Explicitly remove delegate from its supervisor on name conflict

Author: arjan

config/config.exs

@@ -2,4 +2,10 @@ import Config
 
 if Mix.env() == :test do
   config :logger, level: :warn
+
+  # config :logger,
+  #   format: "$message\n",
+  #   level: String.to_atom(System.get_env("LOG_LEVEL") || "info"),
+  #   handle_otp_reports: true,
+  #   handle_sasl_reports: true
 end

lib/sworm/delegate.ex

@@ -114,8 +114,9 @@ defmodule Sworm.Delegate do
     {:stop, :shutdown, state}
   end
 
-  def handle_info({:EXIT, _, {:name_conflict, {_name, _}, _reg, _winner} = r}, state) do
-    {:stop, r, state}
+  def handle_info({:EXIT, _, {:name_conflict, {_name, _}, _reg, _winner}}, state) do
+    Horde.DynamicSupervisor.terminate_child(supervisor_name(state.sworm), self())
+    {:stop, :normal, state}
   end
 
   def handle_info({:EXIT, _, reason}, state) do

mix.lock

@@ -2,15 +2,17 @@
   "delta_crdt": {:hex, :delta_crdt, "0.5.10", "e866f8d1b89bee497a98b9793e9ba0ea514112a1c41a0c30dcde3463d4984d14", [:mix], [{:merkle_map, "~> 0.2.0", [hex: :merkle_map, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "ed5c685df9528788d7c056762c23f75358f3cadd4779698188a55ccae24d087a"},
   "dialyxir": {:hex, :dialyxir, "1.0.0-rc.7", "6287f8f2cb45df8584317a4be1075b8c9b8a69de8eeb82b4d9e6c761cf2664cd", [:mix], [{:erlex, ">= 0.2.5", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "506294d6c543e4e5282d4852aead19ace8a35bedeb043f9256a06a6336827122"},
   "earmark": {:hex, :earmark, "1.4.3", "364ca2e9710f6bff494117dbbd53880d84bebb692dafc3a78eb50aa3183f2bfd", [:mix], [], "hexpm", "8cf8a291ebf1c7b9539e3cddb19e9cef066c2441b1640f13c34c1d3cfc825fec"},
+  "earmark_parser": {:hex, :earmark_parser, "1.4.31", "a93921cdc6b9b869f519213d5bc79d9e218ba768d7270d46fdcf1c01bacff9e2", [:mix], [], "hexpm", "317d367ee0335ef037a87e46c91a2269fef6306413f731e8ec11fc45a7efd059"},
   "erlex": {:hex, :erlex, "0.2.5", "e51132f2f472e13d606d808f0574508eeea2030d487fc002b46ad97e738b0510", [:mix], [], "hexpm", "756d3e19b056339af674b715fdd752c5dac468cf9d0e2d1a03abf4574e99fbf8"},
-  "ex_doc": {:hex, :ex_doc, "0.21.2", "caca5bc28ed7b3bdc0b662f8afe2bee1eedb5c3cf7b322feeeb7c6ebbde089d6", [:mix], [{:earmark, "~> 1.3.3 or ~> 1.4", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm", "f1155337ae17ff7a1255217b4c1ceefcd1860b7ceb1a1874031e7a861b052e39"},
+  "ex_doc": {:hex, :ex_doc, "0.29.3", "f07444bcafb302db86e4f02d8bbcd82f2e881a0dcf4f3e4740e4b8128b9353f7", [:mix], [{:earmark_parser, "~> 1.4.31", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1", [hex: :makeup_erlang, repo: "hexpm", optional: false]}], "hexpm", "3dc6787d7b08801ec3b51e9bd26be5e8826fbf1a17e92d1ebc252e1a1c75bfe1"},
   "ex_unit_clustered_case": {:git, "https://github.com/bitwalker/ex_unit_clustered_case.git", "7762c0a0cce1c78703a1955ce9bc89c0ff9d2f88", []},
