updated cache

util/cache/cache.go

@@ -1,70 +1,91 @@
 package cache
 
-import "sync"
-
-type Cache struct {
-	mu  sync.RWMutex
-	s2c map[string]string
-	c2s map[string]string
-}
-
 func NewCache() *Cache {
-	return &Cache{
+	c := &Cache{}
+	c.state.Store(&mappings{
 		s2c: make(map[string]string),
 		c2s: make(map[string]string),
-	}
+	})
+
+	return c
 }
 
-// Set creates or overwrites the pair a -> b and b -> a.
-// It ensures any previous mappings involving a or b are removed first.
 func (c *Cache) Set(serverId, channelId string) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
-	if old, ok := c.s2c[serverId]; ok && old != channelId {
-		delete(c.c2s, old)
+	current := c.state.Load()
+	next := current.clone()
+
+	if oldCh, ok := next.s2c[serverId]; ok && oldCh != channelId {
+		delete(next.c2s, oldCh)
+	}
+	if oldSrv, ok := next.c2s[channelId]; ok && oldSrv != serverId {
+		delete(next.s2c, oldSrv)
 	}
 
-	if old, ok := c.c2s[channelId]; ok && old != serverId {
-		delete(c.s2c, old)
-	}
+	next.s2c[serverId] = channelId
+	next.c2s[channelId] = serverId
 
-	c.s2c[serverId] = channelId
-	c.c2s[channelId] = serverId
+	c.state.Store(next)
 }
 
 func (c *Cache) GetByServerId(serverId string) (string, bool) {
-	c.mu.RLock()
-	defer c.mu.RUnlock()
-
-	cId, ok := c.s2c[serverId]
-	return cId, ok
+	m := c.state.Load()
+	val, ok := m.s2c[serverId]
+	return val, ok
 }
 
 func (c *Cache) GetByChannelId(channelId string) (string, bool) {
-	c.mu.RLock()
-	defer c.mu.RUnlock()
-
-	sId, ok := c.c2s[channelId]
-	return sId, ok
+	m := c.state.Load()
+	val, ok := m.c2s[channelId]
+	return val, ok
 }
 
 func (c *Cache) RemoveByServerId(serverId string) {
-	c.mu.RLock()
-	defer c.mu.RUnlock()
+	c.mu.Lock()
+	defer c.mu.Unlock()
 
-	if channelId, ok := c.s2c[serverId]; ok {
-		delete(c.s2c, serverId)
-		delete(c.c2s, channelId)
+	current := c.state.Load()
+	if _, ok := current.s2c[serverId]; !ok {
+		return
 	}
+
+	next := current.clone()
+	if channelId, ok := next.s2c[serverId]; ok {
+		delete(next.s2c, serverId)
+		delete(next.c2s, channelId)
+	}
+	c.state.Store(next)
 }
 
 func (c *Cache) RemoveByChannelId(channelId string) {
-	c.mu.RLock()
-	defer c.mu.RUnlock()
+	c.mu.Lock()
+	defer c.mu.Unlock()
 
-	if serverId, ok := c.s2c[channelId]; ok {
-		delete(c.c2s, channelId)
-		delete(c.s2c, serverId)
+	current := c.state.Load()
+	if _, ok := current.c2s[channelId]; !ok {
+		return
 	}
+
+	next := current.clone()
+	if serverId, ok := next.c2s[channelId]; ok {
+		delete(next.c2s, channelId)
+		delete(next.s2c, serverId)
+	}
+	c.state.Store(next)
+}
+
+func (m *mappings) clone() *mappings {
+	newM := &mappings{
+		s2c: make(map[string]string, len(m.s2c)),
+		c2s: make(map[string]string, len(m.c2s)),
+	}
+	for k, v := range m.s2c {
+		newM.s2c[k] = v
+	}
+	for k, v := range m.c2s {
+		newM.c2s[k] = v
+	}
+	return newM
 }