Added more tests and updated the presentation

lib/paxos.ex

@@ -1,3 +1,12 @@
+#
+#
+# Possible actions
+#  :kill_before_decision 
+#  :increase_ballot_number - this makes it so that it does not propose but jump simply increases the number of the current ballot
+#                            this is usefull when forcing a nack
+#
+
+
 defmodule Paxos do
   def start(name, processes) do
     IO.puts("Starting paxos for #{name}")
@@ -73,6 +82,16 @@ defmodule Paxos do
               send(pid_to_inform, {:decision, inst, state.decided[inst]})
               state
 
+            action == :increase_ballot_number ->
+              state = has_or_create(state, inst)
+
+              IO.puts("#{state.name} - Got request to increase ballot number for inst #{inst}")
+
+              # Inform the pid with timeout right way
+              send(pid_to_inform, {:timeout, inst});
+
+              set_instmap(state, inst, fn map -> %{map| ballot: map.ballot + 1} end)
+
             not Map.has_key?(state.instmap, inst) ->
               EagerReliableBroadcast.broadcast(state.name, {:other_propose, inst, value})
               state = has_or_create(state, inst, value, pid_to_inform, action)
@@ -94,6 +113,7 @@ defmodule Paxos do
               )
 
             true ->
+              EagerReliableBroadcast.broadcast(state.name, {:other_propose, inst, value})
               prepare(state, inst)
           end
 
@@ -101,7 +121,7 @@ defmodule Paxos do
           state = %{state | other_values: Map.put(state.other_values, inst, value)}
 
           cond do
-            Map.has_key?(state.decided, inst) ->
+            has_finished(state, inst) ->
               EagerReliableBroadcast.broadcast(
                 state.name,
                 {:decide, inst, state.decided[inst]}
@@ -170,7 +190,7 @@ defmodule Paxos do
                 send(state.instmap[inst].pid_to_inform, {:abort, inst})
               end
 
-              EagerReliableBroadcast.broadcast(state.name, {:abort, inst, ballot, new_ballot})
+              EagerReliableBroadcast.broadcast(state.name, {:abort, inst, ballot})
 
               set_instmap(state, inst, fn map -> %{
                 map | has_sent_accept: false, 
@@ -187,16 +207,15 @@ defmodule Paxos do
             has_finished(state, inst) ->
               state
 
-            state.instmap[inst].ballot == ballot ->
+            true ->
+              IO.puts("#{state.name} - got information to send abort")
+
               if Map.has_key?(state.instmap, inst) and state.instmap[inst].pid_to_inform != nil do
                 send(state.instmap[inst].pid_to_inform, {:abort, inst})
               end
 
               state
 
-            true ->
-              state
-
           end
 
         {:prepared, inst, ballot, accepted_ballot, accepted_value} ->
@@ -218,7 +237,7 @@ defmodule Paxos do
               prepared(state, inst)
 
             ballot > state.instmap[inst].ballot ->
-              IO.puts("Probably recieved this before preare came to self sending with delay")
+              IO.puts("#{state.name} - Probably recieved this before preare came to self sending with delay")
               Process.send_after(self(), {:prepared, inst, ballot, accepted_ballot, accepted_value}, 100)
               state
 
@@ -253,7 +272,7 @@ defmodule Paxos do
           end
 
         {:accepted, inst, ballot} ->
-          IO.puts("#{state.name} accepted #{inspect(inst)} #{inspect(ballot)}")
+          IO.puts("#{state.name} - accepted #{inspect(inst)} #{inspect(ballot)}")
 
           cond do
             has_finished(state, inst) ->
@@ -289,7 +308,7 @@ defmodule Paxos do
           state
 
