#!/usr/bin/perl -w

use POSIX qw(setsid);
use Sys::Syslog;
use Sys::Hostname;
#use LWP::Simple;

$debug = 0;
$proc = "pl_mom";
$alias_addr = "pl-mom\@planet-lab.org";
$from_addr = "support\@planet-lab.org";
$bwcap = "1.5Mbit";

if (! $debug) {
    $kill_thresh = 90;
    $reboot_thresh = 95;
    $log_thresh = 85;
    $change_thresh = 5;
    $min_thresh = 10;
    $byte_cutoff = 16000000000;    # 16GB
    #$byte_cutoff = 5000000000;    # 5GB
    $bwmon_sleep = 900;

    $sendmail = "/usr/sbin/sendmail -t -f$from_addr";
    $pidfile = "/var/run/$proc.pid";
    $rebootfile = "/var/lib/misc/pl_mom.reboot";
    $daily_log = "/var/lib/misc/pl_mom.daily";
    $daily_stamp = "/var/lib/misc/pl_mom.stamp";
} else {
    $kill_thresh = 2;
    $reboot_thresh = 20;
    $log_thresh = 2;
    $change_thresh = 5;
    $min_thresh = 10;
    $byte_cutoff = 16000;
    $bwmon_sleep = 10;

    $sendmail = "cat";
    $pidfile = "./$proc.pid";
    $rebootfile = "./pl_mom.reboot";
    $daily_log = "./pl_mom.daily";
    $daily_stamp = "./pl_mom.stamp";
}

$sleep = 30;

# daemonize the program
if (! $debug) {
    &daemonize;
}

system("echo $$ > $pidfile");

# Check to see whether pl_mom rebooted the node
if (-e $rebootfile) {
    unlink($rebootfile);
    syslog ("warning", "pl_mom: Sending shutdown mail");
    shutdown_mail();
}

my $pid = fork();
if (! $pid) {
    syslog ("info", "pl_mom: Launching reboot kicker");
    reboot_kicker();
    die (0);
}
$pid = fork();
if (! $pid) {
    syslog ("info", "pl_mom: Launching bandwidth monitor");
    bandwidth_monitor();
    die (0);
}

while (1) {
    $used = int(swap_used());

    if (defined($old_used)) {
	if ($used >= $old_used + $change_thresh) {
	    syslog ("info", "pl_mom: %d%% swap consumed in last %d seconds",
		    $used - $old_used, $sleep);
    	}
    }

    if ($used >= $log_thresh) {
	if (! defined($old_used) || $used != $old_used) {
	    syslog ("info", "pl_mom: Swap used: %d%%", $used);
	}
	get_slice_info();
	my $hog = memory_hog();
	if ($hog) {
	    if ($used < $kill_thresh) {
		if (! defined($Warning{$hog})) {
		    $Warning{$hog} = "sent";
		    syslog ("warning", "pl_mom: Slice $hog is ".
			    "using $Slice{$hog}{mem_pct}%% of memory");
		    #slice_warning_mail($hog);
		}
	    } else {
		my $id = `id -u $hog`;
		chomp($id);
		my $top = `chcontext --ctx $id top -b -n 1`;
		syslog ("warning", "pl_mom: Resetting slice $hog");
		if (! $debug) {
		    slice_reset($hog);
		}
		syslog ("warning", "pl_mom: Sending mail to slice $hog");
		slice_reset_mail($hog, $top);
	    }
	}
    }
    
    sleep ($sleep);

    $old_used = $used;
}

sub reboot_kicker {
    while (1) {
	$used = swap_used();

	if ($used >= $reboot_thresh) {
	    syslog ("warning", "pl_mom: Rebooting node");

	    system("touch $rebootfile");
	    if (! $debug) {
		system("shutdown -r now");
	    }
	    die (0);
	}
	
	sleep (1);
    }
}

sub bandwidth_monitor {
    while (1) {
        # See if a new day has started for bandwidth monitoring
	chomp($now = `date -u +%D`);
	if (-e $daily_stamp) {
	    chomp($stamp = `cat $daily_stamp`);
	}
	if (! defined($stamp) || !($stamp =~ $now)) {
	    open (STAMP, ">$daily_stamp") || 
		die "Can't open file $daily_stamp for writing: $!\n";
	    print STAMP "$now\n";
	    close STAMP;
	    unlink ($daily_log);

	    # Could save the list of capped slices in a file in order to
	    # avoid re-sending mails if the daemon restarts.
	    # Also may want a list of slices that are exempt from capping.
	    if (defined(%Start)) { undef %Start; }
	    if (defined(%Now))   { undef %Now; }

	    if (defined(%Cap)) { 
		# Reset bandwidth limits here 
	        chomp($cap = `cat /etc/planetlab/bwcap`);
	        foreach $slice ( sort ( keys %Cap ) ) {
		    cap_bandwidth ($slice, $cap);
		}
		undef %Cap; 
	    }

	    syslog("info", "pl_mom: Beginning bandwidth monitoring for $now");
	}

        # Get baseline counts
	`touch $daily_log`;
	open (BASE, "+<$daily_log") ||
	    print "Cannot open $daily_log; $!\n";
	while (<BASE>) {
	    my ($sliceid, $bytecount) = split(/ /);
	    $Start{$sliceid} = $bytecount;
	}
	
