From: Russell Fulton <r.fulton@...>
Date: 2009-10-01T08:22:26+09:00
Subject: Monitors on data structures

Hi

I am trying to use monitors for the first time in ruby.  I am familiar
with the concept but am having some problems making things work.

Background:  I have a program that uses nmap-parser to parse large nmap
scans and uses the call back to deliver results for each host.  The call
back is threaded.

I want to build lists of IP addresses for further investigation from the
callback routine.  I have made a class AddressList:

class AddressList < Array
  include MonitorMixin

  def initialise  # redundant ?
  super
  end


  def <<(addr)
    synchronise do  # make sure we don't clobber another thread
      super( addr )
    end
  end

end

we need to protect the push code so that to threads don't collide so I
put a synchronise block around it.

What appears to happen is that the code never exits the synchronise
block.

puts before the block get executed but ones after do not and nothing is
ever added to the list.

Clearly I'm missing something.

The callback routine:

    callback = proc do |host|

      return unless host.status == 'up'
      host.scripts do |script|
        s = script.output.gsub(/\n/, ':')
        next if s =~ / 2008 R2|ERROR/;
        next unless s =~ /Vista|2008/
        $addresses << host.addr
      end # scripts
      schedule if $addresses.size > BATCH_SIZE
    end

yes, I'm looking for machines running smb2 to get them before the worm
does :)

BTW I do have this program working without treads but I want to know why
this does not work !


Russell
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