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%% Copyright (c) 2013, Pedram Nimreezi <deadzen@deadzen.com>
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-module(gr_counter).
-behaviour(gen_server).
%% API
-export([start_link/1,
list/1, lookup_element/2,
update/3, reset_counters/2]).
%% gen_server callbacks
-export([init/1,
handle_call/3,
handle_cast/2,
handle_info/2,
terminate/2,
code_change/3]).
-record(state, {init=true, table_id}).
%%%===================================================================
%%% API
%%%===================================================================
list(Server) ->
gen_server:call(Server, list).
lookup_element(Server, Counter) ->
gen_server:call(Server, {lookup_element, Counter}).
update(Server, Counter, Value) ->
gen_server:cast(Server, {update, Counter, Value}).
reset_counters(Server, Counter) ->
gen_server:call(Server, {reset_counters, Counter}).
%%--------------------------------------------------------------------
%% @doc
%% Starts the server
%%
%% @spec start_link() -> {ok, Pid} | ignore | {error, Error}
%% @end
%%--------------------------------------------------------------------
start_link(Name) ->
gen_server:start_link({local, Name}, ?MODULE, [], []).
%%%===================================================================
%%% gen_server callbacks
%%%===================================================================
%%--------------------------------------------------------------------
%% @private
%% @doc
%% Initializes the server
%%
%% @spec init(Args) -> {ok, State} |
%% {ok, State, Timeout} |
%% ignore |
%% {stop, Reason}
%% @end
%%--------------------------------------------------------------------
init([]) ->
{ok, #state{}}.
%%--------------------------------------------------------------------
%% @private
%% @doc
%% Handling call messages
%%
%% @spec handle_call(Request, From, State) ->
%% {reply, Reply, State} |
%% {reply, Reply, State, Timeout} |
%% {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, Reply, State} |
%% {stop, Reason, State}
%% @end
%%--------------------------------------------------------------------
handle_call(list, _From, State) ->
TableId = State#state.table_id,
{reply, {ok, ets:tab2list(TableId)}, State};
handle_call({lookup_element, Counter}, _From, State) ->
TableId = State#state.table_id,
{reply, ets:lookup_element(TableId, Counter, 2), State};
handle_call({reset_counters, Counter}, _From, State) ->
TableId = State#state.table_id,
Reset = case Counter of
_ when is_list(Counter) ->
[{Item, 0} || Item <- Counter];
_ when is_atom(Counter) ->
[{Counter, 0}]
end,
{reply, ets:insert(TableId, Reset), State};
handle_call(_Request, _From, State) ->
Reply = {error, unhandled_message},
{reply, Reply, State}.
%%--------------------------------------------------------------------
%% @private
%% @doc
%% Handling cast messages
%%
%% @spec handle_cast(Msg, State) -> {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State}
%% @end
%%--------------------------------------------------------------------
handle_cast({update, Counter, Value}, State) ->
TableId = State#state.table_id,
ets:update_counter(TableId, Counter, Value),
{noreply, State};
handle_cast(_Msg, State) ->
{noreply, State}.
%%--------------------------------------------------------------------
%% @private
%% @doc
%% Handling all non call/cast messages
%%
%% @spec handle_info(Info, State) -> {noreply, State} |
%% {noreply, State, Timeout} |
%% {stop, Reason, State}
%% @end
%%--------------------------------------------------------------------
handle_info({'ETS-TRANSFER', TableId, _Pid, _Data}, State) ->
{noreply, State#state{table_id=TableId}};
handle_info(_Info, State) ->
{noreply, State}.
%%--------------------------------------------------------------------
%% @private
%% @doc
%% This function is called by a gen_server when it is about to
%% terminate. It should be the opposite of Module:init/1 and do any
%% necessary cleaning up. When it returns, the gen_server terminates
%% with Reason. The return value is ignored.
%%
%% @spec terminate(Reason, State) -> void()
%% @end
%%--------------------------------------------------------------------
terminate(_Reason, _State) ->
ok.
%%--------------------------------------------------------------------
%% @private
%% @doc
%% Convert process state when code is changed
%%
%% @spec code_change(OldVsn, State, Extra) -> {ok, NewState}
%% @end
%%--------------------------------------------------------------------
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%%===================================================================
%%% Internal functions
%%%===================================================================