emqx_pd.erl

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%% Copyright (c) 2018-2022 EMQ Technologies Co., Ltd. All Rights Reserved.
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%% 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
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%%     http://www.apache.org/licenses/LICENSE-2.0
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%% distributed under the License is distributed on an "AS IS" BASIS,
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%% @doc The utility functions for erlang process dictionary.
-module(emqx_pd).

-include("types.hrl").

-export([ get_counters/1
        , get_counter/1
        , inc_counter/2
        , reset_counter/1
        ]).

-compile({inline,
          [ get_counters/1
          , get_counter/1
          , inc_counter/2
          , reset_counter/1
          ]}).

-type(key() :: term()).

-spec(get_counters(list(key())) -> list({key(), number()})).
get_counters(Keys) when is_list(Keys) ->
    [{Key, emqx_pd:get_counter(Key)} || Key <- Keys].

-spec(get_counter(key()) -> number()).
get_counter(Key) ->
    case get(Key) of undefined -> 0; Cnt -> Cnt end.

-spec(inc_counter(key(), number()) -> maybe(number())).
inc_counter(Key, Inc) ->
    put(Key, get_counter(Key) + Inc).

-spec(reset_counter(key()) -> number()).
reset_counter(Key) ->
    case put(Key, 0) of undefined -> 0; Cnt -> Cnt end.