I asked ChatGPT to create a Simple Raft Implementation

main.go

package main

import (
	"fmt"
	"math/rand"
	"time"
)

// LogEntry represents a log entry in the Raft algorithm.
type LogEntry struct {
	Term  int
	Index int
	Data  interface{}
}

// RaftNode represents a node in the Raft cluster.
type RaftNode struct {
	id             int
	currentTerm    int
	votedFor       int
	log            []LogEntry
	commitIndex    int
	lastApplied    int
	nextIndex      []int
	matchIndex     []int
	state          string // "follower", "candidate", or "leader"
	electionTimer  *time.Timer
	heartbeatTimer *time.Timer

	// Channels for communication between different components of the node.
	// For simplicity, we use channels for communication, but in a real-world
	// scenario, you would need to implement network communication.
	appendEntriesChan chan struct{}
	requestVoteChan   chan struct{}
	commitChan        chan struct{}
}

func NewRaftNode(id int) *RaftNode {
	return &RaftNode{
		id:                id,
		currentTerm:      0,
		votedFor:         -1,
		log:              make([]LogEntry, 0),
		commitIndex:      0,
		lastApplied:      0,
		nextIndex:        make([]int, 0),
		matchIndex:       make([]int, 0),
		appendEntriesChan: make(chan struct{}),
		requestVoteChan:   make(chan struct{}),
		commitChan:        make(chan struct{}),
		state:             "follower",
	}
}

func (n *RaftNode) startElectionTimer() {
	timeout := time.Duration(rand.Intn(150)+150) * time.Millisecond
	n.electionTimer = time.NewTimer(timeout)

	go func() {
		for {
			select {
			case <-n.electionTimer.C:
				fmt.Printf("[%d] Election timeout\n", n.id)
				n.startElection()
			}
		}
	}()
}

func (n *RaftNode) resetElectionTimer() {
	n.electionTimer.Stop()
	n.startElectionTimer()
}

func (n *RaftNode) startHeartbeatTimer() {
	heartbeatInterval := 50 * time.Millisecond
	n.heartbeatTimer = time.NewTimer(heartbeatInterval)

	go func() {
		for {
			select {
			case <-n.heartbeatTimer.C:
				fmt.Printf("[%d] Sending heartbeat\n", n.id)
				n.broadcastAppendEntries()
			}
		}
	}()
}

func (n *RaftNode) resetHeartbeatTimer() {
	n.heartbeatTimer.Stop()
	n.startHeartbeatTimer()
}

func (n *RaftNode) startElection() {
	n.state = "candidate"
	n.currentTerm++
	n.votedFor = n.id
	n.resetElectionTimer()

	// Request votes from other nodes.
	n.broadcastRequestVote()
}

func (n *RaftNode) broadcastRequestVote() {
	fmt.Printf("[%d] Broadcasting RequestVote for term %d\n", n.id, n.currentTerm)

	// For simplicity, we'll assume there are two other nodes in the cluster with IDs 2 and 3.
	for _, peerID := range []int{2, 3} {
		go func(peerID int) {
			// Simulate network latency and communication.
			time.Sleep(time.Duration(rand.Intn(50)) * time.Millisecond)

			// For now, we'll just simulate a response from each peer.
			n.handleRequestVoteResponse(peerID, true)
		}(peerID)
	}
}

func (n *RaftNode) handleRequestVoteResponse(peerID int, voteGranted bool) {
	if n.state != "candidate" {
		return
	}

	if voteGranted {
		fmt.Printf("[%d] Received vote from %d\n", n.id, peerID)
		// For simplicity, we'll assume a majority with just one vote.
		n.state = "leader"
		n.resetHeartbeatTimer()

		// Initialize nextIndex and matchIndex for log replication.
		for _, peer := range []int{2, 3} {
			n.nextIndex = append(n.nextIndex, len(n.log)+1)
			n.matchIndex = append(n.matchIndex, 0)
		}

		// Start log replication.
		n.sendAppendEntries()
	} else {
		// TODO: Handle the case where the vote is not granted.
	}
}

func (n *RaftNode) sendAppendEntries() {
	fmt.Printf("[%d] Sending initial AppendEntries for log replication\n", n.id)

	// For simplicity, we'll assume there are two other nodes in the cluster with IDs 2 and 3.
	for _, peerID := range []int{2, 3} {
		go func(peerID int) {
			// Simulate network latency and communication.
			time.Sleep(time.Duration(rand.Intn(50)) * time.Millisecond)

			// For now, we'll just simulate a response from each peer.
			n.handleAppendEntriesResponse(peerID, true)
		}(peerID)
	}
}

func (n *RaftNode) handleAppendEntriesResponse(peerID int, success bool) {
	if n.state != "leader" {
		return
	}

	if success {
		n.nextIndex[peerID-2]++
		n.matchIndex[peerID-2] = n.nextIndex[peerID-2] - 1

		n.commitIndex++
		n.commitChan <- struct{}{}

		// Continue log replication.
		n.sendAppendEntries()
	} else {
		// TODO: Handle the case where log replication is not successful.
	}
}

func (n *RaftNode) StateMachine() {
	for {
		select {
		case <-n.appendEntriesChan:
			// TODO: Handle incoming AppendEntries RPCs.
		case <-n.requestVoteChan:
			// TODO: Handle incoming RequestVote RPCs.
		case <-n.commitChan:
			// Apply committed log entries to the state machine.
			n.applyCommittedEntries()
		}
	}
}

func (n *RaftNode) applyCommittedEntries() {
	for n.lastApplied < n.commitIndex {
		n.lastApplied++
		entry := n.log[n.lastApplied-1]
		// TODO: Apply the log entry to the state machine.
		fmt.Printf("[%d] Applied log entry: %v\n", n.id, entry)
	}
}

func (n *RaftNode) broadcastAppendEntries() {
	fmt.Printf("[%d] Broadcasting AppendEntries\n", n.id)

	// For simplicity, we'll assume there are two other nodes in the cluster with IDs 2 and 3.
	for _, peerID := range []int{2, 3} {
		go func(peerID int) {
			// Simulate network latency and communication.
			time.Sleep(time.Duration(rand.Intn(50)) * time.Millisecond)

			// For now, we'll just simulate a response from each peer.
			n.handleAppendEntriesResponse(peerID, true)
		}(peerID)
	}
}

func (n *RaftNode) Run() {
	go n.StateMachine()
	n.startElectionTimer()
	n.startHeartbeatTimer()

	// TODO: Implement the main Raft loop with leader election, log replication, etc.
	for {
		// Placeholder for the main Raft logic.
		// For simplicity, we'll just sleep for a random duration in this example.
		time.Sleep(time.Duration(rand.Intn(100)) * time.Millisecond)
	}
}

func main() {
	// Create and run a Raft node with ID 1.
	node := NewRaftNode(1)
	node.Run()
}