Allow ggracefl stop of consumer

wallabag_kindle_consumer/consumer.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python3
 import asyncio
+import datetime
 
 from logbook import Logger
 from sqlalchemy.orm import joinedload
@@ -17,6 +18,8 @@ class Consumer:
         self.sender = sender
         self.running = True
 
+        self._wait_fut = None  # type: asyncio.Future
+
     async def fetch_jobs(self, user):
         logger.debug("Fetch entries for user {}", user.name)
         async for entry in self.wallabag.fetch_entries(user):
@@ -31,8 +34,26 @@ class Consumer:
         await self.sender.send_mail(job, data)
         session.delete(job)
 
+    async def _wait_since(self, since: datetime.datetime):
+        now = datetime.datetime.utcnow()
+        wait = max(0.0, self.interval - (now - since).total_seconds())
+
+        if not self.running:
+            return
+
+        self._wait_fut = asyncio.ensure_future(asyncio.sleep(wait))
+
+        try:
+            await self._wait_fut
+        except asyncio.CancelledError:
+            pass
+        finally:
+            self._wait_fut = None
+
     async def consume(self):
         while self.running:
+            start = datetime.datetime.utcnow()
+
             with self.sessionmaker as session:
                 logger.debug("Start consume run")
                 fetches = [self.fetch_jobs(user) for user in session.query(User).filter(User.active == True).all()]
@@ -43,5 +64,8 @@ class Consumer:
                 await asyncio.gather(*jobs)
                 session.commit()
 
-            await asyncio.sleep(self.interval)
+            await self._wait_since(start)
 
+    def stop(self):
+        self.running = False
+        self._wait_fut.cancel()