tests/bindings/python/bt2/utils.py

   1 #
   2 # Copyright (C) 2019 EfficiOS Inc.
   3 #
   4 # This program is free software; you can redistribute it and/or
   5 # modify it under the terms of the GNU General Public License
   6 # as published by the Free Software Foundation; only version 2
   7 # of the License.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU General Public License
  15 # along with this program; if not, write to the Free Software
  16 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17 #
  18
  19 import bt2
  20 import collections.abc
  21
  22
  23 # Run callable `func` in the context of a component's __init__ method.  The
  24 # callable is passed the Component being instantiated.
  25 #
  26 # The value returned by the callable is returned by run_in_component_init.
  27 def run_in_component_init(func):
  28     class MySink(bt2._UserSinkComponent):
  29         def __init__(self, params, obj):
  30             nonlocal res_bound
  31             res_bound = func(self)
  32
  33         def _user_consume(self):
  34             pass
  35
  36     g = bt2.Graph()
  37     res_bound = None
  38     g.add_component(MySink, 'comp')
  39
  40     # We deliberately use a different variable for returning the result than
  41     # the variable bound to the MySink.__init__ context and delete res_bound.
  42     # The MySink.__init__ context stays alive until the end of the program, so
  43     # if res_bound were to still point to our result, it would contribute an
  44     # unexpected reference to the refcount of the result, from the point of view
  45     # of the user of this function.  It would then affect destruction tests,
  46     # for example, which want to test what happens when the refcount of a Python
  47     # object reaches 0.
  48
  49     res = res_bound
  50     del res_bound
  51     return res
  52
  53
  54 # Create an empty trace class with default values.
  55 def get_default_trace_class():
  56     def f(comp_self):
  57         return comp_self._create_trace_class()
  58
  59     return run_in_component_init(f)
  60
  61
  62 # Proxy sink component class.
  63 #
  64 # This sink accepts a list of a single item as its initialization
  65 # object. This sink creates a single input port `in`. When it consumes
  66 # from this port, it puts the returned message in the initialization
  67 # list as the first item.
  68 class TestProxySink(bt2._UserSinkComponent):
  69     def __init__(self, params, msg_list):
  70         assert msg_list is not None
  71         self._msg_list = msg_list
  72         self._add_input_port('in')
  73
  74     def _user_graph_is_configured(self):
  75         self._msg_iter = self._create_input_port_message_iterator(
  76             self._input_ports['in']
  77         )
  78
  79     def _user_consume(self):
  80         assert self._msg_list[0] is None
  81         self._msg_list[0] = next(self._msg_iter)
  82
  83
  84 # This is a helper message iterator for tests.
  85 #
  86 # The constructor accepts a graph and an output port.
  87 #
  88 # Internally, it adds a proxy sink to the graph and connects the
  89 # received output port to the proxy sink's input port. Its __next__()
  90 # method then uses the proxy sink to transfer the consumed message to
  91 # the output port message iterator's user.
  92 #
  93 # This message iterator cannot seek.
  94 class TestOutputPortMessageIterator(collections.abc.Iterator):
  95     def __init__(self, graph, output_port):
  96         self._graph = graph
  97         self._msg_list = [None]
  98         sink = graph.add_component(TestProxySink, 'test-proxy-sink', obj=self._msg_list)
  99         graph.connect_ports(output_port, sink.input_ports['in'])
 100
 101     def __next__(self):
 102         assert self._msg_list[0] is None
 103         self._graph.run_once()
 104         msg = self._msg_list[0]
 105         assert msg is not None
 106         self._msg_list[0] = None
 107         return msg