LumiDBHandler.py

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# Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 
#
# LumiDBHandler
#
# Eric Torrence - October 2010
#
# Contents:
# LumiDBHandler - utility object to handle opening and closing COOL DB connections within
#                 a large python script.  The benefit over just using AtlCoolLib directly
#                 is that each DB connection is cached, so multiple connections to the same
#                 DB will not be made.
#
#                 The parent script should call closeAllDB in its __del__ function to close
#                 the DB connections, even if the script crashes.
#
# General usage example
# dbH = LumiDBHandler()
# myFolder = dbH.getFolder('COOLONL_TRIGGER/COMP200', '/TRIGGER/LUMI/LBLESTONL')
#
# One can then browse the folder as usual using browseObjects
#
# The CoolDataReader uses this class internally to make for more easy access
#
 
from CoolConvUtilities.AtlCoolLib import indirectOpen
 
class LumiDBHandler:
 
    # Define dbDict here at class scope
    # Then access with self.__class__.dbDict and it will be the same for all instances of the class
    # This is a pythonish way to create static classes
 
    # Dict to store DB connection indexed by text DB connection name
    dbDict = dict()
 
    
    def __init__(self):
 
        # Debug output (can be changed for each instance, slick...)
        self.verbose = False
        
    # Return a folder reference for the dbstring, folder specified
    # DB will be opened if necessary
    # Example: getFolder('COOLONL_TRIGGER/COMP200', '/TRIGGER/LUMI/LBLESTONL')
    def getFolder(self, dbstring, folder, force=False):
 
        if self.verbose:
            print('LumiDBHandler.getFolder(', dbstring, ',', folder, ') called')
 
        if not self.openDB(dbstring, force=force):
            print("LumiDBHandler.getFolder - can't connect to DB!")
            return None
 
        return self.__class__.dbDict[dbstring].getFolder(folder)
    
    # Open a COOL DB connection based on a name such as "COOLONL_INDET/OFLP200"
    # Returns True if successful (or DB already open) 
    def openDB(self, dbstring, oracle=False, debug=False, force=False):
 
        if self.verbose:
            print('LumiDBHandler.openDB(', dbstring, ') called')
 
        # Check if already open
        if dbstring in self.__class__.dbDict:
 
            # No force, just return 
            if not force:
                if self.verbose:
                    print('LumiDBHandler.openDB - Connection already exists')
                return True # Yes it is
 
            # Force specified, close so we can re-open
            if self.verbose:
                print('LumiDBHandler.openDB - Connection already exists, closing first due to force=True')
            self.closeDB(dbstring)
 
        # Try to open DB connection
        if self.verbose:
            print(('LumiDBHandler.openDB - Connecting to', dbstring))
            
        try:
            db = indirectOpen(dbstring, readOnly=True, debug=debug)
        except Exception as e:
            print(e)
            return False
 
        # OK, opened.  Save this to our dict for later use
        self.__class__.dbDict[dbstring] = db
        
        return True
 
    # Close specific DB
    def closeDB(self, dbstring):
 
        if self.verbose:
            print('LumiDBHandler.closeDB - Closing connection to', dbstring)
 
        if dbstring not in self.__class__.dbDict:
            print("LumiDBHandler.closeDB - DB doesn't exist:", dbstring)
        else:
            try:
                self.__class__.dbDict[dbstring].closeDatabase()
            except Exception as e:
                print(e)
            self.__class__.dbDict.pop(dbstring)
 
    # Called by default in the destructor, but not guaranteed if there are problems
    def closeAllDB(self):
        self.closeAll()
        
    def closeAll(self):
        
        if self.verbose:
            print('LumiDBHandler.closeAllDB called')
 
        # Can't use iterkeys here as we are deleting the elements
        for dbstring in list(self.__class__.dbDict.keys()):
            self.closeDB(dbstring)