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%% The contents of this file are subject to the Mozilla Public License
%% Version 1.1 (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.mozilla.org/MPL/
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
%% License for the specific language governing rights and limitations
%% under the License.
%%
%% The Original Code is RabbitMQ.
%%
%% The Initial Developers of the Original Code are LShift Ltd,
%% Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd.
%%
%% Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd,
%% Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd
%% are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial
%% Technologies LLC, and Rabbit Technologies Ltd.
%%
%% Portions created by LShift Ltd are Copyright (C) 2007-2009 LShift
%% Ltd. Portions created by Cohesive Financial Technologies LLC are
%% Copyright (C) 2007-2009 Cohesive Financial Technologies
%% LLC. Portions created by Rabbit Technologies Ltd are Copyright
%% (C) 2007-2009 Rabbit Technologies Ltd.
%%
%% All Rights Reserved.
%%
%% Contributor(s): ______________________________________.
%%
-module(rabbit_memsup_linux).
-export([init/0, update/1, get_memory_data/1]).
-record(state, {total_memory,
allocated_memory}).
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-type(state() :: #state { total_memory :: ('undefined' | non_neg_integer()),
allocated_memory :: ('undefined' | non_neg_integer())
}).
-spec(init/0 :: () -> state()).
-spec(update/1 :: (state()) -> state()).
-spec(get_memory_data/1 :: (state()) -> {non_neg_integer(), non_neg_integer(),
('undefined' | pid())}).
-endif.
%%----------------------------------------------------------------------------
init() ->
#state{total_memory = undefined,
allocated_memory = undefined}.
update(State) ->
File = read_proc_file("/proc/meminfo"),
Lines = string:tokens(File, "\n"),
Dict = dict:from_list(lists:map(fun parse_line/1, Lines)),
[MemTotal, MemFree, Buffers, Cached] =
[dict:fetch(Key, Dict) ||
Key <- ['MemTotal', 'MemFree', 'Buffers', 'Cached']],
MemUsed = MemTotal - MemFree - Buffers - Cached,
State#state{total_memory = MemTotal, allocated_memory = MemUsed}.
get_memory_data(State) ->
{State#state.total_memory, State#state.allocated_memory, undefined}.
%%----------------------------------------------------------------------------
-define(BUFFER_SIZE, 1024).
%% file:read_file does not work on files in /proc as it seems to get
%% the size of the file first and then read that many bytes. But files
%% in /proc always have length 0, we just have to read until we get
%% eof.
read_proc_file(File) ->
{ok, IoDevice} = file:open(File, [read, raw]),
Res = read_proc_file(IoDevice, []),
file:close(IoDevice),
lists:flatten(lists:reverse(Res)).
read_proc_file(IoDevice, Acc) ->
case file:read(IoDevice, ?BUFFER_SIZE) of
{ok, Res} -> read_proc_file(IoDevice, [Res | Acc]);
eof -> Acc
end.
%% A line looks like "FooBar: 123456 kB"
parse_line(Line) ->
[Name, RHS | _Rest] = string:tokens(Line, ":"),
[Value | UnitsRest] = string:tokens(RHS, " "),
Value1 = case UnitsRest of
[] -> list_to_integer(Value); %% no units
["kB"] -> list_to_integer(Value) * 1024
end,
{list_to_atom(Name), Value1}.
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