More refactoring work

* Added mysql and sqlite to the data store testing matrix
* Made customizing the SQLAlchemy table metadata easier
* Refactored more classes to use attrs instead of dataclasses
* Added the get_next_schedule_run_time() method to stores
* Made schedulers use get_next_schedule_run_time() to limit their waiting time

1 files changed, 35 insertions, 6 deletions

diff --git a/src/apscheduler/abc.py b/src/apscheduler/abc.py
index acea751..ec77de5 100644
--- a/src/apscheduler/abc.py
+++ b/src/apscheduler/abc.py
@@ -3,9 +3,7 @@ from __future__ import annotations
 from abc import ABCMeta, abstractmethod
 from base64 import b64decode, b64encode
 from datetime import datetime
-from typing import (
-    TYPE_CHECKING, Any, AsyncContextManager, Callable, ContextManager, Iterable, Iterator, List,
-    Optional, Set, Type)
+from typing import TYPE_CHECKING, Any, Callable, Iterable, Iterator, List, Optional, Set, Type
 from uuid import UUID
 
 from .policies import ConflictPolicy
@@ -123,7 +121,7 @@ class DataStore(EventSource):
         """
 
     @abstractmethod
-    def acquire_schedules(self, scheduler_id: str, limit: int) -> ContextManager[List[Schedule]]:
+    def acquire_schedules(self, scheduler_id: str, limit: int) -> List[Schedule]:
         """
         Acquire unclaimed due schedules for processing.
 
@@ -136,6 +134,22 @@ class DataStore(EventSource):
         """
 
     @abstractmethod
+    def release_schedules(self, scheduler_id: str, schedules: List[Schedule]) -> None:
+        """
+        Release the claims on the given schedules and update them on the store.
+
+        :param scheduler_id: unique identifier of the scheduler
+        :param schedules: the previously claimed schedules
+        """
+
+    @abstractmethod
+    def get_next_schedule_run_time(self) -> Optional[datetime]:
+        """
+        Return the earliest upcoming run time of all the schedules in the store, or ``None`` if
+        there are no active schedules.
+        """
+
+    @abstractmethod
     def add_job(self, job: Job) -> None:
         """
         Add a job to be executed by an eligible worker.
@@ -222,8 +236,7 @@ class AsyncDataStore(EventSource):
         """
 
     @abstractmethod
-    async def acquire_schedules(self, scheduler_id: str,
-                                limit: int) -> AsyncContextManager[List[Schedule]]:
+    async def acquire_schedules(self, scheduler_id: str, limit: int) -> List[Schedule]:
         """
         Acquire unclaimed due schedules for processing.
 
@@ -236,6 +249,22 @@ class AsyncDataStore(EventSource):
         """
 
     @abstractmethod
+    async def release_schedules(self, scheduler_id: str, schedules: List[Schedule]) -> None:
+        """
+        Release the claims on the given schedules and update them on the store.
+
+        :param scheduler_id: unique identifier of the scheduler
+        :param schedules: the previously claimed schedules
+        """
+
+    @abstractmethod
+    async def get_next_schedule_run_time(self) -> Optional[datetime]:
+        """
+        Return the earliest upcoming run time of all the schedules in the store, or ``None`` if
+        there are no active schedules.
+        """
+
+    @abstractmethod
     async def add_job(self, job: Job) -> None:
         """
         Add a job to be executed by an eligible worker.