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Diffstat (limited to 'src/vpp-api/python/vpp_papi.py')
| -rw-r--r-- | src/vpp-api/python/vpp_papi.py | 891 |
1 files changed, 891 insertions, 0 deletions
diff --git a/src/vpp-api/python/vpp_papi.py b/src/vpp-api/python/vpp_papi.py new file mode 100644 index 00000000000..ece0e4ee52d --- /dev/null +++ b/src/vpp-api/python/vpp_papi.py @@ -0,0 +1,891 @@ +#!/usr/bin/env python +# +# Copyright (c) 2016 Cisco and/or its affiliates. +# 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. +# + +from __future__ import print_function +import sys +import os +import logging +import collections +import struct +import json +import threading +import fnmatch +import weakref +import atexit +from cffi import FFI +import cffi + +if sys.version[0] == '2': + import Queue as queue +else: + import queue as queue + +ffi = FFI() +ffi.cdef(""" +typedef void (*vac_callback_t)(unsigned char * data, int len); +typedef void (*vac_error_callback_t)(void *, unsigned char *, int); +int vac_connect(char * name, char * chroot_prefix, vac_callback_t cb, + int rx_qlen); +int vac_disconnect(void); +int vac_read(char **data, int *l, unsigned short timeout); +int vac_write(char *data, int len); +void vac_free(void * msg); + +int vac_get_msg_index(unsigned char * name); +int vac_msg_table_size(void); +int vac_msg_table_max_index(void); + +void vac_rx_suspend (void); +void vac_rx_resume (void); +void vac_set_error_handler(vac_error_callback_t); + """) + +# Barfs on failure, no need to check success. +vpp_api = ffi.dlopen('libvppapiclient.so') + + +def vpp_atexit(vpp_weakref): + """Clean up VPP connection on shutdown.""" + vpp_instance = vpp_weakref() + if vpp_instance.connected: + vpp_instance.logger.debug('Cleaning up VPP on exit') + vpp_instance.disconnect() + + +vpp_object = None + + +def vpp_iterator(d): + if sys.version[0] == '2': + return d.iteritems() + else: + return d.items() + + +@ffi.callback("void(unsigned char *, int)") +def vac_callback_sync(data, len): + vpp_object.msg_handler_sync(ffi.buffer(data, len)) + + +@ffi.callback("void(unsigned char *, int)") +def vac_callback_async(data, len): + vpp_object.msg_handler_async(ffi.buffer(data, len)) + + +@ffi.callback("void(void *, unsigned char *, int)") +def vac_error_handler(arg, msg, msg_len): + vpp_object.logger.warning("VPP API client:: %s", ffi.string(msg, msg_len)) + + +class Empty(object): + pass + + +class FuncWrapper(object): + def __init__(self, func): + self._func = func + self.__name__ = func.__name__ + + def __call__(self, **kwargs): + return self._func(**kwargs) + + +class VPP(): + """VPP interface. + + This class provides the APIs to VPP. The APIs are loaded + from provided .api.json files and makes functions accordingly. + These functions are documented in the VPP .api files, as they + are dynamically created. + + Additionally, VPP can send callback messages; this class + provides a means to register a callback function to receive + these messages in a background thread. + """ + def __init__(self, apifiles=None, testmode=False, async_thread=True, + logger=None, loglevel=None, + read_timeout=0): + """Create a VPP API object. + + apifiles is a list of files containing API + descriptions that will be loaded - methods will be + dynamically created reflecting these APIs. If not + provided this will load the API files from VPP's + default install location. + + logger, if supplied, is the logging logger object to log to. + loglevel, if supplied, is the log level this logger is set + to report at (from the loglevels in the logging module). + """ + global vpp_object + vpp_object = self + + if logger is None: + logger = logging.getLogger(__name__) + if loglevel is not None: + logger.setLevel(loglevel) + + self.logger = logger + + self.messages = {} + self.id_names = [] + self.id_msgdef = [] + self.connected = False + self.header = struct.Struct('>HI') + self.apifiles = [] + self.event_callback = None + self.message_queue = queue.Queue() + self.read_timeout = read_timeout + self.vpp_api = vpp_api + self.async_thread = async_thread + + if not apifiles: + # Pick up API definitions from default directory + try: + apifiles = self.find_api_files() + except RuntimeError: + # In test mode we