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paxos_app.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Paxos Visualization</title>
<style>
body {
font-family: Arial, sans-serif;
display: flex;
flex-direction: column;
align-items: center;
background-color: #f4f4f9;
margin: 0;
padding: 20px;
}
canvas {
margin-left: 100px;
border: 1px solid #ccc;
background-color: #fff;
box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
margin-bottom: 20px;
}
.controls {
display: flex;
flex-wrap: wrap;
justify-content: center;
gap: 10px;
margin-bottom: 20px;
}
button {
padding: 10px 20px;
font-size: 16px;
cursor: pointer;
border: none;
background-color: #007bff;
color: white;
border-radius: 5px;
transition: background-color 0.3s;
}
button:hover {
background-color: #0056b3;
}
button.active {
background-color: #28a745;
box-shadow: 0 0 0 2px rgba(40, 167, 69, 0.5);
}
.control-group {
display: flex;
flex-direction: column;
align-items: center;
margin: 0 10px;
}
.speed-control {
display: flex;
align-items: center;
margin-top: 10px;
}
.speed-control label {
margin-right: 10px;
}
.status {
font-weight: bold;
margin-top: 15px;
font-size: 18px;
color: #2c3e50;
}
.info-panel {
background-color: #ecf0f1;
padding: 15px;
border-radius: 5px;
margin-top: 20px;
max-width: 1000px;
}
.majority-tracker {
margin-top: 10px;
font-size: 14px;
color: #7f8c8d;
}
.log-panel {
width: 1000px;
height: 150px;
overflow-y: auto;
background-color: #2c3e50;
color: #ecf0f1;
padding: 10px;
border-radius: 5px;
margin-top: 20px;
font-family: monospace;
}
.log-entry {
margin-bottom: 5px;
border-bottom: 1px solid #34495e;
padding-bottom: 5px;
}
.log-time {
color: #3498db;
}
.log-event {
color: #2ecc71;
}
.log-warning {
color: #f39c12;
}
.log-error {
color: #e74c3c;
}
.timeout-control {
display: flex;
align-items: center;
margin-top: 10px;
}
.timeout-control label {
margin-right: 10px;
}
.issue-explanation {
position: absolute;
left: 20px;
top: 150px;
width: 200px;
background-color: #f8f9fa;
padding: 15px;
border-radius: 5px;
box-shadow: 0 2px 5px rgba(0,0,0,0.1);
border: 1px solid #ddd;
}
.issue-explanation h3 {
margin-top: 0;
color: #343a40;
font-size: 16px;
border-bottom: 1px solid #eee;
padding-bottom: 10px;
}
.issue-explanation ul {
padding-left: 20px;
margin: 10px 0;
}
.issue-icon {
display: inline-block;
width: 12px;
height: 12px;
border-radius: 50%;
margin-right: 8px;
}
.issue-icon.network {
background-color: #ffc107;
}
.issue-icon.crash {
background-color: #dc3545;
}
.issue-icon.slow {
background-color: blue;
}
.issue-icon.unknown {
background-color: #17a2b8;
}
.current-issue {
margin-top: 15px;
padding: 10px;
background-color: #e9ecef;
border-radius: 4px;
font-size: 14px;
color: #495057;
}
</style>
</head>
<body>
<h1>Multi-leader Paxos Algorithm with MySQL</h1>
<div class="issue-explanation">
<h3>Node Issue Types</h3>
<ul>
<li><span class="issue-icon network"></span> Network Issue - Message delay/loss</li>
<li><span class="issue-icon crash"></span> Node Crash - Completely unavailable</li>
<li><span class="issue-icon slow"></span> Slow Response - Processing delay</li>
<li><span class="issue-icon unknown"></span> Unknown Issue - Unknown</li>
</ul>
<div class="current-issue" id="currentIssue">
No current node issues
</div>
</div>
<canvas id="paxosCanvas" width="800" height="500"></canvas>
<div class="controls">
<div class="control-group">
<div>
<button id="startButton">Start</button>
<button id="pauseButton">Pause</button>
<button id="resetButton">Reset</button>
</div>
<div class="speed-control">
<label for="speedSlider">Speed:</label>
<input type="range" id="speedSlider" min="1" max="10" value="5">
<span id="speedValue">5x</span>
</div>
<div class="timeout-control">
<label for="timeoutSlider">Timeout:</label>
<input type="range" id="timeoutSlider" min="0" max="100" value="20">
<span id="timeoutValue">20ms</span>
</div>
<div class="majority-tracker" id="majorityStatus">
Majority: Waiting for first phase...
