From 7dd08d6d41fd77c447c99e07e62898ffcd757684 Mon Sep 17 00:00:00 2001
From: Darren Clark <darren.clark@thescore.com>
Date: Wed, 28 Aug 2019 11:19:05 -0400
Subject: [PATCH] Hardcode `:restart` handoff strategy

GenServer.call was blocking the process in high load situations when a
pod died.  All our processes use the :restart strategy anyways, so just
hardcode it in
---
 lib/swarm/tracker/tracker.ex | 42 +++++++++++++++++++-----------------
 1 file changed, 22 insertions(+), 20 deletions(-)

diff --git a/lib/swarm/tracker/tracker.ex b/lib/swarm/tracker/tracker.ex
index dec282e..a9a9fe9 100644
--- a/lib/swarm/tracker/tracker.ex
+++ b/lib/swarm/tracker/tracker.ex
@@ -856,25 +856,27 @@ defmodule Swarm.Tracker do
               debug("#{inspect(pid)} belongs on #{other_node}")
               # This process needs to be moved to the new node
               try do
-                case GenServer.call(pid, {:swarm, :begin_handoff}) do
-                  :ignore ->
-                    debug("#{inspect(name)} has requested to be ignored")
-                    state
-
-                  {:resume, handoff_state} ->
-                    debug("#{inspect(name)} has requested to be resumed")
-                    {:ok, new_state} = remove_registration(obj, state)
-                    send(pid, {:swarm, :die})
-                    debug("sending handoff for #{inspect(name)} to #{other_node}")
-
-                    GenStateMachine.cast(
-                      {__MODULE__, other_node},
-                      {:handoff, self(), {name, meta, handoff_state, Clock.peek(new_state.clock)}}
-                    )
-
-                    new_state
-
-                  :restart ->
+# All of our processes are meant to work with :restart, so skip the GenServer.call
+
+#                case GenServer.call(pid, {:swarm, :begin_handoff}) do
+#                  :ignore ->
+#                    debug("#{inspect(name)} has requested to be ignored")
+#                    state
+#
+#                  {:resume, handoff_state} ->
+#                    debug("#{inspect(name)} has requested to be resumed")
+#                    {:ok, new_state} = remove_registration(obj, state)
+#                    send(pid, {:swarm, :die})
+#                    debug("sending handoff for #{inspect(name)} to #{other_node}")
+#
+#                    GenStateMachine.cast(
+#                      {__MODULE__, other_node},
+#                      {:handoff, self(), {name, meta, handoff_state, Clock.peek(new_state.clock)}}
+#                    )
+#
+#                    new_state
+
+#                  :restart ->
                     debug("#{inspect(name)} has requested to be restarted")
                     {:ok, new_state} = remove_registration(obj, state)
                     send(pid, {:swarm, :die})
@@ -883,7 +885,7 @@ defmodule Swarm.Tracker do
                       :keep_state_and_data -> new_state
                       {:keep_state, new_state} -> new_state
                     end
-                end
+#                end
               catch
                 _, err ->
                   warn("handoff failed for #{inspect(name)}: #{inspect(err)}")