         {:rb_deliver, _, {:decide, inst, value}} ->
-          IO.puts("#{state.name} decided #{inspect(inst)} #{inspect(value)}")
+          IO.puts("#{state.name} - decided #{inspect(inst)} #{inspect(value)}")
 
           if has_finished(state, inst) do
             state
@@ -333,7 +352,7 @@ defmodule Paxos do
 
       true ->
         ballot = state.instmap[inst].ballot + 1
-        IO.puts("#{state.name} sending all prepare #{inst} #{ballot}")
+        IO.puts("#{state.name} - sending all prepare #{inst} #{ballot}")
         EagerReliableBroadcast.broadcast(state.name, {:prepare, state.name, inst, ballot})
 
         set_instmap(state, inst, fn map -> %{

lib/paxos_test_aditional.ex

@@ -58,5 +58,154 @@ defmodule PaxosTestAditional do
         send(cpid, {:finished, name, pid, status, val, a, ql})
     end
   end
+
+
+  def run_leader_should_nack_simple(name, participants, val) do
+    {cpid, pid} = PaxosTest.init(name, participants, true)
+    send(cpid, :ready)
+
+    {status, val, a, spare} =
+      try do
+        receive do
+          :start ->
+            IO.puts("#{inspect(name)}: started")
+
+            [leader | spare] = Enum.sort(participants)
+            increase_ballot = Enum.take(spare, floor(length(participants) / 2))
+
+            if name == leader do
+              # Propose  when passed with :kill_before_decision will die right before a decision is selected
+              Process.sleep(2000)
+              res = Paxos.propose(pid, 1, val, 10000)
+
+              if res != {:abort} do
+                IO.puts("#{name}: Leader failed to abort")
+                {:failed_to_abort, :none, 10, []}
+              else
+                Paxos.propose(pid, 1, val, 10000)
+
+                {status, val} = PaxosTest.wait_for_decision(pid, 1, 10000)
+
+                if status != :none,
+                  do: IO.puts("#{name}: decided #{inspect(val)}"),
+                  else: IO.puts("#{name}: No decision after 10 seconds")
+
+                {status, val, 10, participants}
+              end
+            else 
+              if name in increase_ballot do
+                Process.sleep(10)
+                # Force the non leader process to have a higher ballot
+                Paxos.propose(pid, 1, nil, 1000, :increase_ballot_number)
+              end
+
+              {status, val} = PaxosTest.wait_for_decision(pid, 1, 10000)
+
+              if status != :none,
+                do: IO.puts("#{name}: decided #{inspect(val)}"),
+                else: IO.puts("#{name}: No decision after 10 seconds")
+
+              {status, val, 10, participants}
+            end
+
+        end
+      rescue
+        _ -> {:none, :none, 10, []}
+      end
+
+    send(cpid, :done)
+
+    receive do
+      :all_done ->
+        Process.sleep(100)
+
+        ql =
+          if name in spare do
+            IO.puts("#{name}: #{inspect(ql = Process.info(pid, :message_queue_len))}")
+            ql
+          else
+            {:message_queue_len, -1}
+          end
+
+        PaxosTest.kill_paxos(pid, name)
+        send(cpid, {:finished, name, pid, status, val, a, ql})
+    end
+  end
+
+  def run_non_leader_should_nack_simple(name, participants, val) do
+    {cpid, pid} = PaxosTest.init(name, participants, true)
+    send(cpid, :ready)
+
+    {status, val, a, spare} =
+      try do
+        receive do
+          :start ->
+            IO.puts("#{inspect(name)}: started")
+
+            participants = Enum.sort(participants)
+
+            [leader | spare ] = participants
+            increase_ballot = Enum.take(spare, floor(length(participants) / 2))
+            [non_leader | _] = Enum.reverse(spare)
+
+            if name == non_leader do
+              # Propose  when passed with :kill_before_decision will die right before a decision is selected
+              Process.sleep(2000)
+              res = Paxos.propose(pid, 1, val, 10000)
+
+              if res != {:abort} do
+                IO.puts("#{name}: non-leader failed to abort")
+                {:failed_to_abort, :none, 10, []}
+              else
+                Paxos.propose(pid, 1, val, 10000)
+
+                {status, val} = PaxosTest.wait_for_decision(pid, 1, 10000)
+
+                if status != :none,
+                  do: IO.puts("#{name}: decided #{inspect(val)}"),
+                  else: IO.puts("#{name}: No decision after 10 seconds")
+
+                {status, val, 10, participants}
+              end
+            else 
+              if name in increase_ballot do
+                Process.sleep(10)
+                # Force the non leader process to have a higher ballot
+                Paxos.propose(pid, 1, nil, 1000, :increase_ballot_number)
+              end
+
+              {status, val} = PaxosTest.wait_for_decision(pid, 1, 10000)
+
+              if status != :none,
+                do: IO.puts("#{name}: decided #{inspect(val)}"),
+                else: IO.puts("#{name}: No decision after 10 seconds")
+
+              {status, val, 10, participants}
+            end
+
+        end
+      rescue
+        _ -> {:none, :none, 10, []}
+      end
+
+    send(cpid, :done)
+
+    receive do
+      :all_done ->
+        Process.sleep(100)
+
+        ql =
+          if name in spare do
+            IO.puts("#{name}: #{inspect(ql = Process.info(pid, :message_queue_len))}")
+            ql
+          else
+            {:message_queue_len, -1}
+          end
+
+        PaxosTest.kill_paxos(pid, name)
+        send(cpid, {:finished, name, pid, status, val, a, ql})
+    end
+  end
+  
 end
 

