source: mauRepo/MolesManager/trunk/src/MolesManager/molesSessionMiddleware.py @ 8229

'''
Created on 9 Jan 2012

@author: mnagni
'''
from MolesManager.moles3epb import Moles3EPB
from libs.migration.client import MigrationThread
from MolesManager.settings import RUN_MIGRATION, MIGRATION_INTERVAL,\
    MIGRATION_DB_CONNECTION, MIGRATION_DB_SCRIPT, MOLES3_DB_CONNECTION,\
    MOLES3_DB_SCRIPT, EVENTS_DB, INFO_DB_CONNECTION
from libs.commons_db import DbManager
from libs.migration.MigrationEPB import MigrationEPB
from libs.migration.InfodbEPB import InfodbEPB
import logging



class MolesSessionMiddleware(object):
    
    #This attribute should be not here.
    #unfortunately I cannot find any start/stop signals from Django
    _migrationThread = MigrationThread(interval = MIGRATION_INTERVAL)
    _epbInitialized = False
    

    def _initSearchIndexes(self, db_manager):
        #To Be Done - CHECK IF THE COLUMN ALREADY EXISTS!
        # We don't want sqlalchemy to know about this column so we add it externally.
        try:
            db_manager._engine.execute("alter table md_identifier add column code_search_vector tsvector")                 

            # This indexes the tsvector column

            db_manager._engine.execute("create index md_identifier_code_search_index on md_identifier using gin(code_search_vector)")

            # This sets up the trigger that keeps the tsvector column up to date.
            db_manager._engine.execute("create trigger md_identifier_code_search_update before update or insert on md_identifier \
                for each row execute procedure tsvector_update_trigger('code_search_vector', 'pg_catalog.english', 'code')")                        
        except Exception as e:
            pass

    def _getNewMolesSession(self):
        session = Moles3EPB.getNewMolesSession() 
        EVENTS_DB(session)
        return session
    
    def _doInitialization(self):
        infoDB = DbManager(INFO_DB_CONNECTION)
        InfodbEPB.overrrideDBManager(infoDB)
           
        migrationDB = DbManager(MIGRATION_DB_CONNECTION, MIGRATION_DB_SCRIPT)
        MigrationEPB.overrrideDBManager(migrationDB)       

        molesDB = DbManager(MOLES3_DB_CONNECTION, MOLES3_DB_SCRIPT)
        Moles3EPB.overrrideDBManager(molesDB)
        MolesSessionMiddleware._epbInitialized = True            
        self._initSearchIndexes(molesDB)
    
    def _getMolesSession(self):
        if not MolesSessionMiddleware._epbInitialized:
            self._doInitialization()

        return self._getNewMolesSession()
    
    def _migration(self, runMigration = RUN_MIGRATION):
        if runMigration and not MolesSessionMiddleware._migrationThread.isAlive():
            #t.setDaemon(False)
            MolesSessionMiddleware._migrationThread.start()
            
    """
        Represents the access to the Moles database.
        Creates from the existing db connections pools a new session
        to be used by all the DB operations involved in the actual HTTPRequest
    """  
    
    def process_request(self, request):        
        self._migration() #see the note on  MolesSessionMiddleware._migration
        
        request.moles_session = self._getMolesSession()


    def process_response(self, request, response):
        if hasattr(request, 'moles_session'):
            request.moles_session.close()

        return response


    def process_exception(self, request, exception):
        try:
            session = request.moles_session            
        except AttributeError:
            return
        session.rollback()
        session.close()