net: remove the alloc from WriteMsgUDPAddrPort

name                       old time/op    new time/op    delta
ReadWriteMsgUDPAddrPort-8    5.12µs ± 8%    4.59µs ± 3%  -10.19%  (p=0.000 n=10+9)

name                       old alloc/op   new alloc/op   delta
ReadWriteMsgUDPAddrPort-8     64.0B ± 0%     32.0B ± 0%  -50.00%  (p=0.000 n=10+10)

name                       old allocs/op  new allocs/op  delta
ReadWriteMsgUDPAddrPort-8      2.00 ± 0%      1.00 ± 0%  -50.00%  (p=0.000 n=10+10)

Change-Id: Idf540b2f9f8035660305a0ab1cfc3e162569db63
Reviewed-on: https://go-review.googlesource.com/c/go/+/361257
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/internal/poll/fd_unix.go

@@ -485,6 +485,58 @@ func (fd *FD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (int, int, err
 	}
 }
 
+// WriteMsgInet4 is WriteMsg specialized for syscall.SockaddrInet4.
+func (fd *FD) WriteMsgInet4(p []byte, oob []byte, sa syscall.SockaddrInet4) (int, int, error) {
+	if err := fd.writeLock(); err != nil {
+		return 0, 0, err
+	}
+	defer fd.writeUnlock()
+	if err := fd.pd.prepareWrite(fd.isFile); err != nil {
+		return 0, 0, err
+	}
+	for {
+		n, err := unix.SendmsgNInet4(fd.Sysfd, p, oob, sa, 0)
+		if err == syscall.EINTR {
+			continue
+		}
+		if err == syscall.EAGAIN && fd.pd.pollable() {
+			if err = fd.pd.waitWrite(fd.isFile); err == nil {
+				continue
+			}
+		}
+		if err != nil {
+			return n, 0, err
+		}
+		return n, len(oob), err
+	}
+}
+
+// WriteMsgInet6 is WriteMsg specialized for syscall.SockaddrInet6.
+func (fd *FD) WriteMsgInet6(p []byte, oob []byte, sa syscall.SockaddrInet6) (int, int, error) {
+	if err := fd.writeLock(); err != nil {
+		return 0, 0, err
+	}
+	defer fd.writeUnlock()
+	if err := fd.pd.prepareWrite(fd.isFile); err != nil {
+		return 0, 0, err
+	}
+	for {
+		n, err := unix.SendmsgNInet6(fd.Sysfd, p, oob, sa, 0)
+		if err == syscall.EINTR {
+			continue
+		}
+		if err == syscall.EAGAIN && fd.pd.pollable() {
+			if err = fd.pd.waitWrite(fd.isFile); err == nil {
+				continue
+			}
+		}
+		if err != nil {
+			return n, 0, err
+		}
+		return n, len(oob), err
+	}
+}
+
 // Accept wraps the accept network call.
 func (fd *FD) Accept() (int, syscall.Sockaddr, string, error) {
 	if err := fd.readLock(); err != nil {

src/internal/poll/fd_windows.go

@@ -1128,25 +1128,35 @@ func (fd *FD) RawWrite(f func(uintptr) bool) error {
 	return syscall.EWINDOWS
 }
 
