initial commit

mac_cache.go

@@ -0,0 +1,108 @@
+package weave
+
+import (
+	"bytes"
+	"fmt"
+	"net"
+	"sync"
+	"time"
+)
+
+type MacCacheEntry struct {
+	lastSeen time.Time
+	peer     *Peer
+}
+
+type MacCache struct {
+	sync.RWMutex
+	table       map[uint64]*MacCacheEntry
+	maxAge      time.Duration
+	expiryTimer *time.Timer
+}
+
+func NewMacCache(maxAge time.Duration) *MacCache {
+	res := &MacCache{
+		table:  make(map[uint64]*MacCacheEntry),
+		maxAge: maxAge}
+	res.setExpiryTimer()
+	return res
+}
+
+func (cache *MacCache) Enter(mac net.HardwareAddr, peer *Peer) bool {
+	key := macint(mac)
+	now := time.Now()
+	cache.RLock()
+	entry, found := cache.table[key]
+	if found && entry.peer == peer && now.Before(entry.lastSeen.Add(cache.maxAge/10)) {
+		cache.RUnlock()
+		return false
+	} else {
+		cache.RUnlock()
+	}
+	cache.Lock()
+	defer cache.Unlock()
+	entry, found = cache.table[key]
+	if !found {
+		cache.table[key] = &MacCacheEntry{lastSeen: now, peer: peer}
+		return true
+	}
+	if entry.peer != peer {
+		entry.lastSeen = now
+		entry.peer = peer
+		return true
+	}
+	if now.After(entry.lastSeen.Add(cache.maxAge / 10)) {
+		entry.lastSeen = now
+	}
+	return false
+}
+
+func (cache *MacCache) Lookup(mac net.HardwareAddr) (*Peer, bool) {
+	key := macint(mac)
+	cache.RLock()
+	defer cache.RUnlock()
+	entry, found := cache.table[key]
+	if !found {
+		return nil, false
+	}
+	return entry.peer, true
+}
+
+func (cache *MacCache) Delete(peer *Peer) bool {
+	found := false
+	cache.Lock()
+	defer cache.Unlock()
+	for key, entry := range cache.table {
+		if entry.peer == peer {
+			delete(cache.table, key)
+			found = true
+		}
+	}
+	return found
+}
+
+func (cache *MacCache) String() string {
+	var buf bytes.Buffer
+	cache.RLock()
+	defer cache.RUnlock()
+	for key, entry := range cache.table {
+		buf.WriteString(fmt.Sprintf("%v -> %s (%v)\n", intmac(key), entry.peer.Name, entry.lastSeen))
+	}
+	return buf.String()
+}
+
+func (cache *MacCache) setExpiryTimer() {
+	cache.expiryTimer = time.AfterFunc(cache.maxAge/10, func() { cache.expire() })
+}
+
+func (cache *MacCache) expire() {
+	now := time.Now()
+	cache.Lock()
+	defer cache.Unlock()
+	for key, entry := range cache.table {
+		if now.After(entry.lastSeen.Add(cache.maxAge)) {
+			delete(cache.table, key)
+		}
+	}
+	cache.setExpiryTimer()
+}