Implemented WAL journal mode for database

Some of the waitress code has been overwritten to make this work (at `backend.db.ThreadedTaskDispatcher`). The `handler_thread` function has been changed so that when the thread shuts down, the database connection for the thread is also closed (this _has_ to happen _in the thread that the connection is for/from_). The `shutdown` function opens and closes a database connection at the end, which triggers the checkpoint of the journal, writing everything to the db file and removing the `-wal` and `-shm` temporary db files.

.dockerignore

@@ -1,5 +1,5 @@
 # Byte-compiled / optimized / DLL files
-__pycache__/
+**/__pycache__/
 *.py[cod]
 *$py.class
 
@@ -129,14 +129,13 @@ dmypy.json
 .pyre/
 
 # Database
-*.db
+**/*.db
 
 # VS code
 *.code-workspace
 .vscode/
 
 # Docker
-Dockerfile
 .dockerignore
 docker-compose.yml
 
@@ -146,7 +145,7 @@ docker-compose.yml
 .github/
 
 # Various files
-*.md
+**/*.md
 LICENSE
 
 # Tests

Dockerfile

@@ -1,6 +1,7 @@
 # syntax=docker/dockerfile:1
 
 FROM python:3.8-slim-buster
+STOPSIGNAL SIGINT
 
 WORKDIR /app
 

MIND.py

@@ -11,7 +11,7 @@ from flask import Flask, render_template, request
 from waitress.server import create_server
 from werkzeug.middleware.dispatcher import DispatcherMiddleware
 
-from backend.db import DBConnection, close_db, setup_db
+from backend.db import DBConnection, ThreadedTaskDispatcher, close_db, setup_db
 from frontend.api import api, api_prefix, reminder_handler
 from frontend.ui import ui
 
@@ -90,7 +90,7 @@ def MIND() -> None:
 	app = _create_app()
 	with app.app_context():
 		if isfile(_folder_path('db', 'Noted.db')):
-			move(_folder_path('db', 'Noted.db'), _folder_path('db', 'MIND.db'))
+			move(_folder_path('db', 'Noted.db'), _folder_path(*DB_FILENAME))
 		db_location = _folder_path(*DB_FILENAME)
 		makedirs(dirname(db_location), exist_ok=True)
 		DBConnection.file = db_location
@@ -98,10 +98,11 @@ def MIND() -> None:
 		reminder_handler.find_next_reminder()
 
 	# Create waitress server and run
-	server = create_server(app, host=HOST, port=PORT, threads=THREADS)
+	dispatcher = ThreadedTaskDispatcher()
+	dispatcher.set_thread_count(THREADS)
+	server = create_server(app, _dispatcher=dispatcher, host=HOST, port=PORT, threads=THREADS)
 	print(f'MIND running on http://{HOST}:{PORT}{URL_PREFIX}')
 	server.run()
-	print(f'\nShutting down MIND...')
 	
 	# Stopping thread
 	reminder_handler.stop_handling()

backend/db.py

@@ -7,8 +7,11 @@ from time import time
 from typing import Union
 
 from flask import g
+from waitress.task import ThreadedTaskDispatcher as OldThreadedTaskDispatcher
 
-__DATABASE_VERSION__ = 5
+from backend.custom_exceptions import AccessUnauthorized, UserNotFound
+
+__DATABASE_VERSION__ = 6
 
 class Singleton(type):
 	_instances = {}
@@ -20,6 +23,18 @@ class Singleton(type):
 
 		return cls._instances[i]
 
+class ThreadedTaskDispatcher(OldThreadedTaskDispatcher):
+	def handler_thread(self, thread_no: int) -> None:
+		super().handler_thread(thread_no)
+		i = f'{DBConnection}{current_thread()}'
+		if i in Singleton._instances and not Singleton._instances[i].closed:
+			Singleton._instances[i].close()
+			
+	def shutdown(self, cancel_pending: bool = True, timeout: int = 5) -> bool:
+		print('Shutting down MIND...')
+		super().shutdown(cancel_pending, timeout)
+		DBConnection(20.0).close()
+
 class DBConnection(Connection, metaclass=Singleton):
 	file = ''
 	
@@ -177,13 +192,22 @@ def migrate_db(current_db_version: int) -> None:
 			COMMIT;
 		""")
 		current_db_version = 5
-	
+
+	if current_db_version == 5:
+		# V5 -> V6
+		from backend.users import User
+		try:
+			User('User1', 'Password1').delete()
+		except (UserNotFound, AccessUnauthorized):
+			pass
+
 	return
 
 def setup_db() -> None:
 	"""Setup the database
 	"""
 	cursor = get_db()
+	cursor.execute("PRAGMA journal_mode = wal;")
 
 	cursor.executescript("""
 		CREATE TABLE IF NOT EXISTS users(