[procedures] Sync only after the db engine is initialized.

platypush/plugins/procedures/__init__.py

@@ -1,10 +1,13 @@
+from functools import wraps
 import json
 import re
 from contextlib import contextmanager
 from dataclasses import dataclass
 from multiprocessing import RLock
 from random import randint
+from threading import Event
 from typing import (
+    Any,
     Callable,
     Collection,
     Dict,
@@ -19,6 +22,7 @@ import yaml
 from sqlalchemy.orm import Session
 
 from platypush.context import get_plugin
+from platypush.entities import get_entities_engine
 from platypush.entities.managers.procedures import ProcedureEntityManager
 from platypush.entities.procedures import Procedure, ProcedureType
 from platypush.message.event.entities import EntityDeleteEvent
@@ -29,6 +33,29 @@ from platypush.utils import run
 from ._serialize import ProcedureEncoder
 
 
+# pylint: disable=protected-access
+def ensure_initialized(f: Callable[..., Any]):
+    """
+    Ensures that the entities engine has been initialized before
+    reading/writing the db.
+    """
+
+    @wraps(f)
+    def wrapper(*args, **kwargs):
+        self: ProceduresPlugin = args[0]
+
+        if not self._initialized.is_set():
+            with self._init_lock:
+                get_entities_engine(timeout=20)
+
+                if not self._initialized.is_set():
+                    self._initialized.set()
+
+        return f(*args, **kwargs)
+
+    return wrapper
+
+
 @dataclass
 class _ProcedureWrapper:
     name: str
@@ -42,6 +69,8 @@ class ProceduresPlugin(RunnablePlugin, ProcedureEntityManager):
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
+        self._initialized = Event()
+        self._init_lock = RLock()
         self._status_lock = RLock()
 
     @action
@@ -306,6 +335,7 @@ class ProceduresPlugin(RunnablePlugin, ProcedureEntityManager):
         else:
             return [cls._serialize_action(item) for item in data if item is not None]
 
+    @ensure_initialized
     @contextmanager
     def _db_session(self) -> Generator[Session, None, None]:
         db: Optional[DbPlugin] = get_plugin(DbPlugin)