+def CheckAgreement():
+ """Check the agreement on who is the master.
+
+ The function uses a very simple algorithm: we must get more positive
+ than negative answers. Since in most of the cases we are the master,
+ we'll use our own config file for getting the node list. In the
+ future we could collect the current node list from our (possibly
+ obsolete) known nodes.
+
+ """
+ myself = utils.HostInfo().name
+ #temp instantiation of a config writer, used only to get the node list
+ cfg = config.ConfigWriter()
+ node_list = cfg.GetNodeList()
+ del cfg
+ try:
+ node_list.remove(myself)
+ except KeyError:
+ pass
+ if not node_list:
+ # either single node cluster, or a misconfiguration, but I won't
+ # break any other node, so I can proceed
+ return True
+ results = rpc.RpcRunner.call_master_info(node_list)
+ if not isinstance(results, dict):
+ # this should not happen (unless internal error in rpc)
+ logging.critical("Can't complete rpc call, aborting master startup")
+ return False
+ positive = negative = 0
+ other_masters = {}
+ for node in results:
+ if not isinstance(results[node], (tuple, list)) or len(results[node]) < 3:
+ logging.warning("Can't contact node %s", node)
+ continue
+ master_node = results[node][2]
+ if master_node == myself:
+ positive += 1
+ else:
+ negative += 1
+ if not master_node in other_masters:
+ other_masters[master_node] = 0
+ other_masters[master_node] += 1
+ if positive <= negative:
+ # bad!
+ logging.critical("It seems we are not the master (%d votes for,"
+ " %d votes against)", positive, negative)
+ if len(other_masters) > 1:
+ logging.critical("The other nodes do not agree on a single master")
+ elif other_masters:
+ # TODO: resync my files from the master
+ logging.critical("It seems the real master is %s",
+ other_masters.keys()[0])
+ else:
+ logging.critical("Can't contact any node for data, aborting startup")
+ return False
+ return True
+
+