plumpy.ProcessListener made persistent

solves aiidateam#273

We implement the persistence of ProcessListener by deriving the class
ProcessListener and EventHelper from persistence.Savable.
The class EventHelper is moved to a new file because of a circular
import with utils and persistence

src/plumpy/event_helper.py

@@ -0,0 +1,52 @@
+# -*- coding: utf-8 -*-
+import logging
+from typing import TYPE_CHECKING, Any, Callable, Set, Type
+
+from . import persistence
+
+if TYPE_CHECKING:
+    from .process_listener import ProcessListener  # pylint: disable=cyclic-import
+
+_LOGGER = logging.getLogger(__name__)
+
+
+@persistence.auto_persist('_listeners')
+class EventHelper(persistence.Savable):
+
+    def __init__(self, listener_type: 'Type[ProcessListener]'):
+        assert listener_type is not None, 'Must provide valid listener type'
+
+        self._listener_type = listener_type
+        self._listeners: 'Set[ProcessListener]' = set()
+
+    def add_listener(self, listener: 'ProcessListener') -> None:
+        assert isinstance(listener, self._listener_type), 'Listener is not of right type'
+        self._listeners.add(listener)
+
+    def remove_listener(self, listener: 'ProcessListener') -> None:
+        self._listeners.discard(listener)
+
+    def remove_all_listeners(self) -> None:
+        self._listeners.clear()
+
+    @property
+    def listeners(self) -> 'Set[ProcessListener]':
+        return self._listeners
+
+    def fire_event(self, event_function: Callable[..., Any], *args: Any, **kwargs: Any) -> None:
+        """Call an event method on all listeners.
+
+        :param event_function: the method of the ProcessListener
+        :param args: arguments to pass to the method
+        :param kwargs: keyword arguments to pass to the method
+
+        """
+        if event_function is None:
+            raise ValueError('Must provide valid event method')
+
+        # Make a copy of the list for iteration just in case it changes in a callback
+        for listener in list(self.listeners):
+            try:
+                getattr(listener, event_function.__name__)(*args, **kwargs)
+            except Exception as exception:  # pylint: disable=broad-except
+                _LOGGER.error("Listener '%s' produced an exception:\n%s", listener, exception)

src/plumpy/process_listener.py

@@ -1,14 +1,36 @@
 # -*- coding: utf-8 -*-
 import abc
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, Dict, Optional
+
+from . import persistence
+from .utils import SAVED_STATE_TYPE, protected
 
 __all__ = ['ProcessListener']
 
 if TYPE_CHECKING:
     from .processes import Process  # pylint: disable=cyclic-import
 
 
-class ProcessListener(metaclass=abc.ABCMeta):
+@persistence.auto_persist('_params')
+class ProcessListener(persistence.Savable, metaclass=abc.ABCMeta):
+
+    # region Persistence methods
+
+    def __init__(self) -> None:
+        super().__init__()
+        self._params: Dict[str, Any] = {}
+
+    def init(self, **kwargs: Any) -> None:
+        self._params = kwargs
+
+    @protected
+    def load_instance_state(
+        self, saved_state: SAVED_STATE_TYPE, load_context: Optional[persistence.LoadSaveContext]
+    ) -> None:
+        super().load_instance_state(saved_state, load_context)
+        self.init(**saved_state['_params'])
+
+    # endregion
 
     def on_process_created(self, process: 'Process') -> None:
         """

src/plumpy/processes.py

@@ -42,6 +42,7 @@
 from .base import state_machine
 from .base.state_machine import StateEntryFailed, StateMachine, TransitionFailed, event
 from .base.utils import call_with_super_check, super_check
+from .event_helper import EventHelper
 from .process_listener import ProcessListener
 from .process_spec import ProcessSpec
 from .utils import PID_TYPE, SAVED_STATE_TYPE, protected
@@ -91,7 +92,9 @@ def func_wrapper(self: Any, *args: Any, **kwargs: Any) -> Any:
     return func_wrapper
 
 
-@persistence.auto_persist('_pid', '_creation_time', '_future', '_paused', '_status', '_pre_paused_status')
+@persistence.auto_persist(
+    '_pid', '_creation_time', '_future', '_paused', '_status', '_pre_paused_status', '_event_helper'
+)
 class Process(StateMachine, persistence.Savable, metaclass=ProcessStateMachineMeta):
     """
     The Process class is the base for any unit of work in plumpy.
@@ -289,7 +292,7 @@ def __init__(
 