</div>
</div>
<div class="control-group">
<div>
<button id="fail1Node">1 Node Issue</button>
<button id="fail2Nodes">2 Nodes Issue</button>
<button id="fail3Nodes">3 Nodes Issue</button>
<button id="failProposerAfterAccept">Fail Proposer After Accept</button>
<button id="recoverAll">Recover All</button>
</div>
</div>
</div>
<div class="status" id="statusText">Status: Ready</div>
<div class="info-panel" id="infoPanel">
<h3>Optimized Paxos Rules:</h3>
<p><strong>1.</strong> The Initial Prepare phase occurs only at startup or when a node issue arises or when a proposed value times out in transmission.</p>
<p><strong>2.</strong> Node 2 has the ACCEPT from the crashed Node 1, but in this animation, it won't reach the cluster because Node 4 wins the competition.</p>
<p><strong>3.</strong> In normal interaction, the prepare phase is not needed, and nodes can directly start from the Accept phase to propose information.</p>
<p><strong>Current State:</strong> All nodes operational - System fully available</p>
</div>
<div class="log-panel" id="logPanel">
<div class="log-entry"><span class="log-time">[System]</span> <span class="log-event">Paxos visualization initialized</span></div>
</div>
<script>
const canvas = document.getElementById('paxosCanvas');
const ctx = canvas.getContext('2d');
const statusText = document.getElementById('statusText');
const majorityStatus = document.getElementById('majorityStatus');
const infoPanel = document.getElementById('infoPanel');
const speedSlider = document.getElementById('speedSlider');
const speedValue = document.getElementById('speedValue');
const timeoutSlider = document.getElementById('timeoutSlider');
const timeoutValue = document.getElementById('timeoutValue');
const logPanel = document.getElementById('logPanel');
const failProposerAfterAcceptBtn = document.getElementById('failProposerAfterAccept');
const nodes = [
{ x: 150, y: 250, color: '#3498db', isDown: false, id: 1, role: 'Proposer' },
{ x: 350, y: 120, color: '#9b59b6', isDown: false, id: 2, role: 'Acceptor' },
{ x: 550, y: 200, color: '#e67e22', isDown: false, id: 3, role: 'Acceptor' },
{ x: 400, y: 400, color: '#2ecc71', isDown: false, id: 4, role: 'Acceptor' },
{ x: 600, y: 350, color: '#1abc9c', isDown: false, id: 5, role: 'Acceptor' }
];
const mysqlNode = {
x: 65,
y: 230,
width: 40,
height: 60,
color: '#4479a1',
status: 'Waiting',
statusColor: '#ff9800'
};
let animationId;
let isPaused = false;
let currentPhase = 0;
let lastTimestamp = 0;
const baseSpeed = 0.002;
let speedMultiplier = 5;
let timeoutDuration = 20;
const phases = ['Prepare', 'Promise', 'Accept', 'Accepted', 'Learn'];
let activeMessages = [];
let sentMessages = new Set();
let receivedPromises = 0;
let receivedAcceptances = 0;
const majorityThreshold = Math.floor(nodes.length / 2) + 1;
let promisedNodes = new Set();
let acceptedNodes = new Set();
let learnedNodes = new Set();
let learnSent = false;
let currentProposer = nodes[0];
let isRunning = false;
let currentRound = 0;
let shouldFailProposerAfterAccept = false;
let isProposerFailed = false;
let timeoutId = null;
let acceptedValue = null;
let highestAcceptedValue = null;
let needsPreparePhase = true;
let isOldAcceptScenario = false;
let proposerFailedAfterAccept = false;
let mysqlState = {
isWaiting: true,
lastCommittedValue: null,
pendingValue: null
};
function updateCurrentIssue() {
const issuePanel = document.getElementById('currentIssue');
const downNodes = nodes.filter(n => n.isDown);
if (downNodes.length === 0) {
