DB and FastAPI: Reconnect if DB goes down, switch to lifespan events in FastAPI, ensure safe startup/shutdown.

.gitignore

@@ -168,3 +168,4 @@ cython_debug/
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
 #.idea/
 
+test.py

src/db.py

@@ -24,17 +24,20 @@ MYSQL_CONFIG = {
 _pool_lock = threading.Lock()
 _connection_pool = None
 
+
 def create_connection_pool():
 	global _connection_pool
 	for attempt in range(1, MAX_RETRIES+1):
 		try:
 			print(f"[MySQL] Attempt {attempt} to connect...")
-			_connection_pool = mysql.connector.pooling.MySQLConnectionPool(
+			pool  = mysql.connector.pooling.MySQLConnectionPool(
 				pool_name="mypool",
 				pool_size=5,
 				pool_reset_session=True,
 				**MYSQL_CONFIG
 			)
+			with _pool_lock:
+				_connection_pool = pool
 			print("[MySQL] Connection pool created successfully.")
 			return
 		except mysql.connector.Error as e:
@@ -44,6 +47,15 @@ def create_connection_pool():
 	print(f"[MySQL] Failed to connect after {MAX_RETRIES} attempts — exiting.")
 	sys.exit(1)
 
+
+def close_connection_pool():
+	global _connection_pool
+	with _pool_lock:
+		if _connection_pool:
+			_connection_pool = None
+			print("[MySQL] Connection pool closed.")
+
+
 def get_connection_pool():
 	global _connection_pool
 	with _pool_lock:
@@ -51,11 +63,18 @@ def get_connection_pool():
 			create_connection_pool()
 	return _connection_pool
 
+
 def get_db():
 	pool = get_connection_pool()
-	conn = pool.get_connection()
+	try:
+		conn = pool.get_connection()
+		if not conn.is_connected():
+			conn.reconnect(attempts=MAX_RETRIES, delay=RETRY_DELAY)
+	except Exception:
+		create_connection_pool()
+		pool = get_connection_pool()
+		conn = pool.get_connection()
 	try:
 		yield conn
 	finally:
 		conn.close()
-

src/main.py

@@ -1,4 +1,4 @@
-from fastapi import FastAPI, Depends, HTTPException
+from fastapi import FastAPI, Depends, HTTPException, Request
 from fastapi.responses import JSONResponse
 from fastapi.security.api_key import APIKeyHeader
 from starlette.exceptions import HTTPException as StarletteHTTPException
@@ -6,12 +6,13 @@ from typing import Optional,List
 from pydantic import BaseModel
 from validator import is_valid_platform,is_valid_token,verify_api_key
 from secret_handler import encrypt_token
-from db import get_db
+from db import get_db, create_connection_pool, close_connection_pool
 from logger_handler import setup_logger
 import uuid
 from hashlib import sha256
 import uvicorn
 from uvicorn_logging_config import LOGGING_CONFIG
+from contextlib import asynccontextmanager
 
 
 
@@ -31,10 +32,24 @@ class TokenRequest(BaseModel):
 	locale : Optional[str] = None
 	topics : Optional[List[str]] = None
 
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+	logger.info("Starting application...")
+
+	logger.info("Creating MySQL connection pool...")
+	create_connection_pool()
+
+	yield
+	logger.info("Closing MySQL connection pool...")
+	close_connection_pool()
+
+
 api = FastAPI(
 		title="Device Token Management",
 		description="API for requesting tokens",
-		version="1.0.0"
+		version="1.0.0",
+		lifespan=lifespan
 )