bindings/python/bt2/bt2/component.py

   1 # The MIT License (MIT)
   2 #
   3 # Copyright (c) 2017 Philippe Proulx <pproulx@efficios.com>
   4 #
   5 # Permission is hereby granted, free of charge, to any person obtaining a copy
   6 # of this software and associated documentation files (the "Software"), to deal
   7 # in the Software without restriction, including without limitation the rights
   8 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9 # copies of the Software, and to permit persons to whom the Software is
  10 # furnished to do so, subject to the following conditions:
  11 #
  12 # The above copyright notice and this permission notice shall be included in
  13 # all copies or substantial portions of the Software.
  14 #
  15 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21 # THE SOFTWARE.
  22
  23 from bt2 import native_bt, object, utils
  24 import bt2.notification_iterator
  25 import collections.abc
  26 import bt2.values
  27 import traceback
  28 import bt2.port
  29 import sys
  30 import bt2
  31 import os
  32
  33
  34 _env_var = os.environ.get('BABELTRACE_PYTHON_BT2_NO_TRACEBACK')
  35 _NO_PRINT_TRACEBACK = _env_var == '1'
  36
  37
  38 # This class wraps a component class pointer. This component class could
  39 # have been created by Python code, but since we only have the pointer,
  40 # we can only wrap it in a generic way and lose the original Python
  41 # class.
  42 class _GenericComponentClass(object._Object):
  43     @property
  44     def name(self):
  45         name = native_bt.component_class_get_name(self._ptr)
  46         assert(name is not None)
  47         return name
  48
  49     @property
  50     def description(self):
  51         return native_bt.component_class_get_description(self._ptr)
  52
  53     @property
  54     def help(self):
  55         return native_bt.component_class_get_help(self._ptr)
  56
  57     def query(self, obj, params=None):
  58         return _query(self._ptr, obj, params)
  59
  60     def __eq__(self, other):
  61         if not isinstance(other, _GenericComponentClass):
  62             try:
  63                 if not issubclass(other, _UserComponent):
  64                     return False
  65             except TypeError:
  66                 return False
  67
  68         return self.addr == other.addr
  69
  70
  71 class _GenericSourceComponentClass(_GenericComponentClass):
  72     pass
  73
  74
  75 class _GenericFilterComponentClass(_GenericComponentClass):
  76     pass
  77
  78
  79 class _GenericSinkComponentClass(_GenericComponentClass):
  80     pass
  81
  82
  83 def _handle_component_status(status, gen_error_msg):
  84     if status == native_bt.COMPONENT_STATUS_END:
  85         raise bt2.Stop
  86     elif status == native_bt.COMPONENT_STATUS_AGAIN:
  87         raise bt2.TryAgain
  88     elif status == native_bt.COMPONENT_STATUS_UNSUPPORTED:
  89         raise bt2.UnsupportedFeature
  90     elif status == native_bt.COMPONENT_STATUS_REFUSE_PORT_CONNECTION:
  91         raise bt2.PortConnectionRefused
  92     elif status == native_bt.COMPONENT_STATUS_GRAPH_IS_CANCELED:
  93         raise bt2.GraphCanceled
  94     elif status < 0:
  95         raise bt2.Error(gen_error_msg)
  96
  97
  98 class _PortIterator(collections.abc.Iterator):
  99     def __init__(self, comp_ports):
 100         self._comp_ports = comp_ports
 101         self._at = 0
 102
 103     def __next__(self):
 104         if self._at == len(self._comp_ports):
 105             raise StopIteration
 106
 107         comp_ports = self._comp_ports
 108         comp_ptr = comp_ports._component._ptr
 109         port_ptr = comp_ports._get_port_at_index_fn(comp_ptr, self._at)
 110         assert(port_ptr)
 111
 112         if comp_ports._is_private:
 113             port_pub_ptr = native_bt.port_from_private_port(port_ptr)
 114             name = native_bt.port_get_name(port_pub_ptr)
 115             native_bt.put(port_pub_ptr)
 116         else:
 117             name = native_bt.port_get_name(port_ptr)
 118
 119         assert(name is not None)
 120         native_bt.put(port_ptr)
 121         self._at += 1
