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 # Run callable `func` in the context of a component's __init__ method.  The
  23 # callable is passed the Component being instantiated.
  24 #
  25 # The value returned by the callable is returned by run_in_component_init.
  26 def run_in_component_init(func):
  27     class MySink(bt2._UserSinkComponent):
  28         def __init__(self, params, obj):
  29             nonlocal res_bound
  30             res_bound = func(self)
  31
  32         def _user_consume(self):
  33             pass
  34
  35     g = bt2.Graph()
  36     res_bound = None
  37     g.add_component(MySink, 'comp')
  38
  39     # We deliberately use a different variable for returning the result than
  40     # the variable bound to the MySink.__init__ context and delete res_bound.
  41     # The MySink.__init__ context stays alive until the end of the program, so
  42     # if res_bound were to still point to our result, it would contribute an
  43     # unexpected reference to the refcount of the result, from the point of view
  44     # of the user of this function.  It would then affect destruction tests,
  45     # for example, which want to test what happens when the refcount of a Python
  46     # object reaches 0.
  47
  48     res = res_bound
  49     del res_bound
  50     return res
  51
  52
  53 # Create an empty trace class with default values.
  54 def get_default_trace_class():
  55     def f(comp_self):
  56         return comp_self._create_trace_class()
  57
  58     return run_in_component_init(f)
  59
  60
  61 # Proxy sink component class.
  62 #
  63 # This sink accepts a list of a single item as its initialization
  64 # object. This sink creates a single input port `in`. When it consumes
  65 # from this port, it puts the returned message in the initialization
  66 # list as the first item.
  67 class TestProxySink(bt2._UserSinkComponent):
  68     def __init__(self, params, msg_list):
  69         assert msg_list is not None
  70         self._msg_list = msg_list
  71         self._add_input_port('in')
  72
  73     def _user_graph_is_configured(self):
  74         self._msg_iter = self._create_input_port_message_iterator(
  75             self._input_ports['in']
  76         )
  77
  78     def _user_consume(self):
  79         assert self._msg_list[0] is None
  80         self._msg_list[0] = next(self._msg_iter)
  81
  82
  83 # This is a helper message iterator for tests.
  84 #
  85 # The constructor accepts a graph and an output port.
  86 #
  87 # Internally, it adds a proxy sink to the graph and connects the
  88 # received output port to the proxy sink's input port. Its __next__()
  89 # method then uses the proxy sink to transfer the consumed message to
  90 # the output port message iterator's user.
  91 #
  92 # This message iterator cannot seek.
  93 class TestOutputPortMessageIterator(collections.abc.Iterator):
  94     def __init__(self, graph, output_port):
  95         self._graph = graph
  96         self._msg_list = [None]
  97         sink = graph.add_component(TestProxySink, 'test-proxy-sink', obj=self._msg_list)
  98         graph.connect_ports(output_port, sink.input_ports['in'])
  99
 100     def __next__(self):
 101         assert self._msg_list[0] is None
 102         self._graph.run_once()
 103         msg = self._msg_list[0]
 104         assert msg is not None
 105         self._msg_list[0] = None
 106         return msg