From: Alexey Tourbin <at@altlinux.ru>
To: ALT Devel discussion list <devel@altlinux.org>
Subject: [devel] cmdcache
Date: Mon, 12 Sep 2005 15:35:51 +0400
Message-ID: <20050912113551.GI3290@solemn.turbinal.org> (raw)
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On Sun, Sep 11, 2005 at 09:06:44PM +0400, Alexey Tourbin wrote:
> Написал на шелле, с кешированием для каталогов. Для робота это важно --
> очень долго (с распаковкой всех rpm'ов) только один раз будет работать.
По поводу кеширования мне пришла в голову ещё одна мысль.
Некоторые команды, которые работают долго, и вывод которых стоит
кешировать, имеют вид
cmd [args...] path
В случае, если состояние сущности path определяется датой модификации
path, то команду можно завернуть в скрипт или функцию, которая перед
запуском команды проверят наличие результата в кеше:
cmdcache cmd [args...] path
Вот предварительная реализация этой идеи. Почему-то очень много кода
получилось. :( Если кто-то знает, как сделать лучше, подскажите плиз.
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#!/bin/sh -ef
cmdcache()
{
if [ $# -lt 2 ]; then
echo "cmdcache: not enough arguments" >&2
pod2usage --exit=2 cmdcache || [ $? = 2 ]
return 2
fi
local cmd="$1"; shift
local cdir="$HOME/.cmdcache/${cmd##*/}"
[ -d "$cdir" ] || mkdir -p -m700 "$cdir" || return 1
[ -n "${RANDOM##*0}" ] || find "$cdir" -type f -mtime +33 -atime +33 -delete
local file; for file; do :; done
if [ ! -e "$file" ]; then
echo "cmdcache: $file: no such file or directory" >&2
return 1
fi
local cache="$*"; cache="$cdir/${cache//[-.\/ ]/_}"
if [ -f "$cache" ] && ! [ "$file" -nt "$cache" -o "$cache" -nt "$file" ]; then
cat "$cache"
return
fi
local rc=0
local mtime0; mtime0="$(stat --format $'%Y\n' "$file")" || return
"$cmd" "$@" >"$cache" && touch -r "$file" "$cache" || rc=$?
cat "$cache"
local mtime1; mtime1="$(stat --format $'%Y\n' "$file")" || rc=$?
if [ $rc = 0 -a "$mtime0" != "$mtime1" ]; then
echo "cmdcache: $file has changed" >&2
rc=1
fi
[ $rc = 0 ] || rm -f "$cache"
return $rc
}
if [ -z "$*" -a "${0##*/}" != cmdcache ]; then
: okay, maybe I am sourced
elif [ "x$*" = x-h -o "x$*" = x--help ]; then
pod2usage --exit=0 "$0"
else
cmdcache "$@"
fi
: <<'__EOF__'
=head1 NAME
cmdcache - simple command cache based on timestamps
=head1 SYNOPSIS
B<cmdcache> I<cmd> [I<args>...] I<FILE>
B<source> B<cmdcache> ''
=head1 AUTHOR
Written by Alexey Tourbin <at@altlinux.org>.
=head1 COPYING
Copyright (c) 2005 Alexey Tourbin, ALT Linux Team.
This is free software; you can redistribute it and/or modify it under the terms
of the GNU General Public License as published by the Free Software Foundation;
either version 2 of the License, or (at your option) any later version.
=cut
__EOF__
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next reply other threads:[~2005-09-12 11:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-12 11:35 Alexey Tourbin [this message]
2005-09-12 13:05 ` [devel] cmdcache Alexey Tourbin
2005-09-12 13:34 ` Dmitry V. Levin
2005-09-12 14:01 ` Alexey Tourbin
2005-09-12 14:57 ` [devel] [JT] " Michael Shigorin
2005-09-12 18:35 ` [devel] " Alexey Tourbin
2005-09-13 5:21 ` [devel] " Alexey Tourbin
2005-09-14 15:35 ` Alexey Tourbin
2005-09-14 15:47 ` Michael Shigorin
2005-09-14 16:12 ` Alexey Tourbin
2005-09-14 16:38 ` Michael Shigorin
2005-09-14 17:10 ` Alexey Tourbin
2005-09-15 9:26 ` [devel] Re: cmdcache hash function Alexey Tourbin
2005-09-15 14:37 ` Alexey Tourbin
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