wterl/src/wterl_ets.erl
2012-04-05 16:10:50 -04:00

91 lines
2.8 KiB
Erlang

%% -------------------------------------------------------------------
%%
%% wterl_ets: ets table owner for wterl_conn
%%
%% Copyright (c) 2012 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you 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(wterl_ets).
-author('Steve Vinoski <steve@basho.com>').
-behaviour(gen_server).
%% ====================================================================
%% The sole purpose of this module is to own the ets table used by the
%% wterl_conn module. Holding the ets table in an otherwise do-nothing
%% server avoids losing the table and its contents should an unexpected
%% error occur in wterl_conn if it were the owner instead. This module
%% is unit-tested as part of the wterl_conn module.
%% ====================================================================
%% API
-export([start_link/0, stop/0,
table_ready/0]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
-record(state, {
monitors :: ets:tid()
}).
%% ====================================================================
%% API
%% ====================================================================
-spec start_link() -> {ok, pid()} | {error, term()}.
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
-spec stop() -> ok.
stop() ->
gen_server:cast(?MODULE, stop).
-spec table_ready() -> boolean().
table_ready() ->
gen_server:call(?MODULE, table_ready).
%% ====================================================================
%% gen_server callbacks
%% ====================================================================
init([]) ->
Monitors = ets:new(?MODULE, [named_table,public]),
{ok, #state{monitors = Monitors}}.
handle_call(table_ready, _From, State) ->
%% Always return true since the table is prepared in init.
{reply, true, State};
handle_call(_Msg, _From, State) ->
{reply, ok, State}.
handle_cast(stop, State) ->
{stop, normal, State};
handle_cast(_Msg, State) ->
{noreply, State}.
handle_info(_Info, State) ->
{noreply, State}.
terminate(_Reason, #state{monitors=Monitors}) ->
ets:delete(Monitors),
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.