   "horde": {:hex, :horde, "0.7.1", "161e140e4e4fab5416b90a4e5b68fbe7fb78f62b265f87f01d661a58aa72be0c", [:mix], [{:delta_crdt, "~> 0.5.10", [hex: :delta_crdt, repo: "hexpm", optional: false]}, {:libring, "~> 1.4", [hex: :libring, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:telemetry_poller, "~> 0.4.0", [hex: :telemetry_poller, repo: "hexpm", optional: false]}], "hexpm", "cbf5416cd4d221be07420d40a575cdaa1300a03d7ef593f805705e6b54f6187c"},
   "libring": {:hex, :libring, "1.6.0", "d5dca4bcb1765f862ab59f175b403e356dec493f565670e0bacc4b35e109ce0d", [:mix], [], "hexpm", "5e91ece396af4bce99953d49ee0b02f698cd38326d93cd068361038167484319"},
-  "makeup": {:hex, :makeup, "1.0.0", "671df94cf5a594b739ce03b0d0316aa64312cee2574b6a44becb83cd90fb05dc", [:mix], [{:nimble_parsec, "~> 0.5.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "a10c6eb62cca416019663129699769f0c2ccf39428b3bb3c0cb38c718a0c186d"},
-  "makeup_elixir": {:hex, :makeup_elixir, "0.14.0", "cf8b7c66ad1cff4c14679698d532f0b5d45a3968ffbcbfd590339cb57742f1ae", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "d4b316c7222a85bbaa2fd7c6e90e37e953257ad196dc229505137c5e505e9eff"},
+  "makeup": {:hex, :makeup, "1.1.0", "6b67c8bc2882a6b6a445859952a602afc1a41c2e08379ca057c0f525366fc3ca", [:mix], [{:nimble_parsec, "~> 1.2.2 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "0a45ed501f4a8897f580eabf99a2e5234ea3e75a4373c8a52824f6e873be57a6"},
+  "makeup_elixir": {:hex, :makeup_elixir, "0.16.0", "f8c570a0d33f8039513fbccaf7108c5d750f47d8defd44088371191b76492b0b", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "28b2cbdc13960a46ae9a8858c4bebdec3c9a6d7b4b9e7f4ed1502f8159f338e7"},
+  "makeup_erlang": {:hex, :makeup_erlang, "0.1.1", "3fcb7f09eb9d98dc4d208f49cc955a34218fc41ff6b84df7c75b3e6e533cc65f", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "174d0809e98a4ef0b3309256cbf97101c6ec01c4ab0b23e926a9e17df2077cbb"},
   "merkle_map": {:hex, :merkle_map, "0.2.0", "5391ac61e016ce4aeb66ce39f05206a382fd4b66ee4b63c08a261d5633eadd76", [:mix], [], "hexpm", "fb1cc3a80e0b0d439a83bdb42bde4d03e8970a436bc949b9fa8d951c18fdafde"},
-  "nimble_parsec": {:hex, :nimble_parsec, "0.5.3", "def21c10a9ed70ce22754fdeea0810dafd53c2db3219a0cd54cf5526377af1c6", [:mix], [], "hexpm", "589b5af56f4afca65217a1f3eb3fee7e79b09c40c742fddc1c312b3ac0b3399f"},
+  "nimble_parsec": {:hex, :nimble_parsec, "1.2.3", "244836e6e3f1200c7f30cb56733fd808744eca61fd182f731eac4af635cc6d0b", [:mix], [], "hexpm", "c8d789e39b9131acf7b99291e93dae60ab48ef14a7ee9d58c6964f59efb570b0"},
   "telemetry": {:hex, :telemetry, "0.4.1", "ae2718484892448a24470e6aa341bc847c3277bfb8d4e9289f7474d752c09c7f", [:rebar3], [], "hexpm", "4738382e36a0a9a2b6e25d67c960e40e1a2c95560b9f936d8e29de8cd858480f"},
   "telemetry_poller": {:hex, :telemetry_poller, "0.4.1", "50d03d976a3b8ab4898d9e873852e688840df47685a13af90af40e1ba43a758b", [:rebar3], [{:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "c5bacbbcd62c1fe4e4517485bd64312622e9b83683273dcf2627ff224d7d485b"},
 }