issuePanel.innerHTML = "No current node issues";
issuePanel.style.color = "#495057";
return;
}
let issueText = "Current Node Issues:<br>";
downNodes.forEach(node => {
const issueTypes = [
{type: "Network Issue", icon: "network", color: "#ffc107"},
{type: "Node Crash", icon: "crash", color: "#dc3545"},
{type: "Slow Response", icon: "slow", color: "blue"},
{type: "Unknown Issue", icon: "unknown", color: "#17a2b8"}
];
const randomIssue = issueTypes[3];
issueText += `
<div style="margin-top: 5px;">
<span style="color: ${randomIssue.color}">Node ${node.id}</span>
</div>
`;
});
issuePanel.innerHTML = issueText;
}
function addLogEntry(message, type = 'event') {
const now = new Date();
const timeStr = now.toTimeString().substring(0, 8) + '.' + now.getMilliseconds().toString().padStart(3, '0');
const logEntry = document.createElement('div');
logEntry.className = 'log-entry';
const timeSpan = document.createElement('span');
timeSpan.className = 'log-time';
timeSpan.textContent = `[${timeStr}]`;
const messageSpan = document.createElement('span');
messageSpan.className = `log-${type}`;
messageSpan.textContent = ` ${message}`;
logEntry.appendChild(timeSpan);
logEntry.appendChild(messageSpan);
logPanel.appendChild(logEntry);
logPanel.scrollTop = logPanel.scrollHeight;
}
speedSlider.addEventListener('input', function() {
speedMultiplier = parseInt(this.value);
speedValue.textContent = speedMultiplier + 'x';
addLogEntry(`Animation speed changed to ${speedMultiplier}x`);
});
timeoutSlider.addEventListener('input', function() {
timeoutDuration = parseInt(this.value);
timeoutValue.textContent = timeoutDuration + 'ms';
addLogEntry(`Timeout duration changed to ${timeoutDuration}ms`);
});
function calculateDistance(x1, y1, x2, y2) {
return Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2));
}
function drawMySQL() {
ctx.fillStyle = mysqlNode.color;
ctx.fillRect(mysqlNode.x, mysqlNode.y, mysqlNode.width, mysqlNode.height);
ctx.strokeStyle = '#34495e';
ctx.strokeRect(mysqlNode.x, mysqlNode.y, mysqlNode.width, mysqlNode.height);
ctx.fillStyle = 'white';
ctx.textAlign = 'center';
ctx.font = 'bold 12px Arial';
ctx.fillText('MySQL', mysqlNode.x + mysqlNode.width/2, mysqlNode.y + mysqlNode.height/2 + 5);
ctx.fillStyle = mysqlNode.statusColor;
ctx.font = '10px Arial';
ctx.fillText(mysqlNode.status, mysqlNode.x + mysqlNode.width/2, mysqlNode.y + mysqlNode.height + 15);
}
function drawNode(node) {
ctx.beginPath();
ctx.arc(node.x, node.y, 20, 0, Math.PI * 2);
ctx.fillStyle = node.isDown ? '#bdc3c7' : node.color;
ctx.fill();
ctx.strokeStyle = '#34495e';
ctx.stroke();
ctx.fillStyle = 'black';
ctx.textAlign = 'center';
ctx.font = 'bold 12px Arial';
ctx.fillText(`Node ${node.id}`, node.x, node.y + 30);
if (node.isDown) {
ctx.fillStyle = '#e67e22';
ctx.fillText('ISSUE', node.x, node.y + 50);
} else if (learnedNodes.has(node.id)) {
ctx.fillStyle = '#27ae60';
ctx.fillText('LEARNED', node.x, node.y - 30);
} else if (acceptedNodes.has(node.id)) {
ctx.fillStyle = '#27ae60';
ctx.fillText('ACCEPTED', node.x, node.y - 30);
} else if (promisedNodes.has(node.id)) {
ctx.fillStyle = '#27ae60';
ctx.fillText('PROMISED', node.x, node.y - 30);
} else {
ctx.fillStyle = '#34495e';
ctx.fillText(node.role, node.x, node.y - 30);
}
}
function drawArrow(fromX, fromY, toX, toY, color) {
const headLength = 10;
const dx = toX - fromX;
const dy = toY - fromY;
const angle = Math.atan2(dy, dx);
const actualToX = toX - 20 * Math.cos(angle);
const actualToY = toY - 20 * Math.sin(angle);
