API: Add support for type aliases
[vpp.git] / src / vpp-api / python / vpp_papi / vpp_papi.py
index 110f4b1..bd2682f 100644 (file)
 #
 
 from __future__ import print_function
-import sys, os, logging, collections, struct, json, threading, glob
+from __future__ import absolute_import
+import sys
+import os
+import logging
+import collections
+import struct
+import json
+import threading
+import fnmatch
+import weakref
 import atexit
+from . vpp_serializer import VPPType, VPPEnumType, VPPUnionType, BaseTypes
+from . vpp_serializer import VPPMessage, vpp_get_type, VPPTypeAlias
+from . vpp_format import VPPFormat
 
-logging.basicConfig(level=logging.DEBUG)
-import vpp_api
+if sys.version[0] == '2':
+    import Queue as queue
+else:
+    import queue as queue
 
-def eprint(*args, **kwargs):
-    """Print critical diagnostics to stderr."""
-    print(*args, file=sys.stderr, **kwargs)
 
-def vpp_atexit(self):
+class VppEnumType(type):
+    def __getattr__(cls, name):
+        t = vpp_get_type(name)
+        return t.enum
+
+
+# Python3
+# class VppEnum(metaclass=VppEnumType):
+#    pass
+class VppEnum(object):
+    __metaclass__ = VppEnumType
+
+
+def vpp_atexit(vpp_weakref):
     """Clean up VPP connection on shutdown."""
-    if self.connected:
-        eprint ('Cleaning up VPP on exit')
-        self.disconnect()
+    vpp_instance = vpp_weakref()
+    if vpp_instance and vpp_instance.transport.connected:
+        vpp_instance.logger.debug('Cleaning up VPP on exit')
+        vpp_instance.disconnect()
+
+
+def vpp_iterator(d):
+    if sys.version[0] == '2':
+        return d.iteritems()
+    else:
+        return d.items()
+
+
+class VppApiDynamicMethodHolder(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():
+
+class VPP(object):
     """VPP interface.
 
     This class provides the APIs to VPP.  The APIs are loaded
@@ -43,7 +89,66 @@ class VPP():
     provides a means to register a callback function to receive
     these messages in a background thread.
     """
-    def __init__(self, apifiles = None, testmode = False):
+
+    def process_json_file(self, apidef_file):
+        api = json.load(apidef_file)
+        types = {}
+        for t in api['enums']:
+            t[0] = 'vl_api_' + t[0] + '_t'
+            types[t[0]] = {'type': 'enum', 'data': t}
+        for t in api['unions']:
+            t[0] = 'vl_api_' + t[0] + '_t'
+            types[t[0]] = {'type': 'union', 'data': t}
+        for t in api['types']:
+            t[0] = 'vl_api_' + t[0] + '_t'
+            types[t[0]] = {'type': 'type', 'data': t}
+        for t, v in api['aliases'].items():
+            types['vl_api_' + t + '_t'] = {'type': 'alias', 'data': v}
+
+        i = 0
+        while True:
+            unresolved = {}
+            for k, v in types.items():
+                t = v['data']
+                if not vpp_get_type(k):
+                    if v['type'] == 'enum':
+                        try:
+                            VPPEnumType(t[0], t[1:])
+                        except ValueError:
+                            unresolved[k] = v
+                    elif v['type'] == 'union':
+                        try:
+                            VPPUnionType(t[0], t[1:])
+                        except ValueError:
+                            unresolved[k] = v
+                    elif v['type'] == 'type':
+                        try:
+                            VPPType(t[0], t[1:])
+                        except ValueError:
+                            unresolved[k] = v
+                    elif v['type'] == 'alias':
+                        try:
+                            VPPTypeAlias(k, t)
+                        except ValueError:
+                            unresolved[k] = v
+            if len(unresolved) == 0:
+                break
+            if i > 3:
+                raise ValueError('Unresolved type definitions {}'
+                                 .format(unresolved))
+            types = unresolved
+            i += 1
+
+        for m in api['messages']:
+            try:
+                self.messages[m[0]] = VPPMessage(m[0], m[1:])
+            except NotImplementedError:
+                self.logger.error('Not implemented error for {}'.format(m[0]))
+
+    def __init__(self, apifiles=None, testmode=False, async_thread=True,
+                 logger=None, loglevel=None,
+                 read_timeout=5, use_socket=False,
+                 server_address='/run/vpp-api.sock'):
         """Create a VPP API object.
 