 122         return name
 123
 124
 125 class _ComponentPorts(collections.abc.Mapping):
 126     def __init__(self, is_private, component,
 127                  get_port_by_name_fn, get_port_at_index_fn,
 128                  get_port_count_fn):
 129         self._is_private = is_private
 130         self._component = component
 131         self._get_port_by_name_fn = get_port_by_name_fn
 132         self._get_port_at_index_fn = get_port_at_index_fn
 133         self._get_port_count_fn = get_port_count_fn
 134
 135     def __getitem__(self, key):
 136         utils._check_str(key)
 137         port_ptr = self._get_port_by_name_fn(self._component._ptr, key)
 138
 139         if port_ptr is None:
 140             raise KeyError(key)
 141
 142         if self._is_private:
 143             return bt2.port._create_private_from_ptr(port_ptr)
 144         else:
 145             return bt2.port._create_from_ptr(port_ptr)
 146
 147     def __len__(self):
 148         if self._is_private:
 149             pub_ptr = native_bt.component_from_private_component(self._component._ptr)
 150             count = self._get_port_count_fn(pub_ptr)
 151             native_bt.put(pub_ptr)
 152         else:
 153             count = self._get_port_count_fn(self._component._ptr)
 154
 155         assert(count >= 0)
 156         return count
 157
 158     def __iter__(self):
 159         return _PortIterator(self)
 160
 161
 162 # This class holds the methods which are common to both generic
 163 # component objects and Python user component objects. They use the
 164 # internal native _ptr, however it was set, to call native API
 165 # functions.
 166 class _Component:
 167     @property
 168     def name(self):
 169         name = native_bt.component_get_name(self._ptr)
 170         assert(name is not None)
 171         return name
 172
 173     @property
 174     def graph(self):
 175         ptr = native_bt.component_get_graph(self._ptr)
 176         assert(ptr)
 177         return bt2.Graph._create_from_ptr(ptr)
 178
 179     @property
 180     def component_class(self):
 181         cc_ptr = native_bt.component_get_class(self._ptr)
 182         assert(cc_ptr)
 183         return _create_generic_component_class_from_ptr(cc_ptr)
 184
 185     def __eq__(self, other):
 186         if not hasattr(other, 'addr'):
 187             return False
 188
 189         return self.addr == other.addr
 190
 191
 192 class _SourceComponent(_Component):
 193     pass
 194
 195
 196 class _FilterComponent(_Component):
 197     pass
 198
 199
 200 class _SinkComponent(_Component):
 201     pass
 202
 203
 204 # This is analogous to _GenericSourceComponentClass, but for source
 205 # component objects.
 206 class _GenericSourceComponent(object._Object, _SourceComponent):
 207     @property
 208     def output_ports(self):
 209         return _ComponentPorts(False, self,
 210                                native_bt.component_source_get_output_port_by_name,
 211                                native_bt.component_source_get_output_port_by_index,
 212                                native_bt.component_source_get_output_port_count)
 213
 214
 215 # This is analogous to _GenericFilterComponentClass, but for filter
 216 # component objects.
 217 class _GenericFilterComponent(object._Object, _FilterComponent):
 218     @property
 219     def output_ports(self):
 220         return _ComponentPorts(False, self,
 221                                native_bt.component_filter_get_output_port_by_name,
 222                                native_bt.component_filter_get_output_port_by_index,
 223                                native_bt.component_filter_get_output_port_count)
 224
 225     @property
 226     def input_ports(self):
 227         return _ComponentPorts(False, self,
 228                                native_bt.component_filter_get_input_port_by_name,
 229                                native_bt.component_filter_get_input_port_by_index,
 230                                native_bt.component_filter_get_input_port_count)
 231
 232
 233 # This is analogous to _GenericSinkComponentClass, but for sink
 234 # component objects.
