Basic support for entities on the local db and implemented support for switch entities on the tplink plugin

platypush/__init__.py

@@ -9,11 +9,13 @@ import argparse
 import logging
 import os
 import sys
+from typing import Optional
 
 from .bus.redis import RedisBus
 from .config import Config
 from .context import register_backends, register_plugins
 from .cron.scheduler import CronScheduler
+from .entities import init_entities_engine, EntitiesEngine
 from .event.processor import EventProcessor
 from .logger import Logger
 from .message.event import Event
@@ -86,6 +88,7 @@ class Daemon:
         self.no_capture_stdout = no_capture_stdout
         self.no_capture_stderr = no_capture_stderr
         self.event_processor = EventProcessor()
+        self.entities_engine: Optional[EntitiesEngine] = None
         self.requests_to_process = requests_to_process
         self.processed_requests = 0
         self.cron_scheduler = None
@@ -161,16 +164,25 @@ class Daemon:
         """ Stops the backends and the bus """
         from .plugins import RunnablePlugin
 
-        for backend in self.backends.values():
-            backend.stop()
+        if self.backends:
+            for backend in self.backends.values():
+                backend.stop()
 
         for plugin in get_enabled_plugins().values():
             if isinstance(plugin, RunnablePlugin):
                 plugin.stop()
 
-        self.bus.stop()
+        if self.bus:
+            self.bus.stop()
+            self.bus = None
+
         if self.cron_scheduler:
             self.cron_scheduler.stop()
+            self.cron_scheduler = None
+
+        if self.entities_engine:
+            self.entities_engine.stop()
+            self.entities_engine = None
 
     def run(self):
         """ Start the daemon """
@@ -192,6 +204,9 @@ class Daemon:
         # Initialize the plugins
         register_plugins(bus=self.bus)
 
+        # Initialize the entities engine
+        self.entities_engine = init_entities_engine()
+
         # Start the cron scheduler
         if Config.get_cronjobs():
             self.cron_scheduler = CronScheduler(jobs=Config.get_cronjobs())

platypush/entities/__init__.py

@@ -0,0 +1,36 @@
+import warnings
+from typing import Collection, Optional
+
+from ._base import Entity
+from ._engine import EntitiesEngine
+from ._registry import manages, register_entity_plugin, get_plugin_registry
+
+_engine: Optional[EntitiesEngine] = None
+
+
+def init_entities_engine() -> EntitiesEngine:
+    from ._base import init_entities_db
+    global _engine
+    init_entities_db()
+    _engine = EntitiesEngine()
+    _engine.start()
+    return _engine
+
+
+def publish_entities(entities: Collection[Entity]):
+    if not _engine:
+        warnings.warn('No entities engine registered')
+        return
+
+    _engine.post(*entities)
+
+__all__ = (
+    'Entity',
+    'EntitiesEngine',
+    'init_entities_engine',
+    'publish_entities',
+    'register_entity_plugin',
+    'get_plugin_registry',
+    'manages',
+)
+

platypush/entities/_base.py

@@ -0,0 +1,73 @@
+import inspect
+import pathlib
+from datetime import datetime
+from typing import Mapping, Type
+
+import pkgutil
+from sqlalchemy import Column, Index, Integer, String, DateTime, JSON, UniqueConstraint
+from sqlalchemy.ext.declarative import declarative_base
+
+Base = declarative_base()
+entities_registry: Mapping[Type['Entity'], Mapping] = {}
+
+
+class Entity(Base):
+    """
+    Model for a general-purpose platform entity
+    """
+
+    __tablename__ = 'entity'
+
+    id = Column(Integer, autoincrement=True, primary_key=True)
+    external_id = Column(String, nullable=True)
+    name = Column(String, nullable=False, index=True)
+    type = Column(String, nullable=False, index=True)
+    plugin = Column(String, nullable=False)
+    data = Column(JSON, default=dict)
+    created_at = Column(DateTime(timezone=False), default=datetime.utcnow(), nullable=False)
+    updated_at = Column(DateTime(timezone=False), default=datetime.utcnow(), onupdate=datetime.now())
+
+    UniqueConstraint(external_id, plugin)
+
+    __table_args__ = (
+        Index(name, plugin),
+    )
+
+    __mapper_args__ = {
+        'polymorphic_identity': __tablename__,
+        'polymorphic_on': type,
+    }
+
+
+def _discover_entity_types():
+    from platypush.context import get_plugin
+    logger = get_plugin('logger')
+    assert logger
+
+    for loader, modname, _ in pkgutil.walk_packages(
+        path=[str(pathlib.Path(__file__).parent.absolute())],
+        prefix=__package__ + '.',
+        onerror=lambda _: None
+    ):
+        try:
+            mod_loader = loader.find_module(modname)  # type: ignore
+            assert mod_loader
+            module = mod_loader.load_module()  # type: ignore
+        except Exception as e:
+            logger.warning(f'Could not import module {modname}')
+            logger.exception(e)
+            continue
+
+        for _, obj in inspect.getmembers(module):
+            if inspect.isclass(obj) and issubclass(obj, Entity):
+                entities_registry[obj] = {}
+
+
+def init_entities_db():
+    from platypush.context import get_plugin
+    _discover_entity_types()
+    db = get_plugin('db')
+    assert db
+    engine = db.get_engine()
+    db.create_all(engine, Base)
+

