X-Git-Url: https://gerrit.o-ran-sc.org/r/gitweb?a=blobdiff_plain;f=ricxappframe%2Fxapp_frame.py;h=994e52b1d7091ab7f16c2110c339c861f2048d6c;hb=refs%2Fchanges%2F68%2F4268%2F1;hp=4321852ddbc145d1c170364571347c2a8a672c2e;hpb=bbc9028aa34ae48e7806596cd05fbe7a5bfd7fb8;p=ric-plt%2Fxapp-frame-py.git diff --git a/ricxappframe/xapp_frame.py b/ricxappframe/xapp_frame.py index 4321852..994e52b 100644 --- a/ricxappframe/xapp_frame.py +++ b/ricxappframe/xapp_frame.py @@ -15,54 +15,64 @@ # limitations under the License. # ================================================================================== """ -Framework for python xapps -Framework here means Xapp classes that can be subclassed +This framework for Python Xapps provides classes that Xapp writers should +instantiate and/or subclass depending on their needs. """ +import json +import os import queue from threading import Thread +import inotify_simple +from mdclogpy import Logger from ricxappframe import xapp_rmr from ricxappframe.rmr import rmr from ricxappframe.xapp_sdl import SDLWrapper -from mdclogpy import Logger -# constants +# message-type constants RIC_HEALTH_CHECK_REQ = 100 RIC_HEALTH_CHECK_RESP = 101 +# environment variable with path to configuration file +CONFIG_FILE_ENV = "CONFIG_FILE" # Private base class; not for direct client use class _BaseXapp: """ - Base xapp; not for client use directly + This base class initializes RMR by starting a thread that checks for + incoming messages, and provisions an SDL object. + + If environment variable CONFIG_FILE_ENV is defined, and that value is a + path to an existing file, a watcher is defined to monitor modifications + (writes) to that file using the Linux kernel's inotify feature, and the + configuration-change handler function is invoked. The watcher can be + polled by calling method config_check(). + + 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 the dbaas "fake dict backend" instead + of Redis or other backends. Set this to true when developing + an xapp or during unit testing to eliminate the need for DBAAS. + + post_init: function (optional) + Runs this user-provided function after the base xapp is + initialized; its signature should be post_init(self) """ 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) + Documented in the class comment. """ # PUBLIC, can be used by xapps using self.(name): self.logger = Logger(name=__name__) @@ -74,6 +84,17 @@ class _BaseXapp: # SDL self._sdl = SDLWrapper(use_fake_sdl) + # Config + # The environment variable specifies the path to the Xapp config file + self._config_path = os.environ.get(CONFIG_FILE_ENV, None) + if self._config_path and os.path.isfile(self._config_path): + self._inotify = inotify_simple.INotify() + self._inotify.add_watch(self._config_path, inotify_simple.flags.MODIFY) + self.logger.debug("__init__: watching config file {}".format(self._config_path)) + else: + self._inotify = None + self.logger.warning("__init__: NOT watching any config file") + # run the optionally provided user post init if post_init: post_init(self) @@ -150,7 +171,7 @@ class _BaseXapp: if sbuf.contents.state == 0: return True - self.logger.info("RTS Failed! Summary: {}".format(rmr.message_summary(sbuf))) + self.logger.warning("RTS Failed! Summary: {}".format(rmr.message_summary(sbuf))) return False def rmr_free(self, sbuf): @@ -168,82 +189,94 @@ class _BaseXapp: """ rmr.rmr_free_msg(sbuf) - # SDL - # NOTE, even though these are passthroughs, the seperate 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. + # Convenience (pass-thru) function for invoking SDL. def sdl_set(self, ns, key, value, usemsgpack=True): """ - set a key + Stores a key-value pair to SDL, optionally serializing the value + to bytes using msgpack. Parameters ---------- ns: string - the sdl namespace + SDL namespace key: string - the sdl key + SDL key value: - if usemsgpack is True, value can be anything serializable by msgpack - if usemsgpack is False, value must be bytes - usemsgpack: boolean (optional) - determines whether the value is serialized using msgpack + 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): """ - get a key + Gets the value for the specified namespace and key from SDL, + optionally deserializing stored bytes using msgpack. Parameters ---------- ns: string - the sdl namespace + SDL namespace key: string - the sdl key - usemsgpack: boolean (optional) - if usemsgpack is True, the value is deserialized using msgpack - if usemsgpack is False, the value is returned as raw bytes + 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 ------- - None (if not exist) or see above; depends on usemsgpack + 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): """ - get all k v pairs that start with prefix + 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 - the sdl namespace - key: string - the sdl key + SDL namespace prefix: string - the prefix - usemsgpack: boolean (optional) - if usemsgpack is True, the value returned is a dict where each value has been deserialized using msgpack - if usemsgpack is False, the value returned is as a dict mapping keys to raw bytes + 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 ------- - {} (if no keys match) or see above; depends on usemsgpack + 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): """ - delete a key + Deletes the key-value pair with the specified key in the specified namespace. Parameters ---------- ns: string - the sdl namespace + SDL namespace key: string - the sdl key + SDL key """ self._sdl.delete(ns, key) @@ -255,6 +288,32 @@ class _BaseXapp: """ return self._rmr_loop.healthcheck() and self._sdl.healthcheck() + # Convenience function for discovering config change events + + def config_check(self, timeout=0): + """ + Checks the watcher for configuration-file events. The watcher + prerequisites and event mask are documented in __init__(). + + Parameters + ---------- + timeout: int (optional) + Number of seconds to wait for a