ctx.beginPath();
ctx.moveTo(fromX, fromY);
ctx.lineTo(actualToX, actualToY);
ctx.strokeStyle = color;
ctx.lineWidth = 2;
ctx.stroke();
ctx.beginPath();
ctx.moveTo(actualToX, actualToY);
ctx.lineTo(actualToX - headLength * Math.cos(angle - Math.PI/6),
actualToY - headLength * Math.sin(angle - Math.PI/6));
ctx.lineTo(actualToX - headLength * Math.cos(angle + Math.PI/6),
actualToY - headLength * Math.sin(angle + Math.PI/6));
ctx.closePath();
ctx.fillStyle = color;
ctx.fill();
}
function drawMessageAnimation(message) {
const { from, to, progress, color, label } = message;
const currentX = from.x + (to.x - from.x) * progress;
const currentY = from.y + (to.y - from.y) * progress;
drawArrow(from.x, from.y, currentX, currentY, color);
ctx.beginPath();
ctx.arc(currentX, currentY, 6, 0, Math.PI * 2);
ctx.fillStyle = color;
ctx.fill();
ctx.fillStyle = '#34495e';
ctx.font = 'bold 12px Arial';
ctx.textAlign = 'center';
ctx.fillText(label, currentX, currentY - 15);
}
function drawScene() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
drawMySQL();
nodes.forEach(drawNode);
activeMessages.forEach(msg => {
drawMessageAnimation(msg);
});
statusText.textContent = `Phase: ${phases[currentPhase]} (Round ${currentRound})`;
updateMajorityStatus();
}
function hasMajority(receivedCount) {
return receivedCount >= majorityThreshold;
}
function updateMajorityStatus() {
let status = '';
switch(currentPhase) {
case 1:
status = `Promises: ${receivedPromises}/${majorityThreshold} (${hasMajority(receivedPromises) ? 'MAJORITY REACHED' : 'waiting'})`;
break;
case 3:
status = `Acceptances: ${receivedAcceptances}/${majorityThreshold} (${hasMajority(receivedAcceptances) ? 'MAJORITY REACHED' : 'waiting'})`;
break;
default:
status = `Majority required: ${majorityThreshold} nodes`;
}
majorityStatus.textContent = status;
}
function sendMessage(from, to, label, color, onReceive, onComplete) {
const messageKey = `${from.id}-${to.id}-${label}-${currentRound}`;
if (sentMessages.has(messageKey)) {
return;
}
sentMessages.add(messageKey);
const distance = calculateDistance(from.x, from.y, to.x, to.y);
const isFailed = to.isDown || (proposerFailedAfterAccept && from.id === 1);
addLogEntry(`${from.role} Node ${from.id} sending ${label} to Node ${to.id}${isFailed ? ' (target has issues)' : ''}`);
const message = {
from: from,
to: to,
progress: 0,
color: color,
label: label,
isFailed: isFailed,
messageKey: messageKey,
speed: baseSpeed * speedMultiplier / (distance / 100),
onReceive: onReceive,
onComplete: () => {
if (!isFailed && onComplete) {
onComplete();
} else if (isFailed) {
addLogEntry(`Message to Node ${to.id} failed (target has issues)`, "warning");
}
activeMessages = activeMessages.filter(m => m !== message);
}
};
activeMessages.push(message);
return message;
}
function electNewProposer() {
const newProposer = nodes.find(node => node.id === 4 && !node.isDown);
if (newProposer) {
currentProposer = newProposer;
addLogEntry(`Node ${newProposer.id} will be elected as new Proposer later`, "event");
return true;
}
addLogEntry("No available node to become new Proposer", "error");
return false;
}
const messageSpeeds = {
2: {3: 1.0, 5: 1.0, 4: 0.5},
4: {1: 1.0, 2: 1.0, 3: 1.0, 5: 1.0}
};
function handleProposerCompetition() {
const node2 = nodes[1];
const node4 = nodes[3];
addLogEntry(`Node ${node2.id} initiating PREPARE (slow to Node 4)`, "event");
acceptedNodes.clear();
drawScene();
sendPrepareMessages(node2, true);
receivedPromises = 0;
setTimeout(() => {