platypush/entities/_engine.py

@@ -0,0 +1,110 @@
+from logging import getLogger
+from queue import Queue, Empty
+from threading import Thread, Event
+from time import time
+from typing import Iterable, List
+
+from sqlalchemy import and_, or_, inspect as schema_inspect
+from sqlalchemy.orm import Session
+from sqlalchemy.sql.elements import Null
+
+from ._base import Entity
+
+
+class EntitiesEngine(Thread):
+    # Processing queue timeout in seconds
+    _queue_timeout = 5.
+
+    def __init__(self):
+        obj_name = self.__class__.__name__
+        super().__init__(name=obj_name)
+        self.logger = getLogger(name=obj_name)
+        self._queue = Queue()
+        self._should_stop = Event()
+
+    def post(self, *entities: Entity):
+        for entity in entities:
+            self._queue.put(entity)
+
+    @property
+    def should_stop(self) -> bool:
+        return self._should_stop.is_set()
+
+    def stop(self):
+        self._should_stop.set()
+
+    def run(self):
+        super().run()
+        self.logger.info('Started entities engine')
+
+        while not self.should_stop:
+            msgs = []
+            last_poll_time = time()
+
+            while not self.should_stop and (
+                    time() - last_poll_time < self._queue_timeout):
+                try:
+                    msg = self._queue.get(block=True, timeout=0.5)
+                except Empty:
+                    continue
+
+                if msg:
+                    msgs.append(msg)
+
+            if not msgs or self.should_stop:
+                continue
+
+            self._process_entities(*msgs)
+
+        self.logger.info('Stopped entities engine')
+
+    def _get_if_exist(self, session: Session, entities: Iterable[Entity]) -> Iterable[Entity]:
+        existing_entities = {
+            (entity.external_id or entity.name, entity.plugin): entity
+            for entity in session.query(Entity).filter(
+                or_(*[
+                    and_(Entity.external_id == entity.external_id, Entity.plugin == entity.plugin)
+                    if entity.external_id is not None else
+                    and_(Entity.name == entity.name, Entity.plugin == entity.plugin)
+                    for entity in entities
+                ])
+            ).all()
+        }
+
+        return [
+            existing_entities.get(
+                (entity.external_id or entity.name, entity.plugin), None
+            ) for entity in entities
+        ]
+
+    def _merge_entities(
+        self, entities: List[Entity],
+        existing_entities: List[Entity]
+    ) -> List[Entity]:
+        new_entities = []
+
+        for i, entity in enumerate(entities):
+            existing_entity = existing_entities[i]
+            if existing_entity:
+                inspector = schema_inspect(entity.__class__)
+                columns = [col.key for col in inspector.mapper.column_attrs]
+                for col in columns:
+                    new_value = getattr(entity, col)
+                    if new_value is not None and new_value.__class__ != Null:
+                        setattr(existing_entity, col, getattr(entity, col))
+
+                new_entities.append(existing_entity)
+            else:
+                new_entities.append(entity)
+
+        return new_entities
+
+    def _process_entities(self, *entities: Entity):
+        from platypush.context import get_plugin
+
+        with get_plugin('db').get_session() as session:  # type: ignore
+            existing_entities = self._get_if_exist(session, entities)
+            entities = self._merge_entities(entities, existing_entities)  # type: ignore
+            session.add_all(entities)
+            session.commit()
+

