Verification: persist task settings in Redis

If tasks are stopped manually, they will not automatically restart
on cog reload or bot restart.

Using `maybe_start_tasks` is necessary because we cannot interface
with Redis from a sync context.

We're using 1 and 0 because RedisCache does not currently permit
bool values due to a typestring conversion bug.

1 files changed, 19 insertions, 3 deletions

diff --git a/bot/cogs/verification.py b/bot/cogs/verification.py
index 152118d92..b4dc1f145 100644
--- a/bot/cogs/verification.py
+++ b/bot/cogs/verification.py
@@ -111,9 +111,7 @@ class Verification(Cog):
     def __init__(self, bot: Bot) -> None:
         """Start internal tasks."""
         self.bot = bot
-
-        self.update_unverified_members.start()
-        self.ping_unverified.start()
+        self.bot.loop.create_task(self.maybe_start_tasks())
 
     def cog_unload(self) -> None:
         """
@@ -129,6 +127,20 @@ class Verification(Cog):
         """Get currently loaded ModLog cog instance."""
         return self.bot.get_cog("ModLog")
 
+    async def maybe_start_tasks(self) -> None:
+        """
+        Poll Redis to check whether internal tasks should start.
+
+        Redis must be interfaced with from an async function.
+        """
+        log.trace("Checking whether background tasks should begin")
+        setting: t.Optional[int] = await self.reminder_cache.get("tasks_running")  # This can be None if never set
+
+        if setting:
+            log.trace("Background tasks will be started")
+            self.update_unverified_members.start()
+            self.ping_unverified.start()
+
     # region: automatically update unverified users
 
     async def _verify_kick(self, n_members: int) -> bool:
@@ -492,6 +504,8 @@ class Verification(Cog):
         if not self.ping_unverified.is_running():
             self.ping_unverified.start()
 
+        await self.reminder_cache.set("tasks_running", 1)
+
         colour = discord.Colour.blurple()
         await ctx.send(embed=discord.Embed(title="Verification system", description="Done. :ok_hand:", colour=colour))
 
@@ -503,6 +517,8 @@ class Verification(Cog):
         self.update_unverified_members.cancel()
         self.ping_unverified.cancel()
 
+        await self.reminder_cache.set("tasks_running", 0)
+
         colour = discord.Colour.blurple()
         await ctx.send(embed=discord.Embed(title="Verification system", description="Tasks canceled.", colour=colour))