if (!node4.isDown) {
addLogEntry(`Node ${node4.id} initiating PREPARE (before receiving Node 2's)`, "event");
sendPrepareMessages(node4, false);
}
}, 50);
}
function sendPrepareMessages(proposer, isNode2) {
if (proposer.isDown) return;
receivedCompeteePromises = 1;
hasStartAccept = 0;
nodes.forEach(acceptor => {
if (acceptor.isDown || acceptor.id === proposer.id) return;
const willRespond = isNode2 ? [3].includes(acceptor.id) : true;
if (hasStartAccept) {
willRespond = 0;
}
if (!isNode2) {
promisedNodes.clear();
}
sendMessage(
proposer,
acceptor,
'PREPARE',
proposer.color,
() => {
if (willRespond) {
addLogEntry(`Node ${acceptor.id} processing PREPARE from Node ${proposer.id}`);
if (!isNode2 || (isNode2 && acceptor.id !== 4)) {
promisedNodes.add(acceptor.id);
sendMessage(
acceptor,
proposer,
'PROMISE',
acceptor.color,
null,
() => {
addLogEntry(`Node ${proposer.id} promise from Node ${acceptor.id}`, "warning");
if (isNode2) {
addLogEntry(`Node ${proposer.id} received PROMISE from Node ${acceptor.id} (but won't proceed)`);
} else {
addLogEntry(`Node ${acceptor.id} received PREPARE and is now PROMISED`);
addLogEntry(`Node ${proposer.id} received PROMISE from Node ${acceptor.id}`);
receivedCompeteePromises++;
if ((!hasStartAccept) && receivedCompeteePromises >= majorityThreshold) {
nodes[1].role = 'Acceptor';
addLogEntry(`Node ${proposer.id} achieved majority -here becoming active Proposer`, "success");
startAcceptPhase(proposer);
hasStartAccept = 1;
}
}
}
);
}
} else {
addLogEntry(`Node ${acceptor.id} ignoring PREPARE from Node ${proposer.id}`, "warning");
}
}
);
});
}
function failCurrentProposer() {
if (!currentProposer || isProposerFailed || currentProposer.id !== 1) return;
isProposerFailed = true;
proposerFailedAfterAccept = true;
addLogEntry(`Proposer Node ${currentProposer.id} failed after receiving ACCEPTED from Node 2`, "warning");
currentProposer.isDown = true;
activeMessages = activeMessages.filter(msg => {
if (msg.from.id === 1) {
addLogEntry(`Dropping ${msg.label} message to Node ${msg.to.id} due to proposer failure`, "warning");
return false;
}
return true;
});
isOldAcceptScenario = true;
if (electNewProposer()) {
needsPreparePhase = true;
} else {
isRunning = false;
}
setTimeout(() => {
handleProposerCompetition();
}, 300);
updateCurrentIssue();
drawScene();
}
function startTimeoutForNewProposer() {
if (timeoutId) {
clearTimeout(timeoutId);
}
addLogEntry(`Starting ${timeoutDuration}ms timeout for Node 2 to take over`, "warning");
timeoutId = setTimeout(() => {
if (isRunning && currentProposer.id === 2 && !isPaused) {
addLogEntry(`Timeout reached - Node 2 initiating new Prepare phase`, "event");
currentPhase = 0;
receivedPromises = 0;
promisedNodes.clear();
startPreparePhase();
}
}, timeoutDuration);
}
function startPreparePhase() {
if (!isRunning) return;
currentPhase = 0;
receivedPromises = 0;
promisedNodes.clear();
acceptedNodes.clear();
learnedNodes.clear();
learnSent = false;
isProposerFailed = false;
proposerFailedAfterAccept = false;
activeMessages = [];
sentMessages.clear();
if (isOldAcceptScenario) {
addLogEntry(`[OLD ACCEPT PREPARE] Starting Prepare phase before sending OLD ACCEPT`, "warning");
} else {
addLogEntry(`Starting Prepare phase (Round ${currentRound})`, "event");
}
nodes.forEach(node => {
if (node.isDown) return;
sendMessage(
currentProposer,
node,
'PREPARE',
currentProposer.color,
() => {
promisedNodes.add(node.id);
addLogEntry(`Node ${node.id} received PREPARE and is now PROMISED`);
},
!node.isDown ? () => {
