raft somewhat working
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Daniel
@@ -1,20 +1,177 @@
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package io.github.lumijiez.raft;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.Random;
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import io.github.lumijiez.app.NodeManager;
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import io.github.lumijiez.data.models.NodeInfo;
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import io.github.lumijiez.network.UdpMessageSender;
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import org.apache.logging.log4j.LogManager;
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import org.apache.logging.log4j.Logger;
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import java.util.*;
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import java.util.concurrent.Executors;
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import java.util.concurrent.ScheduledExecutorService;
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import java.util.concurrent.TimeUnit;
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public class Raft {
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private static final Random RANDOM = new Random();
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private final Logger logger = LogManager.getLogger(Raft.class);
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private static RaftStates STATE = RaftStates.FOLLOWER;
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private static int CURRENT_TERM = 0;
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private static String VOTED_FOR = null;
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private static List<String> LOG = new ArrayList<>();
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private static int COMMIT_INDEX = 0;
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private static int LAST_APPLIED = 0;
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// Configuration Parameters
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private static final int MIN_ELECTION_TIMEOUT = 300;
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private static final int MAX_ELECTION_TIMEOUT = 600;
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private static final int HEARTBEAT_INTERVAL = 100;
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private static final int QUORUM_FACTOR = 2;
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// State Variables
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private RaftStates state = RaftStates.FOLLOWER;
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private int currentTerm = 0;
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private String votedFor = null;
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private Set<String> votesReceived = new HashSet<>();
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private static final int ELECTION_TIMEOUT = 150 + RANDOM.nextInt(151);
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private final NodeManager nodeManager;
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private final UdpMessageSender sender;
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private final ScheduledExecutorService electionExecutor = Executors.newSingleThreadScheduledExecutor();
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public Raft(NodeManager nodeManager, UdpMessageSender sender) {
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this.nodeManager = nodeManager;
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this.sender = sender;
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nodeManager.getNodes().removeIf(node -> node.hostname().equals(NodeManager.HOST) && node.port() == NodeManager.PORT);
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start();
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}
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public void start() {
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logger.info("Raft initialization. Total peers: {}", nodeManager.getNodes().size());
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becomeFollower(1);
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}
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private void becomeFollower(int term) {
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if (term > currentTerm) {
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state = RaftStates.FOLLOWER;
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currentTerm = term;
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votedFor = null;
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votesReceived.clear();
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logger.debug("Transitioned to FOLLOWER. Term: {}", term);
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}
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scheduleElectionTimeout();
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}
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private void becomeCandidate() {
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state = RaftStates.CANDIDATE;
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currentTerm++;
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votedFor = NodeManager.HOST + ":" + NodeManager.PORT;
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votesReceived = new HashSet<>(Set.of(votedFor)); // Self vote
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// logger.info("Starting election in Term {}. Attempting to collect votes.", currentTerm);
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sendVoteRequests();
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}
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private void becomeLeader() {
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if (state == RaftStates.CANDIDATE &&
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votesReceived.size() >= (nodeManager.getNodes().size() / QUORUM_FACTOR + 1)) {
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state = RaftStates.LEADER;
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logger.info("LEADER ELECTION SUCCESS: Becoming LEADER in Term {}", currentTerm);
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votesReceived.clear();
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sendHeartbeats();
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}
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}
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private void sendVoteRequests() {
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String voteRequest = String.format("REQUEST_VOTE|%d|%s:%d",
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currentTerm, NodeManager.HOST, NodeManager.PORT);
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for (NodeInfo peer : nodeManager.getNodes()) {
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sender.sendMessage(peer, voteRequest);
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}
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}
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private void sendHeartbeats() {
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if (state != RaftStates.LEADER) return;
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String heartbeat = String.format("HEARTBEAT|%d|%s:%d",
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currentTerm, NodeManager.HOST, NodeManager.PORT);
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for (NodeInfo peer : nodeManager.getNodes()) {
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sender.sendMessage(peer, heartbeat);
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}
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// Reschedule heartbeats
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electionExecutor.schedule(this::sendHeartbeats, HEARTBEAT_INTERVAL, TimeUnit.MILLISECONDS);
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}
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private void scheduleElectionTimeout() {
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int timeout = MIN_ELECTION_TIMEOUT + RANDOM.nextInt(MAX_ELECTION_TIMEOUT - MIN_ELECTION_TIMEOUT);
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electionExecutor.schedule(() -> {
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if (state != RaftStates.LEADER) {
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logger.debug("Election timeout triggered. Starting new election.");
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becomeCandidate();
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}
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}, timeout, TimeUnit.MILLISECONDS);
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}
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public void processMessage(String message) {
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String[] parts = message.split("\\|");
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if (parts.length < 3) return;
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try {
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String type = parts[0];
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int messageTerm = Integer.parseInt(parts[1]);
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String sender = parts[2];
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// Term comparison and potential state change
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if (messageTerm > currentTerm) {
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becomeFollower(messageTerm);
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}
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switch (type) {
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case "REQUEST_VOTE":
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handleRequestVote(messageTerm, sender);
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break;
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case "HEARTBEAT":
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handleHeartbeat(messageTerm, sender);
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break;
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case "VOTE_GRANTED":
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handleVoteGranted(messageTerm, sender);
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break;
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}
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} catch (NumberFormatException e) {
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logger.error("Error processing message: {}", message);
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}
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}
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private void handleRequestVote(int term, String candidate) {
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boolean voteGranted = false;
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if (term >= currentTerm &&
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(votedFor == null || votedFor.equals(candidate))) {
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voteGranted = true;
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votedFor = candidate;
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currentTerm = term;
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scheduleElectionTimeout();
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}
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String response = String.format("VOTE_GRANTED|%d|%s", term, voteGranted);
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sender.sendMessage(NodeInfo.fromString(candidate), response);
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}
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private void handleHeartbeat(int term, String leader) {
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if (term >= currentTerm) {
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scheduleElectionTimeout();
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becomeFollower(term);
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}
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}
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private void handleVoteGranted(int term, String candidate) {
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if (state == RaftStates.CANDIDATE && term == currentTerm) {
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votesReceived.add(candidate);
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logger.debug("Vote received from {}. Total votes: {}/{}",
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candidate, votesReceived.size(), (nodeManager.getNodes().size() / QUORUM_FACTOR + 1));
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becomeLeader();
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}
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}
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public void shutdown() {
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electionExecutor.shutdownNow();
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}
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}
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