lib/MogileFS/ReplicationPolicy.pm

   1 package MogileFS::ReplicationPolicy;
   2 use strict;
   3
   4 =head1 NAME
   5
   6 MogileFS::ReplicationPolicy - base class for file replication policies
   7
   8 =head1 DESCRIPTION
   9
  10 A MogileFS replication policy class implements policy for how files
  11 should be replicated around.
  12
  13 ....
  14
  15 =cut
  16
  17 # parse a policy description string, instantiating object(s) along the way
  18 # given $str can be either a scalar, or a scalarref that's eaten away as it's parsed.
  19 sub new_from_policy_string {
  20     my ($class, $str_a) = @_;
  21
  22     # simple case for normal callers:  they give us a scalar, but internally
  23     # we work with it as a scalarref that we eat away while parsing.
  24     my $strref = ref $str_a ? $str_a : \$str_a;
  25
  26     $$strref =~ s/^\s*([\w:]+)// or die "Failed to parse policy string: $$strref";
  27     my ($polclass) = ($1);
  28     $polclass = "MogileFS::ReplicationPolicy::$polclass" unless $polclass =~ /:/;
  29
  30     my $rv = eval "use $polclass; 1";
  31     if ($@ || !$rv) {
  32         die "Failed to load replication policy class $polclass: $@\n";
  33     }
  34
  35     return $polclass->new_from_policy_args($strref);
  36 }
  37
  38 # returns:
  39 #   0:      replication sufficient
  40 #   undef:  no suitable recommendations currently.
  41 #   >0:     devid to replicate to.
  42 sub replicate_to {
  43     my ($self, %args) = @_;
  44     my $fid      = delete $args{fid};      # fid scalar to copy
  45     my $on_devs  = delete $args{on_devs};  # arrayref of device objects
  46     my $all_devs = delete $args{all_devs}; # hashref of { devid => MogileFS::Device }
  47     my $failed   = delete $args{failed};   # hashref of { devid => 1 } of failed attempts this round
  48     my $min      = delete $args{min};      # configured min devcount for this class
  49
  50     warn "Unknown parameters: " . join(", ", sort keys %args) if %args;
  51     die "Missing parameters" unless $on_devs && $all_devs && $failed && $fid;
  52
  53     die "UNIMPLEMENTED 'replicate_to' in " . (ref($self) || $self);
  54 }
  55
  56
  57
  58 1;