sendMessage(
node,
currentProposer,
'PROMISE',
node.color,
null,
() => {
receivedPromises++;
addLogEntry(`Proposer received PROMISE from Node ${node.id} (${receivedPromises}/${majorityThreshold})`);
if (hasMajority(receivedPromises) && currentPhase == 0) {
currentPhase = 1;
if (isOldAcceptScenario) {
addLogEntry(`[OLD ACCEPT READY] Majority reached, will send OLD ACCEPT next`);
}
startAcceptPhase();
}
}
);
} : null
);
});
}
function startAcceptPhase() {
addLogEntry(`System accepts its value`, "warning");
if (!isRunning) return;
if (nodes[0].isDown) {
} else {
mysqlNode.status = "Proposing...";
}
currentPhase = 2;
receivedAcceptances = 0;
hasLearned = 0;
learnedNodes.clear();
acceptedValue = isOldAcceptScenario ? `Recovered-Value-Round${currentRound}` : `Value-Round${currentRound}`;
highestAcceptedValue = acceptedValue;
if (shouldFailProposerAfterAccept && currentProposer.id === 1) {
addLogEntry(`System will fail Node 1 after Node 2 accepts its value`, "warning");
addLogEntry(`Starting Accept phase with Proposer Node ${currentProposer.id} proposing: ${acceptedValue}`, "event");
nodes.forEach(node => {
if (node.isDown) return;
if (node.id == 2) {
const isOldAccept = (currentProposer.id === 2 && isOldAcceptScenario);
const acceptLabel = isOldAccept ? 'ACCEPT (OLD)' : 'ACCEPT';
const messageColor = isOldAccept ? '#e67e22' : currentProposer.color;
sendMessage(
currentProposer,
node,
acceptLabel,
messageColor,
() => {
if (node.id === 2 || !proposerFailedAfterAccept) {
acceptedNodes.add(node.id);
addLogEntry(`Node ${node.id} received ACCEPT and is now ACCEPTED here`);
}
},
!node.isDown ? () => {
setTimeout(() => {
failCurrentProposer();
}, 0);
} : null
);
};
});
} else {
addLogEntry(`Starting Accept phase with Proposer Node ${currentProposer.id} proposing: ${acceptedValue}`, "event");
nodes.forEach(node => {
if (node.isDown) return;
const isOldAccept = (currentProposer.id === 2 && isOldAcceptScenario);
const acceptLabel = isOldAccept ? 'ACCEPT (OLD)' : 'ACCEPT';
const messageColor = isOldAccept ? '#e67e22' : currentProposer.color;
sendMessage(
currentProposer,
node,
acceptLabel,
messageColor,
() => {
acceptedNodes.add(node.id);
addLogEntry(`Node ${node.id} received ACCEPT and is now ACCEPTED`);
},
!node.isDown ? () => {
sendMessage(
node,
currentProposer,
'ACCEPTED',
node.color,
null,
() => {
receivedAcceptances++;
addLogEntry(`Proposer received ACCEPTED from Node ${node.id} (${receivedAcceptances}/${majorityThreshold})`);
if ((!hasLearned) && hasMajority(receivedAcceptances)) {
currentPhase = 3;
addLogEntry(`Majority reached - proceeding to Learn phase`);
startLearnPhase();
hasLearned = 1;
}
}
);
} : null
);
});
}
isOldAcceptScenario = false;
}
function startLearnPhase() {
if (!isRunning) return;
learnSent = true;
currentPhase = 4;
if (nodes[0].isDown) {
mysqlNode.status = `Transaction Aborted`;
} else {
mysqlNode.status = `Transaction Committed`;
}
mysqlNode.statusColor = '#4caf50';
addLogEntry(`MySQL notified to commit value: ${acceptedValue}`, "success");
addLogEntry(`Starting Learn phase with Proposer Node ${currentProposer.id}`, "event");
nodes.forEach(node => {
if (node.isDown) return;
sendMessage(
currentProposer,
node,
'LEARN',
'#1abc9c',
() => {
learnedNodes.add(node.id);
addLogEntry(`Node ${node.id} received LEARN and is now LEARNED`);
},
!node.isDown ? () => {
if (activeMessages.filter(m => !m.isFailed).every(msg => msg.progress >= 1)) {
addLogEntry("Paxos round completed successfully", "event");
setTimeout(() => {