configuration-file event, default 0. + + Returns + ------- + List of Events, possibly empty + An event is a tuple with objects wd, mask, cookie and name. + For example:: + + Event(wd=1, mask=1073742080, cookie=0, name='foo') + + """ + if not self._inotify: + return [] + events = self._inotify.read(timeout=timeout) + return list(events) + def stop(self): """ cleans up and stops the xapp rmr thread (currently). This is @@ -267,34 +326,51 @@ class _BaseXapp: self._rmr_loop.stop() -# Public Classes to subclass (these subclass _BaseXapp) +# Public classes that Xapp writers should instantiate or subclass +# to implement an Xapp. class RMRXapp(_BaseXapp): """ - Represents an xapp that is purely driven by 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 - client-provided consume callback on every one. + 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. + + If environment variable CONFIG_FILE_ENV is defined, and that value is a + path to an existing file, the configuration-change handler is invoked at + startup and on each configuration-file write event. If no handler is + supplied, this class defines a default handler that logs each invocation. + + 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. + config_handler: function (optional, default is documented above) + A function with the signature (json) to be called at startup and each time + a configuration-file change event is detected. The JSON object is read from + the configuration file, if the prerequisites are met. + config_handler argument json: dict + The contents of the configuration file, parsed as JSON. + 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): + def __init__(self, default_handler, config_handler=None, rmr_port=4562, rmr_wait_for_ready=True, use_fake_sdl=False, post_init=None): """ - Parameters - ---------- - default_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. - post_init: function (optional) - optionally runs this function after the app initializes and - before the run loop; its signature should be post_init(self) - - For the other parameters, see _BaseXapp + Also see _BaseXapp """ # init base super().__init__( @@ -303,6 +379,7 @@ class RMRXapp(_BaseXapp): # setup callbacks self._default_handler = default_handler + self._config_handler = config_handler self._dispatch = {} # used for thread control @@ -320,6 +397,19 @@ class RMRXapp(_BaseXapp): self.register_callback(handle_healthcheck, RIC_HEALTH_CHECK_REQ) + # define a default configuration-change handler if none was provided. + if not config_handler: + def handle_config_change(self, config): + self.logger.debug("xapp_frame: default config handler invoked") + self._config_handler = handle_config_change + + # call the config handler at startup if prereqs were met + if self._inotify: + with open(self._config_path) as json_file: + data = json.load(json_file) + self.logger.debug("run: invoking config handler at start") + self._config_handler(self, data) + 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 @@ -341,33 +431,53 @@ class RMRXapp(_BaseXapp): """ self._dispatch[message_type] = handler - def run(self, thread=False): + def run(self, thread=False, rmr_timeout=5, inotify_timeout=0): """ - This function should be called when the client xapp is ready to - wait for its handlers to be called on received messages. + 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) + 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 .stop(). If False (the default), execution is not - returned and the framework loops forever. + by calling the .stop() method. + + rmr_timeout: integer (optional, default is 5 seconds) + Length of time to wait for an RMR message to arrive. + + inotify_timeout: integer (optional, default is 0 seconds) + Length of time to wait for an inotify event to arrive. """ def loop(): while self._keep_going: + + # poll RMR try: - (summary, sbuf) = self._rmr_loop.rcv_queue.get(block=True, timeout=5) + (summary, sbuf) = self._rmr_loop.rcv_queue.get(block=True, timeout=rmr_timeout) # dispatch func = self._dispatch.get(summary[rmr.RMR_MS_MSG_TYPE], None) if not func: func = self._default_handler + self.logger.debug("run: invoking msg handler on type {}".format(summary[rmr.RMR_MS_MSG_TYPE])) func(self, summary, sbuf) except queue.Empty: # the get timed out pass + # poll configuration file watcher + try: + events = self.config_check(timeout=inotify_timeout) + for event in events: + with open(self._config_path) as json_file: + data = json.load(json_file) + self.logger.debug("run: invoking config handler on change event {}".format(event)) + self._config_handler(self, data) + except Exception as error: + self.logger.error("run: configuration handler failed: {}".format(error)) + if thread: Thread(target=loop).start() else: @@ -384,19 +494,32 @@ class RMRXapp(_BaseXapp): class Xapp(_BaseXapp): """ - Represents an xapp where the client provides a generic function to - call, which is mostly likely a loop-forever loop. + Represents a generic Xapp where the client provides a single function + for the framework to call at startup time (instead of providing callback + functions by message type). The Xapp writer must implement and provide a + function with a loop-forever construct similar to the `run` function in + the `RMRXapp` class. That function should poll to retrieve RMR messages + and dispatch them appropriately, poll for configuration changes, etc. + + 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 ---------- - entrypoint: function - this function is called when the xapp runs; this is the user code. - its signature should be function(self) - For the other parameters, see _BaseXapp + 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) @@ -404,8 +527,7 @@ class Xapp(_BaseXapp): def run(self): """ - This function should be called when the client xapp is ready to - start their code. + This function should be called when the general Xapp is ready to start. """ self._entrypoint(self)