 235 class _GenericSinkComponent(object._Object, _SinkComponent):
 236     @property
 237     def input_ports(self):
 238         return _ComponentPorts(False, self,
 239                                native_bt.component_sink_get_input_port_by_name,
 240                                native_bt.component_sink_get_input_port_by_index,
 241                                native_bt.component_sink_get_input_port_count)
 242
 243
 244 _COMP_CLS_TYPE_TO_GENERIC_COMP_PYCLS = {
 245     native_bt.COMPONENT_CLASS_TYPE_SOURCE: _GenericSourceComponent,
 246     native_bt.COMPONENT_CLASS_TYPE_FILTER: _GenericFilterComponent,
 247     native_bt.COMPONENT_CLASS_TYPE_SINK: _GenericSinkComponent,
 248 }
 249
 250
 251 _COMP_CLS_TYPE_TO_GENERIC_COMP_CLS_PYCLS = {
 252     native_bt.COMPONENT_CLASS_TYPE_SOURCE: _GenericSourceComponentClass,
 253     native_bt.COMPONENT_CLASS_TYPE_FILTER: _GenericFilterComponentClass,
 254     native_bt.COMPONENT_CLASS_TYPE_SINK: _GenericSinkComponentClass,
 255 }
 256
 257
 258 def _create_generic_component_from_ptr(ptr):
 259     comp_cls_type = native_bt.component_get_class_type(ptr)
 260     return _COMP_CLS_TYPE_TO_GENERIC_COMP_PYCLS[comp_cls_type]._create_from_ptr(ptr)
 261
 262
 263 def _create_generic_component_class_from_ptr(ptr):
 264     comp_cls_type = native_bt.component_class_get_type(ptr)
 265     return _COMP_CLS_TYPE_TO_GENERIC_COMP_CLS_PYCLS[comp_cls_type]._create_from_ptr(ptr)
 266
 267
 268 def _trim_docstring(docstring):
 269     lines = docstring.expandtabs().splitlines()
 270     indent = sys.maxsize
 271
 272     for line in lines[1:]:
 273         stripped = line.lstrip()
 274
 275         if stripped:
 276             indent = min(indent, len(line) - len(stripped))
 277
 278     trimmed = [lines[0].strip()]
 279
 280     if indent < sys.maxsize:
 281         for line in lines[1:]:
 282             trimmed.append(line[indent:].rstrip())
 283
 284     while trimmed and not trimmed[-1]:
 285         trimmed.pop()
 286
 287     while trimmed and not trimmed[0]:
 288         trimmed.pop(0)
 289
 290     return '\n'.join(trimmed)
 291
 292
 293 def _query(comp_cls_ptr, obj, params):
 294     utils._check_str(obj)
 295
 296     if params is None:
 297         params_ptr = native_bt.value_null
 298     else:
 299         params = bt2.create_value(params)
 300         params_ptr = params._ptr
 301
 302     results_ptr = native_bt.component_class_query(comp_cls_ptr, obj,
 303                                                   params_ptr)
 304
 305     if results_ptr is None:
 306         raise bt2.Error('cannot query info with object "{}"'.format(obj))
 307
 308     return bt2.values._create_from_ptr(results_ptr)
 309
 310
 311 # Metaclass for component classes defined by Python code.
 312 #
 313 # The Python user can create a standard Python class which inherits one
 314 # of the three base classes (_UserSourceComponent, _UserFilterComponent,
 315 # or _UserSinkComponent). Those base classes set this class
 316 # (_UserComponentType) as their metaclass.
 317 #
 318 # Once the body of a user-defined component class is executed, this
 319 # metaclass is used to create and initialize the class. The metaclass
 320 # creates a native BT component class of the corresponding type and
 321 # associates it with this user-defined class. The metaclass also defines
 322 # class methods like the `name` and `description` properties to match
 323 # the _GenericComponentClass interface.
 324 #
 325 # The component class name which is used is either:
 326 #
 327 # * The `name` parameter of the class:
 328 #
 329 #       class MySink(bt2.SinkComponent, name='my-custom-sink'):
 330 #           ...
 331 #
 332 # * If the `name` class parameter is not used: the name of the class
 333 #   itself (`MySink` in the example above).
 334 #
 335 # The component class description which is used is the user-defined
 336 # class's docstring:
 337 #
 338 #     class MySink(bt2.SinkComponent):
 339 #         'Description goes here'
 340 #         ...
 341 #
 342 # A user-defined Python component class can have an __init__() method
 343 # which must at least accept the `params` and `name` arguments:
 344 #
 345 #     def __init__(self, params, name, something_else):
 346 #         ...
 347 #
 348 # The user-defined component class can also have a _finalize() method
 349 # (do NOT use __del__()) to be notified when the component object is
 350 # finalized.
 351 #
 352 # User-defined source and filter component classes must use the
 353 # `notification_iterator_class` class parameter to specify the
 354 # notification iterator class to use for this component class:
 355 #
 356 #     class MyNotificationIterator(bt2._UserNotificationIterator):
 357 #         ...