         apifiles is a list of files containing API
@@ -51,379 +156,289 @@ class VPP():
         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).
         """
+        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.buffersize = 10000
-        self.connected = False
-        self.header = struct.Struct('>HI')
-        self.results_lock = threading.Lock()
-        self.results = {}
-        self.timeout = 5
+        self.header = VPPType('header', [['u16', 'msgid'],
+                                         ['u32', 'client_index']])
         self.apifiles = []
         self.event_callback = None
+        self.message_queue = queue.Queue()
+        self.read_timeout = read_timeout
+        self.async_thread = async_thread
+
+        if use_socket:
+            from . vpp_transport_socket import VppTransport
+        else:
+            from . vpp_transport_shmem import VppTransport
 
         if not apifiles:
             # Pick up API definitions from default directory
-            apifiles = glob.glob('/usr/share/vpp/api/*.api.json')
+            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:])
+                self.process_json_file(apidef_file)
 
-                for m in api['messages']:
-                    self.add_message(m[0], m[1:])
-       self.apifiles = apifiles
+        self.apifiles = apifiles
 
         # Basic sanity check
         if len(self.messages) == 0 and not testmode:
             raise ValueError(1, 'Missing JSON message definitions')
 
+        self.transport = VppTransport(self, read_timeout=read_timeout,
+                                      server_address=server_address)
         # Make sure we allow VPP to clean up the message rings.
-        atexit.register(vpp_atexit, self)
+        atexit.register(vpp_atexit, weakref.ref(self))
 
     class ContextId(object):
         """Thread-safe provider of unique context IDs."""
         def __init__(self):
             self.context = 0
-           self.lock = threading.Lock()
+            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
+            with self.lock:
+                self.context += 1
+                return self.context
     get_context = ContextId()
 
-    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',
-                       }
-        pack = None
-        if t in base_types:
-            pack = base_types[t]
-            if not vl:
-                if e > 0 and t == 'u8':
-                    # Fixed byte array
-                    return struct.Struct('>' + str(e) + 's')
-                if e > 0:
-                    # Fixed array of base type
-                    return [e, struct.Struct('>' + base_types[t])]
-                elif e == 0:
-                    # Old style variable array
-                    return [-1, struct.Struct('>' + base_types[t])]
-            else:
-                # Variable length array
-                return [vl, struct.Struct('>s')] if t == 'u8' else \
-                    [vl, struct.Struct('>' + base_types[t])]
-
-            return struct.Struct('>' + base_types[t])
-
-        if t in self.messages:
-            ### Return a list in case of array ###
-            if e > 0 and not vl:
-                return [e, lambda self, encode, buf, offset, args: (
-                    self.__struct_type(encode, self.messages[t], buf, offset,
-                                       args))]
-            if vl:
-                return [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 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, 'Invalid field-name in message call ' + k)
-
-        for k,v in msgdef['args'].iteritems():
-            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]
-                        size = 0
-                        for i in range(e):
-                            size += v[1](self, True, buf, off + size,
-                                         kwargs[k][i])
-                    else:
-                        if v[0] in kwargs:
-                            l = kwargs[v[0]]
-                        else:
-                            l = len(kwargs[k])
-                        if v[1].size == 1:
-                            buf[off:off + l] = bytearray(kwargs[k])
-                            size = l
-                        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:
-                        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 get_type(self, name):
+        return vpp_get_type(name)
 
+    @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.
 
