move currentMs() to kcp.go

kcp.go

@@ -3,6 +3,7 @@ package kcp
 import (
 	"encoding/binary"
 	"sync/atomic"
+	"time"
 )
 
 const (
@@ -29,6 +30,12 @@ const (
 	IKCP_PROBE_LIMIT = 120000 // up to 120 secs to probe window
 )
 
+// monotonic reference time point
+var refTime time.Time = time.Now()
+
+// currentMs returns current elasped monotonic milliseconds since program startup
+func currentMs() uint32 { return uint32(time.Now().Sub(refTime) / time.Millisecond) }
+
 // output_callback is a prototype which ought capture conn and call conn.Write
 type output_callback func(buf []byte, size int)
 

sess.go

@@ -984,9 +984,3 @@ func NewConn(raddr string, block BlockCrypt, dataShards, parityShards int, conn
 	}
 	return NewConn2(udpaddr, block, dataShards, parityShards, conn)
 }
-
-// monotonic reference time point
-var refTime time.Time = time.Now()
-
-// currentMs returns current elasped monotonic milliseconds since program startup
-func currentMs() uint32 { return uint32(time.Now().Sub(refTime) / time.Millisecond) }