 358 #
 359 #     class MySource(bt2._UserSourceComponent,
 360 #                    notification_iterator_class=MyNotificationIterator):
 361 #         ...
 362 #
 363 # This notification iterator class must inherit
 364 # bt2._UserNotificationIterator, and it must define the _get() and
 365 # _next() methods. The notification iterator class can also define an
 366 # __init__() method: this method has access to the original Python
 367 # component object which was used to create it as the `component`
 368 # property. The notification iterator class can also define a
 369 # _finalize() method (again, do NOT use __del__()): this is called when
 370 # the notification iterator is (really) destroyed.
 371 #
 372 # When the user-defined class is destroyed, this metaclass's __del__()
 373 # method is called: the native BT component class pointer is put (not
 374 # needed anymore, at least not by any Python code since all references
 375 # are dropped for __del__() to be called).
 376 class _UserComponentType(type):
 377     # __new__() is used to catch custom class parameters
 378     def __new__(meta_cls, class_name, bases, attrs, **kwargs):
 379         return super().__new__(meta_cls, class_name, bases, attrs)
 380
 381     def __init__(cls, class_name, bases, namespace, **kwargs):
 382         super().__init__(class_name, bases, namespace)
 383
 384         # skip our own bases; they are never directly instantiated by the user
 385         own_bases = (
 386             '_UserComponent',
 387             '_UserFilterSinkComponent',
 388             '_UserSourceComponent',
 389             '_UserFilterComponent',
 390             '_UserSinkComponent',
 391         )
 392
 393         if class_name in own_bases:
 394             return
 395
 396         comp_cls_name = kwargs.get('name', class_name)
 397         utils._check_str(comp_cls_name)
 398         comp_cls_descr = None
 399         comp_cls_help = None
 400
 401         if hasattr(cls, '__doc__') and cls.__doc__ is not None:
 402             utils._check_str(cls.__doc__)
 403             docstring = _trim_docstring(cls.__doc__)
 404             lines = docstring.splitlines()
 405
 406             if len(lines) >= 1:
 407                 comp_cls_descr = lines[0]
 408
 409             if len(lines) >= 3:
 410                 comp_cls_help = '\n'.join(lines[2:])
 411
 412         iter_cls = kwargs.get('notification_iterator_class')
 413
 414         if _UserSourceComponent in bases:
 415             _UserComponentType._set_iterator_class(cls, iter_cls)
 416             cc_ptr = native_bt.py3_component_class_source_create(cls,
 417                                                                  comp_cls_name,
 418                                                                  comp_cls_descr,
 419                                                                  comp_cls_help)
 420         elif _UserFilterComponent in bases:
 421             _UserComponentType._set_iterator_class(cls, iter_cls)
 422             cc_ptr = native_bt.py3_component_class_filter_create(cls,
 423                                                                  comp_cls_name,
 424                                                                  comp_cls_descr,
 425                                                                  comp_cls_help)
 426         elif _UserSinkComponent in bases:
 427             if not hasattr(cls, '_consume'):
 428                 raise bt2.IncompleteUserClass("cannot create component class '{}': missing a _consume() method".format(class_name))
 429
 430             cc_ptr = native_bt.py3_component_class_sink_create(cls,
 431                                                                comp_cls_name,
 432                                                                comp_cls_descr,
 433                                                                comp_cls_help)
 434         else:
 435             raise bt2.IncompleteUserClass("cannot find a known component class base in the bases of '{}'".format(class_name))
 436
 437         if cc_ptr is None:
 438             raise bt2.CreationError("cannot create component class '{}'".format(class_name))
 439
 440         cls._cc_ptr = cc_ptr
 441
 442     def _init_from_native(cls, comp_ptr, params_ptr):
 443         # create instance, not user-initialized yet
 444         self = cls.__new__(cls)
 445
 446         # pointer to native private component object (weak/borrowed)
 447         self._ptr = comp_ptr
 448
 449         # call user's __init__() method
 450         if params_ptr is not None:
 451             native_bt.get(params_ptr)
 452             params = bt2.values._create_from_ptr(params_ptr)
 453         else:
 454             params = None
 455
 456         self.__init__(params)
