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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) 2007-2010 LShift
%% Ltd. Portions created by Cohesive Financial Technologies LLC are
%% Copyright (C) 2007-2010 Cohesive Financial Technologies
%% LLC. Portions created by Rabbit Technologies Ltd are Copyright
%% (C) 2007-2010 Rabbit Technologies Ltd.
%%
%% All Rights Reserved.
%%
%% Contributor(s): ______________________________________.
%%
-module(rabbit_alarm).
-behaviour(gen_event).
-export([start/0, stop/0, register/2]).
-export([init/1, handle_call/2, handle_event/2, handle_info/2,
terminate/2, code_change/3]).
-record(alarms, {alertees, vm_memory_high_watermark = false}).
%%----------------------------------------------------------------------------
-ifdef(use_specs).
-type(mfa_tuple() :: {atom(), atom(), list()}).
-spec(start/0 :: () -> 'ok').
-spec(stop/0 :: () -> 'ok').
-spec(register/2 :: (pid(), mfa_tuple()) -> 'ok').
-endif.
%%----------------------------------------------------------------------------
start() ->
ok = alarm_handler:add_alarm_handler(?MODULE, []),
{ok, MemoryWatermark} = application:get_env(vm_memory_high_watermark),
ok = case MemoryWatermark == 0 of
true ->
ok;
false ->
rabbit_sup:start_child(vm_memory_monitor, [MemoryWatermark])
end,
ok.
stop() ->
ok = alarm_handler:delete_alarm_handler(?MODULE).
register(Pid, HighMemMFA) ->
ok = gen_event:call(alarm_handler, ?MODULE,
{register, Pid, HighMemMFA},
infinity).
%%----------------------------------------------------------------------------
init([]) ->
{ok, #alarms{alertees = dict:new()}}.
handle_call({register, Pid, {M, F, A} = HighMemMFA},
State = #alarms{alertees = Alertess}) ->
_MRef = erlang:monitor(process, Pid),
ok = case State#alarms.vm_memory_high_watermark of
true -> apply(M, F, A ++ [Pid, true]);
false -> ok
end,
NewAlertees = dict:store(Pid, HighMemMFA, Alertess),
{ok, ok, State#alarms{alertees = NewAlertees}};
handle_call(_Request, State) ->
{ok, not_understood, State}.
handle_event({set_alarm, {vm_memory_high_watermark, []}}, State) ->
ok = alert(true, State#alarms.alertees),
{ok, State#alarms{vm_memory_high_watermark = true}};
handle_event({clear_alarm, vm_memory_high_watermark}, State) ->
ok = alert(false, State#alarms.alertees),
{ok, State#alarms{vm_memory_high_watermark = false}};
handle_event(_Event, State) ->
{ok, State}.
handle_info({'DOWN', _MRef, process, Pid, _Reason},
State = #alarms{alertees = Alertess}) ->
{ok, State#alarms{alertees = dict:erase(Pid, Alertess)}};
handle_info(_Info, State) ->
{ok, State}.
terminate(_Arg, _State) ->
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%----------------------------------------------------------------------------
alert(_Alert, undefined) ->
ok;
alert(Alert, Alertees) ->
dict:fold(fun (Pid, {M, F, A}, Acc) ->
ok = erlang:apply(M, F, A ++ [Pid, Alert]),
Acc
end, ok, Alertees).
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