don't care that we can't find the API files + if testmode: + apifiles = [] + else: + raise + + for file in apifiles: + with open(file) as apidef_file: + api = json.load(apidef_file) + for t in api['types']: + self.add_type(t[0], t[1:]) + + for m in api['messages']: + self.add_message(m[0], m[1:]) + self.apifiles = apifiles + + # Basic sanity check + if len(self.messages) == 0 and not testmode: + raise ValueError(1, 'Missing JSON message definitions') + + # Make sure we allow VPP to clean up the message rings. + atexit.register(vpp_atexit, weakref.ref(self)) + + # Register error handler + vpp_api.vac_set_error_handler(vac_error_handler) + + # Support legacy CFFI + # from_buffer supported from 1.8.0 + (major, minor, patch) = [int(s) for s in + cffi.__version__.split('.', 3)] + if major >= 1 and minor >= 8: + self._write = self._write_new_cffi + else: + self._write = self._write_legacy_cffi + + class ContextId(object): + """Thread-safe provider of unique context IDs.""" + def __init__(self): + self.context = 0 + self.lock = threading.Lock() + + def __call__(self): + """Get a new unique (or, at least, not recently used) context.""" + with self.lock: + self.context += 1 + return self.context + get_context = ContextId() + + @classmethod + def find_api_dir(cls): + """Attempt to find the best directory in which API definition + files may reside. If the value VPP_API_DIR exists in the environment + then it is first on the search list. If we're inside a recognized + location in a VPP source tree (src/scripts and src/vpp-api/python) + then entries from there to the likely locations in build-root are + added. Finally the location used by system packages is added. + + :returns: A single directory name, or None if no such directory + could be found. + """ + dirs = [] + + if 'VPP_API_DIR' in os.environ: + dirs.append(os.environ['VPP_API_DIR']) + + # perhaps we're in the 'src/scripts' or 'src/vpp-api/python' dir; + # in which case, plot a course to likely places in the src tree + import __main__ as main + if hasattr(main, '__file__'): + # get the path of the calling script + localdir = os.path.dirname(os.path.realpath(main.__file__)) + else: + # use cwd if there is no calling script + localdir = os.getcwd() + localdir_s = localdir.split(os.path.sep) + + def dmatch(dir): + """Match dir against right-hand components of the script dir""" + d = dir.split('/') # param 'dir' assumes a / separator + length = len(d) + return len(localdir_s) > length and localdir_s[-length:] == d + + def sdir(srcdir, variant): + """Build a path from srcdir to the staged API files of + 'variant' (typically '' or '_debug')""" + # Since 'core' and 'plugin' files are staged + # in separate directories, we target the parent dir. + return os.path.sep.join(( + srcdir, + 'build-root', + 'install-vpp%s-native' % variant, + 'vpp', + 'share', + 'vpp', + 'api', + )) + + srcdir = None + if dmatch('src/scripts'): + srcdir = os.path.sep.join(localdir_s[:-2]) + elif dmatch('src/vpp-api/python'): + srcdir = os.path.sep.join(localdir_s[:-3]) + elif dmatch('test'): + # we're apparently running tests + srcdir = os.path.sep.join(localdir_s[:-1]) + + if srcdir: + # we're in the source tree, try both the debug and release + # variants. + dirs.append(sdir(srcdir, '_debug')) + dirs.append(sdir(srcdir, '')) + + # Test for staged copies of the scripts + # For these, since we explicitly know if we're running a debug versus + # release variant, target only the relevant directory + if dmatch('build-root/install-vpp_debug-native/vpp/bin'): + srcdir = os.path.sep.join(localdir_s[:-4]) + dirs.append(sdir(srcdir, '_debug')) + if dmatch('build-root/install-vpp-native/vpp/bin'): + srcdir = os.path.sep.join(localdir_s[:-4]) + dirs.append(sdir(srcdir, '')) + + # finally, try the location system packages typically install into + dirs.append(os.path.sep.join(('', 'usr', 'share', 'vpp', 'api'))) + + # check the directories for existance; first one wins + for dir in dirs: + if os.path.isdir(dir): + return dir + + return None + + @classmethod + def find_api_files(cls, api_dir=None, patterns='*'): + """Find API definition files from the given directory tree with the + given pattern. If no directory is given then find_api_dir() is used + to locate