+class DispenseDatabase:
+ def __init__(self, vending_machine):
+ self.vending_machine = vending_machine
+ self.db = pg.DB(dbname = 'dispense', host = 'dispense.ucc.gu.uwa.edu.au', user = 'vendserver', passwd = 'revresdnev')
+ self.db.query('LISTEN vend_requests')
+
+ def process_requests(self):
+ print 'processing'
+ query = 'SELECT request_id, request_slot FROM vend_requests WHERE request_handled = false'
+ try:
+ outstanding = self.db.query(query).getresult()
+ except (pg.error,), db_err:
+ sys.stderr.write('Failed to query database: %s\n'%(db_err.strip()))
+ return
+ for (id, slot) in outstanding:
+ (worked, code, string) = self.vending_machine.vend(slot)
+ print (worked, code, string)
+ if worked:
+ query = 'SELECT vend_success(%s)'%id
+ self.db.query(query).getresult()
+ else:
+ query = 'SELECT vend_failed(%s)'%id
+ self.db.query(query).getresult()
+
+ def handle_events(self):
+ notifier = self.db.getnotify()
+ while notifier is not None:
+ self.process_requests()
+ notify = self.db.getnotify()
+