re-formatted, better structure

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
+}