cic cache build

apps/cic-cache/cic_cache/db/models/base.py

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+# stanard imports
+import logging
+
+# third-party imports
+from sqlalchemy import Column, Integer
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+logg = logging.getLogger()
+
+Model = declarative_base(name='Model')
+
+
+class SessionBase(Model):
+    """The base object for all SQLAlchemy enabled models. All other models must extend this.
+    """
+    __abstract__ = True
+ 
+    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, 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:
+            e = create_engine(
+                    dsn,
+                    max_overflow=50,
+                    pool_pre_ping=True,
+                    pool_size=20,
+                    pool_recycle=10,
+                    echo=debug,
+                )
+        else:
+            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 == 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('destroying session {}'.format(session_key))
+            session.commit()
+            session.close()