# class Rinda::RingServer

A `RingServer` allows a `Rinda::TupleSpace` to be located via UDP broadcasts. Default service location uses the following steps:

1. A `RingServer` begins listening on the network broadcast UDP address.

2. A `RingFinger` sends a UDP packet containing the `DRb` `URI` where it will listen for a reply.

3. The `RingServer` receives the UDP packet and connects back to the provided `DRb` `URI` with the `DRb` service.

A `RingServer` requires a TupleSpace:

    ts = Rinda::TupleSpace.new
    rs = Rinda::RingServer.new

`RingServer` can also listen on multicast addresses for announcements. This allows multiple RingServers to run on the same host. To use network broadcast and multicast:

    ts = Rinda::TupleSpace.new
    rs = Rinda::RingServer.new ts, %w[Socket::INADDR_ANY, 239.0.0.1 ff02::1]

### Public Class Methods

new(ts, addresses=[Socket::INADDR_ANY], port=Ring_PORT) click to toggle source

Advertises `ts` on the given `addresses` at `port`.

If `addresses` is omitted only the UDP broadcast address is used.

`addresses` can contain multiple addresses. If a multicast address is given in `addresses` then the `RingServer` will listen for multicast queries.

If you use IPv4 multicast you may need to set an address of the inbound interface which joins a multicast group.

    ts = Rinda::TupleSpace.new
    rs = Rinda::RingServer.new(ts, [['239.0.0.1', '9.5.1.1']])

You can set addresses as an `Array` `Object`. The first element of the `Array` is a multicast address and the second is an inbound interface address. If the second is omitted then ‘0.0.0.0’ is used.

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

    rs = Rinda::RingServer.new(ts, [['ff02::1', '::1', 1]])

The first element is a multicast address and the second is an inbound interface address. The third is an inbound interface index.

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

If the second is omitted then ‘::1’ is used. If the third is omitted then 0 (default interface) is used.

    # File lib/rinda/ring.rb, line 94
    def initialize(ts, addresses=[Socket::INADDR_ANY], port=Ring_PORT)
      @port = port

      if Integer === addresses then
        addresses, @port = [Socket::INADDR_ANY], addresses
      end

      @renewer = Renewer.new

      @ts = ts
      @sockets = []
      addresses.each do |address|
        if Array === address
          make_socket(*address)
        else
          make_socket(address)
        end
      end

      @w_services = write_services
      @r_service  = reply_service
    end

### Public Instance Methods

do_reply() click to toggle source

Pulls lookup tuples out of the `TupleSpace` and sends their `DRb` object the address of the local `TupleSpace`.

    # File lib/rinda/ring.rb, line 218
    def do_reply
      tuple = @ts.take([:lookup_ring, nil], @renewer)
      Thread.new { tuple[1].call(@ts) rescue nil}
    rescue
    end

do_write(msg) click to toggle source

Extracts the response `URI` from `msg` and adds it to `TupleSpace` where it will be picked up by `reply_service` for notification.

    # File lib/rinda/ring.rb, line 193
    def do_write(msg)
      Thread.new do
        begin
          tuple, sec = Marshal.load(msg)
          @ts.write(tuple, sec)
        rescue
        end
      end
    end

make_socket(address, interface_address=nil, multicast_interface=0) click to toggle source

Creates a socket at `address`

If `address` is multicast address then `interface_address` and `multicast_interface` can be set as optional.

A created socket is bound to `interface_address`. If you use IPv4 multicast then the interface of `interface_address` is used as the inbound interface. If `interface_address` is omitted or nil then ‘0.0.0.0’ or ‘::1’ is used.

If you use IPv6 multicast then `multicast_interface` is used as the inbound interface. `multicast_interface` is a network interface index. If `multicast_interface` is omitted then 0 (default interface) is used.

    # File lib/rinda/ring.rb, line 132
    def make_socket(address, interface_address=nil, multicast_interface=0)
      addrinfo = Addrinfo.udp(address, @port)

      socket = Socket.new(addrinfo.pfamily, addrinfo.socktype,
                          addrinfo.protocol)

      if addrinfo.ipv4_multicast? or addrinfo.ipv6_multicast? then
        if Socket.const_defined?(:SO_REUSEPORT) then
          socket.setsockopt(:SOCKET, :SO_REUSEPORT, true)
        else
          socket.setsockopt(:SOCKET, :SO_REUSEADDR, true)
        end

        if addrinfo.ipv4_multicast? then
          interface_address = '0.0.0.0' if interface_address.nil?
          socket.bind(Addrinfo.udp(interface_address, @port))

          mreq = IPAddr.new(addrinfo.ip_address).hton +
            IPAddr.new(interface_address).hton

          socket.setsockopt(:IPPROTO_IP, :IP_ADD_MEMBERSHIP, mreq)
        else
          interface_address = '::1' if interface_address.nil?
          socket.bind(Addrinfo.udp(interface_address, @port))

          mreq = IPAddr.new(addrinfo.ip_address).hton +
            [multicast_interface].pack('I')

          socket.setsockopt(:IPPROTO_IPV6, :IPV6_JOIN_GROUP, mreq)
        end
      else
        socket.bind(addrinfo)
      end

      socket
    rescue
      socket = socket.close if socket
      raise
    ensure
      @sockets << socket if socket
    end

reply_service() click to toggle source

Creates a thread that notifies waiting clients from the `TupleSpace`.

    # File lib/rinda/ring.rb, line 206
    def reply_service
      Thread.new do
        loop do
          do_reply
        end
      end
    end

shutdown() click to toggle source

Shuts down the `RingServer`

    # File lib/rinda/ring.rb, line 227
    def shutdown
      @renewer.renew = false

      @w_services.each do |thread|
        thread.kill
        thread.join
      end

      @sockets.each do |socket|
        socket.close
      end

      @r_service.kill
      @r_service.join
    end

write_services() click to toggle source

Creates threads that pick up UDP packets and passes them to `do_write` for decoding.

    # File lib/rinda/ring.rb, line 178
    def write_services
      @sockets.map do |s|
        Thread.new(s) do |socket|
          loop do
            msg = socket.recv(1024)
            do_write(msg)
          end
        end
      end
    end