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

.finger

Creates a singleton RingFinger and looks for a RingServer.
.new(broadcast_list = @@broadcast_list, port = Ring_PORT) ⇒ RingFinger constructor

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

Returns the first advertised TupleSpace.
.to_a

Contains all discovered TupleSpaces except for the primary.

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

#each {|@primary| ... }

Iterates over all discovered TupleSpaces starting with the primary.
#lookup_ring(timeout = 5, &block)

Looks up RingServers waiting timeout seconds.
#lookup_ring_any(timeout = 5)

Returns the first found remote TupleSpace.
#to_a

Contains all discovered TupleSpaces except for the primary.
#make_socket(address) Internal use only

Creates a socket for address with the appropriate multicast options for multicast addresses.
#send_message(address, message) Internal use only

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 344


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 288


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 299


def self.primary
  finger.primary
end

.to_a

Contains all discovered TupleSpaces except for the primary.

[ GitHub ]

# File 'lib/rinda/ring.rb', line 306


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 313


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 320


attr_accessor :multicast_hops

#multicast_interface (rw)

The interface index to send IPv6 multicast packets from.

[ GitHub ]

# File 'lib/rinda/ring.rb', line 325


attr_accessor :multicast_interface

#port (rw)

The port that RingFinger will send query packets to.

[ GitHub ]

# File 'lib/rinda/ring.rb', line 330


attr_accessor :port

#primary (rw)

Contain the first advertised TupleSpace after lookup_ring_any is called.

[ GitHub ]

# File 'lib/rinda/ring.rb', line 335


attr_accessor :primary

Instance Method Details

#each {|@primary| ... }

Iterates over all discovered TupleSpaces starting with the primary.

Yields:

(@primary)

[ GitHub ]

# File 'lib/rinda/ring.rb', line 364


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 376


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 390


def lookup_ring_any(timeout=5)
  queue = Thread::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

#make_socket(address)

This method is for internal use only.

Creates a socket for address with the appropriate multicast options for multicast addresses.

[ GitHub ]

# File 'lib/rinda/ring.rb', line 416


def make_socket(address) # :nodoc:
  addrinfo = Addrinfo.udp(address, @port)

  soc = Socket.new(addrinfo.pfamily, addrinfo.socktype, addrinfo.protocol)
  begin
    if addrinfo.ipv4_multicast? then
      soc.setsockopt(Socket::Option.ipv4_multicast_loop(1))
      soc.setsockopt(Socket::Option.ipv4_multicast_ttl(@multicast_hops))
    elsif addrinfo.ipv6_multicast? then
      soc.setsockopt(:IPPROTO_IPV6, :IPV6_MULTICAST_LOOP, true)
      soc.setsockopt(:IPPROTO_IPV6, :IPV6_MULTICAST_HOPS,
                     [@multicast_hops].pack('I'))
      soc.setsockopt(:IPPROTO_IPV6, :IPV6_MULTICAST_IF,
                     [@multicast_interface].pack('I'))
    else
      soc.setsockopt(:SOL_SOCKET, :SO_BROADCAST, true)
    end

    soc.connect(addrinfo)
  rescue Exception
    soc.close
    raise
  end

  soc
end

#send_message(address, message)

This method is for internal use only.

[ GitHub ]

# File 'lib/rinda/ring.rb', line 443


def send_message(address, message) # :nodoc:
  soc = make_socket(address)

  soc.send(message, 0)
rescue
  nil
ensure
  soc.close if soc
end

#to_a

Contains all discovered TupleSpaces except for the primary.

[ GitHub ]

# File 'lib/rinda/ring.rb', line 357


def to_a
  @rings
end

Class: Rinda::RingFinger

Overview

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

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

Class Method Details

.finger

.primary

.to_a

Instance Attribute Details

#broadcast_list (rw)

#multicast_hops (rw)

#multicast_interface (rw)

#port (rw)

#primary (rw)

Instance Method Details

#each {|@primary| ... }

#lookup_ring(timeout = 5, &block)

#lookup_ring_any(timeout = 5)

#make_socket(address)

#send_message(address, message)

#to_a

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