register their own handler
# if they wish since the "last registered callback wins".
def handle_healthcheck(self, summary, sbuf):
ok = self.healthcheck()
payload = b"OK\n" if ok else b"ERROR [RMR or SDL is unhealthy]\n"
self.rmr_rts(sbuf, new_payload=payload, new_mtype=RIC_HEALTH_CHECK_RESP)
self.rmr_free(sbuf)
self.register_callback(handle_healthcheck, RIC_HEALTH_CHECK_REQ)
[docs] def register_callback(self, handler, message_type):
"""
registers this xapp to call handler(summary, buf) when an rmr message is received of type message_type
Parameters
----------
handler: function
a function with the signature (summary, sbuf) to be called
when a message of type message_type is received
summary: dict
the rmr message summary
sbuf: ctypes c_void_p
Pointer to an rmr message buffer. The user must call free on this when done.
message:type: int
the message type to look for
Note if this method is called multiple times for a single message type, the "last one wins".
"""
self._dispatch[message_type] = handler
[docs] def run(self, thread=False):
"""
This function should be called when the reactive Xapp is ready to start.
After start, the Xapp's handlers will be called on received messages.
Parameters
----------
thread: bool (optional, default is False)
If False, execution is not returned and the framework loops forever.
If True, a thread is started to run the queue read/dispatch loop
and execution is returned to caller; the thread can be stopped
by calling the .stop() method.
"""
def loop():
while self._keep_going:
try:
(summary, sbuf) = self._rmr_loop.rcv_queue.get(block=True, timeout=5)
# dispatch
func = self._dispatch.get(summary[rmr.RMR_MS_MSG_TYPE], None)
if not func:
func = self._default_handler
func(self, summary, sbuf)
except queue.Empty:
# the get timed out
pass
if thread:
Thread(target=loop).start()
else:
loop()
[docs] def stop(self):
"""
Sets the flag to end the dispatch loop.
"""
super().stop()
self.logger.debug("Setting flag to end framework work loop.")
self._keep_going = False
[docs]class Xapp(_BaseXapp):
"""
Represents a generic Xapp where the client provides a function for the framework to call,
which usually contains a loop-forever construct.
Parameters
----------
entrypoint: function
This function is called when the Xapp class's run method is invoked.
The function signature must be just function(self)
rmr_port: integer (optional, default is 4562)
Initialize RMR to listen on this port
rmr_wait_for_ready: boolean (optional, default is True)
Wait for RMR to signal ready before starting the dispatch loop
use_fake_sdl: boolean (optional, default is False)
Use an in-memory store instead of the real SDL service
"""
def __init__(self, entrypoint, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False):
"""
Parameters
----------
For the other parameters, see class _BaseXapp.
"""
# init base
super().__init__(rmr_port=rmr_port, rmr_wait_for_ready=rmr_wait_for_ready, use_fake_sdl=use_fake_sdl)
self._entrypoint = entrypoint
[docs] def run(self):
"""
This function should be called when the general Xapp is ready to start.
"""
self._entrypoint(self)
# there is no need for stop currently here (base has, and nothing
# special to do here)