Added clustering and clean up

pkg/conn/cluster.go

@@ -0,0 +1,73 @@
+package conn
+
+import (
+	"errors"
+	"math"
+	"math/rand"
+	"slices"
+)
+
+// ConnCluster splits nodes into clusters where nodes in a cluster communicate
+// frequently and nodes outside of a cluster communicate infrequently
+type ConnCluster interface {
+	GetNeighbours(global []string, selfId string) []string
+	GetInterCluster(global []string, selfId string) string
+}
+
+type ConnClusterImpl struct {
+	clusterSize int
+}
+
+func binarySearch(global []string, selfId string, groupSize int) (int, int) {
+	slices.Sort(global)
+
+	lower := 0
+	higher := len(global) - 1
+	mid := lower + (lower+higher)/2
+
+	for (higher+1)-lower > groupSize {
+		if global[mid] <= selfId {
+			lower = mid
+		} else {
+			higher = mid
+		}
+
+		mid = lower + (lower+higher)/2
+	}
+
+	return lower, higher + 1
+}
+
+// GetNeighbours return the neighbours 'nearest' to you. In this implementation the
+// neighbours aren't actually the ones nearest to you but just the ones nearest
+// to you alphabetically. Perform binary search to get the total group
+func (i *ConnClusterImpl) GetNeighbours(global []string, selfId string) []string {
+	slices.Sort(global)
+
+	lower, higher := binarySearch(global, selfId, i.clusterSize)
+	// slice the list to get the neighbours
+	return global[lower:higher]
+}
+
+// GetInterCluster get nodes not in your cluster. Every round there is a given chance
+// you will communicate with a random node that is not in your cluster.
+func (i *ConnClusterImpl) GetInterCluster(global []string, selfId string) string {
+	// Doesn't matter if not in it. Get index of where the node 'should' be
+	index, _ := binarySearch(global, selfId, 1)
+	numClusters := math.Ceil(float64(len(global)) / float64(i.clusterSize))
+
+	randomCluster := rand.Intn(int(numClusters)-1) + 1
+
+	neighbourIndex := (index + randomCluster) % len(global)
+	return global[neighbourIndex]
+}
+
+func NewConnCluster(clusterSize int) (ConnCluster, error) {
+	log2Cluster := math.Log2(float64(clusterSize))
+
+	if float64((log2Cluster))-log2Cluster != 0 {
+		return nil, errors.New("cluster must be a power of 2")
+	}
+
+	return &ConnClusterImpl{clusterSize: clusterSize}, nil
+}

pkg/conn/window.go

@@ -0,0 +1,84 @@
+package conn
+
+import (
+	"errors"
+	"slices"
+
+	"github.com/tim-beatham/wgmesh/pkg/lib"
+)
+
+// ConnectionWindow maintains a sliding window of connections between users
+type ConnectionWindow interface {
+	// GetWindow is a list of connections to choose from
+	GetWindow() []string
+	// SlideConnection removes a node from the window and adds a random node
+	// not already in the window. connList represents the list of possible
+	// connections to choose from
+	SlideConnection(connList []string) error
+	// PushConneciton is used when connection list less than window size.
+	PutConnection(conn []string) error
+	// IsFull returns true if the window is full. In which case we must slide the window
+	IsFull() bool
+}
+
+type ConnectionWindowImpl struct {
+	window     []string
+	windowSize int
+}
+
+// GetWindow gets the current list of active connections in
+// the window
+func (c *ConnectionWindowImpl) GetWindow() []string {
+	return c.window
+}
+
+// SlideConnection slides the connection window by one shuffling items
+// in the windows
+func (c *ConnectionWindowImpl) SlideConnection(connList []string) error {
+	// If the number of peer connections is less than the length of the window
+	// then exit early. Can't slide the window it should contain all nodes!
+	if len(c.window) < c.windowSize {
+		return nil
+	}
+
+	filter := func(node string) bool {
+		return !slices.Contains(c.window, node)
+	}
+
+	pool := lib.Filter(connList, filter)
+	newNode := lib.RandomSubsetOfLength(pool, 1)
+
+	if len(newNode) == 0 {
+		return errors.New("could not slide window")
+	}
+
+	for i := len(c.window) - 1; i >= 1; i-- {
+		c.window[i] = c.window[i-1]
+	}
+
+	c.window[0] = newNode[0]
+	return nil
+}
+
+// PutConnection put random connections in the connection
+func (c *ConnectionWindowImpl) PutConnection(connList []string) error {
+	if len(c.window) >= c.windowSize {
+		return errors.New("cannot place connection. Window full need to slide")
+	}
+
+	c.window = lib.RandomSubsetOfLength(connList, c.windowSize)
+	return nil
+}
+
+func (c *ConnectionWindowImpl) IsFull() bool {
+	return len(c.window) >= c.windowSize
+}
+
+func NewConnectionWindow(windowLength int) ConnectionWindow {
+	window := &ConnectionWindowImpl{
+		window:     make([]string, 0),
+		windowSize: windowLength,
+	}
+
+	return window
+}