# ==================================================================================
-# Copyright (c) 2019 Nokia
-# Copyright (c) 2018-2019 AT&T Intellectual Property.
+# Copyright (c) 2019-2020 Nokia
+# Copyright (c) 2018-2020 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.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==================================================================================
+"""
+A1 RMR functionality
+"""
import os
-import gevent
-from rmr import rmr, helpers
-from a1 import get_module_logger
+import queue
+import time
+import json
+from threading import Thread
+from ricxappframe.rmr import rmr, helpers
+from mdclogpy import Logger
+from a1 import data, messages
+from a1.exceptions import PolicyTypeNotFound, PolicyInstanceNotFound
-logger = get_module_logger(__name__)
+mdc_logger = Logger(name=__name__)
-RETRY_TIMES = int(os.environ.get("RMR_RETRY_TIMES", 4))
-MRC = None
+# With Nanomsg and NNG it was possible for a send attempt to have a "soft"
+# failure which did warrant some retries if the status of the send is RMR_ERR_RETRY.
+# Because of the way NNG worked, it sometimes required many tens of retries,
+# and a retry state happened often for even moderately "verbose" applications.
+# With SI95 there is still a possibility that a retry is necessary, but it is very rare.
+RETRY_TIMES = int(os.environ.get("A1_RMR_RETRY_TIMES", 4))
+A1_POLICY_REQUEST = 20010
+A1_POLICY_RESPONSE = 20011
+A1_POLICY_QUERY = 20012
-def init_rmr():
+# Note; yes, globals are bad, but this is a private (to this module) global
+# No other module can import/access this (well, python doesn't enforce this, but all linters will complain)
+__RMR_LOOP__ = None
+
+
+class _RmrLoop:
"""
- called from run; not called for unit tests
+ Class represents an rmr loop that constantly reads from rmr and performs operations
+ based on waiting messages. This launches a thread, it should probably only be called
+ once; the public facing method to access these ensures this.
+
+ TODO: the xapp frame has a version of this looping structure. See if A1 can switch to that.
"""
- global MRC
- # rmr.RMRFL_MTCALL puts RMR into a multithreaded mode, where a receiving thread populates an
- # internal ring of messages, and receive calls read from that
- # currently the size is 2048 messages, so this is fine for the foreseeable future
- MRC = rmr.rmr_init(b"4562", rmr.RMR_MAX_RCV_BYTES, rmr.RMRFL_MTCALL)
- while rmr.rmr_ready(MRC) == 0:
- gevent.sleep(1)
- logger.debug("not yet ready")
+ def __init__(self, init_func_override=None, rcv_func_override=None):
+ """
+ Init
+
+ Parameters
+ ----------
+ init_func_override: function (optional)
+ Function that initializes RMR and answers an RMR context.
+ Supply an empty function to skip initializing RMR.
+
+ rcv_func_override: function (optional)
+ Function that receives messages from RMR and answers a list.
+ Supply a trivial function to skip reading from RMR.
+ """
+ self.keep_going = True
+ self.rcv_func = None
+ self.last_ran = time.time()
+
+ # see docs/overview#resiliency for a discussion of this
+ self.instance_send_queue = queue.Queue() # thread safe queue https://docs.python.org/3/library/queue.html
+
+ # intialize rmr context
+ if init_func_override:
+ self.mrc = init_func_override()
+ else:
+ mdc_logger.debug("Waiting for rmr to initialize..")
+ # rmr.RMRFL_MTCALL puts RMR into a multithreaded mode, where a receiving thread
+ # populates an internal ring of messages, and receive calls read from that.
+ # currently the size is 2048 messages, so this is fine for the foreseeable future
+ self.mrc = rmr.rmr_init(b"4562", rmr.RMR_MAX_RCV_BYTES, rmr.RMRFL_MTCALL)
+ while rmr.rmr_ready(self.mrc) == 0:
+ time.sleep(0.5)
+
+ # set the receive function
+ self.rcv_func = (
+ rcv_func_override
+ if rcv_func_override
+ else lambda: helpers.rmr_rcvall_msgs_raw(self.mrc, [A1_POLICY_RESPONSE, A1_POLICY_QUERY])
+ )
+
+ # start the work loop
+ self.thread = Thread(target=self.loop)
+ self.thread.start()
+
+ def _assert_good_send(self, sbuf, pre_send_summary):
+ """
+ Extracts the send result and logs a detailed warning if the send failed.
+ Returns the message state, an integer that indicates the result.
+ """
+ post_send_summary = rmr.message_summary(sbuf)
+ if post_send_summary[rmr.RMR_MS_MSG_STATE] != rmr.RMR_OK:
+ mdc_logger.warning("RMR send failed; pre-send summary: {0}, post-send summary: {1}".format(pre_send_summary, post_send_summary))
+ return post_send_summary[rmr.RMR_MS_MSG_STATE]
+
+ def _send_msg(self, pay, mtype, subid):
+ """
+ Creates and sends a message via RMR's send-message feature with the specified payload
+ using the specified message type and subscription ID.
