Implement SQLAlchemy Pool.pre_ping

Fixes #241

app/config.py

@@ -39,6 +39,7 @@ class Config(object):
     DEFAULT_COLUMN_WIDTH = 200
     DISPLAY_SQL = False
     EPOCH = dt.datetime(1970, 1, 1)
+    ENGINE_OPTIONS = dict(pool_pre_ping=True)
     ERRORS_FROM = ["noreply@midnighthax.com"]
     ERRORS_TO = ["kae@midnighthax.com"]
     FADE_CURVE_BACKGROUND = "lightyellow"

app/models.py

@@ -33,7 +33,7 @@ if ALCHEMICAL_DATABASE_URI is None:
     raise ValueError("ALCHEMICAL_DATABASE_URI is undefined")
 if "unittest" in sys.modules and "sqlite" not in ALCHEMICAL_DATABASE_URI:
     raise ValueError("Unit tests running on non-Sqlite database")
-db = Alchemical(ALCHEMICAL_DATABASE_URI)
+db = Alchemical(ALCHEMICAL_DATABASE_URI, engine_options=Config.ENGINE_OPTIONS)
 
 
 # Database classes