From d495265dcf9f24464d5f33e2d012eb98a2d1ca32 Mon Sep 17 00:00:00 2001
From: olverhijnzoon <olver.hijnzoon@gmail.com>
Date: Sun, 20 Aug 2023 21:53:57 +0200
Subject: [PATCH] Getting started on a Raft Golang implementation regarding
 Nodes

---
 golangraft/consensus.go | 12 ++----
 golangraft/node.go      | 81 +++++++++++++++++++++++++++++++++++++++++
 golangraft/node_test.go | 37 +++++++++++++++++++
 3 files changed, 121 insertions(+), 9 deletions(-)
 create mode 100644 golangraft/node.go
 create mode 100644 golangraft/node_test.go

diff --git a/golangraft/consensus.go b/golangraft/consensus.go
index 7e11d48..c24130f 100644
--- a/golangraft/consensus.go
+++ b/golangraft/consensus.go
@@ -13,12 +13,6 @@ const (
 	Leader
 )
 
-// Node represents a node in the Raft cluster.
-type Node struct {
-	ID   int
-	Addr string // Address of the node for communication
-}
-
 // LogEntry represents an entry in the Raft log.
 type LogEntry struct {
 	Term    int
@@ -38,10 +32,10 @@ type Consensus struct {
 }
 
 // Assuming a list of all nodes in the cluster:
-var nodes = []Node{
+var nodes = []*Node{
 	// TODO: Add nodes here
-	// Example: {ID: 1, Addr: "localhost:8001"},
-	//          {ID: 2, Addr: "localhost:8002"},
+	// Example: &Node{ID: 1, Addr: "localhost:8001"},
+	//          &Node{ID: 2, Addr: "localhost:8002"},
 }
 
 func NewConsensus() *Consensus {
diff --git a/golangraft/node.go b/golangraft/node.go
new file mode 100644
index 0000000..1d35b2c
--- /dev/null
+++ b/golangraft/node.go
@@ -0,0 +1,81 @@
+package main
+
+import (
+	"sync"
+	"time"
+)
+
+const HeartbeatInterval = 100 * time.Millisecond
+
+type Node struct {
+	mu    sync.Mutex
+	ID    int
+	State int
+	Consensus
+	// Channel to signal stopping of heartbeat
+	stopHeartbeat chan bool
+}
+
+func NewNode(id int) *Node {
+	return &Node{
+		ID:        id,
+		State:     Follower,
+		Consensus: *NewConsensus(),
+	}
+}
+
+func (n *Node) TransitionToCandidate() {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+
+	n.StartElection()
+	if n.State != Candidate {
+		n.State = Candidate
+	}
+}
+
+func (n *Node) SendHeartbeat() {
+	// TODO: Implement sending of AppendEntries RPC to all followers.
+}
+
+func (n *Node) StartHeartbeatLoop() {
+	ticker := time.NewTicker(HeartbeatInterval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			n.SendHeartbeat()
+		// Exit the loop when a signal is received on stopHeartbeat channel
+		case <-n.stopHeartbeat:
+			return
+		}
+	}
+}
+
+// Send a signal to stop the heartbeat loop
+func (n *Node) StopHeartbeat() {
+	n.stopHeartbeat <- true
+}
+
+func (n *Node) TransitionToLeader() {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+
+	n.becomeLeader()
+	if n.State != Leader {
+		n.State = Leader
+		n.stopHeartbeat = make(chan bool) // Initialize the channel
+		go n.StartHeartbeatLoop()         // Start sending heartbeats
+	}
+}
+
+func (n *Node) TransitionToFollower() {
+	n.mu.Lock()
+	defer n.mu.Unlock()
+
+	if n.State == Leader {
+		n.StopHeartbeat() // Stop sending heartbeats if the node was previously a leader
+	}
+	n.State = Follower
+}
diff --git a/golangraft/node_test.go b/golangraft/node_test.go
new file mode 100644
index 0000000..c651574
--- /dev/null
+++ b/golangraft/node_test.go
@@ -0,0 +1,37 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestNewNode(t *testing.T) {
+	node := NewNode(1)
+	if node.ID != 1 {
+		t.Errorf("Expected node ID to be 1, got %v", node.ID)
+	}
+	if node.State != Follower {
+		t.Errorf("Expected initial node state to be Follower, got %v", node.State)
+	}
+}
+
+func TestNodeTransitions(t *testing.T) {
+	node := NewNode(1)
+
+	// Test transition to Candidate
+	node.TransitionToCandidate()
+	if node.State != Candidate {
+		t.Errorf("Expected node state to be Candidate after transition, got %v", node.State)
+	}
+
+	// Test transition back to Follower
+	node.TransitionToFollower()
+	if node.State != Follower {
+		t.Errorf("Expected node state to be Follower after transition, got %v", node.State)
+	}
+
+	// Test transition to Leader
+	node.TransitionToLeader()
+	if node.State != Leader {
+		t.Errorf("Expected node state to be Leader after transition, got %v", node.State)
+	}
+}