platypush/entities/_registry.py

@@ -0,0 +1,62 @@
+from datetime import datetime
+from typing import Optional, Mapping, Dict, Collection, Type
+
+from platypush.plugins import Plugin
+from platypush.utils import get_plugin_name_by_class
+
+from ._base import Entity
+
+_entity_plugin_registry: Mapping[Type[Entity], Dict[str, Plugin]] = {}
+
+
+def register_entity_plugin(entity_type: Type[Entity], plugin: Plugin):
+    plugins = _entity_plugin_registry.get(entity_type, {})
+    plugin_name = get_plugin_name_by_class(plugin.__class__)
+    assert plugin_name
+    plugins[plugin_name] = plugin
+    _entity_plugin_registry[entity_type] = plugins
+
+
+def get_plugin_registry():
+    return _entity_plugin_registry.copy()
+
+
+class EntityManagerMixin:
+    def transform_entities(self, entities):
+        entities = entities or []
+        for entity in entities:
+            if entity.id:
+                # Entity IDs can only refer to the internal primary key
+                entity.external_id = entity.id
+                entity.id = None  # type: ignore
+
+            entity.plugin = get_plugin_name_by_class(self.__class__)  # type: ignore
+            entity.updated_at = datetime.utcnow()
+
+        return entities
+
+    def publish_entities(self, entities: Optional[Collection[Entity]]):
+        from . import publish_entities
+        entities = self.transform_entities(entities)
+        publish_entities(entities)
+
+
+def manages(*entities: Type[Entity]):
+    def wrapper(plugin: Type[Plugin]):
+        init = plugin.__init__
+
+        def __init__(self, *args, **kwargs):
+            for entity_type in entities:
+                register_entity_plugin(entity_type, self)
+
+            init(self, *args, **kwargs)
+
+        plugin.__init__ = __init__
+        # Inject the EntityManagerMixin
+        if EntityManagerMixin not in plugin.__bases__:
+            plugin.__bases__ = (EntityManagerMixin,) + plugin.__bases__
+
+        return plugin
+
+    return wrapper
+

platypush/entities/devices.py

@@ -0,0 +1,14 @@
+from sqlalchemy import Column, Integer, ForeignKey
+
+from ._base import Entity
+
+
+class Device(Entity):
+    __tablename__ = 'device'
+
+    id = Column(Integer, ForeignKey(Entity.id), primary_key=True)
+
+    __mapper_args__ = {
+        'polymorphic_identity': __tablename__,
+    }
+

platypush/entities/lights.py

@@ -0,0 +1,14 @@
+from sqlalchemy import Column, Integer, ForeignKey
+
+from .devices import Device
+
+
+class Light(Device):
+    __tablename__ = 'light'
+
+    id = Column(Integer, ForeignKey(Device.id), primary_key=True)
+
+    __mapper_args__ = {
+        'polymorphic_identity': __tablename__,
+    }
+

platypush/entities/switches.py

@@ -0,0 +1,15 @@
+from sqlalchemy import Column, Integer, ForeignKey, Boolean
+
+from .devices import Device
+
+
+class Switch(Device):
+    __tablename__ = 'switch'
+
+    id = Column(Integer, ForeignKey(Device.id), primary_key=True)
+    state = Column(Boolean)
+
+    __mapper_args__ = {
+        'polymorphic_identity': __tablename__,
+    }
+

platypush/plugins/db/__init__.py

@@ -1,11 +1,11 @@
-"""
-.. moduleauthor:: Fabio Manganiello <blacklight86@gmail.com>
-"""
-
 import time
+from contextlib import contextmanager
+from multiprocessing import RLock
+from typing import Generator
 
 from sqlalchemy import create_engine, Table, MetaData
 from sqlalchemy.engine import Engine
+from sqlalchemy.orm import Session, sessionmaker, scoped_session
 
 from platypush.plugins import Plugin, action
 
@@ -30,22 +30,23 @@ class DbPlugin(Plugin):
         """
 
         super().__init__()
-        self.engine = self._get_engine(engine, *args, **kwargs)
+        self.engine = self.get_engine(engine, *args, **kwargs)
+        self._session_locks = {}
 