+func sockaddrInet4ToRaw(sa syscall.SockaddrInet4) (unsafe.Pointer, int32) {
+	var raw syscall.RawSockaddrInet4
+	raw.Family = syscall.AF_INET
+	p := (*[2]byte)(unsafe.Pointer(&raw.Port))
+	p[0] = byte(sa.Port >> 8)
+	p[1] = byte(sa.Port)
+	raw.Addr = sa.Addr
+	return unsafe.Pointer(&raw), int32(unsafe.Sizeof(raw))
+}
+
+func sockaddrInet6ToRaw(sa syscall.SockaddrInet6) (unsafe.Pointer, int32) {
+	var raw syscall.RawSockaddrInet6
+	raw.Family = syscall.AF_INET6
+	p := (*[2]byte)(unsafe.Pointer(&raw.Port))
+	p[0] = byte(sa.Port >> 8)
+	p[1] = byte(sa.Port)
+	raw.Scope_id = sa.ZoneId
+	raw.Addr = sa.Addr
+	return unsafe.Pointer(&raw), int32(unsafe.Sizeof(raw))
+}
+
 func sockaddrToRaw(sa syscall.Sockaddr) (unsafe.Pointer, int32, error) {
 	switch sa := sa.(type) {
 	case *syscall.SockaddrInet4:
-		var raw syscall.RawSockaddrInet4
-		raw.Family = syscall.AF_INET
-		p := (*[2]byte)(unsafe.Pointer(&raw.Port))
-		p[0] = byte(sa.Port >> 8)
-		p[1] = byte(sa.Port)
-		raw.Addr = sa.Addr
-		return unsafe.Pointer(&raw), int32(unsafe.Sizeof(raw)), nil
+		ptr, sz := sockaddrInet4ToRaw(*sa)
+		return ptr, sz, nil
 	case *syscall.SockaddrInet6:
-		var raw syscall.RawSockaddrInet6
-		raw.Family = syscall.AF_INET6
-		p := (*[2]byte)(unsafe.Pointer(&raw.Port))
-		p[0] = byte(sa.Port >> 8)
-		p[1] = byte(sa.Port)
-		raw.Scope_id = sa.ZoneId
-		raw.Addr = sa.Addr
-		return unsafe.Pointer(&raw), int32(unsafe.Sizeof(raw)), nil
+		ptr, sz := sockaddrInet6ToRaw(*sa)
+		return ptr, sz, nil
 	default:
 		return nil, 0, syscall.EWINDOWS
 	}
@@ -1206,3 +1216,47 @@ func (fd *FD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (int, int, err
 	})
 	return n, int(o.msg.Control.Len), err
 }
+
+// WriteMsgInet4 is WriteMsg specialized for syscall.SockaddrInet4.
+func (fd *FD) WriteMsgInet4(p []byte, oob []byte, sa syscall.SockaddrInet4) (int, int, error) {
+	if len(p) > maxRW {
+		return 0, 0, errors.New("packet is too large (only 1GB is allowed)")
+	}
+
+	if err := fd.writeLock(); err != nil {
+		return 0, 0, err
+	}
+	defer fd.writeUnlock()
+
+	o := &fd.wop
+	o.InitMsg(p, oob)
+	rsa, len := sockaddrInet4ToRaw(sa)
+	o.msg.Name = (syscall.Pointer)(rsa)
+	o.msg.Namelen = len
+	n, err := execIO(o, func(o *operation) error {
+		return windows.WSASendMsg(o.fd.Sysfd, &o.msg, 0, &o.qty, &o.o, nil)
+	})
+	return n, int(o.msg.Control.Len), err
+}
+
+// WriteMsgInet6 is WriteMsg specialized for syscall.SockaddrInet6.
+func (fd *FD) WriteMsgInet6(p []byte, oob []byte, sa syscall.SockaddrInet6) (int, int, error) {
+	if len(p) > maxRW {
+		return 0, 0, errors.New("packet is too large (only 1GB is allowed)")
+	}
+
+	if err := fd.writeLock(); err != nil {
+		return 0, 0, err
+	}
+	defer fd.writeUnlock()
+
+	o := &fd.wop
+	o.InitMsg(p, oob)
+	rsa, len := sockaddrInet6ToRaw(sa)
+	o.msg.Name = (syscall.Pointer)(rsa)
+	o.msg.Namelen = len
+	n, err := execIO(o, func(o *operation) error {
+		return windows.WSASendMsg(o.fd.Sysfd, &o.msg, 0, &o.qty, &o.o, nil)
+	})
+	return n, int(o.msg.Control.Len), err
+}

src/internal/syscall/unix/net.go

@@ -26,3 +26,11 @@ func SendtoInet4(fd int, p []byte, flags int, to syscall.SockaddrInet4) (err err
 //go:linkname SendtoInet6 syscall.sendtoInet6
 //go:noescape
 func SendtoInet6(fd int, p []byte, flags int, to syscall.SockaddrInet6) (err error)
+
+//go:linkname SendmsgNInet4 syscall.sendmsgNInet4
+//go:noescape
+func SendmsgNInet4(fd int, p, oob []byte, to syscall.SockaddrInet4, flags int) (n int, err error)
+
+//go:linkname SendmsgNInet6 syscall.sendmsgNInet6
+//go:noescape
+func SendmsgNInet6(fd int, p, oob []byte, to syscall.SockaddrInet6, flags int) (n int, err error)

