perl中看门狗的实现

Question

我需要将外部进程（命令行调用）的执行包含在固定的时间窗口中。

经过几次阅读后，我编写了这个实现：

#/bin/perl -w

use IPC::System::Simple qw( capture );

use strict;
use threads;
use threads::shared;
use warnings;

my $timeout = 4;
share($timeout);

my $stdout;
share($stdout);

my $can_proceed = 1;
share($can_proceed);

sub watchdogFork {
    my $time1 = time;

    my $ml = async {
        my $sleepTime = 2;
        my $thr = threads->self();
        $stdout = capture("sleep $sleepTime; echo \"Good morning\n\";");
        print "From ml: " . $stdout;
        $thr->detach();
    };

    my $time2;
    do {
        $time2 = time - $time1;
    } while ( $time2 < $timeout );
    print "\n";

    if ( $ml->is_running() ) {
        print "From watchdog: timeout!\n";
        $can_proceed = 0;
        $ml->detach();
    }
}
my $wd = threads->create('watchdogFork');
$wd->join();

print "From main: " . $stdout if ($can_proceed);

当$timeout > $sleepTime 返回时：

From ml: Good morning
From main: Good morning

另一方面，当$timeout < $sleepTime：

From watchdog: timeout!

获得的行为是正确的，但我认为这种方法有点原始。

我想知道是否有库可以帮助改进源代码以提高可读性和性能。有什么建议吗？

Answer 1

IPC::Run 允许您运行子进程并与它们的stdin、stdout 和stderr 交互。也可以设置timeouts，超过时抛出异常：

use IPC::Run qw(harness run timeout);

my @cmd = qw(sleep 10); 
my $harness = harness \@cmd, \undef, \my $out, \my $err, timeout(3);

eval {
    run $harness or die "sleep: $?";
};
if ($@) {
    my $exception = $@; # Preserve $@ in case another exception occurs
    $harness->kill_kill;

    print $exception; # and continue with the rest of the program
}

注意有一些limitations when running on Windows。

Answer 2

您可以从Proc::Background 使用timeout_system：

use Proc::Background qw(timeout_system);

my $wait_status = timeout_system($seconds, $command, $arg1, $arg2);
my $exit_code = $wait_status >> 8;

进程将在$seconds 秒后被杀死。