-    def _get_engine(self, engine=None, *args, **kwargs):
+    def get_engine(self, engine=None, *args, **kwargs) -> Engine:
         if engine:
             if isinstance(engine, Engine):
                 return engine
             if engine.startswith('sqlite://'):
                 kwargs['connect_args'] = {'check_same_thread': False}
 
-            return create_engine(engine, *args, **kwargs)
+            return create_engine(engine, *args, **kwargs)  # type: ignore
 
+        assert self.engine
         return self.engine
 
-    # noinspection PyUnusedLocal
     @staticmethod
-    def _build_condition(table, column, value):
+    def _build_condition(_, column, value):
         if isinstance(value, str):
             value = "'{}'".format(value)
         elif not isinstance(value, int) and not isinstance(value, float):
@@ -73,14 +74,14 @@ class DbPlugin(Plugin):
         :param kwargs: Extra kwargs that will be passed to ``sqlalchemy.create_engine`` (seehttps:///docs.sqlalchemy.org/en/latest/core/engines.html)
         """
 
-        engine = self._get_engine(engine, *args, **kwargs)
+        engine = self.get_engine(engine, *args, **kwargs)
 
         with engine.connect() as connection:
             connection.execute(statement)
 
     def _get_table(self, table, engine=None, *args, **kwargs):
         if not engine:
-            engine = self._get_engine(engine, *args, **kwargs)
+            engine = self.get_engine(engine, *args, **kwargs)
 
         db_ok = False
         n_tries = 0
@@ -98,7 +99,7 @@ class DbPlugin(Plugin):
                 self.logger.exception(e)
                 self.logger.info('Waiting {} seconds before retrying'.format(wait_time))
                 time.sleep(wait_time)
-                engine = self._get_engine(engine, *args, **kwargs)
+                engine = self.get_engine(engine, *args, **kwargs)
 
         if not db_ok and last_error:
             raise last_error
@@ -163,7 +164,7 @@ class DbPlugin(Plugin):
                 ]
         """
 
-        engine = self._get_engine(engine, *args, **kwargs)
+        engine = self.get_engine(engine, *args, **kwargs)
 
         if table:
             table, engine = self._get_table(table, engine=engine, *args, **kwargs)
@@ -234,7 +235,7 @@ class DbPlugin(Plugin):
         if key_columns is None:
             key_columns = []
 
-        engine = self._get_engine(engine, *args, **kwargs)
+        engine = self.get_engine(engine, *args, **kwargs)
 
         for record in records:
             table, engine = self._get_table(table, engine=engine, *args, **kwargs)
@@ -293,7 +294,7 @@ class DbPlugin(Plugin):
                 }
         """
 
-        engine = self._get_engine(engine, *args, **kwargs)
+        engine = self.get_engine(engine, *args, **kwargs)
 
         for record in records:
             table, engine = self._get_table(table, engine=engine, *args, **kwargs)
@@ -341,7 +342,7 @@ class DbPlugin(Plugin):
                 }
         """
 
-        engine = self._get_engine(engine, *args, **kwargs)
+        engine = self.get_engine(engine, *args, **kwargs)
 
         for record in records:
             table, engine = self._get_table(table, engine=engine, *args, **kwargs)
@@ -352,5 +353,22 @@ class DbPlugin(Plugin):
 
             engine.execute(delete)
 
+    def create_all(self, engine, base):
+        self._session_locks[engine.url] = self._session_locks.get(engine.url, RLock())
+        with self._session_locks[engine.url]:
+            base.metadata.create_all(engine)
+
+    @contextmanager
+    def get_session(self, engine=None, *args, **kwargs) -> Generator[Session, None, None]:
+        engine = self.get_engine(engine, *args, **kwargs)
+        self._session_locks[engine.url] = self._session_locks.get(engine.url, RLock())
+        with self._session_locks[engine.url]:
+            session = scoped_session(sessionmaker(expire_on_commit=False))
+            session.configure(bind=engine)
+            s = session()
+            yield s
+            s.commit()
+            s.close()
+
 
 # vim:sw=4:ts=4:et:

platypush/plugins/switch/__init__.py

@@ -1,9 +1,12 @@
 from abc import ABC, abstractmethod
 from typing import List, Union
 
+from platypush.entities import manages
+from platypush.entities.switches import Switch
 from platypush.plugins import Plugin, action
 
 
+@manages(Switch)
 class SwitchPlugin(Plugin, ABC):
     """
     Abstract class for interacting with switch devices
@@ -46,7 +49,7 @@ class SwitchPlugin(Plugin, ABC):
         return devices
 
