lib/Mogstored/ChildProcess/DiskUsage.pm

   1 package Mogstored::ChildProcess::DiskUsage;
   2 use strict;
   3 use base 'Mogstored::ChildProcess';
   4
   5 my $docroot;
   6
   7 sub pre_exec_init {
   8     my $class = shift;
   9     $SIG{TERM} = 'DEFAULT'; # override custom one from earlier
  10     $ENV{MOG_DOCROOT} = Perlbal->service('mogstored')->{docroot};
  11 }
  12
  13 sub run {
  14     $docroot = $ENV{MOG_DOCROOT};
  15     die "\$ENV{MOG_DOCROOT} not set"                unless $docroot;
  16     die "\$ENV{MOG_DOCROOT} not set to a directory" unless -d $docroot;
  17
  18     # (runs in exec'd child process)
  19     $0 = "mogstored [diskusage]";
  20     select((select(STDOUT), $|++)[0]);
  21
  22     my $start_ppid = getppid();
  23
  24     # Discover whether or not we have GNU df.
  25     my $gnu_df = '';
  26     `df -P / 2>/dev/null >/dev/null`;
  27     if ($? eq 0) {
  28        $gnu_df = '-P';
  29     }
  30
  31     while (1) {
  32         look_at_disk_usage($gnu_df);
  33         sleep 10;
  34
  35         # shut ourselves down if our parent mogstored
  36         # has gone away.
  37         my $ppid = getppid();
  38         exit(0) unless $ppid == $start_ppid && kill(0,$ppid);
  39     }
  40 }
  41
  42 sub look_at_disk_usage {
  43     my $err = sub { warn "$_[0]\n"; };
  44     my $path = $ENV{MOG_DOCROOT};
  45     $path =~ s!/$!!;
  46     my $gnu_df = shift;
  47
  48     # find all devices below us
  49     my @devnum;
  50     if (opendir(D, $path)) {
  51         @devnum = grep { /^dev\d+$/ } readdir(D);
  52         closedir(D);
  53     } else {
  54         return $err->("Failed to open $path: $!");
  55     }
  56
  57     foreach my $devnum (@devnum) {
  58         my $rval = `df $gnu_df -l -k $path/$devnum`;
  59         my $uperK = ($rval =~ /512-blocks/i) ? 2 : 1; # units per kB
  60         foreach my $l (split /\r?\n/, $rval) {
  61             next unless $l =~ /^(.+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(.+)\s+(.+)$/;
  62             my ($dev, $total, $used, $avail, $useper, $disk) = ($1, $2, $3, $4, $5, $6);
  63
  64             unless ($disk =~ m!$devnum/?$!) {
  65                 $disk = "$path/$devnum";
  66             }
  67
  68             # FIXME: We're stupidly throwing away the 'avail' value here.
  69             # This causes mogilefs to run aground when used with ext
  70             # partitions using reserved space. Drop the reserved space from
  71             # the total, and in the future add available to the device table
  72             # and just use that.
  73             $total = $used + $avail;
  74
  75             # create string to print
  76             my $now = time;
  77             my $output = {
  78                 time      => time(),
  79                 device    => $dev,    # /dev/sdh1
  80                 total     => int($total / $uperK), # integer: total KiB blocks
  81                 used      => int($used  / $uperK), # integer: used KiB blocks
  82                 available => int($avail / $uperK),  # integer: available KiB blocks
  83                 'use'     => $useper, # "45%"
  84                 disk      => $disk,   # mount point of disk (/var/mogdata/dev8), or path if not a mount
  85             };
  86
  87             if ($ENV{MOG_DEV_USAGE_VIA_DU}) {
  88                 my $size = `du -k -c -s $path/$devnum`;
  89                 if ($size =~ /^(\d+)/) {
  90                     $output->{used} = $1;
  91                 }
  92             }
  93
  94             # size of old file we'll be overwriting in place (we'll want
  95             # to pad with newlines/spaces, before we truncate it, for
  96             # minimizing races)
  97             my $ufile    = "$disk/usage";
  98             my $old_size = (-s $ufile) || 0;
  99             my $mode     = $old_size ? "+<" : ">";
 100
 101             # string we'll be writing
 102             my $new_data = "";
 103             foreach (sort keys %$output) {
 104                 $new_data .= "$_: $output->{$_}\n";
 105             }
 106
 107             my $new_size = length $new_data;
 108             my $pad_len  = $old_size > $new_size ? ($old_size - $new_size) : 0;
 109             $new_data   .= "\n" x $pad_len;
 110
 111             # write the file, all at once (with padding) then remove padding
 112             my $rv = open(my $fh, $mode, $ufile);
 113             unless ($rv) {
 114                 $err->("Unable to open '$ufile' for writing: $!");
 115                 next;
 116             }
 117             unless (syswrite($fh, $new_data)) {
 118                 close($fh);
 119                 $err->("Error writing to '$ufile': $!");
 120                 next;
 121             }
 122             truncate($fh, $new_size) if $pad_len;
 123             close($fh);
 124         }
 125     }
 126 }
 127
 128
 129 1;