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Class: Rinda::RingFinger

Relationships & Source Files
Inherits: Object
Defined in: lib/rinda/ring.rb

Overview

RingFinger is used by RingServer clients to discover the RingServer's TupleSpace. Typically, all a client needs to do is call .primary to retrieve the remote TupleSpace, which it can then begin using.

To find the first available remote TupleSpace:

Rinda::RingFinger.primary

To create a RingFinger that broadcasts to a custom list:

rf = Rinda::RingFinger.new  ['localhost', '192.0.2.1']
rf.primary

RingFinger also understands multicast addresses and sets them up properly. This allows you to run multiple RingServers on the same host:

rf = Rinda::RingFinger.new ['239.0.0.1']
rf.primary

You can set the hop count (or TTL) for multicast searches using #multicast_hops.

If you use IPv6 multicast you may need to set both an address and the outbound interface index:

rf = Rinda::RingFinger.new ['ff02::1']
rf.multicast_interface = 1
rf.primary

At this time there is no easy way to get an interface index by name.

Class Method Summary

Instance Attribute Summary

  • #broadcast_list rw

    The list of addresses where RingFinger will send query packets.

  • #multicast_hops rw

    Maximum number of hops for sent multicast packets (if using a multicast address in the broadcast list).

  • #multicast_interface rw

    The interface index to send IPv6 multicast packets from.

  • #port rw

    The port that RingFinger will send query packets to.

  • #primary rw

    Contain the first advertised TupleSpace after lookup_ring_any is called.

Instance Method Summary

Constructor Details

.new(broadcast_list = @@broadcast_list, port = Ring_PORT) ⇒ RingFinger

Creates a new RingFinger that will look for RingServers at #port on the addresses in #broadcast_list.

If #broadcast_list contains a multicast address then multicast queries will be made using the given multicast_hops and multicast_interface.

[ GitHub ] 

  


# File 'lib/rinda/ring.rb', line 340



def initialize(broadcast_list=@@broadcast_list, port=Ring_PORT)
  @broadcast_list = broadcast_list || ['localhost']
  @port = port
  @primary = nil
  @rings = []

  @multicast_hops = 1
  @multicast_interface = 0
end


  







Class Method Details



  

    .finger  
  



  

    

Creates a singleton RingFinger and looks for a RingServer.  Returns the created RingFinger.


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 284



def self.finger
  unless @@finger
    @@finger = self.new
    @@finger.lookup_ring_any
  end
  @@finger
end


  








  

    .primary  
  



  

    

Returns the first advertised TupleSpace.


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 295



def self.primary
  finger.primary
end


  








  

    .to_a  
  



  

    

Contains all discovered TupleSpaces except for the primary.


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 302



def self.to_a
  finger.to_a
end


  







Instance Attribute Details



  

    #broadcast_list   (rw)
  



  

    

The list of addresses where RingFinger will send query packets.


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 309



attr_accessor :broadcast_list


  








  

    #multicast_hops   (rw)
  



  

    

Maximum number of hops for sent multicast packets (if using a multicast address in the broadcast list).  The default is 1 (same as UDP broadcast).


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 316



attr_accessor :multicast_hops


  








  

    #multicast_interface   (rw)
  



  

    

The interface index to send IPv6 multicast packets from.


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 321



attr_accessor :multicast_interface


  








  

    #port   (rw)
  



  

    

The port that RingFinger will send query packets to.


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 326



attr_accessor :port


  








  

    #primary   (rw)
  



  

    

Contain the first advertised TupleSpace after lookup_ring_any is called.


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 331



attr_accessor :primary


  







Instance Method Details



  

    #each {|@primary| ... } 
  



  

    

Iterates over all discovered TupleSpaces starting with the primary.


  





  
Yields:





  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 360



def each
  lookup_ring_any unless @primary
  return unless @primary
  yield(@primary)
  @rings.each { |x| yield(x) }
end


  








  

    #lookup_ring(timeout = 5, &block)  
  



  

    

Looks up RingServers waiting timeout seconds.  RingServers will be given block as a callback, which will be called with the remote TupleSpace.


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 372



def lookup_ring(timeout=5, &block)
  return lookup_ring_any(timeout) unless block_given?

  msg = Marshal.dump([[:lookup_ring, DRbObject.new(block)], timeout])
  @broadcast_list.each do |it|
    send_message(it, msg)
  end
  sleep(timeout)
end


  








  

    #lookup_ring_any(timeout = 5)  
  



  

    

Returns the first found remote TupleSpace.  Any further recovered TupleSpaces can be found by calling .to_a.


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 386



def lookup_ring_any(timeout=5)
  queue = Queue.new

  Thread.new do
    self.lookup_ring(timeout) do |ts|
      queue.push(ts)
    end
    queue.push(nil)
  end

  @primary = queue.pop
  raise('RingNotFound') if @primary.nil?

  Thread.new do
    while it = queue.pop
      @rings.push(it)
    end
  end

  @primary
end


  








  

    #to_a  
  



  

    

Contains all discovered TupleSpaces except for the primary.


  



  [ GitHub ]


  

  


# File 'lib/rinda/ring.rb', line 353



def to_a
  @rings
end