[PATCH v3 10/11] discord: listener: Add handle_db_error to handle the MySQL errors

[Muhammad Rizki <kiizuha@gnuweeb.org>]

After adding a ping() method to the database, you should handle database
errors such as connection errors. This function will be used to handle
connection errors that occur when the MySQL service is restarted.

Signed-off-by: Muhammad Rizki <kiizuha@gnuweeb.org>
---
 daemon/dscord/mailer/listener.py | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/daemon/dscord/mailer/listener.py b/daemon/dscord/mailer/listener.py
index aa44603..fc066b7 100644
--- a/daemon/dscord/mailer/listener.py
+++ b/daemon/dscord/mailer/listener.py
@@ -6,6 +6,7 @@
 
 import asyncio
 import re
+from mysql.connector.errors import OperationalError, DatabaseError
 from apscheduler.schedulers.asyncio import AsyncIOScheduler
 from discord import File
 from discord import Message
@@ -50,6 +51,24 @@ class Listener:
 		self.runner = self.sched.add_job(func=self.__run)
 
 
+	async def handle_db_error(self, e):
+		#
+		# TODO(ammarfaizi2):
+		# Ideally, we also want to log and report this situation.
+		#
+		self.logger.error(f"Database error: {str(e)}")
+		self.logger.info("Reconnecting to the database...")
+
+		#
+		# Don't do this too often to avoid reconnect burst.
+		#
+		delay_in_secs = 3
+		reconnect_attempts = 3
+
+		self.db.ping(reconnect=True, attempts=reconnect_attempts,
+			     delay=delay_in_secs)
+
+
 	async def __run(self):
 		self.logger.info("Running...")
 		url = None
@@ -57,6 +76,8 @@ class Listener:
 		try:
 			for url in self.db.get_atom_urls():
 				await self.__handle_atom_url(url)
+		except (OperationalError, DatabaseError) as e:
+			await self.handle_db_error(e)
 		except DaemonException as e:
 			e.set_atom_url(url)
 			await self.client.report_err(e)
-- 
Muhammad Rizki