Merge pull request #12 from leagueutils/fix/safeguard-early-trigger

fix: add safeguard against early triggers

Author: lukasthaler

triggers/triggers.py

@@ -87,6 +87,7 @@ def __init__(
 
         self._trigger_count = 0
         self.task = None  # placeholder for the repeat task created in self.__wrapper
+        self.__next_run_time = None  # placeholder for the current target run time
 
     def __call__(self, func: CoroFunction):
         return self.__wrapper(func)
@@ -102,13 +103,13 @@ async def wrapped() -> None:
             async def inner():
                 # maybe wait for next trigger cycle
                 if not self.on_startup:
-                    next_run = self.next_run
+                    self.__next_run_time = self.next_run
                     if self.logger:
                         self.logger.info(
                             f'`on_startup` is set to `False`. First run of {self.__class__.__name__} for '
-                            f'{func.__name__}: {next_run.isoformat()}'
+                            f'{func.__name__}: {self.__next_run_time.isoformat()}'
                         )
-                    await self.sleep_until(next_run)
+                    await self.sleep_until(self.__next_run_time)
 
                 # repeat indefinitely
                 while True:
@@ -118,6 +119,13 @@ async def inner():
                     if self.max_trigger_count is not None:
                         self._trigger_count += 1
 
+                    # safeguard against early triggers - apparently, a desync is possible
+                    if (
+                        self.__next_run_time is not None
+                        and (now := datetime.datetime.now().astimezone()) < self.__next_run_time
+                    ):
+                        await asyncio.sleep(max((self.__next_run_time - now).total_seconds(), 0))
+
                     # call the decorated function
                     try:
                         if self.iter_args:
@@ -154,23 +162,24 @@ async def inner():
 
                     # sleep until next execution time
                     try:
-                        next_run = self.next_run
+                        self.__next_run_time = self.next_run
                     except StopRunning:
                         if self.logger:
                             self.logger.info(
                                 f'{self.__class__.__name__} received StopRunning for {func.__name__}. Terminating'
                             )
                         break
-                    if self.logger and datetime.datetime.now().astimezone() <= next_run:
+                    if self.logger and datetime.datetime.now().astimezone() <= self.__next_run_time:
                         self.logger.info(
-                            f'{self.__class__.__name__} finished for {func.__name__}. Next run: {next_run.isoformat()}'
+                            f'{self.__class__.__name__} finished for {func.__name__}. '
+                            f'Next run: {self.__next_run_time.isoformat()}'
                         )
                     elif self.logger:  # i.e. next_run is in the past
                         self.logger.warning(
                             f'{self.__class__.__name__} missed the scheduled run time for {func.__name__}. Running now'
                         )
 
-                    await self.sleep_until(next_run)
+                    await self.sleep_until(self.__next_run_time)
 
             # create a reference to the repeating task to prevent it from accidentally being garbage collected
             self.task = self.loop.create_task(inner())