private void runElection() {
NodeID myNodeID = getLocalNodeID();
NodeID winner = ServerID.NULL_ID;
int count = 0;
// Only new L2 if the DB was empty (no previous state) and the current state is START (as in
// before any elections
// concluded)
boolean isNew = state == START_STATE && clusterStatePersistor.getInitialState() == null;
while (getActiveNodeID().isNull()) {
if (++count > 1) {
logger.info(
"Rerunning election since node " + winner + " never declared itself as ACTIVE !");
}
debugInfo("Running election - isNew: " + isNew);
winner = electionMgr.runElection(myNodeID, isNew, weightsFactory);
if (winner == myNodeID) {
debugInfo("Won Election, moving to active state. myNodeID/winner=" + myNodeID);
moveToActiveState();
} else {
electionMgr.reset(null);
// Election is lost, but we wait for the active node to declare itself as winner. If this
// doesn't happen in a
// finite time we restart the election. This is to prevent some weird cases where two nodes
// might end up
// thinking the other one is the winner.
// @see MNK-518
debugInfo("Lost election, waiting for winner to declare as active, winner=" + winner);
waitUntilActiveNodeIDNotNull(electionMgr.getElectionTime());
}
}
}
private void handleElectionAbort(L2StateMessage clusterMsg) {
if (state == ACTIVE_COORDINATOR) {
// Cant get Abort back to ACTIVE, if so then there is a split brain
String error = state + " Received Abort Election Msg : Possible split brain detected ";
logger.error(error);
groupManager.zapNode(
clusterMsg.messageFrom(), L2HAZapNodeRequestProcessor.SPLIT_BRAIN, error);
} else {
debugInfo("ElectionMgr handling election abort");
electionMgr.handleElectionAbort(clusterMsg);
}
}
private void handleStartElectionRequest(L2StateMessage msg) throws GroupException {
if (state == ACTIVE_COORDINATOR) {
// This is either a new L2 joining a cluster or a renegade L2. Force it to abort
GroupMessage abortMsg =
L2StateMessage.createAbortElectionMessage(
msg, EnrollmentFactory.createTrumpEnrollment(getLocalNodeID(), weightsFactory));
info("Forcing Abort Election for " + msg + " with " + abortMsg);
groupManager.sendTo(msg.messageFrom(), abortMsg);
} else if (!electionMgr.handleStartElectionRequest(msg)) {
// TODO::FIXME:: Commenting so that stage thread is not held up doing election.
// startElectionIfNecessary(NodeID.NULL_ID);
logger.warn("Not starting election as it was commented out");
}
}
private synchronized void moveToActiveState() {
if (state == START_STATE || state == PASSIVE_STANDBY) {
// TODO :: If state == START_STATE publish cluster ID
debugInfo("Moving to active state");
StateChangedEvent event = new StateChangedEvent(state, ACTIVE_COORDINATOR);
state = ACTIVE_COORDINATOR;
setActiveNodeID(getLocalNodeID());
info("Becoming " + state, true);
fireStateChangedOperatorEvent();
electionMgr.declareWinner(this.activeNode);
stateChangeSink.add(event);
} else {
throw new AssertionError("Cant move to " + ACTIVE_COORDINATOR + " from " + state);
}
}
private synchronized void handleElectionResultMessage(L2StateMessage msg) throws GroupException {
if (activeNode.equals(msg.getEnrollment().getNodeID())) {
Assert.assertFalse(ServerID.NULL_ID.equals(activeNode));
// This wouldn't normally happen, but we agree - so ack
GroupMessage resultAgreed =
L2StateMessage.createResultAgreedMessage(msg, msg.getEnrollment());
logger.info("Agreed with Election Result from " + msg.messageFrom() + " : " + resultAgreed);
groupManager.sendTo(msg.messageFrom(), resultAgreed);
} else if (state == ACTIVE_COORDINATOR
|| !activeNode.isNull()
|| (msg.getEnrollment().isANewCandidate() && state != START_STATE)) {
// Condition 1 :
// Obviously an issue.
// Condition 2 :
// This shouldn't happen normally, but is possible when there is some weird network error
// where A sees B,
// B sees A/C and C sees B and A is active and C is trying to run election
// Force other node to rerun election so that we can abort
// Condition 3 :
// We don't want new L2s to win an election when there are old L2s in PASSIVE states.
GroupMessage resultConflict =
L2StateMessage.createResultConflictMessage(
msg, EnrollmentFactory.createTrumpEnrollment(getLocalNodeID(), weightsFactory));
warn(
"WARNING :: Active Node = "
+ activeNode
+ " , "
+ state
+ " received ELECTION_RESULT message from another node : "
+ msg
+ " : Forcing re-election "
+ resultConflict);
groupManager.sendTo(msg.messageFrom(), resultConflict);
} else {
debugInfo("ElectionMgr handling election result msg: " + msg);
electionMgr.handleElectionResultMessage(msg);
}
}
private synchronized void moveToPassiveState(Enrollment winningEnrollment) {
electionMgr.reset(winningEnrollment);
if (state == START_STATE) {
state = PASSIVE_UNINITIALIZED;
info("Moved to " + state, true);
fireStateChangedOperatorEvent();
stateChangeSink.add(new StateChangedEvent(START_STATE, state));
} else if (state == ACTIVE_COORDINATOR) {
// TODO:: Support this later
throw new AssertionError(
"Cant move to "
+ PASSIVE_UNINITIALIZED
+ " from "
+ ACTIVE_COORDINATOR
+ " at least for now");
} else {
debugInfo(
"Move to passive state ignored - state="
+ state
+ ", winningEnrollment: "
+ winningEnrollment);
}
}
