add alarm

apps/emqttd/src/emqttd_alarm.erl

@@ -0,0 +1,98 @@
+%%%-----------------------------------------------------------------------------
+%%% Copyright (c) 2012-2015 eMQTT.IO, All Rights Reserved.
+%%%
+%%% Permission is hereby granted, free of charge, to any person obtaining a copy
+%%% of this software and associated documentation files (the "Software"), to deal
+%%% in the Software without restriction, including without limitation the rights
+%%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+%%% copies of the Software, and to permit persons to whom the Software is
+%%% furnished to do so, subject to the following conditions:
+%%%
+%%% The above copyright notice and this permission notice shall be included in all
+%%% copies or substantial portions of the Software.
+%%%
+%%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+%%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+%%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+%%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+%%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+%%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+%%% SOFTWARE.
+%%%-----------------------------------------------------------------------------
+%%% @doc
+%%% copy alarm_handler.
+%%%
+%%% @end
+%%%-----------------------------------------------------------------------------
+
+-module(emqttd_alarm).
+
+-export([start_link/0, set_alarm/1, clear_alarm/1, get_alarms/0,
+	 add_alarm_handler/1, add_alarm_handler/2,
+	 delete_alarm_handler/1]).
+
+-export([init/1, handle_event/2, handle_call/2, handle_info/2,
+         terminate/2]).
+
+-define(SERVER, ?MODULE).
+
+-type alarm() :: {AlarmId :: any(), AlarmDescription :: string() | binary()}.
+
+start_link() ->
+    case gen_event:start_link({local, ?SERVER}) of
+	{ok, Pid} ->
+	    gen_event:add_handler(?SERVER, ?MODULE, []),
+	    {ok, Pid};
+	Error ->
+        Error
+    end.
+
+-spec set_alarm(alarm()) -> ok.
+set_alarm(Alarm) ->
+    gen_event:notify(?SERVER, {set_alarm, Alarm}).
+
+-spec clear_alarm(any()) -> ok.
+clear_alarm(AlarmId) ->
+    gen_event:notify(?SERVER, {clear_alarm, AlarmId}).
+
+get_alarms() ->
+    gen_event:call(?SERVER, ?MODULE, get_alarms).
+
+add_alarm_handler(Module) when is_atom(Module) ->
+    gen_event:add_handler(?SERVER, Module, []).
+
+add_alarm_handler(Module, Args) when is_atom(Module) ->
+    gen_event:add_handler(?SERVER, Module, Args).
+
+delete_alarm_handler(Module) when is_atom(Module) ->
+    gen_event:delete_handler(?SERVER, Module, []).
+
+%%-----------------------------------------------------------------
+%% Default Alarm handler
+%%-----------------------------------------------------------------
+   
+init(_) -> {ok, []}.
+    
+handle_event({set_alarm, Alarm}, Alarms)->
+    %%TODO: publish to $SYS
+    {ok, [Alarm | Alarms]};
+
+handle_event({clear_alarm, AlarmId}, Alarms)->
+    %TODO: publish to $SYS
+    {ok, lists:keydelete(AlarmId, 1, Alarms)};
+
+handle_event(_, Alarms)->
+    {ok, Alarms}.
+
+handle_info(_, Alarms) -> {ok, Alarms}.
+
+handle_call(get_alarms, Alarms) -> {ok, Alarms, Alarms};
+
+handle_call(_Query, Alarms)     -> {ok, {error, bad_query}, Alarms}.
+
+terminate(swap, Alarms) ->
+    {?MODULE, Alarms};
+
+terminate(_, _) ->
+    ok.
+