[PATCH v2 0/2] Automatic recovery from a MySQL restart

[Ammar Faizi <ammarfaizi2@gnuweeb.org>]

Hi,

This series adds a mechanism for the daemon to recover from a MySQL
restart event. Currently, the daemon is totally unusable when the MySQL
server is restarted. It's spinning in a loop with the following error:

   mysql.connector.errors.OperationalError: 2013 (HY000): Lost connection to MySQL server during query

When it happens, the only way to fix the situation is: restart the
daemon manually, which is obviously not productive. Create a mechanism
in the class DB to allow the caller to reconnect.

Handle MySQL error in the main daemon loop path. Do reconnect to the
database if such an error happens. This way, the daemon can
automatically recover from the MySQL server restart without having the
user restart the daemon.

There are two patches in this series:

  - Patch 1 is a preparation patch to create a recover mechanism.
  - Patch 2 is to implement the recover mechanism in the main daemon
    loop path.

## Changelog

v1 -> v2:

  - Use conn.ping(reconnect=True) instead of creating a new MySQL
    connection object (comment from Muhammad Rizki).

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---

Ammar Faizi (2):
  daemon: telegram: db: Allow the caller to reconnect
  daemon: telegram: Handle MySQL error

 daemon/telegram/database/core.py   |  5 +++++
 daemon/telegram/mailer/listener.py | 31 ++++++++++++++++++++++++++----
 2 files changed, 32 insertions(+), 4 deletions(-)


base-commit: 6e94cf607287e5bc209e9c14c8156c7ad49455e3
-- 
Ammar Faizi