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      1 // Copyright 2015 The Go Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style
      3 // license that can be found in the LICENSE file.
      4 
      5 package net
      6 
      7 import (
      8 	"runtime"
      9 	"syscall"
     10 	"time"
     11 )
     12 
     13 func setKeepAlivePeriod(fd *netFD, d time.Duration) error {
     14 	// The kernel expects milliseconds so round to next highest
     15 	// millisecond.
     16 	d += (time.Millisecond - time.Nanosecond)
     17 	msecs := int(d / time.Millisecond)
     18 
     19 	// Normally we'd do
     20 	//	syscall.SetsockoptInt(fd.sysfd, syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, secs)
     21 	// here, but we can't because Solaris does not have TCP_KEEPINTVL.
     22 	// Solaris has TCP_KEEPALIVE_ABORT_THRESHOLD, but it's not the same
     23 	// thing, it refers to the total time until aborting (not between
     24 	// probes), and it uses an exponential backoff algorithm instead of
     25 	// waiting the same time between probes. We can't hope for the best
     26 	// and do it anyway, like on Darwin, because Solaris might eventually
     27 	// allocate a constant with a different meaning for the value of
     28 	// TCP_KEEPINTVL on illumos.
     29 
     30 	err := fd.pfd.SetsockoptInt(syscall.IPPROTO_TCP, syscall.TCP_KEEPALIVE_THRESHOLD, msecs)
     31 	runtime.KeepAlive(fd)
     32 	return wrapSyscallError("setsockopt", err)
     33 }
     34