one. If no pattern is given then all definition files found + in the directory tree are used. + + :param api_dir: A directory tree in which to locate API definition + files; subdirectories are descended into. + If this is None then find_api_dir() is called to discover it. + :param patterns: A list of patterns to use in each visited directory + when looking for files. + This can be a list/tuple object or a comma-separated string of + patterns. Each value in the list will have leading/trialing + whitespace stripped. + The pattern specifies the first part of the filename, '.api.json' + is appended. + The results are de-duplicated, thus overlapping patterns are fine. + If this is None it defaults to '*' meaning "all API files". + :returns: A list of file paths for the API files found. + """ + if api_dir is None: + api_dir = cls.find_api_dir() + if api_dir is None: + raise RuntimeError("api_dir cannot be located") + + if isinstance(patterns, list) or isinstance(patterns, tuple): + patterns = [p.strip() + '.api.json' for p in patterns] + else: + patterns = [p.strip() + '.api.json' for p in patterns.split(",")] + + api_files = [] + for root, dirnames, files in os.walk(api_dir): + # iterate all given patterns and de-dup the result + files = set(sum([fnmatch.filter(files, p) for p in patterns], [])) + for filename in files: + api_files.append(os.path.join(root, filename)) + + return api_files + + def status(self): + """Debug function: report current VPP API status to stdout.""" + print('Connected') if self.connected else print('Not Connected') + print('Read API definitions from', ', '.join(self.apifiles)) + + def __struct(self, t, n=None, e=-1, vl=None): + """Create a packing structure for a message.""" + base_types = {'u8': 'B', + 'u16': 'H', + 'u32': 'I', + 'i32': 'i', + 'u64': 'Q', + 'f64': 'd', } + + if t in base_types: + if not vl: + if e > 0 and t == 'u8': + # Fixed byte array + s = struct.Struct('>' + str(e) + 's') + return s.size, s + if e > 0: + # Fixed array of base type + s = struct.Struct('>' + base_types[t]) + return s.size, [e, s] + elif e == 0: + # Old style variable array + s = struct.Struct('>' + base_types[t]) + return s.size, [-1, s] + else: + # Variable length array + if t == 'u8': + s = struct.Struct('>s') + return s.size, [vl, s] + else: + s = struct.Struct('>' + base_types[t]) + return s.size, [vl, s] + + s = struct.Struct('>' + base_types[t]) + return s.size, s + + if t in self.messages: + size = self.messages[t]['sizes'][0] + + # Return a list in case of array + if e > 0 and not vl: + return size, [e, lambda self, encode, buf, offset, args: ( + self.__struct_type(encode, self.messages[t], buf, offset, + args))] + if vl: + return size, [vl, lambda self, encode, buf, offset, args: ( + self.__struct_type(encode, self.messages[t], buf, offset, + args))] + elif e == 0: + # Old style VLA + raise NotImplementedError(1, + 'No support for compound types ' + t) + return size, lambda self, encode, buf, offset, args: ( + self.__struct_type(encode, self.messages[t], buf, offset, args) + ) + + raise ValueError(1, 'Invalid message type: ' + t) + + def __struct_type(self, encode, msgdef, buf, offset, kwargs): + """Get a message packer or unpacker.""" + if encode: + return self.__struct_type_encode(msgdef, buf, offset, kwargs) + else: + return self.__struct_type_decode(msgdef, buf, offset) + + def __struct_type_encode(self, msgdef, buf, offset, kwargs): + off = offset + size = 0 + + for k in kwargs: + if k not in msgdef['args']: + raise ValueError(1, 'Non existing argument [' + k + ']' + + ' used in call to: ' + + self.id_names[kwargs['_vl_msg_id']] + '()') + + for k, v in vpp_iterator(msgdef['args']): + off += size + if k in kwargs: + if type(v) is list: + if callable(v[1]): + e = kwargs[v[0]] if v[0] in kwargs else v[0] + if e != len(kwargs[k]): + raise (ValueError(1, + 'Input list length mismatch: ' + '%s (%s != %s)' % + (k, e, len(kwargs[k])))) + size = 0 + for i in range(e): + size += v[1](self, True, buf, off + size, + kwargs[k][i]) + else: + if v[0] in kwargs: + kwargslen = kwargs[v[0]] + if kwargslen != len(kwargs[k]): + raise ValueError(1, + 'Input list length mismatch:' + ' %s (%s != %s)' % + (k, kwargslen, + len(kwargs[k]))) + else: + kwargslen = len(kwargs[k]) + if v[1].size == 1: + buf[off:off + kwargslen] = bytearray(kwargs[k]) + size = kwargslen + else: + size = 0 + for i in kwargs[k]: + v[1].pack_into(buf, off + size, i) + size += v[1].size + else: + if callable(v): + size = v(self, True, buf, off, kwargs[k]) + else: + if type(kwargs[k]) is str and v.size < len(kwargs[k]): + raise ValueError(1, + 'Input list length mismatch: ' + '%s (%s < %s)' % + (k, v.size, len(kwargs[k]))) + v.pack_into(buf, off, kwargs[k]) + size = v.size + else: + size = v.size if not type(v) is list else 0 + + return off + size - offset + + def __getitem__(self, name): + if name in self.messages: + return self.messages[name] + return None + + def get_size(self, sizes, kwargs): + total_size = sizes[0] + for e in sizes[1]: + if e in kwargs and type(kwargs[e]) is list: + total_size += len(kwargs[e]) * sizes[1][e] + return total_size + + def encode(self, msgdef, kwargs): + # Make suitably large buffer + size = self.get_size(msgdef['sizes'], kwargs) + buf = bytearray(size) + offset = 0 + size = self.__struct_type(True, msgdef, buf, offset, kwargs) + return buf[:offset + size] + + def decode(self, msgdef, buf): + return self.__struct_type(False, msgdef, buf, 0, None)[1] + + def __struct_type_decode(self, msgdef, buf, offset): + res = [] + off = offset + size = 0 + for k, v in vpp_iterator(msgdef['args']): + off += size + if type(v) is list: + lst = [] + if callable(v[1]): # compound type + size = 0 + if v[0] in msgdef['args']: # vla + e = res[v[2]] + else: # fixed array + e = v[0] + res.append(lst) + for i in range(e): + (s, l) = v[1](self, False, buf, off + size, None) + lst.append(l) + size += s + continue + if v[1].size == 1: + if type(v[0]) is int: + size = len(buf) - off + else: + size = res[v[2]] + res.append(buf[off:off + size]) + else: + e = v[0] if type(v[0]) is int else res[v[2]] + if e == -1: + e = (len(buf) - off) / v[1].size + lst = [] + res.append(lst) + size = 0 + for i in range(e): + lst.append(v[1].unpack_from(buf, off + size)[0]) + size += v[1].size + else: + if callable(v): + size = 0 + (s, l) = v(self, False, buf, off, None) + res.append(l) + size += s + else: + res.append(v.unpack_from(buf, off)[0]) + size = v.size + + return off + size - offset, msgdef['return_tuple']._make(res) + + def ret_tup(self, name): + if name in self.messages and 'return_tuple' in self.messages[name]: + return self.messages[name]['return_tuple'] + return None + + def duplicate_check_ok(self, name, msgdef): + crc = None + for c in msgdef: + if type(c) is dict and 'crc' in c: + crc = c['crc'] + break + if crc: + # We can get duplicates because of imports + if crc == self.messages[name]['crc']: + return True + return False + + def add_message(self, name, msgdef, typeonly=False): + if name in self.messages: + if typeonly: + if self.duplicate_check_ok(name, msgdef): + return + raise ValueError('Duplicate message name: ' + name) + + args = collections.OrderedDict() + argtypes = collections.OrderedDict() + fields = [] + msg = {} + total_size = 0 + sizes = {} + for i, f in enumerate(msgdef): + if type(f) is dict and 'crc' in f: + msg['crc'] = f['crc'] + continue + field_type = f[0] + field_name = f[1] + if len(f) == 3 and f[2] == 0 and i != len(msgdef) - 2: + raise ValueError('Variable Length Array must be last: ' + name) + size, s = self.__struct(*f) + args[field_name] = s + if type(s) == list and type(s[0]) == int and \ + type(s[1]) == struct.Struct: + if s[0] < 0: + sizes[field_name] = size + else: + sizes[field_name] = size + total_size += s[0] * size + else: + sizes[field_name] = size + total_size += size + + argtypes[field_name] = field_type + if len(f) == 4: # Find offset to # elements field + idx = list(args.keys()).index(f[3]) - i + args[field_name].append(idx) + fields.append(field_name) + msg['return_tuple'] = collections.namedtuple(name, fields, + rename=True) + self.messages[name] = msg + self.messages[name]['args'] = args + self.messages[name]['argtypes'] = argtypes + self.messages[name]['typeonly'] = typeonly + self.messages[name]['sizes'] = [total_size, sizes] + return self.messages[name] + + def add_type(self, name, typedef): + return self.add_message('vl_api_' + name + '_t', typedef, + typeonly=True) + + def make_function(self, name, i, msgdef, multipart, async): + if (async): + def f(**kwargs): + return self._call_vpp_async(i, msgdef, **kwargs) + else: + def f(**kwargs): + return self._call_vpp(i, msgdef, multipart, **kwargs) + args = self.messages[name]['args'] + argtypes = self.messages[name]['argtypes'] + f.