Try a better fix for rare ssl error with freedom splice

It seems the root cause is if the flag set at the inbound pipe reader, it is a race condition and freedom outbound can possibly do splice at the same time with inbound xtls writer.
Now we set the flag at the earliest and always do splice at the next buffer cycle.

proxy/proxy.go

@@ -13,7 +13,6 @@ import (
 	"math/big"
 	"runtime"
 	"strconv"
-	"time"
 
 	"github.com/pires/go-proxyproto"
 	"github.com/xtls/xray-core/common/buf"
@@ -479,7 +478,6 @@ func CopyRawConnIfExist(ctx context.Context, readerConn net.Conn, writerConn net
 				if inbound.CanSpliceCopy == 1 {
 					newError("CopyRawConn splice").WriteToLog(session.ExportIDToError(ctx))
 					runtime.Gosched() // necessary
-					time.Sleep(time.Millisecond) // without this, there will be a rare ssl error for freedom splice
 					w, err := tc.ReadFrom(readerConn)
 					if readCounter != nil {
 						readCounter.Add(w)

proxy/vless/encoding/encoding.go

@@ -225,15 +225,6 @@ func XtlsWrite(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdate
 		var ct stats.Counter
 		for {
 			buffer, err := reader.ReadMultiBuffer()
-			if trafficState.WriterSwitchToDirectCopy {
-				if inbound := session.InboundFromContext(ctx); inbound != nil && inbound.CanSpliceCopy == 2 {
-					inbound.CanSpliceCopy = 1 // force the value to 1, don't use setter
-				}
-				rawConn, _, writerCounter := proxy.UnwrapRawConn(conn)
-				writer = buf.NewWriter(rawConn)
-				ct = writerCounter
-				trafficState.WriterSwitchToDirectCopy = false
-			}
 			if !buffer.IsEmpty() {
 				if ct != nil {
 					ct.Add(int64(buffer.Len()))
@@ -242,6 +233,15 @@ func XtlsWrite(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdate
 				if werr := writer.WriteMultiBuffer(buffer); werr != nil {
 					return werr
 				}
+				if trafficState.WriterSwitchToDirectCopy {
+					rawConn, _, writerCounter := proxy.UnwrapRawConn(conn)
+					writer = buf.NewWriter(rawConn)
+					ct = writerCounter
+					trafficState.WriterSwitchToDirectCopy = false
+					if inbound := session.InboundFromContext(ctx); inbound != nil && inbound.CanSpliceCopy == 2 {
+						inbound.CanSpliceCopy = 1 // force the value to 1, don't use setter
+					}
+				}
 			}
 			if err != nil {
 				return err