     @action
-    def status(self, device=None, *args, **kwargs) -> Union[dict, List[dict]]:
+    def status(self, device=None, *_, **__) -> Union[dict, List[dict]]:
         """
         Get the status of all the devices, or filter by device name or ID (alias for :meth:`.switch_status`).
 

platypush/plugins/switch/tplink/__init__.py

@@ -1,4 +1,4 @@
-from typing import Union, Dict, List
+from typing import Union, Mapping, List, Collection, Optional
 
 from pyHS100 import SmartDevice, SmartPlug, SmartBulb, SmartStrip, Discover, SmartDeviceException
 
@@ -20,8 +20,12 @@ class SwitchTplinkPlugin(SwitchPlugin):
     _ip_to_dev = {}
     _alias_to_dev = {}
 
-    def __init__(self, plugs: Union[Dict[str, str], List[str]] = None, bulbs: Union[Dict[str, str], List[str]] = None,
-                 strips: Union[Dict[str, str], List[str]] = None, **kwargs):
+    def __init__(
+        self,
+        plugs: Optional[Union[Mapping[str, str], List[str]]] = None,
+        bulbs: Optional[Union[Mapping[str, str], List[str]]] = None,
+        strips: Optional[Union[Mapping[str, str], List[str]]] = None, **kwargs
+    ):
         """
         :param plugs: Optional list of IP addresses or name->address mapping if you have a static list of
             TpLink plugs and you want to save on the scan time.
@@ -62,7 +66,7 @@ class SwitchTplinkPlugin(SwitchPlugin):
 
         self._update_devices()
 
-    def _update_devices(self, devices: Dict[str, SmartDevice] = None):
+    def _update_devices(self, devices: Optional[Mapping[str, SmartDevice]] = None):
         for (addr, info) in self._static_devices.items():
             try:
                 dev = info['type'](addr)
@@ -75,6 +79,26 @@ class SwitchTplinkPlugin(SwitchPlugin):
             self._ip_to_dev[ip] = dev
             self._alias_to_dev[dev.alias] = dev
 
+        if devices:
+            self.publish_entities(devices.values())  # type: ignore
+
+    def transform_entities(self, devices: Collection[SmartDevice]):
+        from platypush.entities.switches import Switch
+        return super().transform_entities([   # type: ignore
+            Switch(
+                id=dev.host,
+                name=dev.alias,
+                state=dev.is_on,
+                data={
+                    'current_consumption': dev.current_consumption(),
+                    'ip': dev.host,
+                    'host': dev.host,
+                    'hw_info': dev.hw_info,
+                }
+            )
+            for dev in (devices or [])
+        ])
+
     def _scan(self):
         devices = Discover.discover()
         self._update_devices(devices)
@@ -95,8 +119,15 @@ class SwitchTplinkPlugin(SwitchPlugin):
         else:
             raise RuntimeError('Device {} not found'.format(device))
 
+    def _set(self, device: SmartDevice, state: bool):
+        action_name = 'turn_on' if state else 'turn_off'
+        action = getattr(device, action_name)
+        action()
+        self.publish_entities([device])   # type: ignore
+        return self._serialize(device)
+
     @action
-    def on(self, device, **kwargs):
+    def on(self, device, **_):
         """
         Turn on a device
 
@@ -105,11 +136,10 @@ class SwitchTplinkPlugin(SwitchPlugin):
         """
 
         device = self._get_device(device)
-        device.turn_on()
-        return self.status(device)
+        return self._set(device, True)
 
     @action
-    def off(self, device, **kwargs):
+    def off(self, device, **_):
         """
         Turn off a device
 
@@ -118,11 +148,10 @@ class SwitchTplinkPlugin(SwitchPlugin):
         """
 
         device = self._get_device(device)
-        device.turn_off()
-        return self.status(device)
+        return self._set(device, False)
 
     @action
-    def toggle(self, device, **kwargs):
+    def toggle(self, device, **_):
         """
         Toggle the state of a device (on/off)
 
@@ -131,12 +160,10 @@ class SwitchTplinkPlugin(SwitchPlugin):
         """
 
         device = self._get_device(device)
+        return self._set(device, not device.is_on)
 
