Add pragmas to SQLite DBs and add retry logic to BaseModel

src/ddns_service/models.py

@@ -2,6 +2,7 @@
 
 import logging
 import os
+import time
 
 from . import datetime_naive_utc, datetime_aware_utc, now_utc
 from .dns import encode_dnsname, EncodingError
@@ -78,11 +79,21 @@ class DateTimeFieldUTC(DateTimeField):
 
 
 class BaseModel(Model):
-    """Base model with database binding."""
+    """Base model with database binding and save retry."""
 
     class Meta:
         database = db
 
+    def save(self, *args, max_retries=3, retry_delay=0.1, **kwargs):
+        """Save with retry on DatabaseError (exponential backoff)."""
+        for attempt in range(max_retries):
+            try:
+                return super().save(*args, **kwargs)
+            except DatabaseError:
+                if attempt == max_retries - 1:
+                    raise
+                time.sleep(retry_delay * (2 ** attempt))
+
 
 class User(BaseModel):
     """User model for authentication."""
@@ -152,7 +163,10 @@ def init_database(config: dict):
         db_dir = os.path.dirname(db_path)
         if db_dir:
             os.makedirs(db_dir, exist_ok=True)
-        actual_db = SqliteDatabase(db_path)
+        actual_db = SqliteDatabase(db_path, pragmas={
+            'journal_mode': 'wal',
+            'busy_timeout': 5000,
+        })
         db.initialize(actual_db)
         logging.debug(f"Database backend: SQLite path={db_path}")