-    def __getitem__(self, name):
-        if name in self.messages:
-            return self.messages[name]
-        return None
+        :returns: A single directory name, or None if no such directory
+            could be found.
+        """
+        dirs = []
 
-    def encode(self, msgdef, kwargs):
-        # Make suitably large buffer
-        buf = bytearray(self.buffersize)
-        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 msgdef['args'].iteritems():
-            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):
-                    (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
+        if 'VPP_API_DIR' in os.environ:
+            dirs.append(os.environ['VPP_API_DIR'])
 
-        return off + size - offset, msgdef['return_tuple']._make(res)
+        # 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
 
-    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 add_message(self, name, msgdef):
-        if name in self.messages:
-            raise ValueError('Duplicate message name: ' + name)
-
-        args = collections.OrderedDict()
-        argtypes = collections.OrderedDict()
-        fields = []
-        msg = {}
-        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)
-            args[field_name] = self.__struct(*f)
-            argtypes[field_name] = field_type
-            if len(f) == 4: # Find offset to # elements field
-                args[field_name].append(args.keys().index(f[3]) - i)
-            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
-        return self.messages[name]
-
-    def add_type(self, name, typedef):
-        return self.add_message('vl_api_' + name + '_t', typedef)
-
-    def make_function(self, name, i, msgdef, multipart, async):
-        if (async):
-            f = lambda **kwargs: (self._call_vpp_async(i, msgdef, **kwargs))
+    @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
+
+    @property
+    def api(self):
+        if not hasattr(self, "_api"):
+            raise Exception("Not connected, api definitions not available")
+        return self._api
+
+    def make_function(self, msg, i, multipart, do_async):
+        if (do_async):
+            def f(**kwargs):
+                return self._call_vpp_async(i, msg, **kwargs)
         else:
-            f = lambda **kwargs: (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()])
+            def f(**kwargs):
+                return self._call_vpp(i, msg, multipart, **kwargs)
+
+        f.__name__ = str(msg.name)
+        f.__doc__ = ", ".join(["%s %s" %
+                               (msg.fieldtypes[j], k)
+                               for j, k in enumerate(msg.fields)])
         return f
 
-    def _register_functions(self, async=False):
+    def _register_functions(self, do_async=False):
         self.id_names = [None] * (self.vpp_dictionary_maxid + 1)
         self.id_msgdef = [None] * (self.vpp_dictionary_maxid + 1)
-        for name, msgdef in self.messages.iteritems():
-            if name in self.vpp_dictionary:
-                if self.messages[name]['crc'] != self.vpp_dictionary[name]['crc']:
-                    raise ValueError(3, 'Failed CRC checksum ' + name +
-                                     ' ' + self.messages[name]['crc'] +
-                                     ' ' + self.vpp_dictionary[name]['crc'])
-                i = self.vpp_dictionary[name]['id']
-                self.id_msgdef[i] = msgdef
+        self._api = VppApiDynamicMethodHolder()
+        for name, msg in vpp_iterator(self.messages):
+            n = name + '_' + msg.crc[2:]
+            i = self.transport.get_msg_index(n.encode())
+            if i > 0:
+                self.id_msgdef[i] = msg
                 self.id_names[i] = name
+                # TODO: Fix multipart (use services)
                 multipart = True if name.find('_dump') > 0 else False
-                setattr(self, name, self.make_function(name, i, msgdef, multipart, async))
-
-    def _write (self, buf):
-        """Send a binary-packed message to VPP."""
-        if not self.connected:
-            raise IOError(1, 'Not connected')
-        return vpp_api.write(str(buf))
-
-    def _load_dictionary(self):
-        self.vpp_dictionary = {}
-        self.vpp_dictionary_maxid = 0
-        d = vpp_api.msg_table()
-
-        if not d:
-            raise IOError(3, 'Cannot get VPP API dictionary')
-        for i,n in d:
-            name, crc =  n.rsplit('_', 1)
-            crc = '0x' + crc
-            self.vpp_dictionary[name] = { 'id' : i, 'crc' : crc }
-            self.vpp_dictionary_maxid = max(self.vpp_dictionary_maxid, i)
-
-    def connect(self, name, chroot_prefix = None, async = False, rx_qlen = 32):
-        """Attach to VPP.
+                f = self.make_function(msg, i, multipart, do_async)
+                setattr(self._api, name, FuncWrapper(f))
+            else:
+                self.logger.debug(
+                    'No such message type or failed CRC checksum: %s', n)
 