__name__ = str(name) + f.__doc__ = ", ".join(["%s %s" % + (argtypes[k], k) for k in args.keys()]) + return f + + @property + def api(self): + if not hasattr(self, "_api"): + raise Exception("Not connected, api definitions not available") + return self._api + + def _register_functions(self, async=False): + self.id_names = [None] * (self.vpp_dictionary_maxid + 1) + self.id_msgdef = [None] * (self.vpp_dictionary_maxid + 1) + self._api = Empty() + for name, msgdef in vpp_iterator(self.messages): + if self.messages[name]['typeonly']: + continue + crc = self.messages[name]['crc'] + n = name + '_' + crc[2:] + i = vpp_api.vac_get_msg_index(n.encode()) + if i > 0: + self.id_msgdef[i] = msgdef + self.id_names[i] = name + multipart = True if name.find('_dump') > 0 else False + f = self.make_function(name, i, msgdef, multipart, async) + setattr(self._api, name, FuncWrapper(f)) + else: + self.logger.debug( + 'No such message type or failed CRC checksum: %s', n) + + def _write_new_cffi(self, buf): + """Send a binary-packed message to VPP.""" + if not self.connected: + raise IOError(1, 'Not connected') + return vpp_api.vac_write(ffi.from_buffer(buf), len(buf)) + + def _write_legacy_cffi(self, buf): + """Send a binary-packed message to VPP.""" + if not self.connected: + raise IOError(1, 'Not connected') + return vpp_api.vac_write(bytes(buf), len(buf)) + + def _read(self): + if not self.connected: + raise IOError(1, 'Not connected') + mem = ffi.new("char **") + size = ffi.new("int *") + rv = vpp_api.vac_read(mem, size, self.read_timeout) + if rv: + raise IOError(rv, 'vac_read failed') + msg = bytes(ffi.buffer(mem[0], size[0])) + vpp_api.vac_free(mem[0]) + return msg + + def connect_internal(self, name, msg_handler, chroot_prefix, rx_qlen, + async): + pfx = chroot_prefix.encode() if chroot_prefix else ffi.NULL + rv = vpp_api.vac_connect(name.encode(), pfx, msg_handler, rx_qlen) + if rv != 0: + raise IOError(2, 'Connect failed') + self.connected = True + + self.vpp_dictionary_maxid = vpp_api.vac_msg_table_max_index() + self._register_functions(async=async) + + # Initialise control ping + crc = self.messages['control_ping']['crc'] + self.control_ping_index = vpp_api.vac_get_msg_index( + ('control_ping' + '_' + crc[2:]).encode()) + self.control_ping_msgdef = self.messages['control_ping'] + if self.async_thread: + self.event_thread = threading.Thread( + target=self.thread_msg_handler) + self.event_thread.daemon = True + self.event_thread.start() + return rv + + def connect(self, name, chroot_prefix=None, async=False, rx_qlen=32): + """Attach to VPP. + + name - the name of the client. + chroot_prefix - if VPP is chroot'ed, the prefix of the jail + async - if true, messages are sent without waiting for a reply + rx_qlen - the length of the VPP message receive queue between + client and server. + """ + msg_handler = vac_callback_sync if not async else vac_callback_async + return self.connect_internal(name, msg_handler, chroot_prefix, rx_qlen, + async) + + def connect_sync(self, name, chroot_prefix=None, rx_qlen=32): + """Attach to VPP in synchronous mode. Application must poll for events. + + name - the name of the client. + chroot_prefix - if VPP is chroot'ed, the prefix of the jail + rx_qlen - the length of the VPP message receive queue between + client and server. + """ + + return self.connect_internal(name, ffi.NULL, chroot_prefix, rx_qlen, + async=False) + + def disconnect(self): + """Detach from VPP.""" + rv = vpp_api.vac_disconnect() + self.connected = False + self.message_queue.put("terminate event thread") + return rv + + def msg_handler_sync(self, msg): + """Process an incoming message from VPP in sync mode. + + The message may be a reply or it may be an async notification. + """ + r = self.decode_incoming_msg(msg) + if r is None: + return + + # If we have a context, then use the context to find any + # request waiting for a reply + context = 0 + if hasattr(r, 'context') and r.context > 