	$status = `tc -s -d qdisc show`;
	@lines = split(/\n/, $status);
	for ($i = 0; $i < @lines; $i++) {
	    if ($lines[$i] =~ /qdisc pfifo/) {
		$lines[$i] =~ s/^ +//;
		@fields = split(/ /, $lines[$i]);
		$slice = $fields[2];
		$slice =~ s/://;

		if ($slice != 9999) {
		    $lines[$i+1] =~ s/^ +//;
		    @fields = split(/ /, $lines[$i+1]);
		    $bytes = $fields[1];
		    #if ($bytes) {print "Slice $slice sent $bytes bytes\n";}
		    
		    if (! defined($Start{$slice})) {
			print BASE "$slice $bytes\n";
			$Start{$slice} = $bytes;
		    }
		    $Now{$slice} = $bytes;
		}
	    }
	}
	close (BASE);

	foreach $slice ( sort (keys %Start) ) {
	    if (defined $Now{$slice}) {
		$today = $Now{$slice} - $Start{$slice};
		if ($today >= $byte_cutoff && ! defined($Cap{$slice})) {
		    $Cap{$slice} = "sent";
		    $slicename = get_slice_name($slice);
		    if ($slicename) {
			bw_cap_mail($slicename);
			# Cap bandwidth here
			cap_bandwidth($slicename, $bwcap);
		    } else {
			syslog("warning", "pl_mom: Could not find slice name".
			       " for slice ID $slice");
		    }
		}
	    } else {
		# The /proc/virtual/<id> directory is gone...
	    }
	}

	sleep($bwmon_sleep);
    }
}

sub send_mail {
    # Arg 0: recipient addresses, comma-separated string
    # Arg 1: subject line
    # Arg 2: body of message
    my $to = "To: $_[0]\n";
    my $from = "From: $from_addr\n";
    my $subject = "Subject: $_[1]\n";
    my $msg = $_[2];

    open(SENDMAIL, "|$sendmail") or die "Cannot open $sendmail: $!";
    print SENDMAIL $to;
    print SENDMAIL $from;
    print SENDMAIL $subject;
    print SENDMAIL "Content-type: text/plain\n\n";
    print SENDMAIL $msg;
    close(SENDMAIL);
}

sub cap_bandwidth {
    # Arg 0: slice name
    # Arg 1: bandwidth cap for 'tc'
    `bwlimit setcap $_[0] $_[1]`;
    `bwlimit on $_[0]`;
}

sub get_date {
    my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdat) 
	= localtime(time);
    my $date = sprintf("%4d-%02d-%02d %02d:%02d:%02d", 
		       $year+1900, $mon+1, $mday, $hour, $min, $sec);
    return $date;
}

sub get_slice_name {
    # Arg 0: slice ID

    # Need to map slice id to slice name; is there a sensor?
    # For now, get it from /etc/passwd
    my $name = "";
    open (PASSWD, "</etc/passwd") ||
	print "Cannot open /etc/passwd; $!\n";
    while (<PASSWD>) {
	my ($slicename, $passwd, $sliceid) = split(/:/);
	if ($sliceid == $_[0]) {
	    $name = $slicename;
	}
    }
    close PASSWD;
    return $name;
}

sub bw_cap_mail {
    my $hostname = hostname();
    my $date = get_date();
    my $sent = int($byte_cutoff/1000000000);

    # Put this here because this is where we have the 
    syslog("warning", "pl_mom: Capping bandwidth of slice ".
	   "$slicename at $bwcap until midnight GMT.");

    send_mail($alias_addr,
	      "$proc capped bandwidth of slice $slicename on $hostname",
	      "Slice $slicename has transmitted more than ${sent}GB today".
	      " on $hostname.  ".
	      "Its bandwidth will be capped at $bwcap until midnight GMT.".
	      "\n\n$date $hostname bwcap $slicename\n");
}

sub shutdown_mail {
    my $hostname = hostname(); 
    my $date = get_date();
    send_mail($alias_addr, 
	      "$proc rebooted $hostname", 
	      "Swap space was exhausted on $hostname and so $proc rebooted ".
	      "it.\n\nAs of $date, the node has successfully come back ".
	      "online.\n\n$date $hostname reboot\n");
}

sub slice_reset_mail {
    my $hog = $_[0];
    my $top = $_[1];
    my $hog_mem = sprintf ("%0.f", $Slice{$hog}{pmem}/1000);
    my $hog_pct = $Slice{$hog}{mem_pct};
    my $hostname = hostname(); 
    my $date = get_date();
    send_mail("$alias_addr, $hog\@slices.planet-lab.org",
	      "$proc reset slice $hog on $hostname",
	      "As of $date, swap space is nearly exhausted on $hostname.\n\n".
	      "Slice $hog is being reset since it is the largest consumer ".
	      "of physical memory at ${hog_mem}MB ($hog_pct%).\n\n".
	      "Please reply to this message explaining the nature of your ".
	      "experiment, and what you are doing to address the problem.\n".
	      "\nOutput of 'top -b -n 1' in your slice prior to reset:\n".
	      "$top\n\n$date $hostname reset $hog\n");
}

