github.com/MangoDowner/go-gm@v0.0.0-20180818020936-8baa2bd4408c/src/net/sock_bsd.go (about)

     1  // Copyright 2009 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  // +build darwin dragonfly freebsd netbsd openbsd
     6  
     7  package net
     8  
     9  import (
    10  	"runtime"
    11  	"syscall"
    12  )
    13  
    14  func maxListenerBacklog() int {
    15  	var (
    16  		n   uint32
    17  		err error
    18  	)
    19  	switch runtime.GOOS {
    20  	case "darwin", "freebsd":
    21  		n, err = syscall.SysctlUint32("kern.ipc.somaxconn")
    22  	case "netbsd":
    23  		// NOTE: NetBSD has no somaxconn-like kernel state so far
    24  	case "openbsd":
    25  		n, err = syscall.SysctlUint32("kern.somaxconn")
    26  	}
    27  	if n == 0 || err != nil {
    28  		return syscall.SOMAXCONN
    29  	}
    30  	// FreeBSD stores the backlog in a uint16, as does Linux.
    31  	// Assume the other BSDs do too. Truncate number to avoid wrapping.
    32  	// See issue 5030.
    33  	if n > 1<<16-1 {
    34  		n = 1<<16 - 1
    35  	}
    36  	return int(n)
    37  }