Add pickle support to FMUModel classes via __reduce__/__setstate__

src/pyfmi/fmi1.pyx

@@ -418,6 +418,22 @@ cdef class FMUModelBase(FMI_BASE.ModelBase):
 
         self._log = []
 
+    def __reduce__(self):
+        _log_file_name = self._get_log_file_name()
+        fmu_path = self._fmu_full_path
+        if isinstance(fmu_path, bytes):
+            fmu_path = pyfmi_util.decode(fmu_path)
+        return (
+            self.__class__,
+            (fmu_path, _log_file_name, self._loaded_with_log_level,
+             None, bool(self._allocated_dll), bool(self._allow_unzipped_fmu)),
+            {'cache': self.cache} if self.cache else {}
+        )
+
+    def __setstate__(self, state):
+        if 'cache' in state:
+            self.cache = state['cache']
+
     def _setup_log_state(self, log_level):
         if log_level >= FMIL.jm_log_level_nothing and log_level <= FMIL.jm_log_level_all:
             self._enable_logging = log_level != FMIL.jm_log_level_nothing

src/pyfmi/fmi2.pyx

@@ -681,6 +681,22 @@ cdef class FMUModelBase2(FMI_BASE.ModelBase):
 
         self._log = []
 
+    def __reduce__(self):
+        _log_file_name = self._get_log_file_name()
+        fmu_path = self._fmu_full_path
+        if isinstance(fmu_path, bytes):
+            fmu_path = pyfmi_util.decode(fmu_path)
+        return (
+            self.__class__,
+            (fmu_path, _log_file_name, self._loaded_with_log_level,
+             None, bool(self._allocated_dll), bool(self._allow_unzipped_fmu)),
+            {'cache': self.cache} if self.cache else {}
+        )
+
+    def __setstate__(self, state):
+        if 'cache' in state:
+            self.cache = state['cache']
+
     def _setup_log_state(self, log_level):
         if log_level >= FMIL.jm_log_level_nothing and log_level <= FMIL.jm_log_level_all:
             self._enable_logging = log_level != FMIL.jm_log_level_nothing

src/pyfmi/fmi3.pyx

@@ -477,7 +477,23 @@ cdef class FMUModelBase3(FMI_BASE.ModelBase):
         self._event_info_nominals_of_continuous_states_changed = FMIL3.fmi3_false
         self._event_info_values_of_continuous_states_changed   = FMIL3.fmi3_true
         self._event_info_next_event_time_defined               = FMIL3.fmi3_false
-        self._event_info_next_event_time                       = 0.0
+        self._event_info_next_event_time = 0.0
+
+    def __reduce__(self):
+        _log_file_name = self._get_log_file_name()
+        fmu_path = self._fmu_full_path
+        if isinstance(fmu_path, bytes):
+            fmu_path = pyfmi_util.decode(fmu_path)
+        return (
+            self.__class__,
+            (fmu_path, _log_file_name, self._loaded_with_log_level,
+             None, bool(self._allocated_dll), bool(self._allow_unzipped_fmu)),
+            {'cache': self.cache} if self.cache else {}
+        )
+
+    def __setstate__(self, state):
+        if 'cache' in state:
+            self.cache = state['cache']
 
     def _setup_log_state(self, log_level):
         if isinstance(log_level, int) and (log_level >= FMIL.jm_log_level_nothing and log_level <= FMIL.jm_log_level_all):

src/pyfmi/fmi_base.pyx

@@ -84,6 +84,11 @@ cdef class ModelBase:
         self._max_log_size_msg_sent = False
         self._log_handler = LogHandlerDefault(self._max_log_size)
 
+    def _get_log_file_name(self):
+        if self._fmu_log_name != NULL:
+            return pyfmi_util.decode(self._fmu_log_name)
+        return None
+
     def _set_log_stream(self, stream):
         """ Function that sets the class property 'log_stream' and does error handling. """
         if not hasattr(stream, 'write'):

tests/test_fmi2.py

@@ -105,6 +105,22 @@ def test_erroneous_ncp(self):
         with pytest.raises(FMUException):
             model.simulate(options=opts)
 
+    def test_pickle(self):
+        import pickle
+
+        fmu = FMUModelCS2(
+            os.path.join(file_path, "files", "FMUs", "XML", "CS2.0", "CoupledClutches.fmu"),
+            _connect_dll=False
+        )
+        log_name = fmu.get_log_filename()
+        fmu.cache['test_key'] = 'test_value'
+
+        data = pickle.dumps(fmu)
+        fmu2 = pickle.loads(data)
+
+        assert fmu2.get_log_filename() == log_name
+        assert fmu2.cache['test_key'] == 'test_value'
+
 class Test_Downsample:
     """Tests for the 'result_downsampling_factor' option for CS FMUs."""
     def _verify_downsample_result(self, ref_traj, test_traj, ncp, factor):
@@ -1115,6 +1131,22 @@ def test_get_variable_description(self):
         model = FMUModelME2(FMU_PATHS.ME2.coupled_clutches, _connect_dll=False)
         assert model.get_variable_description("J1.phi") == "Absolute rotation angle of component"
 
+    def test_pickle(self):
+        import pickle
+
+        fmu = FMUModelME2(
+            os.path.join(file_path, "files", "FMUs", "XML", "ME2.0", "CoupledClutches.fmu"),
+            _connect_dll=False
+        )
+        log_name = fmu.get_log_filename()
+        fmu.cache['test_key'] = 'test_value'
+
+        data = pickle.dumps(fmu)
+        fmu2 = pickle.loads(data)
+
+        assert fmu2.get_log_filename() == log_name
+        assert fmu2.cache['test_key'] == 'test_value'
+
 @uses_test_fmus
 @pytest.mark.parametrize("fmu_path", 
     [