Date: Thu, 02 Jun 2011 11:17:53 +0900 (JST) From: Hiroki Sato <hrs@FreeBSD.org> To: dougb@FreeBSD.org Cc: bz@FreeBSD.org, freebsd-rc@FreeBSD.org Subject: Re: afexists() Message-ID: <20110602.111753.392307987943310561.hrs@allbsd.org> In-Reply-To: <4DE6D3C8.1050503@FreeBSD.org> References: <4DE588B4.7090908@FreeBSD.org> <20110601.130434.820821962809263631.hrs@allbsd.org> <4DE6D3C8.1050503@FreeBSD.org>
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Doug Barton <dougb@FreeBSD.org> wrote
in <4DE6D3C8.1050503@FreeBSD.org>:
do> On 05/31/2011 21:04, Hiroki Sato wrote:
do> > I think it would be great if it is possible to create a wrapper
do> > function for testing and caching. I expects testing kern.features.*
do> > is likely added again to somewhere in rc.d scripts, and adding a long
do> > lines of "[ -n ... ]&& return 0; if sysctl...; fi" each time
do> > degrades readability.
do>
do> I think that's definitely an interesting idea, and I'd love to review
do> patches that implement it. :) Unfortunately I don't have time to do so
do> atm, and would prefer to focus on a specific case where a small
do> optimization leads to a big gain.
A patch is attached.
-- Hiroki
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Index: etc/rc.subr
===================================================================
--- etc/rc.subr (revision 222591)
+++ etc/rc.subr (working copy)
@@ -1734,6 +1734,28 @@
fi
+# check_kern_features mib
+# Return existence of kern.features.* sysctl MIB as true or
+# false. The result will be cached in $_rc_cache_kern_features_
+# namespace. "0" means the kern.features.X exists.
+
+check_kern_features()
+{
+ local _v
+
+ [ -n "$1" ] || return 1;
+ _v=`eval echo "\\$_rc_cache_kern_features_$1"`
+ [ -n "$_v" ] && return "$_v";
+
+ if ${SYSCTL_N} kern.features.$1 > /dev/null 2>&1; then
+ eval _rc_cache_kern_features_$1=0
+ return 0
+ else
+ eval _rc_cache_kern_features_$1=1
+ return 1
+ fi
+}
+
# _echoonce var msg mode
# mode=0: Echo $msg if ${$var} is empty.
# After doing echo, a string is set to ${$var}.
Index: etc/network.subr
===================================================================
--- etc/network.subr (revision 222591)
+++ etc/network.subr (working copy)
@@ -355,12 +355,9 @@
_af=$1
case ${_af} in
- inet)
- ${SYSCTL_N} kern.features.inet > /dev/null 2>&1
+ inet|inet6)
+ check_kern_features ${_af}
;;
- inet6)
- ${SYSCTL_N} kern.features.inet6 > /dev/null 2>&1
- ;;
ipx)
${SYSCTL_N} net.ipx > /dev/null 2>&1
;;
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