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-module(kvs). | |
-behavior(gen_server). | |
-export([start/0, store/2, retrieve/1]). | |
-export([init/1, handle_call/3, handle_cast/2]). | |
-type from() :: {pid(), Tag :: term()}. %% gen_server doesn't export a from/0 type | |
-type key() :: atom(). | |
-type value() :: term(). | |
-type data() :: #{key() => value()}. | |
-type state() :: #{data := data()}. | |
-export_type([key/0, value/0]). | |
-spec start() -> {ok, pid()} | {error, term()}. | |
start() -> gen_server:start({local, ?MODULE}, ?MODULE, #{}, []). | |
-spec store(key(), value()) -> ok. | |
store(K, V) -> gen_server:cast(?MODULE, {store, K, V}). | |
-spec retrieve(key()) -> notfound | value(). | |
retrieve(K) -> gen_server:call(?MODULE, {retrieve, K}). | |
-spec init(map()) -> {ok, state()}. | |
init(#{}) -> {ok, #{data => #{}}}. | |
-spec handle_cast({store, key(), value()}, state()) -> {noreply, state()}. | |
handle_cast({store, K, V}, State = #{data := Data}) -> | |
{noreply, State#{data := Data#{K => V}}}. | |
-spec handle_call({retrieve, key()}, from(), state()) -> | |
{reply, notfound | value(), state()}. | |
handle_call({retrieve, K}, _From, State = #{data := Data}) -> | |
{reply, maps:get(K, Data, notfound), State}. |
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