test/cluster_test.exs

@@ -51,7 +51,7 @@ defmodule SwormClusterTest do
       # settle
       wait_until(fn ->
         match?(
-          [[{"hi", _}], [{"hi", _}]],
+          [[{"hi", p}], [{"hi", p}]],
           Cluster.members(c) |> Enum.map(fn n -> Cluster.call(n, Swurm, :registered, []) end)
         )
       end)
@@ -180,4 +180,42 @@ defmodule SwormClusterTest do
       until_match([_], Cluster.call(a, Sworm.DirectoryManager, :nodes_for_sworm, [Swurm]))
     end
   end
+
+  require Logger
+
+  sworm_scenario Swurm, "given a partitioned cluster" do
+    test "resolves name conflicts", %{cluster: c} do
+      [a, b] = Cluster.members(c)
+      Cluster.partition(c, [[a], [b]])
+
+      assert {:ok, pid_a} = Cluster.call(a, Swurm, :start_one, ["hi"])
+      assert {:ok, pid_b} = Cluster.call(b, Swurm, :start_one, ["hi"])
+
+      assert pid_a != pid_b
+
+      Process.sleep(500)
+
+      Cluster.heal(c)
+
+      wait_until(fn ->
+        case {Cluster.call(a, Swurm, :registered, []), Cluster.call(b, Swurm, :registered, [])} do
+          {[{"hi", pid}], [{"hi", pid}]} ->
+            true
+
+          _ ->
+            false
+        end
+      end)
+
+      # we now have only one pid
+      [{"hi", pid}] = Cluster.call(a, Swurm, :registered, [])
+      [{"hi", ^pid}] = Cluster.call(b, Swurm, :registered, [])
+
+      # stop it before exiting
+      GenServer.stop(pid)
+
+      until_match([], Cluster.call(a, Swurm, :registered, []))
+      until_match([], Cluster.call(b, Swurm, :registered, []))
+    end
+  end
 end

test/support/helpers.ex

@@ -17,7 +17,8 @@ defmodule Sworm.Support.Helpers do
               Process.unlink(pid)
 
             mod ->
-              {:ok, pid} = mod.start_link()
+              opts = [delta_crdt_options: [sync_interval: 50]]
+              {:ok, pid} = mod.start_link(opts)
               Process.unlink(pid)
           end
 

test/sworm_test.exs

@@ -13,11 +13,13 @@ defmodule SwormTest do
   defmodule TestServer do
     use GenServer
 
-    def start_link() do
-      GenServer.start_link(__MODULE__, [])
+    def start_link(arg \\ []) do
+      GenServer.start_link(__MODULE__, arg)
     end
 
-    def init([]), do: {:ok, nil}
+    def init(_arg) do
+      {:ok, nil}
+    end
 
     def handle_call(:x, _from, state) do
       {:reply, :y, state}
@@ -117,16 +119,18 @@ defmodule SwormTest do
     assert [_] = delegates()
   end
 
+  require Logger
+
   test "remove from supervisor on name conflict" do
     # Simulate a network partition healing, 2 processes registered on
     # different nodes are reconciled.
 
     sworm(A)
     sworm(B)
 
-    assert {:ok, pid_a} = Sworm.register_name(A, "foo", TestServer, :start_link, [])
+    assert {:ok, pid_a} = Sworm.register_name(A, "foo", TestServer, :start_link, ["foo.A"])
     Process.sleep(10)
-    assert {:ok, pid_b} = Sworm.register_name(B, "foo", TestServer, :start_link, [])
+    assert {:ok, pid_b} = Sworm.register_name(B, "foo", TestServer, :start_link, ["foo.B"])
 
     Horde.Cluster.set_members(A.Registry, [A.Registry, B.Registry])
     Horde.Cluster.set_members(A.Supervisor, [A.Supervisor, B.Supervisor])
@@ -139,11 +143,13 @@ defmodule SwormTest do
     assert([{"foo", ^pid_b}] = Sworm.registered(A))
     assert([{"foo", ^pid_b}] = Sworm.registered(B))
 
+    # removed from A.Supervisor
     until_match(
-      [{:undefined, _delegate, _, _}],
+      [],
       Horde.DynamicSupervisor.which_children(A.Supervisor)
     )
 
+    # still exists on B.Supervisor
     until_match(
       [{:undefined, _delegate, _, _}],
       Horde.DynamicSupervisor.which_children(B.Supervisor)