re-formatted, better structure

util/cache/cache.go

@@ -0,0 +1,70 @@
+package cache
+
+import "sync"
+
+type Cache struct {
+	mu  sync.RWMutex
+	s2c map[string]string
+	c2s map[string]string
+}
+
+func NewCache() *Cache {
+	return &Cache{
+		s2c: make(map[string]string),
+		c2s: make(map[string]string),
+	}
+}
+
+// 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)
+	}
+
+	if old, ok := c.c2s[channelId]; ok && old != serverId {
+		delete(c.s2c, old)
+	}
+
+	c.s2c[serverId] = channelId
+	c.c2s[channelId] = serverId
+}
+
+func (c *Cache) GetByServerId(serverId string) (string, bool) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	cId, ok := c.s2c[serverId]
+	return cId, ok
+}
+
+func (c *Cache) GetByChannelId(channelId string) (string, bool) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	sId, ok := c.c2s[channelId]
+	return sId, ok
+}
+
+func (c *Cache) RemoveByServerId(serverId string) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	if channelId, ok := c.s2c[serverId]; ok {
+		delete(c.s2c, serverId)
+		delete(c.c2s, channelId)
+	}
+}
+
+func (c *Cache) RemoveByChannelId(channelId string) {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+
+	if serverId, ok := c.s2c[channelId]; ok {
+		delete(c.c2s, channelId)
+		delete(c.s2c, serverId)
+	}
+}

util/cache/structs.go

@@ -0,0 +1,16 @@
+package cache
+
+import (
+	"sync"
+)
+
+type ShardedCache struct {
+	shards    []*shard
+	shardMask uint32
+}
+
+type shard struct {
+	mu  sync.RWMutex
+	s2c map[string]string // serverId -> channelId
+	c2s map[string]string // channelId -> serverId
+}