fix windows + fix const

cmd/agent/app/builder.go

@@ -39,7 +39,7 @@ import (
 const (
 	defaultQueueSize     = 1000
 	defaultMaxPacketSize = 65000
-	defaultBufferSize    = 16 * 1024 * 1024
+	defaultBufferSize    = 4 * 1024
 	defaultServerWorkers = 10
 
 	jaegerModel Model = "jaeger"

cmd/agent/app/servers/thriftudp/socket_buffer_linux_darwin.go

@@ -2,8 +2,16 @@
 
 package thriftudp
 
-import "syscall"
+import (
+	"net"
+	"syscall"
+)
 
-func setSocketBuffer(fd uintptr, level, opt, value int) error {
-	return syscall.SetsockoptInt(int(fd), level, opt, value)
+func setSocketBuffer(conn *net.UDPConn, bufferSize int) error {
+	file, err := conn.File()
+	if err != nil {
+		return err
+	}
+
+	return syscall.SetsockoptInt(int(file.Fd()), syscall.SOL_SOCKET, syscall.SO_RCVBUF, bufferSize)
 }

cmd/agent/app/servers/thriftudp/socket_buffer_windows.go

@@ -2,8 +2,11 @@
 
 package thriftudp
 
-import "syscall"
+import (
+	"net"
+)
 
-func setSocketBuffer(fd uintptr, level, opt, value int) error {
-	return syscall.SetsockoptInt(syscall.Handle(fd), level, opt, value)
+// Not supported on windows, so windows version just returns nil
+func setSocketBuffer(_ *net.UDPConn, _ int) error {
+	return nil
 }

cmd/agent/app/servers/thriftudp/transport.go

@@ -20,15 +20,14 @@ import (
 	"errors"
 	"net"
 	"sync/atomic"
-	"syscall"
 
 	"github.com/apache/thrift/lib/go/thrift"
 )
 
 //MaxLength of UDP packet
 const (
 	MaxLength  = 65000
-	BufferSize = 16 * 1024 * 1024
+	BufferSize = 4 * 1024
 )
 
 var errConnAlreadyClosed = errors.New("connection already closed")
@@ -85,12 +84,7 @@ func NewTUDPServerTransport(hostPort string, bufferSize int) (*TUDPTransport, er
 		return nil, thrift.NewTTransportException(thrift.NOT_OPEN, err.Error())
 	}
 
-	file, err := conn.File()
-	if err != nil {
-		return nil, err
-	}
-
-	if err = setSocketBuffer(file.Fd(), syscall.SOL_SOCKET, syscall.SO_RCVBUF, bufferSize); err != nil {
+	if err = setSocketBuffer(conn, bufferSize); err != nil {
 		return nil, err
 	}