+ """
+ sbuf = rmr.rmr_alloc_msg(self.mrc, len(pay), payload=pay, gen_transaction_id=True, mtype=mtype, sub_id=subid)
+ sbuf.contents.sub_id = subid
+ pre_send_summary = rmr.message_summary(sbuf)
+ for _ in range(0, RETRY_TIMES):
+ mdc_logger.debug("_send_msg: sending: {}".format(pre_send_summary))
+ sbuf = rmr.rmr_send_msg(self.mrc, sbuf)
+ msg_state = self._assert_good_send(sbuf, pre_send_summary)
+ mdc_logger.debug("_send_msg: result message state: {}".format(msg_state))
+ if msg_state != rmr.RMR_ERR_RETRY:
+ break
+
+ rmr.rmr_free_msg(sbuf)
+ if msg_state != rmr.RMR_OK:
+ mdc_logger.warning("_send_msg: failed after {} retries".format(RETRY_TIMES))
+
+ def _rts_msg(self, pay, sbuf_rts, mtype):
+ """
+ Sends a message via RMR's return-to-sender feature.
+ This neither allocates nor frees a message buffer because we may rts many times.
+ Returns the message buffer from the RTS function, which may reallocate it.
+ """
+ pre_send_summary = rmr.message_summary(sbuf_rts)
+ for _ in range(0, RETRY_TIMES):
+ mdc_logger.debug("_rts_msg: sending: {}".format(pre_send_summary))
+ sbuf_rts = rmr.rmr_rts_msg(self.mrc, sbuf_rts, payload=pay, mtype=mtype)
+ msg_state = self._assert_good_send(sbuf_rts, pre_send_summary)
+ mdc_logger.debug("_rts_msg: result message state: {}".format(msg_state))
+ if msg_state != rmr.RMR_ERR_RETRY:
+ break
+
+ if msg_state != rmr.RMR_OK:
+ mdc_logger.warning("_rts_msg: failed after {} retries".format(RETRY_TIMES))
+ return sbuf_rts # in some cases rts may return a new sbuf
+
+ def _handle_sends(self):
+ # send out all messages waiting for us
+ while not self.instance_send_queue.empty():
+ work_item = self.instance_send_queue.get(block=False, timeout=None)
+ payload = json.dumps(messages.a1_to_handler(*work_item)).encode("utf-8")
+ self._send_msg(payload, A1_POLICY_REQUEST, work_item[1])
+
+ def loop(self):
+ """
+ This loop runs forever, and has 3 jobs:
+ - send out any messages that have to go out (create instance, delete instance)
+ - read a1s mailbox and update the status of all instances based on acks from downstream policy handlers
+ - clean up the database (eg delete the instance) under certain conditions based on those statuses (NOT DONE YET)
+ """
+ # loop forever
+ mdc_logger.debug("Work loop starting")
+ while self.keep_going:
+
+ # Update 3/20/2020
+ # We now handle our sends in a thread (that will just exit when it's done) because there is a difference between how send works in SI95 vs NNG.
+ # Send_msg via NNG formerly never blocked.
+ # However under SI95 this send may block for some arbitrary period of time on the first send to an endpoint for which a connection is not established
+ # If this send takes too long, this loop blocks, and the healthcheck will fail, which will cause A1s healthcheck to fail, which will cause Kubernetes to whack A1 and all kinds of horrible things happen.
+ # Therefore, now under SI95, we thread this.