lib/test_script.exs

@@ -73,6 +73,19 @@ test_suite = [
    "Leader crashes right before decision, no concurrent ballots, 5 nodes"},
   {&PaxosTestAditional.run_leader_crash_simple_before_decision/3, TestUtil.get_local_config(5), 10,
    "Leader crashes right before decision, no concurrent ballots, 5 local procs"},
+
+  {&PaxosTestAditional.run_leader_should_nack_simple/3, TestUtil.get_dist_config(host, 5), 10,
+   "Leader should nack before decision and then come to decision, no concurrent ballots, 5 nodes"},
+  {&PaxosTestAditional.run_leader_should_nack_simple/3, TestUtil.get_local_config(5), 10,
+   "Leader should nack before decision and then come to decision, 5 local procs"},
+
+  {&PaxosTestAditional.run_non_leader_should_nack_simple/3, TestUtil.get_dist_config(host, 5), 10,
+   "Non-Leader should nack before decision and then come to decision, no concurrent ballots, 5 nodes"},
+  {&PaxosTestAditional.run_non_leader_should_nack_simple/3, TestUtil.get_local_config(5), 10,
+   "Non-Leader should nack before decision and then come to decision, 5 local procs"},
+
+   
+   
 ]
 
 Node.stop()

presentation/presentation.md

@@ -61,18 +61,56 @@ end
 
 ---
 
+### Step 1 - "Requirements" non-trivial aspects
+
+```elixir
+receive do
+  {:propose, inst, value, t, pid_to_inform} ->
+    ...
+    broadcast({:other_propose, inst, value})
+    ...
+  {:other_propose, inst, value} -> ...
+end
+```
+
 ### Step 2 - "Prepare"
 
 ![w:600 center](./second-step.png)
 
 ---
 
+### Step 2 - "Prepare" non-trivial aspects
+
+```elixir
+receive do
+  {:nack, inst, ballot, new_ballot} ->
+    ...
+    broadcast({:abort, inst, ballot})
+    ...
+  {:abort, inst, ballot} -> ...
+end
+```
+
+---
+
 ### Step 3 - "Accept"
 
 ![w:600 center](./third-step.png)
 
 ---
 
+### Step 3 - "Accept" non-trivial aspects
+
+```elixir
+receive do
+  {:accepted, inst, ballot} ->
+    ...
+    broadcast({:decide, inst, value})
+    ...
+  {:decide, inst, value} -> ...
+end
+```
+
 ### Step 4 - "Leader Crash"
 
 ![w:600 center](./fourth-step.png)