src/internal/syscall/unix/net_js.go

@@ -26,3 +26,11 @@ func SendtoInet4(fd int, p []byte, flags int, to syscall.SockaddrInet4) (err err
 func SendtoInet6(fd int, p []byte, flags int, to syscall.SockaddrInet6) (err error) {
 	return syscall.ENOSYS
 }
+
+func SendmsgNInet4(fd int, p, oob []byte, to syscall.SockaddrInet4, flags int) (n int, err error) {
+	return 0, syscall.ENOSYS
+}
+
+func SendmsgNInet6(fd int, p, oob []byte, to syscall.SockaddrInet6, flags int) (n int, err error) {
+	return 0, syscall.ENOSYS
+}

src/net/fd_posix.go

@@ -110,6 +110,18 @@ func (fd *netFD) writeMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oob
 	return n, oobn, wrapSyscallError(writeMsgSyscallName, err)
 }
 
+func (fd *netFD) writeMsgInet4(p []byte, oob []byte, sa syscall.SockaddrInet4) (n int, oobn int, err error) {
+	n, oobn, err = fd.pfd.WriteMsgInet4(p, oob, sa)
+	runtime.KeepAlive(fd)
+	return n, oobn, wrapSyscallError(writeMsgSyscallName, err)
+}
+
+func (fd *netFD) writeMsgInet6(p []byte, oob []byte, sa syscall.SockaddrInet6) (n int, oobn int, err error) {
+	n, oobn, err = fd.pfd.WriteMsgInet6(p, oob, sa)
+	runtime.KeepAlive(fd)
+	return n, oobn, wrapSyscallError(writeMsgSyscallName, err)
+}
+
 func (fd *netFD) SetDeadline(t time.Time) error {
 	return fd.pfd.SetDeadline(t)
 }

src/net/net_fake.go

@@ -279,6 +279,14 @@ func (fd *netFD) readMsg(p []byte, oob []byte, flags int) (n, oobn, retflags int
 	return 0, 0, 0, nil, syscall.ENOSYS
 }
 
+func (fd *netFD) writeMsgInet4(p []byte, oob []byte, sa syscall.SockaddrInet4) (n int, oobn int, err error) {
+	return 0, 0, syscall.ENOSYS
+}
+
+func (fd *netFD) writeMsgInet6(p []byte, oob []byte, sa syscall.SockaddrInet6) (n int, oobn int, err error) {
+	return 0, 0, syscall.ENOSYS
+}
+
 func (fd *netFD) writeTo(p []byte, sa syscall.Sockaddr) (n int, err error) {
 	return 0, syscall.ENOSYS
 }

src/net/udpsock_posix.go

@@ -188,15 +188,13 @@ func (c *UDPConn) writeMsgAddrPort(b, oob []byte, addr netip.AddrPort) (n, oobn
 		if err != nil {
 			return 0, 0, err
 		}
-		// TODO: Implement writeMsgInet4 to avoid allocation converting sa to an interface.
-		return c.fd.writeMsg(b, oob, &sa)
+		return c.fd.writeMsgInet4(b, oob, sa)
 	case syscall.AF_INET6:
 		sa, err := addrPortToSockaddrInet6(addr)
 		if err != nil {
 			return 0, 0, err
 		}
-		// TODO: Implement writeMsgInet6 to avoid allocation converting sa to an interface.
-		return c.fd.writeMsg(b, oob, &sa)
+		return c.fd.writeMsgInet6(b, oob, sa)
 	default:
 		return 0, 0, &AddrError{Err: "invalid address family", Addr: addr.Addr().String()}
 	}

src/syscall/syscall_unix.go

@@ -351,6 +351,22 @@ func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error)
 	return sendmsgN(fd, p, oob, ptr, salen, flags)
 }
 
+func sendmsgNInet4(fd int, p, oob []byte, to SockaddrInet4, flags int) (n int, err error) {
+	ptr, salen, err := to.sockaddr()
+	if err != nil {
+		return 0, err
+	}
+	return sendmsgN(fd, p, oob, ptr, salen, flags)
+}
+
+func sendmsgNInet6(fd int, p, oob []byte, to SockaddrInet6, flags int) (n int, err error) {
+	ptr, salen, err := to.sockaddr()
+	if err != nil {
+		return 0, err
+	}
+	return sendmsgN(fd, p, oob, ptr, salen, flags)
+}
+
 func sendtoInet4(fd int, p []byte, flags int, to SockaddrInet4) (err error) {
 	ptr, n, err := to.sockaddr()
 	if err != nil {