persistence: simplify init and pass db_url via config dict

freqtrade/persistence.py

@@ -10,13 +10,11 @@ from typing import Dict, Optional, Any
 import arrow
 from sqlalchemy import (Boolean, Column, DateTime, Float, Integer, String,
                         create_engine)
-from sqlalchemy.engine import Engine
+from sqlalchemy import inspect
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm.scoping import scoped_session
 from sqlalchemy.orm.session import sessionmaker
 from sqlalchemy.pool import StaticPool
-from sqlalchemy import inspect
-
 
 logger = logging.getLogger(__name__)
 
@@ -24,30 +22,30 @@ _CONF = {}
 _DECL_BASE: Any = declarative_base()
 
 
-def init(config: dict, engine: Optional[Engine] = None) -> None:
+def init(config: Dict) -> None:
     """
     Initializes this module with the given config,
     registers all known command handlers
     and starts polling for message updates
     :param config: config to use
-    :param engine: database engine for sqlalchemy (Optional)
     :return: None
     """
     _CONF.update(config)
-    if not engine:
-        if _CONF.get('dry_run', False):
-            # the user wants dry run to use a DB
-            if _CONF.get('dry_run_db', False):
-                engine = create_engine('sqlite:///tradesv3.dry_run.sqlite')
-            # Otherwise dry run will store in memory
-            else:
-                engine = create_engine('sqlite://',
-                                       connect_args={'check_same_thread': False},
-                                       poolclass=StaticPool,
-                                       echo=False)
-        else:
-            engine = create_engine('sqlite:///tradesv3.sqlite')
 
+    db_url = _CONF.get('db_url', None)
+    kwargs = {}
+
+    if not db_url and _CONF.get('dry_run', False):
+        # Default to in-memory db if not specified
+        # and take care of thread ownership if in-memory db
+        db_url = 'sqlite://'
+        kwargs.update({
+            'connect_args': {'check_same_thread': False},
+            'poolclass': StaticPool,
+            'echo': False,
+        })
+
+    engine = create_engine(db_url, **kwargs)
     session = scoped_session(sessionmaker(bind=engine, autoflush=True, autocommit=True))
     Trade.session = session()
     Trade.query = session.query_property()
@@ -55,7 +53,7 @@ def init(config: dict, engine: Optional[Engine] = None) -> None:
     check_migrate(engine)
 
     # Clean dry_run DB
-    if _CONF.get('dry_run', False) and _CONF.get('dry_run_db', False):
+    if _CONF.get('dry_run', False) and db_url != 'sqlite://':
         clean_dry_run_db()