From ac2041abf768e94c38b0c9906959568e66183b1a Mon Sep 17 00:00:00 2001
From: Nick Vatamaniuc <vatamane@apache.org>
Date: Wed, 1 May 2019 10:05:44 -0400
Subject: Revert to using the older rexi kill messages

In a future release, once all nodes know how to handle kill_all message will
re-enable it.

In low traffic clusters this might not be an issue, as the extra workers would
time out and exit eventually, but in busy clusters this could cause
couch_server and other message backups as while the upgrade is happening
workers would not be terminate quickly enough.
---
 src/rexi/src/rexi.erl | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/src/rexi/src/rexi.erl b/src/rexi/src/rexi.erl
index 21e2b5388..712e4c3c3 100644
--- a/src/rexi/src/rexi.erl
+++ b/src/rexi/src/rexi.erl
@@ -80,13 +80,22 @@ kill(Node, Ref) ->
 %% No rexi_EXIT message will be sent.
 -spec kill_all([{node(), reference()}]) -> ok.
 kill_all(NodeRefs) when is_list(NodeRefs) ->
-    PerNodeMap = lists:foldl(fun({Node, Ref}, Acc) ->
-        maps:update_with(Node, fun(Refs) -> [Ref | Refs] end, [Ref], Acc)
-    end, #{}, NodeRefs),
-    maps:map(fun(Node, Refs) ->
-        rexi_utils:send(rexi_utils:server_pid(Node), cast_msg({kill_all, Refs}))
-    end, PerNodeMap),
-    ok.
+    lists:foreach(fun({Node, Ref}) -> kill(Node, Ref) end, NodeRefs).
+
+%% Upgrade clause. Since kill_all is a new message, nodes in a mixed
+%% cluster won't know how to process it. In that case, opt to send the older
+%% kill message. In a future release, once all the nodes know how to handle
+%% kill_all, switch to using this implemention
+%%
+%% kill_all(NodeRefs) when is_list(NodeRefs) ->
+%%     PerNodeMap = lists:foldl(fun({Node, Ref}, Acc) ->
+%%         maps:update_with(Node, fun(Refs) -> [Ref | Refs] end, [Ref], Acc)
+%%     end, #{}, NodeRefs),
+%%     maps:map(fun(Node, Refs) ->
+%%         rexi_utils:send(rexi_utils:server_pid(Node), cast_msg({kill_all, Refs}))
+%%     end, PerNodeMap),
+%%     ok.
+
 
 %% @equiv async_server_call(Server, self(), Request)
 -spec async_server_call(pid() | {atom(),node()}, any()) -> reference().
-- 
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