// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package net

import (
	"runtime"
	"syscall"
	"time"
)

func setNoDelay(fd *netFD, noDelay bool) error {
	b := make([]byte, 4)
	if noDelay {
		b[0] = 1
	}
	err := fd.sock.SetSockOpt(syscall.SOL_TCP, syscall.TCP_NODELAY, b)
	runtime.KeepAlive(fd)
	return err
}

func setKeepAlivePeriod(fd *netFD, d time.Duration) error {
	// The socket option expects seconds so round to next highest second.
	secs := uint32((d + time.Second - 1) / time.Second)

	b := make([]byte, 4)
	putUint32(b, secs)

	if err := fd.sock.SetSockOpt(syscall.SOL_TCP, syscall.TCP_KEEPINTVL, b); err != nil {
		return wrapSyscallError("setsockopt", err)
	}
	err := fd.sock.SetSockOpt(syscall.SOL_TCP, syscall.TCP_KEEPIDLE, b)
	runtime.KeepAlive(fd)
	return wrapSyscallError("setsockopt", err)
}

func putUint32(b []byte, v uint32) {
	_ = b[3] // early bounds check to guarantee safety of writes below
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
}