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lib/App/Diskd.pm  view on Meta::CPAN

# consequence of having distinct sessions for each program area, when
# we need to have inter-session communication, we need to use POE's
# post method. An alias is also used to identify each of the sessions.
#


##
## The DiskWatcher package sets up a session to periodically run
## blkid, parse the results and store them in our Info object. Since
## blkid can sometimes hang (due to expected devices or media not
## being present), a timer is set and if the command hasn't completed
## within that timeout, the child process is killed and the child
## session garbage collected.
##

package Local::DiskWatcher;

use POE qw(Wheel::Run Filter::Line);

sub new {

lib/App/Diskd.pm  view on Meta::CPAN

  $heap->{delay}   = $args{frequency};
  $heap->{child}   = undef;

  $kernel->yield('start_child');
}

# start_child is responsible for running the program with a timeout
sub start_child {
  my ($kernel, $heap) = @_[KERNEL, HEAP];

  # Using a named timer for timeouts. Set it to undef to deactivate.
  $kernel->delay(child_timeout => $heap->{timeout});

  $heap->{child} = POE::Wheel::Run->new(
    Program      => [$heap->{program}],
    StdioFilter  => POE::Filter::Line->new(),
    StderrFilter => POE::Filter::Line->new(),
    StdoutEvent  => "got_child_stdout",
    StderrEvent  => "got_child_stderr",
    CloseEvent   => "child_cleanup",
  );

lib/App/Diskd.pm  view on Meta::CPAN

# For our purposes, we don't care whether the child exited by closing
# its output or throwing a SIGCHLD. Wrap the deletion of references to
# the child in if(defined()) to avoid warnings.
sub child_cleanup {

  #print "DiskWatcher: child_cleanup args: ". (join ", ", @_). "\n";

  my ($heap,$kernel) = @_[HEAP,KERNEL];

  # Deactivate the kill timer
  $kernel->delay(child_timeout => undef);

  # We need to commit the new list of disks and recycle the child
  # object. Both of these should only be called once, even if this
  # routine is called twice.
  if (defined($heap->{child})) {
    my $info = $heap->{info};
    $info->commit_our_disk_info;

    delete $heap->{child};