better sqlite connection handling

photoapp/dbutils.py

@@ -51,9 +51,6 @@ class SATool(cherrypy.Tool):
     def bind_session(self):
         cherrypy.engine.publish('bind', self.session)
         cherrypy.request.db = self.session
-        con = cherrypy.request.db.connection().connection.connection
-        if hasattr(con, "ping"):  # not available on sqlite
-            con.ping()
 
     def commit_transaction(self):
         cherrypy.request.db = None

photoapp/library.py

@@ -3,9 +3,9 @@ import sys
 import traceback
 from time import time
 from sqlalchemy import create_engine
-from sqlalchemy.pool import StaticPool
+from sqlalchemy.pool import StaticPool, AssertionPool, NullPool  # NOQA
 from sqlalchemy.orm import sessionmaker
-from photoapp.types import Base, Photo, PhotoSet  # need to be loaded for orm setup
+from photoapp.types import Base, Photo, PhotoSet  # NOQA need to be loaded for orm setup
 from sqlalchemy.exc import IntegrityError
 from collections import defaultdict
 from multiprocessing import Process
@@ -16,8 +16,11 @@ class PhotoLibrary(object):
     def __init__(self, db_path, lib_path, cache_path):
         self.path = lib_path
         self.cache_path = cache_path
+        # TODO configure from env var
+        # TODO use the right pool and connection args depending on the url
+        # https://docs.sqlalchemy.org/en/13/core/pooling.html
         self.engine = create_engine('sqlite:///{}'.format(db_path),
-                                    connect_args={'check_same_thread': False}, poolclass=StaticPool)
+                                    connect_args={'check_same_thread': False}, poolclass=NullPool, pool_pre_ping=True)
         Base.metadata.create_all(self.engine)
         self.session = sessionmaker()
         self.session.configure(bind=self.engine)

requirements.txt

@@ -2,7 +2,7 @@ backports.functools-lru-cache==1.5
 certifi==2019.6.16
 chardet==3.0.4
 cheroot==6.5.2
-CherryPy==18.1.1
+CherryPy==18.1.2
 contextlib2==0.5.5
 idna==2.8
 jaraco.functools==1.20