+ Thread(target=self._handle_sends).start()
+
+ # read our mailbox
+ for (msg, sbuf) in self.rcv_func():
+ # TODO: in the future we may also have to catch SDL errors
+ try:
+ mtype = msg[rmr.RMR_MS_MSG_TYPE]
+ except (KeyError, TypeError, json.decoder.JSONDecodeError):
+ mdc_logger.warning("Dropping malformed message: {0}".format(msg))
+ if mtype == A1_POLICY_RESPONSE:
+ try:
+ # got a policy response, update status
+ pay = json.loads(msg[rmr.RMR_MS_PAYLOAD])
+ data.set_policy_instance_status(
+ pay["policy_type_id"], pay["policy_instance_id"], pay["handler_id"], pay["status"]
+ )
+ mdc_logger.debug("Successfully received status update: {0}".format(pay))
+ except (PolicyTypeNotFound, PolicyInstanceNotFound):
+ mdc_logger.warning("Received a response for a non-existent type/instance: {0}".format(msg))
+ except (KeyError, TypeError, json.decoder.JSONDecodeError):
+ mdc_logger.warning("Dropping malformed policy response: {0}".format(msg))
-def send(payload, message_type=0):
+ elif mtype == A1_POLICY_QUERY:
+ try:
+ # got a query, do a lookup and send out all instances
+ pti = json.loads(msg[rmr.RMR_MS_PAYLOAD])["policy_type_id"]
+ instance_list = data.get_instance_list(pti) # will raise if a bad type
+ mdc_logger.debug("Received a query for a known policy type: {0}".format(msg))
+ for pii in instance_list:
+ instance = data.get_policy_instance(pti, pii)
+ payload = json.dumps(messages.a1_to_handler("CREATE", pti, pii, instance)).encode("utf-8")
+ sbuf = self._rts_msg(payload, sbuf, A1_POLICY_REQUEST)
+ except (PolicyTypeNotFound):
+ mdc_logger.warning("Received a policy query for a non-existent type: {0}".format(msg))
+ except (KeyError, TypeError, json.decoder.JSONDecodeError):
+ mdc_logger.warning("Dropping malformed policy query: {0}".format(msg))
+
+ else:
+ mdc_logger.warning("Received message type {0} but A1 does not handle this".format(mtype))
+
+ # we must free each sbuf
+ rmr.rmr_free_msg(sbuf)
+
+ self.last_ran = time.time()
+ time.sleep(1)
+
+ mdc_logger.debug("RMR Thread Ending!")
+
+
+# Public
+
+
+def start_rmr_thread(init_func_override=None, rcv_func_override=None):
"""
- Sends a message up to RETRY_TIMES
- If the message is sent successfully, it returns the transactionid
- Does nothing otherwise
+ Start a1s rmr thread
+
+ Parameters
+ ----------
+ init_func_override: function (optional)
+ Function that initializes RMR and answers an RMR context.
+ Supply an empty function to skip initializing RMR.
+
+ rcv_func_override: function (optional)
+ Function that receives messages from RMR and answers a list.
+ Supply a trivial function to skip reading from RMR.
"""
- # we may be called many times in asynchronous loops, so for now, it is safer not to share buffers. We can investigate later whether this is really a problem.
- sbuf = rmr.rmr_alloc_msg(MRC, 4096)
- payload = payload if isinstance(payload, bytes) else payload.encode("utf-8")
-
- # retry RETRY_TIMES to send the message
- for _ in range(0, RETRY_TIMES):
- # setup the send message
- rmr.set_payload_and_length(payload, sbuf)
- rmr.generate_and_set_transaction_id(sbuf)
- sbuf.contents.state = 0
- sbuf.contents.mtype = message_type
- pre_send_summary = rmr.message_summary(sbuf)
- logger.debug("Pre message send summary: %s", pre_send_summary)
- transaction_id = pre_send_summary["transaction id"] # save the transactionid because we need it later
+ global __RMR_LOOP__
+ if __RMR_LOOP__ is None:
+ __RMR_LOOP__ = _RmrLoop(init_func_override, rcv_func_override)
- # send
- sbuf = rmr.rmr_send_msg(MRC, sbuf)
- post_send_summary = rmr.message_summary(sbuf)
- logger.debug("Post message send summary: %s", rmr.message_summary(sbuf))
- # check success or failure
- if post_send_summary["message state"] == 0 and post_send_summary["message status"] == "RMR_OK":
- # we are good
- logger.debug("Message sent successfully!")
- rmr.rmr_free_msg(sbuf)
- return transaction_id
+def stop_rmr_thread():
+ """
+ stops the rmr thread
+ """
+ __RMR_LOOP__.keep_going = False
- # we failed all RETRY_TIMES
- logger.debug("Send failed all %s times, stopping", RETRY_TIMES)
- rmr.rmr_free_msg(sbuf)
- return None
+
+def queue_instance_send(item):
+ """
+ push an item into the work queue
+ currently the only type of work is to send out messages
+ """
+ __RMR_LOOP__.instance_send_queue.put(item)
-def dequeue_all_waiting_messages(filter_type=[]):
+def healthcheck_rmr_thread(seconds=30):
"""
- dequeue all waiting rmr messages from rmr
+ returns a boolean representing whether the rmr loop is healthy, by checking two attributes:
+ 1. is it running?,
+ 2. is it stuck in a long (> seconds) loop?
"""
- return helpers.rmr_rcvall_msgs(MRC, filter_type)
+ return __RMR_LOOP__.thread.is_alive() and ((time.time() - __RMR_LOOP__.last_ran) < seconds)
+
+
+def replace_rcv_func(rcv_func):
+ """purely for the ease of unit testing to test different rcv scenarios"""
+ __RMR_LOOP__.rcv_func = rcv_func
Code Review / ric-plt / a1.git / blobdiff