125 lines
3.9 KiB
Python
125 lines
3.9 KiB
Python
# stanard imports
|
|
import logging
|
|
import datetime
|
|
|
|
# external imports
|
|
from sqlalchemy import Column, Integer, DateTime
|
|
from sqlalchemy.ext.declarative import declarative_base
|
|
from sqlalchemy import create_engine
|
|
from sqlalchemy.orm import sessionmaker
|
|
from sqlalchemy.pool import (
|
|
StaticPool,
|
|
QueuePool,
|
|
AssertionPool,
|
|
NullPool,
|
|
)
|
|
|
|
logg = logging.getLogger().getChild(__name__)
|
|
|
|
Model = declarative_base(name='Model')
|
|
|
|
|
|
class SessionBase(Model):
|
|
"""The base object for all SQLAlchemy enabled models. All other models must extend this.
|
|
"""
|
|
__abstract__ = True
|
|
|
|
created = Column(DateTime, default=datetime.datetime.utcnow)
|
|
updated = Column(DateTime, default=datetime.datetime.utcnow, onupdate=datetime.datetime.utcnow)
|
|
|
|
id = Column(Integer, primary_key=True)
|
|
|
|
engine = None
|
|
"""Database connection engine of the running aplication"""
|
|
sessionmaker = None
|
|
"""Factory object responsible for creating sessions from the connection pool"""
|
|
transactional = True
|
|
"""Whether the database backend supports query transactions. Should be explicitly set by initialization code"""
|
|
poolable = True
|
|
"""Whether the database backend supports connection pools. Should be explicitly set by initialization code"""
|
|
procedural = True
|
|
"""Whether the database backend supports stored procedures"""
|
|
localsessions = {}
|
|
"""Contains dictionary of sessions initiated by db model components"""
|
|
|
|
@staticmethod
|
|
def create_session():
|
|
"""Creates a new database session.
|
|
"""
|
|
return SessionBase.sessionmaker()
|
|
|
|
@staticmethod
|
|
def _set_engine(engine):
|
|
"""Sets the database engine static property
|
|
"""
|
|
SessionBase.engine = engine
|
|
SessionBase.sessionmaker = sessionmaker(bind=SessionBase.engine)
|
|
|
|
@staticmethod
|
|
def connect(dsn, pool_size=16, debug=False):
|
|
"""Create new database connection engine and connect to database backend.
|
|
|
|
:param dsn: DSN string defining connection.
|
|
:type dsn: str
|
|
"""
|
|
e = None
|
|
if SessionBase.poolable:
|
|
poolclass = QueuePool
|
|
if pool_size > 1:
|
|
logg.info('db using queue pool')
|
|
e = create_engine(
|
|
dsn,
|
|
max_overflow=pool_size * 3,
|
|
pool_pre_ping=True,
|
|
pool_size=pool_size,
|
|
pool_recycle=60,
|
|
poolclass=poolclass,
|
|
echo=debug,
|
|
)
|
|
else:
|
|
if pool_size == 0:
|
|
poolclass = NullPool
|
|
elif debug:
|
|
poolclass = AssertionPool
|
|
else:
|
|
poolclass = StaticPool
|
|
e = create_engine(
|
|
dsn,
|
|
poolclass=poolclass,
|
|
echo=debug,
|
|
)
|
|
else:
|
|
logg.info('db connection not poolable')
|
|
e = create_engine(
|
|
dsn,
|
|
echo=debug,
|
|
)
|
|
|
|
SessionBase._set_engine(e)
|
|
|
|
@staticmethod
|
|
def disconnect():
|
|
"""Disconnect from database and free resources.
|
|
"""
|
|
SessionBase.engine.dispose()
|
|
SessionBase.engine = None
|
|
|
|
@staticmethod
|
|
def bind_session(session=None):
|
|
localsession = session
|
|
if localsession is None:
|
|
localsession = SessionBase.create_session()
|
|
localsession_key = str(id(localsession))
|
|
logg.debug('creating new session {}'.format(localsession_key))
|
|
SessionBase.localsessions[localsession_key] = localsession
|
|
return localsession
|
|
|
|
@staticmethod
|
|
def release_session(session=None):
|
|
session_key = str(id(session))
|
|
if SessionBase.localsessions.get(session_key) != None:
|
|
logg.debug('commit and destroy session {}'.format(session_key))
|
|
session.commit()
|
|
session.close()
|
|
del SessionBase.localsessions[session_key]
|