From fefb5d039e87ff7137e78b3d5f2eaf01e498ec4d Mon Sep 17 00:00:00 2001
From: Sverker Eriksson <sverker@erlang.org>
Date: Tue, 25 Sep 2018 13:34:52 +0200
Subject: erts: Add new module 'counters'

---
 erts/preloaded/src/counters.erl | 90 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 erts/preloaded/src/counters.erl

(limited to 'erts/preloaded/src/counters.erl')

diff --git a/erts/preloaded/src/counters.erl b/erts/preloaded/src/counters.erl
new file mode 100644
index 0000000000..67354f648d
--- /dev/null
+++ b/erts/preloaded/src/counters.erl
@@ -0,0 +1,90 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2018. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+
+%% Purpose : Main atomics API module.
+
+-module(counters).
+
+-export([new/2,
+         get/2,
+         add/3,
+         sub/3,
+         info/1]).
+
+-export_type([counters_ref/0]).
+
+-opaque counters_ref() :: {atomics, reference()} | {write_concurrency, reference()}.
+
+-spec new(Size, Opts) -> counters_ref() when
+      Size :: pos_integer(),
+      Opts :: [Opt],
+      Opt :: atomics | write_concurrency.
+new(Size, [atomics]) ->
+    {atomics, atomics:new(Size, [{signed, true}])};
+new(Size, [write_concurrency]) ->
+    {write_concurrency, erts_internal:counters_new(Size)};
+new(Size, []) ->
+    new(Size, [atomics]);
+new(_, _) ->
+    erlang:error(badarg).
+
+-spec get(Ref, Ix) -> integer() when
+      Ref  :: counters_ref(),
+      Ix :: integer().
+get({atomics,Ref}, Ix) ->
+    atomics:get(Ref, Ix);
+get({write_concurrency, Ref}, Ix) ->
+    erts_internal:counters_get(Ref, Ix);
+get(_, _) ->
+    erlang:error(badarg).
+
+
+
+-spec add(Ref, Ix, Incr) -> ok when
+      Ref  :: counters_ref(),
+      Ix :: integer(),
+      Incr :: integer().
+add({atomics, Ref}, Ix, Incr) ->
+    atomics:add(Ref, Ix, Incr);
+add({write_concurrency, Ref}, Ix, Incr) ->
+    erts_internal:counters_add(Ref, Ix, Incr);
+add(_, _, _) ->
+    erlang:error(badarg).
+
+
+-spec sub(Ref, Ix, Decr) -> ok when
+      Ref  :: counters_ref(),
+      Ix :: integer(),
+      Decr :: integer().
+sub(Ref, Ix, Decr) ->
+    add(Ref, Ix, -Decr).
+
+-spec info(Ref) -> Info when
+      Ref  :: counters_ref(),
+      Info :: #{'size':=Size, 'memory':=Memory},
+      Size :: non_neg_integer(),
+      Memory :: non_neg_integer().
+info({atomics, Ref}) ->
+    atomics:info(Ref);
+info({write_concurrency, Ref}) ->
+    erts_internal:counters_info(Ref);
+info(_) ->
+    erlang:error(badarg).
+
-- 
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