0: + context = r.context + + if context == 0: + # No context -> async notification that we feed to the callback + self.message_queue.put_nowait(r) + else: + raise IOError(2, 'RPC reply message received in event handler') + + def decode_incoming_msg(self, msg): + if not msg: + self.logger.warning('vpp_api.read failed') + return + + i, ci = self.header.unpack_from(msg, 0) + if self.id_names[i] == 'rx_thread_exit': + return + + # + # Decode message and returns a tuple. + # + msgdef = self.id_msgdef[i] + if not msgdef: + raise IOError(2, 'Reply message undefined') + + r = self.decode(msgdef, msg) + + return r + + def msg_handler_async(self, msg): + """Process a message from VPP in async mode. + + In async mode, all messages are returned to the callback. + """ + r = self.decode_incoming_msg(msg) + if r is None: + return + + msgname = type(r).__name__ + + if self.event_callback: + self.event_callback(msgname, r) + + def _control_ping(self, context): + """Send a ping command.""" + self._call_vpp_async(self.control_ping_index, + self.control_ping_msgdef, + context=context) + + def _call_vpp(self, i, msgdef, multipart, **kwargs): + """Given a message, send the message and await a reply. + + msgdef - the message packing definition + i - the message type index + multipart - True if the message returns multiple + messages in return. + context - context number - chosen at random if not + supplied. + The remainder of the kwargs are the arguments to the API call. + + The return value is the message or message array containing + the response. It will raise an IOError exception if there was + no response within the timeout window. + """ + + if 'context' not in kwargs: + context = self.get_context() + kwargs['context'] = context + else: + context = kwargs['context'] + kwargs['_vl_msg_id'] = i + b = self.encode(msgdef, kwargs) + + vpp_api.vac_rx_suspend() + self._write(b) + + if multipart: + # Send a ping after the request - we use its response + # to detect that we have seen all results. + self._control_ping(context) + + # Block until we get a reply. + rl = [] + while (True): + msg = self._read() + if not msg: + raise IOError(2, 'VPP API client: read failed') + + r = self.decode_incoming_msg(msg) + msgname = type(r).__name__ + if context not in r or r.context == 0 or context != r.context: + self.message_queue.put_nowait(r) + continue + + if not multipart: + rl = r + break + if msgname == 'control_ping_reply': + break + + rl.append(r) + + vpp_api.vac_rx_resume() + + return rl + + def _call_vpp_async(self, i, msgdef, **kwargs): + """Given a message, send the message and await a reply. + + msgdef - the message packing definition + i - the message type index + context - context number - chosen at random if not + supplied. + The remainder of the kwargs are the arguments to the API call. + """ + if 'context' not in kwargs: + context = self.get_context() + kwargs['context'] = context + else: + context = kwargs['context'] + kwargs['_vl_msg_id'] = i + b = self.encode(msgdef, kwargs) + + self._write(b) + + def register_event_callback(self, callback): + """Register a callback for async messages. + + This will be called for async notifications in sync mode, + and all messages in async mode. In sync mode, replies to + requests will not come here. + + callback is a fn(msg_type_name, msg_type) that will be + called when a message comes in. While this function is + executing, note that (a) you are in a background thread and + may wish to use threading.Lock to protect your datastructures, + and (b) message processing from VPP will stop (so if you take + a long while about it you may provoke reply timeouts or cause + VPP to fill the RX buffer). Passing None will disable the + callback. + """ + self.event_callback = callback + + def thread_msg_handler(self): + """Python thread calling the user registerd message handler. + + This is to emulate the old style event callback scheme. Modern + clients should provide their own thread to poll the event + queue. + """ + while True: + r = self.message_queue.get() + if r == "terminate event thread": + break + msgname = type(r).__name__ + if self.event_callback: + self.event_callback(msgname, r) + + +# vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4 |