From faf86cb3cee3b241faf82b4dc347b0d2b0c58201 Mon Sep 17 00:00:00 2001
From: Anders Svensson <anders@erlang.org>
Date: Wed, 22 Jul 2015 00:43:35 +0200
Subject: Make ets diameter_stats a set

There's no need for it to be ordered, and the ordering has been seen to
have an unexpectedly negative impact on performance in some cases. Order
when retrieving statistics instead, so as not to change the
presentation in diameter:service_info/2.
---
 lib/diameter/src/base/diameter_stats.erl | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/lib/diameter/src/base/diameter_stats.erl b/lib/diameter/src/base/diameter_stats.erl
index d2c760317a..79a5c7b947 100644
--- a/lib/diameter/src/base/diameter_stats.erl
+++ b/lib/diameter/src/base/diameter_stats.erl
@@ -142,9 +142,14 @@ read(Refs, B) ->
     L.
 
 to_refdict(L) ->
-    lists:foldl(fun({{C,R}, N}, D) -> orddict:append(R, {C,N}, D) end,
-                orddict:new(),
-                L).
+    lists:foldl(fun append/2, orddict:new(), L).
+
+%% Order both references and counters in the returned list.
+append({{Ctr, Ref}, N}, Dict) ->
+    orddict:update(Ref,
+                   fun(D) -> orddict:store(Ctr, N, D) end,
+                   [{Ctr, N}],
+                   Dict).
 
 %% ---------------------------------------------------------------------------
 %% # sum(Refs)
@@ -220,10 +225,7 @@ uptime() ->
 %% ----------------------------------------------------------
 
 init([]) ->
-    ets:new(?TABLE, [named_table,
-                     ordered_set,
-                     public,
-                     {write_concurrency, true}]),
+    ets:new(?TABLE, [named_table, set, public, {write_concurrency, true}]),
     {ok, #state{}}.
 
 %% ----------------------------------------------------------
-- 
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