rrdtoolプロセスをTCPサーバにしてみる

rrd-server.pl

use strict;
use warnings;
use IO::Socket::INET;
use Parallel::Prefork;
use IPC::Open3;

sub MaxRequestsPerChild () { 100 }

my $listen_sock = IO::Socket::INET->new(
    Listen    => 5,
    LocalAddr => '0.0.0.0:10000',
    Proto     => 'tcp',
) or die $!;

my $pm = Parallel::Prefork->new({
    max_workers  => 10,
    trap_signals => {
        TERM => 'TERM',
        HUP  => 'TERM',
    },
});

while ($pm->signal_received ne 'TERM') {
    $pm->start and next;

    my $reqs_before_exit = MaxRequestsPerChild;
    $SIG{TERM} = sub { $reqs_before_exit = 0 };
    my ($wtr, $rdr);
    my $rrdtool_pid = open3($wtr, $rdr, 0, qw(rrdtool - /tmp));
    while ($reqs_before_exit-- > 0) {
        my $s = $listen_sock->accept();
        while (defined $s and my $q = $s->getline) {
            if ($q =~ /^[\s|\t]*cd/) {
                $s->print("ERROR: don't use cd command!!\n");
                next;
            }
            print $wtr $q;
            while (my $stdout = <$rdr>) {
                $s->print($stdout);
                last if($stdout =~ /^(OK|ERROR:) /);
            }
        }
    }
    kill 'TERM', $rrdtool_pid;
    waitpid($rrdtool_pid, 0);
    $pm->finish;
}

$pm->wait_all_children;

__END__

$ perl rrd-server.pl &
[1] 67379
$ telnel localhost 10000
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
help
RRDtool 1.4.5  Copyright 1997-2010 by Tobias Oetiker <[email protected]>
               Compiled Nov 29 2011 11:22:47

Usage: rrdtool [options] command command_options
Valid commands: create, update, updatev, graph, graphv,  dump, restore,
		last, lastupdate, first, info, fetch, tune,
		resize, xport, flushcached

Valid remote commands: quit, ls, cd, mkdir, pwd

RRDtool is distributed under the Terms of the GNU General
Public License Version 2. (www.gnu.org/copyleft/gpl.html)

For more information read the RRD manpages

OK u:0.01 s:0.01 r:20.79
ls       
d .
d ..
- temperature.rrd
OK u:0.01 s:0.01 r:30.63
info temperature.rrd
filename = "temperature.rrd"
rrd_version = "0003"
(snip)
rra[3].cdp_prep[0].unknown_datapoints = 0
OK u:0.01 s:0.01 r:39.75
^]	
telnet> q
Connection closed.

kill -TERM 67379
ってすると
Can't call method "getline" on an undefined value at rrd-server.pl line 34.
って出てしまう。
forgroundでCtrl+Cだったら出ない。

acceptの度にforkするのでいいか。。。
cdしたらずれちゃうしｗ

cdできないようにして、rrdtool自体はprefork時点で作ったものを使い回す。
シグナル受信時はacceptをスルーするみたいなのでdefined $sすればok。

外部プロセスをfork & execだったらopen3で十分だったorz

参考

• IPC::Open3 の正しい使い方 (re .pl な config ファイルのコンパイルがとおるかチェックしてみる - TokuLog 改メ tokuhirom’s blog) - kazuhoのメモ置き場
  • Kazuho@Cybozu Labs: Parallel::Prefork - Perl でマルチプロセスなサーバを書く方法
  • Kazuho@Cybozu Labs: Perl で並列処理 (using マルチプロセス)

kazuho++