public static void handleGetDecision(Message msg) throws Exception {
System.out.println("Starting to handle GET_DECISION message");
LogRecord log =
ThreePhaseCommitUtility.fetchRecordForTransaction(processId, msg.getTransactionId());
Message decision = new Message();
decision.setMessage(log.getMessage());
decision.setProcessId(processId);
decision.setTransactionId(log.getTransactionId());
decision.setPlaylistCommand(log.getPlayListCommand());
if (COMMIT.equals(decision.getMessage()) || ABORT.equals(decision.getMessage())) {
netController.sendMsg(msg.getProcessId(), ThreePhaseCommitUtility.serializeMessage(decision));
System.out.println(
"Process " + processId + " has sent a response to a GET_DECISION " + decision);
}
}
public static void participantTerminationProtocol() throws Exception {
System.out.println("Process " + processId + " is initiating participant termination protocol");
List<String> receivedMsgs = new ArrayList<String>();
boolean notCommitted = true;
System.out.println("Process " + processId + " is waiting for STATE_REQ");
while (notCommitted && processId != coordinatorId) {
Timer timer = new Timer(PARTICIPANT_TIME_OUT_IN_SECONDS);
timer.start();
while (receivedMsgs.isEmpty() && !timer.hasTimedOut()) {
receivedMsgs.addAll(netController.getReceivedMsgs());
}
// if time-out has happened
if (timer.hasTimedOut() && (participant_waiting_for.equals(STATE_RESP))) {
System.out.println(
"Process " + processId + " has timed out while waiting for response from co-ordinator");
initiateElection();
if (coordinatorId == processId) {
// invoke co-ordinator's termination protocol
List<Integer> participants = new ArrayList<Integer>(activeProcesses);
System.out.println("active processes!" + activeProcesses);
participants.remove((Object) new Integer(processId));
coordinatorTerminationProtocol(participants);
}
}
for (String message : receivedMsgs) {
Message msg = ThreePhaseCommitUtility.deserializeMessage(message);
if (msg.getProcessId() == coordinatorId && msg.getMessage().equals(STATE_REQ)) {
Message state = new Message();
state.setProcessId(processId);
state.setTransactionId(msg.getTransactionId());
System.out.println("msg of process " + processId + " is " + msg);
if (my_current_state.equals(ABORTED)) {
state.setMessage(ABORTED);
} else if (my_current_state.equals(COMMIT)) {
state.setMessage(COMMITTED);
} else if (my_current_state.equals(PRE_COMMIT)) {
state.setMessage(COMMITTABLE);
} else {
state.setMessage(UNCERTAIN);
}
netController.sendMsg(coordinatorId, ThreePhaseCommitUtility.serializeMessage(state));
participant_waiting_for = STATE_RESP;
System.out.println(
"Process " + processId + " sends its current state " + state.getMessage());
} else if (msg.getProcessId() == coordinatorId && msg.getMessage().equals(ABORT)) {
LogRecord myState =
ThreePhaseCommitUtility.fetchRecordForTransaction(processId, msg.getTransactionId());
if (!myState.getMessage().equals(ABORT))
ThreePhaseCommitUtility.writeMessageToDTLog(
processId, new LogRecord(msg.getTransactionId(), ABORT, msg.getPlaylistCommand()));
System.out.println(
"Process " + processId + " received abort during the termination protocol");
participant_waiting_for = "";
notCommitted = false;
my_current_state = ABORTED;
} else if (msg.getProcessId() == coordinatorId && msg.getMessage().equals(COMMIT)) {
LogRecord myState =
ThreePhaseCommitUtility.fetchRecordForTransaction(processId, msg.getTransactionId());
if (!myState.getMessage().equals(COMMIT)) {
ThreePhaseCommitUtility.writeMessageToDTLog(
processId, new LogRecord(msg.getTransactionId(), COMMIT, msg.getPlaylistCommand()));
executeCommand(msg.getPlaylistCommand());
}
participant_waiting_for = "";
my_current_state = COMMIT;
System.out.println(
"Process " + processId + " received commit during the termination protocol");
notCommitted = false;
} else if (msg.getMessage().equals(GET_DECISION)) {
System.out.println(
"Process " + processId + " got a GET_DECISION from process " + msg.getProcessId());
handleGetDecision(msg);
} else if (msg.getMessage().equals(PRE_COMMIT)) {
my_current_state = PRE_COMMIT;
Message ack = new Message();
ack.setProcessId(processId);
ack.setMessage(ACK);
netController.sendMsg(coordinatorId, ThreePhaseCommitUtility.serializeMessage(ack));
System.out.println(
"Process "
+ processId
+ " received pre_commit during the termination protocol and has sent ACK");
}
}
receivedMsgs.clear();
}
System.out.println("Process " + processId + " has completed participant termination protocol");
}