add a note about $Object::Remote::FatNode::REMOTE_NODE

[scpubgit/Object-Remote.git] / lib / Object / Remote / Role / Connector / PerlInterpreter.pm

package Object::Remote::Role::Connector::PerlInterpreter;

use IPC::Open3; 
use IO::Handle;
use Symbol; 
use Object::Remote::Logging qw(:log :dlog router);
use Object::Remote::ModuleSender;
use Object::Remote::Handle;
use Object::Remote::Future;
use Scalar::Util qw(blessed weaken);
use Moo::Role;

with 'Object::Remote::Role::Connector';

has module_sender => (is => 'lazy');
has ulimit => ( is => 'ro');
has nice => ( is => 'ro');
has watchdog_timeout => ( is => 'ro', required => 1, default => sub { undef });
has forward_env => (is => 'ro', required => 1, builder => 1);
has perl_command => (is => 'lazy');
has pid => (is => 'rwp');
has connection_id => (is => 'rwp');

#if no child_stderr file handle is specified then stderr
#of the child will be connected to stderr of the parent
has stderr => ( is => 'rw', default => sub { undef } );

BEGIN { router()->exclude_forwarding; }

sub _build_module_sender {
  my ($hook) =
    grep {blessed($_) && $_->isa('Object::Remote::ModuleLoader::Hook') }
      @INC;
  return $hook ? $hook->sender : Object::Remote::ModuleSender->new;
}

#FIXME by policy object-remote does not invoke a shell
sub _build_perl_command {
  my ($self) = @_;
  my $nice = $self->nice;
  my $ulimit = $self->ulimit;
  my $perl_path = 'perl';
  my $shell_code = '';

  if (defined($ulimit)) {
    $shell_code .= "ulimit $ulimit || exit 1; ";
  }

  if (defined($nice)) {
    $shell_code .= "nice -n $nice ";
  }

  if (defined($ENV{OBJECT_REMOTE_PERL_BIN})) {
    log_debug { "Using OBJECT_REMOTE_PERL_BIN environment variable as perl path" };
    $perl_path = $ENV{OBJECT_REMOTE_PERL_BIN};
  }

  $shell_code .= $perl_path . ' -';

  return [ 'bash', '-c', $shell_code ];
}

sub _build_forward_env {
  return [qw(
    OBJECT_REMOTE_PERL_BIN
    OBJECT_REMOTE_LOG_LEVEL OBJECT_REMOTE_LOG_FORMAT OBJECT_REMOTE_LOG_SELECTIONS
    OBJECT_REMOTE_LOG_FORWARDING
  )];
}

around connect => sub {
  my ($orig, $self) = (shift, shift);
  my $f = $self->$start::start($orig => @_);
  return future {
    $f->on_done(sub {
      my ($conn) = $f->get;
      $self->_setup_watchdog_reset($conn);
      my $sub = $conn->remote_sub('Object::Remote::Logging::init_remote_logging');
      $sub->('Object::Remote::Logging', router => router(), connection_id => $conn->_id);
      Object::Remote::Handle->new(
        connection => $conn,
        class => 'Object::Remote::ModuleLoader',
        args => { module_sender => $self->module_sender }
      )->disarm_free;
      require Object::Remote::Prompt;
      Object::Remote::Prompt::maybe_set_prompt_command_on($conn);
    });
    $f;
  } 2;
};

sub final_perl_command { shift->perl_command }

sub _start_perl {
  my $self = shift;
  my $given_stderr = $self->stderr;
  my $foreign_stderr;
 
  Dlog_verbose {
    s/\n/ /g; "invoking connection to perl interpreter using command line: $_"
  } @{$self->final_perl_command};
    
  if (defined($given_stderr)) {
    #if the stderr data goes to an existing file handle
    #an anonymous file handle is required
    #as the other half of a pipe style file handle pair
    #so the file handles can go into the run loop
    $foreign_stderr = gensym();
  } else {
    #if no file handle has been specified
    #for the child's stderr then connect
    #the child stderr to the parent stderr
    $foreign_stderr = ">&STDERR";
  }
  
  my $pid = open3(
    my $foreign_stdin,
    my $foreign_stdout,
    $foreign_stderr,
    @{$self->final_perl_command},
  ) or die "Failed to run perl at '$_[0]': $!";
  
  $self->_set_pid($pid);
  
  if (defined($given_stderr)) {   
    Dlog_debug { "Child process STDERR is being handled via run loop" };
        
