cloudi_core

%-*-Mode:erlang;coding:utf-8;tab-width:4;c-basic-offset:4;indent-tabs-mode:()-*-
% ex: set ft=erlang fenc=utf-8 sts=4 ts=4 sw=4 et nomod:
%%%
%%%------------------------------------------------------------------------
%%% @doc
%%% ==CloudI Concurrency==
%%% @end
%%%
%%% BSD LICENSE
%%% 
%%% Copyright (c) 2014, Michael Truog <mjtruog at gmail dot com>
%%% All rights reserved.
%%% 
%%% Redistribution and use in source and binary forms, with or without
%%% modification, are permitted provided that the following conditions are met:
%%% 
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%%%       notice, this list of conditions and the following disclaimer.
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%%%       the documentation and/or other materials provided with the
%%%       distribution.
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%%%       software must display the following acknowledgment:
%%%         This product includes software developed by Michael Truog
%%%     * The name of the author may not be used to endorse or promote
%%%       products derived from this software without specific prior
%%%       written permission
%%% 
%%% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
%%% CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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%%% @author Michael Truog <mjtruog [at] gmail (dot) com>
%%% @copyright 2014 Michael Truog
%%% @version 1.3.3 {@date} {@time}
%%%------------------------------------------------------------------------

-module(cloudi_concurrency).
-author('mjtruog [at] gmail (dot) com').

%% external interface
-export([count/1]).

%%%------------------------------------------------------------------------
%%% External interface functions
%%%------------------------------------------------------------------------

%%-------------------------------------------------------------------------
%% @doc
%% ===A count to be used for the number of service processes used.===
%% An integer is an absolute count while a floating point number is a
%% multiplier on the number of CPU cores available.  A floating point
%% number is rounded (or floor-ed) to be close to the CPU core count,
%% to avoid extremes.
%% @end
%%-------------------------------------------------------------------------

-spec count(I :: pos_integer() | float()) ->
    pos_integer().

count(I)
    when is_integer(I), I > 0 ->
    I;
count(I)
    when is_float(I) ->
    if
        I > 1.0 ->
            cloudi_math:floor(I * erlang:system_info(schedulers));
        I > 0.0, I < 1.0 ->
            erlang:max(1, erlang:round(I * erlang:system_info(schedulers)));
        I == 1.0 ->
            erlang:system_info(schedulers)
    end.