Filled in proposer.rb, added empty superclass of all Paxos roles

paxos_replica.rb

@@ -1,5 +1,6 @@
 class PaxosReplica
-  def initialize
+  def initialize(supervisor)
     @proposer, @acceptor, @learner = Proposer.new, Acceptor.new, Learner.new
+    supervisor.add_replica(self)
   end
 end

paxos_role.rb

@@ -0,0 +1,2 @@
+class PaxosRole
+end

proposer.rb

@@ -1,2 +1,53 @@
-class Proposer
+class Proposer < PaxosRole
+  def initialize(supervisor)
+    @supervisor = supervisor
+    @propose_mutex = Mutex.new
+    @propose_thread = nil
+    @n = 0
+  end
+
+  protected
+  def propose(value)
+    kill_thread
+
+    @propose_thread = Thread.new do 
+      loop do
+        @propose_mutex.synchronize do 
+          replicas = @supervisor.replicas
+
+          responses = replicas.inject([]) do |memo, replica|
+            response = replica.paxos_instance.acceptor.prepare(@n)
+            memo << response if response
+          end
+
+          next if responses.size < (replicas.size / 2.0).ceil
+
+          number = responses.inject(nil) do |memo, response|
+            if response.highest_accepted
+              unless memo and response.highest_accepted <= memo
+                memo = response.highest_accepted 
+              end
+            end
+          end
+
+          number = @n unless number
+
+          responses.each do |response|
+            response.acceptor.request_accept(Proposal.new(number, value, self))
+          end
+        end
+
+        @n += 1
+      end
+    end
+  end
+
+  def value_learned!
+    @propose_thread.kill if @propose_thread 
+  end
+
+  alias_method :value_learned!, :kill_thread
+
+  private
+  Proposal = Struct.new :number, :value, :proposer
 end