 457         return self
 458
 459     def __call__(cls, *args, **kwargs):
 460         raise bt2.Error('cannot directly instantiate a user component from a Python module')
 461
 462     @staticmethod
 463     def _set_iterator_class(cls, iter_cls):
 464         if iter_cls is None:
 465             raise bt2.IncompleteUserClass("cannot create component class '{}': missing notification iterator class".format(cls.__name__))
 466
 467         if not issubclass(iter_cls, bt2.notification_iterator._UserNotificationIterator):
 468             raise bt2.IncompleteUserClass("cannot create component class '{}': notification iterator class does not inherit bt2._UserNotificationIterator".format(cls.__name__))
 469
 470         if not hasattr(iter_cls, '__next__'):
 471             raise bt2.IncompleteUserClass("cannot create component class '{}': notification iterator class is missing a __next__() method".format(cls.__name__))
 472
 473         cls._iter_cls = iter_cls
 474
 475     @property
 476     def name(cls):
 477         return native_bt.component_class_get_name(cls._cc_ptr)
 478
 479     @property
 480     def description(cls):
 481         return native_bt.component_class_get_description(cls._cc_ptr)
 482
 483     @property
 484     def help(cls):
 485         return native_bt.component_class_get_help(cls._cc_ptr)
 486
 487     @property
 488     def addr(cls):
 489         return int(cls._cc_ptr)
 490
 491     def query(cls, obj, params=None):
 492         return _query(cls._cc_ptr, obj, params)
 493
 494     def _query_from_native(cls, obj, params_ptr):
 495         # this can raise, in which case the native call to
 496         # bt_component_class_query() returns NULL
 497         if params_ptr is not None:
 498             native_bt.get(params_ptr)
 499             params = bt2.values._create_from_ptr(params_ptr)
 500         else:
 501             params = None
 502
 503         try:
 504             results = cls._query(obj, params)
 505         except:
 506             if not _NO_PRINT_TRACEBACK:
 507                 traceback.print_exc()
 508
 509             return
 510
 511         if results is NotImplemented:
 512             return results
 513
 514         try:
 515             results = bt2.create_value(results)
 516         except:
 517             if not _NO_PRINT_TRACEBACK:
 518                 traceback.print_exc()
 519
 520             return
 521
 522         if results is None:
 523             results_addr = int(native_bt.value_null)
 524         else:
 525             # return new reference
 526             results._get()
 527             results_addr = int(results._ptr)
 528
 529         return results_addr
 530
 531     @classmethod
 532     def _query(cls, obj, params):
 533         # BT catches this and returns NULL to the user
 534         return NotImplemented
 535
 536     def __eq__(self, other):
 537         if not hasattr(other, 'addr'):
 538             return False
 539
 540         return self.addr == other.addr
 541
 542     def __del__(cls):
 543         if hasattr(cls, '_cc_ptr'):
 544             native_bt.put(cls._cc_ptr)
 545
 546
 547 class _UserComponent(metaclass=_UserComponentType):
 548     @property
 549     def name(self):
 550         pub_ptr = native_bt.component_from_private_component(self._ptr)
 551         name = native_bt.component_get_name(pub_ptr)
 552         native_bt.put(pub_ptr)
 553         assert(name is not None)
 554         return name
 555
 556     @property
 557     def graph(self):
 558         pub_ptr = native_bt.component_from_private_component(self._ptr)
 559         ptr = native_bt.component_get_graph(pub_ptr)
 560         native_bt.put(pub_ptr)
 561         assert(ptr)
 562         return bt2.Graph._create_from_ptr(ptr)
 563
 564     @property
 565     def component_class(self):
 566         pub_ptr = native_bt.component_from_private_component(self._ptr)
 567         cc_ptr = native_bt.component_get_class(pub_ptr)
 568         native_bt.put(pub_ptr)
 569         assert(cc_ptr)
 570         return _create_generic_component_class_from_ptr(cc_ptr)
 571
 572     @property
 573     def addr(self):
 574         return int(self._ptr)
 575
 576     def __init__(self, params=None):
 577         pass
 578
 579     def _finalize(self):
 580         pass
 581
 582     def _accept_port_connection(self, port, other_port):
 583         return True
 584
 585     def _accept_port_connection_from_native(self, port_ptr, other_port_ptr):
 586         native_bt.get(port_ptr)
 587         native_bt.get(other_port_ptr)
 588         port = bt2.port._create_private_from_ptr(port_ptr)
 589         other_port = bt2.port._create_from_ptr(other_port_ptr)
 590         res = self._accept_port_connection(port, other_port_ptr)
 591
