Add a locker module

src/emqx_locker.erl

@@ -0,0 +1,41 @@
+%%--------------------------------------------------------------------
+%% Copyright (c) 2013-2018 EMQ Enterprise, Inc. All Rights Reserved.
+%%
+%% 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(emqx_locker).
+
+-export([start_link/0]).
+
+%% Lock/Unlock API based on canal-lock.
+-export([lock/1, unlock/1]).
+
+%% @doc Starts the lock server
+-spec(start_link() -> {ok, pid()} | ignore | {error, any()}).
+start_link() ->
+    canal_lock:start_link(?MODULE, 1).
+
+%% @doc Lock a Key
+-spec(lock(binary()) -> boolean()).
+lock(Key) ->
+    case canal_lock:acquire(?MODULE, Key, 1, 1) of
+        {acquired, 1} -> true;
+        full -> false
+    end.
+
+%% @doc Unlock a Key
+-spec(unlock(binary()) -> ok).
+unlock(Key) ->
+    canal_lock:release(?MODULE, Key, 1, 1).
+