    Object::Remote->current_loop
                  ->watch_io(
                      handle => $foreign_stderr,
                      on_read_ready => sub {
                        my $buf = ''; 
                        my $len = sysread($foreign_stderr, $buf, 32768);
                        if (!defined($len) or $len == 0) {
                          log_trace { "Got EOF or error on child stderr, removing from watcher" };
                          $self->stderr(undef);
                          Object::Remote->current_loop->unwatch_io(
                                         handle => $foreign_stderr,
                                         on_read_ready => 1
                                       );
                          } else {
                            Dlog_trace { "got $len characters of stderr data for connection" };
                            print $given_stderr $buf or die "could not send stderr data: $!";
                          }
                         } 
                      );     
  }
      
  return ($foreign_stdin, $foreign_stdout, $pid);
}

sub _open2_for {
  my $self = shift;
  my ($foreign_stdin, $foreign_stdout, $pid) = $self->_start_perl(@_);
  my $to_send = $self->fatnode_text;
  log_debug { my $len = length($to_send); "Sending contents of fat node to remote node; size is '$len' characters" };
  Object::Remote->current_loop
                ->watch_io(
                    handle => $foreign_stdin,
                    on_write_ready => sub {
                      my $len = syswrite($foreign_stdin, $to_send, 32768);
                      if (defined $len) {
                        substr($to_send, 0, $len) = '';
                      }
                      # if the stdin went away, we'll never get Shere
                      # so it's not a big deal to simply give up on !defined
                      if (!defined($len) or 0 == length($to_send)) {
                        log_trace { "Got EOF or error when writing fatnode data to filehandle, unwatching it" };
                        Object::Remote->current_loop
                                      ->unwatch_io(
                                          handle => $foreign_stdin,
                                          on_write_ready => 1
                                      );
                      } else {
                          log_trace { "Sent $len bytes of fatnode data to remote side" };
                      }
                    }
                  );
  return ($foreign_stdin, $foreign_stdout, $pid);
}

sub _setup_watchdog_reset {
  my ($self, $conn) = @_;
  my $timer_id; 
    
  return unless $self->watchdog_timeout;
        
  Dlog_trace { "Creating Watchdog management timer for connection id $_" } $conn->_id;
    
  weaken($conn);
        
  $timer_id = Object::Remote->current_loop->watch_time(
    every => $self->watchdog_timeout / 3,
    code => sub {
      unless(defined($conn)) {
        log_warn { "Weak reference to connection in Watchdog was lost, terminating update timer $timer_id" };
        Object::Remote->current_loop->unwatch_time($timer_id);
        return;
      }
      
      unless($conn->is_valid) {
        log_warn { "Watchdog timer found an invalid connection, removing the timer" };
        Object::Remote->current_loop->unwatch_time($timer_id);
        return;
      }
      
      Dlog_trace { "Reseting Watchdog for connection id $_" } $conn->_id;
      #we do not want to block in the run loop so send the
      #update off and ignore any result, we don't need it
      #anyway
      $conn->send_class_call(0, 'Object::Remote::WatchDog', 'reset');
    }
  );
  
  $conn->on_close->on_ready(sub {
    log_debug { "Removing watchdog for connection that is now closed" };
    Object::Remote->current_loop->unwatch_time($timer_id);
  });
}

sub fatnode_text {
  my ($self) = @_;
  my $connection_timeout = $self->timeout;
  my $watchdog_timeout = $self->watchdog_timeout;
  my $text = '';

  require Object::Remote::FatNode;
  
  if (defined($connection_timeout)) {
    $text .= "alarm($connection_timeout);\n";
  }
  
  if (defined($watchdog_timeout)) {
    $text .= "my \$WATCHDOG_TIMEOUT = $watchdog_timeout;\n";
  } else {
    $text .= "my \$WATCHDOG_TIMEOUT = undef;\n";
  }
  
  $text .= $self->_create_env_forward(@{$self->forward_env});

  #Action at a distance but at least it's not spooky - the logging
  #system needs to know if a node is remote but there is a period
  #during init where the remote connection information has not been
  #setup on the remote side yet so this flag allows a graceful
  #degredation to happen
  $text .= '$Object::Remote::FatNode::REMOTE_NODE = "1";' . "\n";
  
  $text .= <<'END';
$INC{'Object/Remote/FatNode.pm'} = __FILE__;
$Object::Remote::FatNode::DATA = <<'ENDFAT';
END
  $text .= do { no warnings 'once'; $Object::Remote::FatNode::DATA };
  $text .= "ENDFAT\n";
  $text .= <<'END';
eval $Object::Remote::FatNode::DATA;
die $@ if $@;
END
  
  $text .= "__END__\n";
  return $text;
}

sub _create_env_forward {
  my ($self, @env_names) = @_;
  my $code = '';

  foreach my $name (@env_names) {
    next unless exists $ENV{$name};
    my $value = $ENV{$name};
    $name =~ s/'/\\'/g;
    if(defined($value)) {
      $value =~ s/'/\\'/g;
      $value = "'$value'";
    } else {
      $value = 'undef';
    }
    $code .= "\$ENV{'$name'} = $value;\n";
  }

  return $code;
}

1;