import fcntl
import os
import logging

#---------------------------------------------------------------
# meccanismo di file lock per evitare multiple instances
# The function will try to lock the file specified , if it success, return True, else return False.
# The nice thing is that the lock will be dropped when the program terminates.
# >>>Use : 
# if not lockFile(".lock.pod"):
#        sys.exit(0)

def lockFile ( lockfile ) :

    fd = os.open ( lockfile , os.O_CREAT | os.O_TRUNC | os.O_WRONLY )
    try:
        # Request exclusive (EX) non-blocking (NB) advisory lock.
        fcntl.lockf ( fd , fcntl.LOCK_EX | fcntl.LOCK_NB )
    except IOError:
        return False

    return True

if not lockFile ( ".lockfile" ) :
    print '\n noi non siamo soli ...\n'
    logging.error( "LOCK: Piu istanze aperte")
    #sys.exit ( 0 )

#- print '\n running alone ...\n'