-        if device.is_on:
-            device.turn_off()
-        else:
-            device.turn_on()
-
+    @staticmethod
+    def _serialize(device: SmartDevice) -> dict:
         return {
             'current_consumption': device.current_consumption(),
             'id': device.host,
@@ -150,15 +177,8 @@ class SwitchTplinkPlugin(SwitchPlugin):
     @property
     def switches(self) -> List[dict]:
         return [
-            {
-                'current_consumption': dev.current_consumption(),
-                'id': ip,
-                'ip': ip,
-                'host': dev.host,
-                'hw_info': dev.hw_info,
-                'name': dev.alias,
-                'on': dev.is_on,
-            } for (ip, dev) in self._scan().items()
+            self._serialize(dev)
+            for dev in self._scan().values()
         ]
 
 

platypush/user/__init__.py

@@ -13,7 +13,7 @@ except ImportError:
     from jwt import PyJWTError, encode as jwt_encode, decode as jwt_decode
 
 from sqlalchemy import Column, Integer, String, DateTime, ForeignKey
-from sqlalchemy.orm import sessionmaker, scoped_session
+from sqlalchemy.orm import make_transient
 from sqlalchemy.ext.declarative import declarative_base
 
 from platypush.context import get_plugin
@@ -28,126 +28,124 @@ class UserManager:
     Main class for managing platform users
     """
 
-    # noinspection PyProtectedMember
     def __init__(self):
-        db_plugin = get_plugin('db')
-        if not db_plugin:
-            raise ModuleNotFoundError('Please enable/configure the db plugin for multi-user support')
+        self.db = get_plugin('db')
+        assert self.db
+        self._engine = self.db.get_engine()
+        self.db.create_all(self._engine, Base)
 
-        self._engine = db_plugin._get_engine()
-
-    def get_user(self, username):
-        session = self._get_db_session()
-        user = self._get_user(session, username)
-        if not user:
-            return None
-
-        # Hide password
+    @staticmethod
+    def _mask_password(user):
+        make_transient(user)
         user.password = None
         return user
 
+    def get_user(self, username):
+        with self.db.get_session() as session:
+            user = self._get_user(session, username)
+            if not user:
+                return None
+
+            session.expunge(user)
+            return self._mask_password(user)
+
     def get_user_count(self):
-        session = self._get_db_session()
-        return session.query(User).count()
+        with self.db.get_session() as session:
+            return session.query(User).count()
 
     def get_users(self):
-        session = self._get_db_session()
-        return session.query(User)
+        with self.db.get_session() as session:
+            return session.query(User)
 
     def create_user(self, username, password, **kwargs):
-        session = self._get_db_session()
         if not username:
             raise ValueError('Invalid or empty username')
         if not password:
             raise ValueError('Please provide a password for the user')
 
-        user = self._get_user(session, username)
-        if user:
-            raise NameError('The user {} already exists'.format(username))
+        with self.db.get_session() as session:
+            user = self._get_user(session, username)
+            if user:
+                raise NameError('The user {} already exists'.format(username))
 
-        record = User(username=username, password=self._encrypt_password(password),
-                      created_at=datetime.datetime.utcnow(), **kwargs)
+            record = User(username=username, password=self._encrypt_password(password),
+                          created_at=datetime.datetime.utcnow(), **kwargs)
 
-        session.add(record)
-        session.commit()
-        user = self._get_user(session, username)
+            session.add(record)
+            session.commit()
+            user = self._get_user(session, username)
 
-        # Hide password
-        user.password = None
-        return user
+        return self._mask_password(user)
 
     def update_password(self, username, old_password, new_password):
-        session = self._get_db_session()
-        if not self._authenticate_user(session, username, old_password):
-            return False
+        with self.db.get_session() as session:
+            if not self._authenticate_user(session, username, old_password):
+                return False
 
-        user = self._get_user(session, username)
-        user.password = self._encrypt_password(new_password)
-        session.commit()
-        return True
+            user = self._get_user(session, username)
+            user.password = self._encrypt_password(new_password)
+            session.commit()
+            return True
 
     def authenticate_user(self, username, password):
-        session = self._get_db_session()
-        return self._authenticate_user(session, username, password)
+        with self.db.get_session() as session:
+            return self._authenticate_user(session, username, password)
 
     def authenticate_user_session(self, session_token):
-        session = self._get_db_session()
-        user_session = session.query(UserSession).filter_by(session_token=session_token).first()
+        with self.db.get_session() as session:
+            user_session = session.query(UserSession).filter_by(session_token=session_token).first()
 
