lib/MogileFS/DeviceState.pm

   1 package MogileFS::DeviceState;
   2 use strict;
   3
   4 # properties are:
   5 #    read:  can it serve traffic?
   6 #    drain: should its file_on be drained?
   7 #    new_files: does it get new files
   8 #    write:  is it writable?  (for instance, for deletes)
   9 #    dead:  permanently dead, files lost, not coming back to service
  10 my $singleton = {
  11     'alive' => bless({
  12         read => 1,
  13         write => 1,
  14         monitor => 1,
  15         new_files => 1,
  16     }),
  17     'dead' => bless({
  18         # Note that 'dead' doesn't include 'drain', since that's
  19         # handled (specially) by the reap job.
  20         dead => 1,
  21     }),
  22     'down' => bless({
  23     }),
  24     'readonly' => bless({
  25         read => 1,
  26         monitor => 1,
  27     }),
  28     'drain' => bless({
  29         read => 1,
  30         write => 1,
  31         drain => 1,
  32         monitor => 1,
  33     }),
  34 };
  35
  36 # returns undef if unknown state
  37 sub of_string {
  38     my ($class, $state) = @_;
  39     return $state ? $singleton->{$state} : undef;
  40 }
  41
  42 sub should_drain      { $_[0]->{drain}     }
  43 sub can_delete_from   { $_[0]->{write}     }
  44 sub can_read_from     { $_[0]->{read}      }
  45 sub should_get_new_files { $_[0]->{new_files} }
  46 sub should_get_repl_files { $_[0]->{new_files} }
  47 sub should_have_files { ! ($_[0]->{drain} || $_[0]->{dead}) }
  48 sub should_monitor    { $_[0]->{monitor}   }
  49
  50 # named inconveniently so it's not taken to mean equalling string
  51 # "dead"
  52 sub is_perm_dead      { $_[0]->{dead}   }
  53
  54 sub should_wake_reaper { $_[0]->{dead}   }
  55
  56 sub should_fsck_search_on {
  57     my $ds = shift;
  58     return $ds->can_read_from || $ds->should_have_files;
  59 }
  60
  61 1;
  62