 592         if type(res) is not bool:
 593             raise TypeError("'{}' is not a 'bool' object")
 594
 595         return res
 596
 597     def _port_connected(self, port, other_port):
 598         pass
 599
 600     def _port_connected_from_native(self, port_ptr, other_port_ptr):
 601         native_bt.get(port_ptr)
 602         native_bt.get(other_port_ptr)
 603         port = bt2.port._create_private_from_ptr(port_ptr)
 604         other_port = bt2.port._create_from_ptr(other_port_ptr)
 605
 606         try:
 607             self._port_connected(port, other_port_ptr)
 608         except:
 609             if not _NO_PRINT_TRACEBACK:
 610                 traceback.print_exc()
 611
 612     def _port_disconnected(self, port):
 613         pass
 614
 615     def _port_disconnected_from_native(self, port_ptr):
 616         native_bt.get(port_ptr)
 617         port = bt2.port._create_private_from_ptr(port_ptr)
 618
 619         try:
 620             self._port_disconnected(port)
 621         except:
 622             if not _NO_PRINT_TRACEBACK:
 623                 traceback.print_exc()
 624
 625
 626 class _UserSourceComponent(_UserComponent, _SourceComponent):
 627     @property
 628     def _output_ports(self):
 629         return _ComponentPorts(True, self,
 630                                native_bt.private_component_source_get_output_private_port_by_name,
 631                                native_bt.private_component_source_get_output_private_port_by_index,
 632                                native_bt.component_source_get_output_port_count)
 633
 634     def _add_output_port(self, name):
 635         utils._check_str(name)
 636         fn = native_bt.private_component_source_add_output_private_port
 637         comp_status, priv_port_ptr = fn(self._ptr, name, None)
 638         _handle_component_status(comp_status,
 639                                  'cannot add output port to source component object')
 640         assert(priv_port_ptr)
 641         return bt2.port._create_private_from_ptr(priv_port_ptr)
 642
 643
 644 class _UserFilterComponent(_UserComponent, _FilterComponent):
 645     @property
 646     def _output_ports(self):
 647         return _ComponentPorts(True, self,
 648                                native_bt.private_component_filter_get_output_private_port_by_name,
 649                                native_bt.private_component_filter_get_output_private_port_by_index,
 650                                native_bt.component_filter_get_output_port_count)
 651
 652     @property
 653     def _input_ports(self):
 654         return _ComponentPorts(True, self,
 655                                native_bt.private_component_filter_get_input_private_port_by_name,
 656                                native_bt.private_component_filter_get_input_private_port_by_index,
 657                                native_bt.component_filter_get_input_port_count)
 658
 659     def _add_output_port(self, name):
 660         utils._check_str(name)
 661         fn = native_bt.private_component_filter_add_output_private_port
 662         comp_status, priv_port_ptr = fn(self._ptr, name, None)
 663         _handle_component_status(comp_status,
 664                                  'cannot add output port to filter component object')
 665         assert(priv_port_ptr)
 666         return bt2.port._create_private_from_ptr(priv_port_ptr)
 667
 668     def _add_input_port(self, name):
 669         utils._check_str(name)
 670         fn = native_bt.private_component_filter_add_input_private_port
 671         comp_status, priv_port_ptr = fn(self._ptr, name, None)
 672         _handle_component_status(comp_status,
 673                                  'cannot add input port to filter component object')
 674         assert(priv_port_ptr)
 675         return bt2.port._create_private_from_ptr(priv_port_ptr)
 676
 677
 678 class _UserSinkComponent(_UserComponent, _SinkComponent):
 679     @property
 680     def _input_ports(self):
 681         return _ComponentPorts(True, self,
 682                                native_bt.private_component_sink_get_input_private_port_by_name,
 683                                native_bt.private_component_sink_get_input_private_port_by_index,
 684                                native_bt.component_sink_get_input_port_count)
 685
 686     def _add_input_port(self, name):
 687         utils._check_str(name)
 688         fn = native_bt.private_component_sink_add_input_private_port
 689         comp_status, priv_port_ptr = fn(self._ptr, name, None)
 690         _handle_component_status(comp_status,
 691                                  'cannot add input port to sink component object')
 692         assert(priv_port_ptr)
 693         return bt2.port._create_private_from_ptr(priv_port_ptr)