sub slice_warning_mail {
    my $hog = $_[0];
    my $hog_mem = sprintf ("%0.f", $Slice{$hog}{pmem}/1000);
    my $hog_pct = $Slice{$hog}{mem_pct};
    my $hostname = hostname(); 
    my $date = get_date();

    if ($hog =~ /^root$/) {
	$to = $alias_addr;
    } else {
	$to = "$alias_addr, $hog\@slices.planet-lab.org";
    }	

    send_mail($to,
	      "$proc may reset slice $hog on $hostname",
	      "As of $date, swap space is over $log_thresh% full on ".
	      "$hostname.\n\nSlice $hog is the largest consumer ".
	      "of physical memory at ${hog_mem}MB ($hog_pct%).\n".
	      "Please check the memory usage of your slice to avoid a ".
	      "reset.\n\n$date $hostname warning $hog\n");
}

sub unkillable_alarm_mail {
    my $hog = $_[0];
    my $hog_mem = sprintf ("%0.f", $Slice{$hog}{pmem}/1000);
    my $hog_pct = $Slice{$hog}{mem_pct};
    my $hostname = hostname(); 
    my $date = get_date();

    if ($hog =~ /^root$/) {
	$to = $alias_addr;
    } else {
	$to = "$alias_addr, $hog\@slices.planet-lab.org";
    }

    send_mail($to,
	      "$proc: alarm for slice $hog on $hostname",
	      "As of $date, swap space is over $log_thresh% full on ".
	      "$hostname.\n\nSlice $hog is the largest consumer ".
	      "of physical memory at ${hog_mem}MB ($hog_pct%).\n".
	      "The slice will not be reset, but please verify its behavior.\n".
	      "\n$date $hostname alarm $hog\n");
}

sub slice_reset {
    my $slice = $_[0];
    my $sliceid = $Slice{$slice}{ctx};
    system("chcontext --ctx $sliceid sudo kill -9 -1");
    system("/etc/init.d/vserver-init start $slice");
}

sub swap_used {
    open (SWAP, "</proc/swaps") ||
        die "Cannot open /proc/swaps; $!\n";

    $line = <SWAP>;
    $line = <SWAP>;
    $line =~ s/[\t ]+/ /g;

    my ($filename, $type, $size, $used, $priority) = split(/ /, $line);
    close SWAP;
 
    return 100*($used/$size);
}

sub get_slice_info {
    if (! $debug) {
	#$content = get "http://127.0.0.1:3100/slicestat";
	$content = `curl -s http://127.0.0.1:3100/slicestat`;
    } else {
	$content = `cat ../pl_mom-deploy/slicestat`
    }
    my @lines = split(/\n/, $content);
    %Slice = ();
    foreach $line (@lines) {
	my ($slice, $ctx, $cpu_pct, $mem_pct, $pmem, $vmem, $ntasks) 
	    = split(/,/,$line);
	$Slice{$slice}{ctx} = $ctx;
	$Slice{$slice}{cpu_pct} = $cpu_pct;
	$Slice{$slice}{mem_pct} = $mem_pct;
	$Slice{$slice}{pmem} = $pmem;
	$Slice{$slice}{vmem} = $vmem;
	$Slice{$slice}{ntasks} = $ntasks;
    }
}

sub memory_hog {
    @keys = sort { $Slice{$b}{mem_pct} <=> $Slice{$a}{mem_pct} } (keys %Slice);
    foreach $key (@keys) {
	if ($Slice{$key}{mem_pct} >= $min_thresh) {
	    if ($key =~ /^root$/ || $key =~ /slicestat/ || $key =~ /netflow/) {
		if (! defined ($Warning{$key})) {
		    $Warning{$key} = "sent";
		    syslog ("warning", "pl_mom: Sending alarm mail to ".
			    "unkillable slice $key, using ".
			    "$Slice{$key}{mem_pct}%% of memory");
		    unkillable_alarm_mail($key);
		}
	    } else {
		return $key;
	    }
	} else {
	    #syslog ("info", "pl_mom: No killable slice using > ".
	    #    "$min_thresh%% memory");
	    return;
	}
    }
}

sub daemonize {
    chdir '/'                 or die "Can't chdir to /: $!";
    open STDIN, '/dev/null'   or die "Can't read /dev/null: $!";
    open STDOUT, '>>/dev/null' or die "Can't write to /dev/null: $!";
    open STDERR, '>>/dev/null' or die "Can't write to /dev/null: $!";
    defined(my $pid = fork)   or die "Can't fork: $!";
    exit if $pid;
    setsid                    or die "Can't start a new session: $!";
    umask 0;
}
