Reminders: make operations mutually exclusive

This fixes race conditions between editing, deleting, and sending a
reminder. If one operation is already happening, the others will be
aborted.

1 files changed, 7 insertions, 0 deletions

diff --git a/bot/cogs/reminders.py b/bot/cogs/reminders.py
index a043b7d75..1a0a9d303 100644
--- a/bot/cogs/reminders.py
+++ b/bot/cogs/reminders.py
@@ -4,6 +4,7 @@ import random
 import textwrap
 import typing as t
 from datetime import datetime, timedelta
+from functools import partial
 from operator import itemgetter
 
 import discord
@@ -14,14 +15,17 @@ from discord.ext.commands import Cog, Context, Greedy, group
 from bot.bot import Bot
 from bot.constants import Guild, Icons, MODERATION_ROLES, POSITIVE_REPLIES, STAFF_ROLES
 from bot.converters import Duration
+from bot.decorators import mutually_exclusive
 from bot.pagination import LinePaginator
 from bot.utils.checks import without_role_check
+from bot.utils.function import get_arg_value
 from bot.utils.messages import send_denial
 from bot.utils.scheduling import Scheduler
 from bot.utils.time import humanize_delta
 
 log = logging.getLogger(__name__)
 
+NAMESPACE = "reminders"  # Used for the mutually_exclusive decorator; constant to prevent typos
 WHITELISTED_CHANNELS = Guild.reminder_whitelist
 MAXIMUM_REMINDERS = 5
 
@@ -164,6 +168,7 @@ class Reminders(Cog):
         log.trace(f"Scheduling new task #{reminder['id']}")
         self.schedule_reminder(reminder)
 
+    @mutually_exclusive(NAMESPACE, lambda args: get_arg_value("reminder", args)["id"])
     async def send_reminder(self, reminder: dict, late: relativedelta = None) -> None:
         """Send the reminder."""
         is_valid, user, channel = self.ensure_valid_reminder(reminder)
@@ -370,6 +375,7 @@ class Reminders(Cog):
         mention_ids = [mention.id for mention in mentions]
         await self.edit_reminder(ctx, id_, {"mentions": mention_ids})
 
+    @mutually_exclusive(NAMESPACE, partial(get_arg_value, "id_"))
     async def edit_reminder(self, ctx: Context, id_: int, payload: dict) -> None:
         """Edits a reminder with the given payload, then sends a confirmation message."""
         reminder = await self._edit_reminder(id_, payload)
@@ -387,6 +393,7 @@ class Reminders(Cog):
         await self._reschedule_reminder(reminder)
 
     @remind_group.command("delete", aliases=("remove", "cancel"))
+    @mutually_exclusive(NAMESPACE, partial(get_arg_value, "id_"))
     async def delete_reminder(self, ctx: Context, id_: int) -> None:
         """Delete one of your active reminders."""
         await self.bot.api_client.delete(f"bot/reminders/{id_}")