server/db: make query counter thread-local

server/szurubooru/db/session.py

@@ -1,29 +1,27 @@
+import threading
 import sqlalchemy
 from szurubooru import config
 
 
-class QueryCounter(object):
-    _query_count = 0
-
-    @staticmethod
-    def bump():
-        QueryCounter._query_count += 1
-
-    @staticmethod
-    def reset():
-        QueryCounter._query_count = 0
-
-    @staticmethod
-    def get():
-        return QueryCounter._query_count
-
-
 # pylint: disable=invalid-name
 _engine = sqlalchemy.create_engine(config.config['database'])
 sessionmaker = sqlalchemy.orm.sessionmaker(bind=_engine)
 session = sqlalchemy.orm.scoped_session(sessionmaker)
-reset_query_count = QueryCounter.reset
-get_query_count = QueryCounter.get
+
+_data = threading.local()
+
+
+def reset_query_count():
+    _data.query_count = 0
+
+
+def get_query_count():
+    return _data.query_count
+
+
+def _bump_query_count():
+    _data.query_count = getattr(_data, 'query_count', 0) + 1
+
 
 sqlalchemy.event.listen(
-    _engine, 'after_execute', lambda *args: QueryCounter.bump())
+    _engine, 'after_execute', lambda *args: _bump_query_count())

server/szurubooru/middleware/db_session.py

@@ -5,7 +5,6 @@ from szurubooru.rest import middleware
 @middleware.pre_hook
 def _process_request(ctx):
     ctx.session = db.session()
-    db.reset_query_count()
 
 
 @middleware.post_hook

server/szurubooru/middleware/request_logger.py

@@ -6,6 +6,11 @@ from szurubooru.rest import middleware
 logger = logging.getLogger(__name__)
 
 
+@middleware.pre_hook
+def process_request(_ctx):
+    db.reset_query_count()
+
+
 @middleware.post_hook
 def process_response(ctx):
     logger.info(