add rinda, (import from drb-2.0.4)

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@4696 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/rinda/ring.rb

@@ -0,0 +1,164 @@
+#
+# Note: Rinda::Ring API is unstable.
+#
+require 'drb/drb'
+require 'rinda/rinda'
+require 'thread'
+
+module Rinda
+  Ring_PORT = 7647
+  class RingServer
+    include DRbUndumped
+
+    def initialize(ts, port=Ring_PORT)
+      @ts = ts
+      @soc = UDPSocket.open
+      @soc.bind('', port)
+      @w_service = write_service
+      @r_service = reply_service
+    end
+
+    def write_service
+      Thread.new do
+	loop do
+	  msg, addr = @soc.recvfrom(1024)
+	  do_write(msg)
+	end
+      end
+    end
+  
+    def do_write(msg)
+      Thread.new do
+	begin
+	  tuple, sec = Marshal.load(msg)
+	  @ts.write(tuple, sec)
+	rescue
+	end
+      end
+    end
+
+    def reply_service
+      Thread.new do
+	loop do
+	  do_reply
+	end
+      end
+    end
+    
+    def do_reply
+      tuple = @ts.take([:lookup_ring, DRbObject])
+      Thread.new { tuple[1].call(@ts) rescue nil}
+    rescue
+    end
+  end
+
+  class RingFinger
+    @@finger = nil
+    def self.finger
+      unless @@finger 
+	@@finger = self.new
+	@@finger.lookup_ring_any
+      end
+      @@finger
+    end
+
+    def self.primary
+      finger.primary
+    end
+
+    def self.to_a
+      finger.to_a
+    end
+
+    @@broadcast_list = ['<broadcast>', 'localhost']
+    def initialize(broadcast_list=@@broadcast_list, port=Ring_PORT)
+      @broadcast_list = broadcast_list || ['localhost']
+      @port = port
+      @primary = nil
+      @rings = []
+    end
+    attr_accessor :broadcast_list, :port, :primary
+
+    def to_a
+      @rings
+    end
+
+    def each
+      lookup_ring_any unless @primary
+      return unless @primary
+      yield(@primary)
+      @rings.each { |x| yield(x) }
+    end
+
+    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|
+	soc = UDPSocket.open
+	begin
+	  soc.setsockopt(Socket::SOL_SOCKET, Socket::SO_BROADCAST, true)
+	  soc.send(msg, 0, it, @port)
+	rescue
+	  nil
+	ensure
+	  soc.close
+	end
+      end
+      sleep(timeout)
+    end
+
+    def lookup_ring_any(timeout=5)
+      queue = Queue.new
+
+      th = Thread.new do
+	self.lookup_ring(timeout) do |ts|
+	  queue.push(ts)
+	end
+	queue.push(nil)
+	while it = queue.pop
+	  @rings.push(it)
+	end
+      end
+      
+      @primary = queue.pop
+      raise('RingNotFound') if @primary.nil?
+      @primary
+    end
+  end
+
+  class RingProvider
+    def initialize(klass, front, desc, renewer = nil)
+      @tuple = [:name, klass, front, desc]
+      @renewer = renewer || Rinda::SimpleRenewer.new
+    end
+
+    def provide
+      ts = Rinda::RingFinger.primary
+      ts.write(@tuple, @renewer)
+    end
+  end
+end
+
+if __FILE__ == $0
+  DRb.start_service
+  case ARGV.shift
+  when 's'
+    require 'rinda/tuplespace'
+    ts = Rinda::TupleSpace.new
+    place = Rinda::RingServer.new(ts)
+    $stdin.gets
+  when 'w'
+    finger = Rinda::RingFinger.new(nil)
+    finger.lookup_ring do |ts|
+      p ts
+      ts.write([:hello, :world])
+    end
+  when 'r'
+    finger = Rinda::RingFinger.new(nil)
+    finger.lookup_ring do |ts|
+      p ts
+      p ts.take([nil, nil])
+    end
+  end
+end