         # Runtime variables
         self._future = persistence.SavableFuture(loop=self._loop)
-        self.__event_helper = utils.EventHelper(ProcessListener)
+        self._event_helper = EventHelper(ProcessListener)
         self._logger = logger
         self._communicator = communicator
 
@@ -597,6 +600,9 @@ def save_instance_state(
         if self.outputs:
             out_state[BundleKeys.OUTPUTS] = self.encode_input_args(self.outputs)
 
+        print(type(out_state))
+        print(out_state)
+
     @protected
     def load_instance_state(self, saved_state: SAVED_STATE_TYPE, load_context: persistence.LoadSaveContext) -> None:
         """Load the process from its saved instance state.
@@ -612,7 +618,7 @@ def load_instance_state(self, saved_state: SAVED_STATE_TYPE, load_context: persi
 
         # Runtime variables, set initial states
         self._future = persistence.SavableFuture()
-        self.__event_helper = utils.EventHelper(ProcessListener)
+        self._event_helper = EventHelper(ProcessListener)
         self._logger = None
         self._communicator = None
 
@@ -621,6 +627,9 @@ def load_instance_state(self, saved_state: SAVED_STATE_TYPE, load_context: persi
         else:
             self._loop = asyncio.get_event_loop()
 
+        print('saved_state')
+        print(saved_state)
+
         self._state: process_states.State = self.recreate_state(saved_state['_state'])
 
         if 'communicator' in load_context:
@@ -661,11 +670,11 @@ def add_process_listener(self, listener: ProcessListener) -> None:
 
         """
         assert (listener != self), 'Cannot listen to yourself!'  # type: ignore
-        self.__event_helper.add_listener(listener)
+        self._event_helper.add_listener(listener)
 
     def remove_process_listener(self, listener: ProcessListener) -> None:
         """Remove a process listener from the process."""
-        self.__event_helper.remove_listener(listener)
+        self._event_helper.remove_listener(listener)
 
     @protected
     def set_logger(self, logger: logging.Logger) -> None:
@@ -778,7 +787,7 @@ def on_output_emitting(self, output_port: str, value: Any) -> None:
         """Output is about to be emitted."""
 
     def on_output_emitted(self, output_port: str, value: Any, dynamic: bool) -> None:
-        self.__event_helper.fire_event(ProcessListener.on_output_emitted, self, output_port, value, dynamic)
+        self._event_helper.fire_event(ProcessListener.on_output_emitted, self, output_port, value, dynamic)
 
     @super_check
     def on_wait(self, awaitables: Sequence[Awaitable]) -> None:
@@ -891,7 +900,7 @@ def on_close(self) -> None:
             self._closed = True
 
     def _fire_event(self, evt: Callable[..., Any], *args: Any, **kwargs: Any) -> None:
-        self.__event_helper.fire_event(evt, self, *args, **kwargs)
+        self._event_helper.fire_event(evt, self, *args, **kwargs)
 
     # endregion
 

src/plumpy/utils.py

@@ -27,47 +27,6 @@
 PID_TYPE = Hashable  # pylint: disable=invalid-name
 
 
-class EventHelper:
-
-    def __init__(self, listener_type: 'Type[ProcessListener]'):
-        assert listener_type is not None, 'Must provide valid listener type'
-
-        self._listener_type = listener_type
-        self._listeners: 'Set[ProcessListener]' = set()
-
-    def add_listener(self, listener: 'ProcessListener') -> None:
-        assert isinstance(listener, self._listener_type), 'Listener is not of right type'
-        self._listeners.add(listener)
-
-    def remove_listener(self, listener: 'ProcessListener') -> None:
-        self._listeners.discard(listener)
-
-    def remove_all_listeners(self) -> None:
-        self._listeners.clear()
-
-    @property
-    def listeners(self) -> 'Set[ProcessListener]':
-        return self._listeners
-
-    def fire_event(self, event_function: Callable[..., Any], *args: Any, **kwargs: Any) -> None:
-        """Call an event method on all listeners.
-
-        :param event_function: the method of the ProcessListener
-        :param args: arguments to pass to the method
-        :param kwargs: keyword arguments to pass to the method
-
-        """
-        if event_function is None:
-            raise ValueError('Must provide valid event method')
-
-        # Make a copy of the list for iteration just in case it changes in a callback
-        for listener in list(self.listeners):
-            try:
-                getattr(listener, event_function.__name__)(*args, **kwargs)
-            except Exception as exception:  # pylint: disable=broad-except
-                _LOGGER.error("Listener '%s' produced an exception:\n%s", listener, exception)
-
-
 class Frozendict(Mapping):
     """
     An immutable wrapper around dictionaries that implements the complete :py:class:`collections.abc.Mapping`