1 files changed, 34 insertions, 24 deletions
diff --git a/src/apscheduler/datastores/base.py b/src/apscheduler/datastores/base.py
index c05d28c..5c7ef7d 100644
--- a/src/apscheduler/datastores/base.py
+++ b/src/apscheduler/datastores/base.py
@@ -1,37 +1,47 @@
 from __future__ import annotations
 
-from apscheduler.abc import (
-    AsyncDataStore,
-    AsyncEventBroker,
-    DataStore,
-    EventBroker,
-    EventSource,
-)
+from contextlib import AsyncExitStack
+from logging import Logger, getLogger
 
+import attrs
 
+from .._retry import RetryMixin
+from ..abc import DataStore, EventBroker, Serializer
+from ..serializers.pickle import PickleSerializer
+
+
+@attrs.define(kw_only=True)
 class BaseDataStore(DataStore):
-    _events: EventBroker
+    """
+    Base class for data stores.
 
-    def start(self, event_broker: EventBroker) -> None:
-        self._events = event_broker
+    :param lock_expiration_delay: maximum amount of time (in seconds) that a scheduler
+        or worker can keep a lock on a schedule or task
+    """
 
-    def stop(self, *, force: bool = False) -> None:
-        del self._events
+    lock_expiration_delay: float = 30
+    _event_broker: EventBroker = attrs.field(init=False)
+    _logger: Logger = attrs.field(init=False)
 
-    @property
-    def events(self) -> EventSource:
-        return self._events
+    async def start(
+        self, exit_stack: AsyncExitStack, event_broker: EventBroker
+    ) -> None:
+        self._event_broker = event_broker
 
+    def __attrs_post_init__(self):
+        self._logger = getLogger(self.__class__.__name__)
 
-class BaseAsyncDataStore(AsyncDataStore):
-    _events: AsyncEventBroker
 
-    async def start(self, event_broker: AsyncEventBroker) -> None:
-        self._events = event_broker
+@attrs.define(kw_only=True)
+class BaseExternalDataStore(BaseDataStore, RetryMixin):
+    """
+    Base class for data stores using an external service such as a database.
 
-    async def stop(self, *, force: bool = False) -> None:
-        del self._events
+    :param serializer: the serializer used to (de)serialize tasks, schedules and jobs
+        for storage
+    :param start_from_scratch: erase all existing data during startup (useful for test
+        suites)
+    """
 
-    @property
-    def events(self) -> EventSource:
-        return self._events
+    serializer: Serializer = attrs.field(factory=PickleSerializer)
+    start_from_scratch: bool = attrs.field(default=False)