if (isRunning) {
currentRound++;
promisedNodes.clear();
acceptedNodes.clear();
learnedNodes.clear();
needsPreparePhase = false;
if (shouldFailProposerAfterAccept && currentProposer.id === 1) {
isOldAcceptScenario = true;
failCurrentProposer();
} else {
startAcceptPhase();
}
}
}, 1000);
}
} : null
);
});
}
function mysqlPropose(value) {
if (!isRunning || !mysqlState.isWaiting) return;
mysqlState.pendingValue = value;
mysqlNode.status = "Proposing...";
mysqlNode.statusColor = '#ff9800';
addLogEntry(`MySQL proposing new value: ${value}`, "event");
}
function updateAnimation(timestamp) {
if (isPaused) return;
if (timestamp - lastTimestamp >= 16) {
lastTimestamp = timestamp;
activeMessages.forEach(msg => {
if (msg.progress < 1) {
msg.progress += msg.speed;
if (msg.progress >= 1.0 && !msg.receivedCalled && msg.onReceive) {
msg.receivedCalled = true;
msg.onReceive();
}
if (msg.progress >= 1) {
msg.progress = 1;
if (msg.onComplete) {
msg.onComplete();
}
}
}
});
drawScene();
}
animationId = requestAnimationFrame(updateAnimation);
}
function updateScenarioInfo() {
const downCount = nodes.filter(n => n.isDown).length;
let analysis = "";
if (downCount === 0) {
analysis = "All nodes operational - System fully available";
} else if (downCount === 1) {
analysis = "1 Node with Issues - Tolerates failure (needs 3/5 for majority)";
} else if (downCount === 2) {
analysis = "2 Nodes with Issues - System may hang (needs 3/5 but only 3 available)";
} else if (downCount === 3) {
analysis = "3 Nodes with Issues - System unavailable (cannot reach majority)";
} else {
analysis = "4+ Nodes with Issues - System completely down";
}
infoPanel.querySelector('p:last-child').innerHTML = `<strong>Current State:</strong> ${analysis}`;
addLogEntry(`System state changed: ${analysis}`, downCount >= 3 ? "error" : downCount > 0 ? "warning" : "event");
}
function setFailureScenario(count) {
nodes.forEach(node => {
node.isDown = false;
if (node.id === 1) node.role = 'Proposer';
else node.role = 'Acceptor';
});
shouldFailProposerAfterAccept = false;
failProposerAfterAcceptBtn.classList.remove('active');
proposerFailedAfterAccept = false;
if (timeoutId) {
clearTimeout(timeoutId);
timeoutId = null;
}
const availableNodes = nodes.filter(n => n.id !== 2);
const shuffled = [...availableNodes].sort(() => 0.5 - Math.random());
for (let i = 0; i < count && i < shuffled.length; i++) {
shuffled[i].isDown = true;
if (shuffled[i].role === 'Proposer') {
const node2 = nodes.find(n => n.id === 2);
if (node2) {
node2.role = 'Proposer';
addLogEntry(`Node 2 promoted to Proposer due to issues with original proposer`, "warning");
}
}
}
if (count > 0) {
const failedNodes = shuffled.slice(0, count).map(n => n.id).join(', ');
addLogEntry(`Simulating issues with ${count} node(s): ${failedNodes}`, "warning");
} else {
addLogEntry("All nodes recovered", "event");
}
currentPhase = 0;
receivedPromises = 0;
receivedAcceptances = 0;
promisedNodes.clear();
acceptedNodes.clear();
learnedNodes.clear();
activeMessages = [];
sentMessages.clear();
learnSent = false;
currentRound = 0;
isProposerFailed = false;
needsPreparePhase = true;
isOldAcceptScenario = false;
mysqlNode.status = "Waiting";
mysqlNode.statusColor = "#ff9800";
currentProposer = nodes.find(node => node.role === 'Proposer' && !node.isDown);
if (!currentProposer) {
electNewProposer();
}
updateCurrentIssue();
drawScene();
updateScenarioInfo();
}
document.getElementById('startButton').addEventListener('click', () => {
if (!animationId) {