Add emqttd_misc module

src/emqttd_misc.erl

@@ -0,0 +1,63 @@
+%%--------------------------------------------------------------------
+%% Copyright (c) 2013-2017 EMQ Enterprise, Inc. (http://emqtt.io)
+%%
+%% 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
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%--------------------------------------------------------------------
+
+-module(emqttd_misc).
+
+-author("Feng Lee <feng@emqtt.io>").
+
+-export([merge_opts/2, start_timer/2, start_timer/3, cancel_timer/1,
+         proc_stats/0, proc_stats/1]).
+
+%% @doc Merge Options
+merge_opts(Defaults, Options) ->
+    lists:foldl(
+        fun({Opt, Val}, Acc) ->
+                case lists:keymember(Opt, 1, Acc) of
+                    true  -> lists:keyreplace(Opt, 1, Acc, {Opt, Val});
+                    false -> [{Opt, Val}|Acc]
+                end;
+            (Opt, Acc) ->
+                case lists:member(Opt, Acc) of
+                    true  -> Acc;
+                    false -> [Opt | Acc]
+                end
+        end, Defaults, Options).
+
+-spec(start_timer(integer(), term()) -> reference()).
+start_timer(Interval, Msg) ->
+    start_timer(Interval, self(), Msg).
+
+-spec(start_timer(integer(), pid() | atom(), term()) -> reference()).
+start_timer(Interval, Dest, Msg) ->
+    erlang:start_timer(Interval, Dest, Msg).
+
+-spec(cancel_timer(undefined | reference()) -> ok).
+cancel_timer(undefined) ->
+    ok;
+cancel_timer(Timer) ->
+    case catch erlang:cancel_timer(Timer) of
+        false -> receive {timeout, Timer, _} -> ok after 0 -> ok end;
+        _ -> ok
+    end.
+
+proc_stats() ->
+    proc_stats(self()).
+
+proc_stats(Pid) ->
+    Stats = process_info(Pid, [message_queue_len, heap_size, reductions]),
+    {value, {_, V}, Stats1} = lists:keytake(message_queue_len, 1, Stats),
+    [{mailbox_len, V} | Stats1].
+