-        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 = self.msg_handler_sync if not async else self.msg_handler_async
-       if chroot_prefix is not None:
-           rv = vpp_api.connect(name, msg_handler, rx_qlen, chroot_prefix)
-        else:
-           rv = vpp_api.connect(name, msg_handler, rx_qlen)
+    def connect_internal(self, name, msg_handler, chroot_prefix, rx_qlen,
+                         do_async):
+        pfx = chroot_prefix.encode() if chroot_prefix else None
 
+        rv = self.transport.connect(name.encode(), pfx, msg_handler, rx_qlen)
         if rv != 0:
             raise IOError(2, 'Connect failed')
-        self.connected = True
-
-        self._load_dictionary()
-        self._register_functions(async=async)
+        self.vpp_dictionary_maxid = self.transport.msg_table_max_index()
+        self._register_functions(do_async=do_async)
 
         # Initialise control ping
-        self.control_ping_index = self.vpp_dictionary['control_ping']['id']
+        crc = self.messages['control_ping'].crc
+        self.control_ping_index = self.transport.get_msg_index(
+            ('control_ping' + '_' + crc[2:]).encode())
         self.control_ping_msgdef = self.messages['control_ping']
-
-    def disconnect(self):
-        """Detach from VPP."""
-        rv = vpp_api.disconnect()
-        self.connected = False
+        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 results_wait(self, context):
-        """In a sync call, wait for the reply
+    def connect(self, name, chroot_prefix=None, do_async=False, rx_qlen=32):
+        """Attach to VPP.
 
-        The context ID is used to pair reply to request.
+        name - the name of the client.
+        chroot_prefix - if VPP is chroot'ed, the prefix of the jail
+        do_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 = self.transport.get_callback(do_async)
+        return self.connect_internal(name, msg_handler, chroot_prefix, rx_qlen,
+                                     do_async)
 
-        # Results is filled by the background callback.  It will
-        # raise the event when the context receives a response.
-        # Given there are two threads we have to be careful with the
-        # use of results and the structures under it, hence the lock.
-        with self.results_lock:
-            result = self.results[context]
-            ev = result['e']
-
-       timed_out = not ev.wait(self.timeout)
-
-       if timed_out:
-          raise IOError(3, 'Waiting for reply timed out')
-       else:
-           with self.results_lock:
-                result = self.results[context]
-               del self.results[context]
-               return result['r']
-
-    def results_prepare(self, context, multi=False):
-        """Prep for receiving a result in response to a request msg
-
-        context - unique context number sent in request and
-        returned in reply or replies
-        multi - true if we expect multiple messages from this
-        reply.
-        """
+    def connect_sync(self, name, chroot_prefix=None, rx_qlen=32):
+        """Attach to VPP in synchronous mode. Application must poll for events.
 
-        # The event is used to indicate that all results are in
-        new_result = {
-            'e': threading.Event(),
-        }
-        if multi:
-            # Make it clear to the BG thread it's going to see several
-            # messages; messages are stored in a results array
-            new_result['m'] = True
-            new_result['r'] = []
+        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.
+        """
 
-        new_result['e'].clear()
+        return self.connect_internal(name, None, chroot_prefix, rx_qlen,
+                                     do_async=False)
 
-        # Put the prepped result structure into results, at which point
-        # the bg thread can also access it (hence the thread lock)
-        with self.results_lock:
-            self.results[context] = new_result
+    def disconnect(self):
+        """Detach from VPP."""
+        rv = self.transport.disconnect()
+        self.message_queue.put("terminate event thread")
+        return rv
 
     def msg_handler_sync(self, msg):
         """Process an incoming message from VPP in sync mode.
@@ -440,55 +455,28 @@ class VPP():
         if hasattr(r, 'context') and r.context > 0:
             context = r.context
 
-        msgname = type(r).__name__
-
         if context == 0:
             # No context -> async notification that we feed to the callback
-           if self.event_callback:
-               self.event_callback(msgname, r)
+            self.message_queue.put_nowait(r)
         else:
-            # Context -> use the results structure (carefully) to find
-            # who we're responding to and return the message to that
-            # thread
-            with self.results_lock:
-                if context not in self.results:
-                    eprint('Not expecting results for this context', context, r)
-                else:
-                    result = self.results[context]
-
-                    #
-                    # Collect results until control ping
-                    #
-
-                    if msgname == 'control_ping_reply':
-                        # End of a multipart
-                        result['e'].set()
-                    elif 'm' in self.results[context]:
-                        # One element in a multipart
-                        result['r'].append(r)
-                    else:
-                        # All of a single result
-                        result['r'] = r
-                        result['e'].set()
+            raise IOError(2, 'RPC reply message received in event handler')
 
