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%%% Copyright (c) 2015, NORDUnet A/S.
%%% See LICENSE for licensing information.
%%%
-module(ratelimit).
-behaviour(gen_server).
-export([start_link/0, stop/0]).
-export([get_token/1]).
%% gen_server callbacks.
-export([init/1, handle_call/3, terminate/2, handle_cast/2, handle_info/2,
code_change/3]).
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE,
application:get_env(catlfish, ratelimits, []), []).
stop() ->
gen_server:call(?MODULE, stop).
get_token(Type) ->
gen_server:call(?MODULE, {get_token, Type}).
init(Types) ->
lager:debug("starting ratelimit service"),
State = dict:from_list([{Type, {Rules, queue:new()}}
|| {Type, Rules} <- Types]),
{ok, State}.
rule_interval_atom([{_, Interval}]) ->
Interval.
rule_interval([{_, second}]) ->
1000;
rule_interval([{_, minute}]) ->
60*1000;
rule_interval([{_, hour}]) ->
60*60*1000.
rule_times([{Times, _}]) when is_integer(Times) ->
Times.
clean_queue(Interval, Queue) ->
Now = plop:generate_timestamp(),
case queue:peek(Queue) of
{value, Item} when Item + Interval < Now ->
clean_queue(Interval, queue:drop(Queue));
_ ->
Queue
end.
get_token_for_type({none, Queue}) ->
{ok, {none, Queue}};
get_token_for_type({Rules, Queue}) ->
CleanedQueue = clean_queue(rule_interval(Rules), Queue),
MaxTimes = rule_times(Rules),
QueueLength = queue:len(CleanedQueue),
if
QueueLength < MaxTimes ->
Now = plop:generate_timestamp(),
{ok, {Rules, queue:in(Now, CleanedQueue)}};
true ->
{overload, {Rules, CleanedQueue}}
end.
handle_call(stop, _From, State) ->
{stop, normal, stopped, State};
handle_call({get_token, Type}, _From, State) ->
case dict:find(Type, State) of
{ok, TypeState} ->
{Result, NewTypeState} = get_token_for_type(TypeState),
{Rules, Queue} = NewTypeState,
lager:debug("current rate: ~p per ~p",
[queue:len(Queue), rule_interval_atom(Rules)]),
{reply, Result, dict:store(Type, NewTypeState, State)};
error ->
{reply, ok, State}
end.
handle_cast(_Request, State) ->
{noreply, State}.
handle_info(_Info, State) ->
{noreply, State}.
code_change(_OldVersion, State, _Extra) ->
{ok, State}.
terminate(_Reason, _State) ->
ok.
|
