Added PreWrite

evio.go

@@ -111,6 +111,8 @@ type Events struct {
 	// underlying socket connection. It can be freely used in goroutines
 	// and should be closed when it's no longer needed.
 	Detached func(c Conn, rwc io.ReadWriteCloser) (action Action)
+	// PreWrite fires just before any data is written to any client socket.
+	PreWrite func()
 	// Data fires when a connection sends the server data.
 	// The in parameter is the incoming data.
 	// Use the out return value to write data to the connection.

evio_std.go

@@ -369,6 +369,9 @@ func stdloopRead(s *stdserver, l *stdloop, c *stdconn, in []byte) error {
 	if s.events.Data != nil {
 		out, action := s.events.Data(c, in)
 		if len(out) > 0 {
+			if s.events.PreWrite != nil {
+				s.events.PreWrite()
+			}
 			c.conn.Write(out)
 		}
 		switch action {
@@ -387,6 +390,9 @@ func stdloopReadUDP(s *stdserver, l *stdloop, c *stdudpconn) error {
 	if s.events.Data != nil {
 		out, action := s.events.Data(c, c.in)
 		if len(out) > 0 {
+			if s.events.PreWrite != nil {
+				s.events.PreWrite()
+			}
 			s.lns[c.addrIndex].pconn.WriteTo(out, c.remoteAddr)
 		}
 		switch action {
@@ -418,6 +424,9 @@ func stdloopAccept(s *stdserver, l *stdloop, c *stdconn) error {
 	if s.events.Opened != nil {
 		out, opts, action := s.events.Opened(c)
 		if len(out) > 0 {
+			if s.events.PreWrite != nil {
+				s.events.PreWrite()
+			}
 			c.conn.Write(out)
 		}
 		if opts.TCPKeepAlive > 0 {

evio_unix.go

@@ -315,6 +315,9 @@ func loopUDPRead(s *server, l *loop, lnidx, fd int) error {
 		in := append([]byte{}, l.packet[:n]...)
 		out, action := s.events.Data(c, in)
 		if len(out) > 0 {
+			if s.events.PreWrite != nil {
+				s.events.PreWrite()
+			}
 			syscall.Sendto(fd, out, 0, sa)
 		}
 		switch action {
@@ -350,6 +353,9 @@ func loopOpened(s *server, l *loop, c *conn) error {
 }
 
 func loopWrite(s *server, l *loop, c *conn) error {
+	if s.events.PreWrite != nil {
+		s.events.PreWrite()
+	}
 	n, err := syscall.Write(c.fd, c.out)
 	if err != nil {
 		if err == syscall.EAGAIN {