     def decode_incoming_msg(self, msg):
         if not msg:
-            eprint('vpp_api.read failed')
+            self.logger.warning('vpp_api.read failed')
             return
-
-        i, ci = self.header.unpack_from(msg, 0)
+        (i, ci), size = self.header.unpack(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:
+        msgobj = self.id_msgdef[i]
+        if not msgobj:
             raise IOError(2, 'Reply message undefined')
 
-        r = self.decode(msgdef, msg)
-
+        r, size = msgobj.unpack(msg)
         return r
 
     def msg_handler_async(self, msg):
@@ -502,16 +490,22 @@ class VPP():
 
         msgname = type(r).__name__
 
-       if self.event_callback:
-           self.event_callback(msgname, r)
+        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,
+                             self.control_ping_msgdef,
                              context=context)
 
-    def _call_vpp(self, i, msgdef, multipart, **kwargs):
+    def validate_args(self, msg, kwargs):
+        d = set(kwargs.keys()) - set(msg.field_by_name.keys())
+        if d:
+            raise ValueError('Invalid argument {} to {}'
+                             .format(list(d), msg.name))
+
+    def _call_vpp(self, i, msg, multipart, **kwargs):
         """Given a message, send the message and await a reply.
 
         msgdef - the message packing definition
@@ -527,16 +521,23 @@ class VPP():
         no response within the timeout window.
         """
 
-        # We need a context if not supplied, in order to get the
-        # response
-        context = kwargs.get('context', self.get_context())
-       kwargs['context'] = context
+        if 'context' not in kwargs:
+            context = self.get_context()
+            kwargs['context'] = context
+        else:
+            context = kwargs['context']
+        kwargs['_vl_msg_id'] = i
 
-        # Set up to receive a response
-        self.results_prepare(context, multi=multipart)
+        try:
+            if self.transport.socket_index:
+                kwargs['client_index'] = self.transport.socket_index
+        except AttributeError:
+            pass
+        self.validate_args(msg, kwargs)
+        b = msg.pack(kwargs)
+        self.transport.suspend()
 
-        # Output the message
-        self._call_vpp_async(i, msgdef, **kwargs)
+        self.transport.write(b)
 
         if multipart:
             # Send a ping after the request - we use its response
@@ -544,11 +545,31 @@ class VPP():
             self._control_ping(context)
 
         # Block until we get a reply.
-        r = self.results_wait(context)
+        rl = []
+        while (True):
+            msg = self.transport.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:
+                # Message being queued
+                self.message_queue.put_nowait(r)
+                continue
 
-        return r
+            if not multipart:
+                rl = r
+                break
+            if msgname == 'control_ping_reply':
+                break
+
+            rl.append(r)
+
+        self.transport.resume()
+
+        return rl
 
-    def _call_vpp_async(self, i, msgdef, **kwargs):
+    def _call_vpp_async(self, i, msg, **kwargs):
         """Given a message, send the message and await a reply.
 
         msgdef - the message packing definition
@@ -557,15 +578,20 @@ class VPP():
         supplied.
         The remainder of the kwargs are the arguments to the API call.
         """
-        if not 'context' in kwargs:
+        if 'context' not in kwargs:
             context = self.get_context()
             kwargs['context'] = context
         else:
             context = kwargs['context']
+        try:
+            if self.transport.socket_index:
+                kwargs['client_index'] = self.transport.socket_index
+        except AttributeError:
+            kwargs['client_index'] = 0
         kwargs['_vl_msg_id'] = i
-        b = self.encode(msgdef, kwargs)
+        b = msg.pack(kwargs)
 
-        self._write(b)
+        self.transport.write(b)
 
     def register_event_callback(self, callback):
         """Register a callback for async messages.
@@ -584,3 +610,21 @@ class VPP():
         callback.
         """
         self.event_callback = callback
+
+    def thread_msg_handler(self):
+        """Python thread calling the user registered 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