-        if not user_session or (
-                user_session.expires_at and user_session.expires_at < datetime.datetime.utcnow()):
-            return None, None
+            if not user_session or (
+                    user_session.expires_at and user_session.expires_at < datetime.datetime.utcnow()):
+                return None, None
 
-        user = session.query(User).filter_by(user_id=user_session.user_id).first()
-
-        # Hide password
-        user.password = None
-        return user, session
+            user = session.query(User).filter_by(user_id=user_session.user_id).first()
+            return self._mask_password(user), user_session
 
     def delete_user(self, username):
-        session = self._get_db_session()
-        user = self._get_user(session, username)
-        if not user:
-            raise NameError('No such user: {}'.format(username))
+        with self.db.get_session() as session:
+            user = self._get_user(session, username)
+            if not user:
+                raise NameError('No such user: {}'.format(username))
 
-        user_sessions = session.query(UserSession).filter_by(user_id=user.user_id).all()
-        for user_session in user_sessions:
-            session.delete(user_session)
+            user_sessions = session.query(UserSession).filter_by(user_id=user.user_id).all()
+            for user_session in user_sessions:
+                session.delete(user_session)
 
-        session.delete(user)
-        session.commit()
-        return True
+            session.delete(user)
+            session.commit()
+            return True
 
     def delete_user_session(self, session_token):
-        session = self._get_db_session()
-        user_session = session.query(UserSession).filter_by(session_token=session_token).first()
+        with self.db.get_session() as session:
+            user_session = session.query(UserSession).filter_by(session_token=session_token).first()
 
-        if not user_session:
-            return False
+            if not user_session:
+                return False
 
-        session.delete(user_session)
-        session.commit()
-        return True
+            session.delete(user_session)
+            session.commit()
+            return True
 
     def create_user_session(self, username, password, expires_at=None):
-        session = self._get_db_session()
-        user = self._authenticate_user(session, username, password)
-        if not user:
-            return None
+        with self.db.get_session() as session:
+            user = self._authenticate_user(session, username, password)
+            if not user:
+                return None
 
-        if expires_at:
-            if isinstance(expires_at, int) or isinstance(expires_at, float):
-                expires_at = datetime.datetime.fromtimestamp(expires_at)
-            elif isinstance(expires_at, str):
-                expires_at = datetime.datetime.fromisoformat(expires_at)
+            if expires_at:
+                if isinstance(expires_at, int) or isinstance(expires_at, float):
+                    expires_at = datetime.datetime.fromtimestamp(expires_at)
+                elif isinstance(expires_at, str):
+                    expires_at = datetime.datetime.fromisoformat(expires_at)
 
-        user_session = UserSession(user_id=user.user_id, session_token=self.generate_session_token(),
-                                   csrf_token=self.generate_session_token(), created_at=datetime.datetime.utcnow(),
-                                   expires_at=expires_at)
+            user_session = UserSession(user_id=user.user_id, session_token=self.generate_session_token(),
+                                       csrf_token=self.generate_session_token(), created_at=datetime.datetime.utcnow(),
+                                       expires_at=expires_at)
 
-        session.add(user_session)
-        session.commit()
-        return user_session
+            session.add(user_session)
+            session.commit()
+            return user_session
 
     @staticmethod
     def _get_user(session, username):
@@ -180,8 +178,8 @@ class UserManager:
 
         :param session_token: Session token.
         """
-        session = self._get_db_session()
-        return session.query(User).join(UserSession).filter_by(session_token=session_token).first()
+        with self.db.get_session() as session:
+            return session.query(User).join(UserSession).filter_by(session_token=session_token).first()
 
     def generate_jwt_token(self, username: str, password: str, expires_at: Optional[datetime.datetime] = None) -> str:
         """
@@ -240,12 +238,6 @@ class UserManager:
 
         return payload
 
-    def _get_db_session(self):
-        Base.metadata.create_all(self._engine)
-        session = scoped_session(sessionmaker(expire_on_commit=False))
-        session.configure(bind=self._engine)
-        return session()
-
     def _authenticate_user(self, session, username, password):
         """
         :return: :class:`platypush.user.User` instance if the user exists and the password is valid, ``None`` otherwise.