[GitHub] couchdb-couch-epi pull request: Simplify couch epi

[rnewson <gi...@git.apache.org>]

Github user rnewson commented on a diff in the pull request:

    https://github.com/apache/couchdb-couch-epi/pull/12#discussion_r40695366
  
    --- Diff: src/couch_epi_data.erl ---
    @@ -12,131 +12,103 @@
     
     -module(couch_epi_data).
     
    --behaviour(gen_server).
    +-include("couch_epi.hrl").
     
     %% ------------------------------------------------------------------
     %% API Function Exports
     %% ------------------------------------------------------------------
     
    --export([childspec/4]).
    --export([start_link/4, reload/1]).
    --export([wait/1, stop/1]).
    -
    -%% ------------------------------------------------------------------
    -%% gen_server Function Exports
    -%% ------------------------------------------------------------------
    -
    --export([init/1, handle_call/3, handle_cast/2, handle_info/2,
    -         terminate/2, code_change/3]).
    -
    --record(state, {
    -    subscriber, module, key, hash, handle,
    -    initialized = false, pending = []}).
    +-export([interval/1, data/1]).
     
     %% ------------------------------------------------------------------
     %% API Function Definitions
     %% ------------------------------------------------------------------
     
    -childspec(Id, App, EpiKey, Module) ->
    -    {
    -        Id,
    -        {?MODULE, start_link, [
    -            App,
    -            EpiKey,
    -            Module,
    -            []
    -        ]},
    -        permanent,
    -        5000,
    -        worker,
    -        [Module]
    -    }.
    -
    -start_link(SubscriberApp, {epi_key, Key}, Module, Options) ->
    -    maybe_start_keeper(Key),
    -    gen_server:start_link(?MODULE, [SubscriberApp, Module, Key, Options], []).
    -
    -reload(Server) ->
    -    gen_server:call(Server, reload).
    -
    -wait(Server) ->
    -    gen_server:call(Server, wait).
    -
    -stop(Server) ->
    -    catch gen_server:call(Server, stop).
    +interval(Specs) ->
    +    extract_minimal_interval(Specs).
     
    -%% ------------------------------------------------------------------
    -%% gen_server Function Definitions
    -%% ------------------------------------------------------------------
    -
    -init([Subscriber, Module, Key, _Options]) ->
    -    gen_server:cast(self(), init),
    -    {ok, #state{
    -        subscriber = Subscriber,
    -        module = Module,
    -        key = Key,
    -        handle = couch_epi_data_gen:get_handle(Key)}}.
    -
    -handle_call(wait, _From, #state{initialized = true} = State) ->
    -    {reply, ok, State};
    -handle_call(wait, From, #state{pending = Pending} = State) ->
    -    {noreply, State#state{pending = [From | Pending]}};
    -handle_call(reload, _From, State) ->
    -    {Res, NewState} = reload_if_updated(State),
    -    {reply, Res, NewState};
    -handle_call(stop, _From, State) ->
    -    {stop, normal, State};
    -handle_call(_Request, _From, State) ->
    -    {reply, ok, State}.
    -
    -handle_cast(init, #state{pending = Pending} = State) ->
    -    {_, NewState} = reload_if_updated(State),
    -    [gen_server:reply(Client, ok) || Client <- Pending],
    -    {noreply, NewState#state{initialized = true, pending = []}};
    -handle_cast(_Msg, State) ->
    -    {noreply, State}.
    -
    -handle_info(_Info, State) ->
    -    {noreply, State}.
    -
    -terminate(_Reason, _State) ->
    -    ok.
    -
    -code_change(_OldVsn, State, _Extra) ->
    -    {_, NewState} = reload_if_updated(State),
    -    {ok, NewState}.
    +data(Specs) ->
    +    Locators = locate_sources(Specs),
    +    case lists:foldl(fun collect_data/2, {ok, [], []}, Locators) of
    +        {ok, Hashes, Data} ->
    +            {ok, couch_epi_util:hash(Hashes), Data};
    +        Error ->
    +            Error
    +    end.
     
     %% ------------------------------------------------------------------
     %% Internal Function Definitions
     %% ------------------------------------------------------------------
     
    -reload_if_updated(#state{hash = OldHash, module = Module} = State) ->
    -    case couch_epi_functions_gen:hash([Module]) of
    -        OldHash ->
    -            {ok, State};
    -        Hash ->
    -            safe_set(Hash, State)
    +collect_data({App, Locator}, {ok, HashAcc, DataAcc}) ->
    +    case definitions(Locator) of
    +        {ok, Hash, Data} ->
    +            {ok, [Hash | HashAcc], [{App, Data} | DataAcc]};
    +        Error ->
    +            Error
    +    end;
    +collect_data({_App, _Locator}, Error) ->
    +    Error.
    +
    +extract_minimal_interval(Specs) ->
    +    lists:foldl(fun minimal_interval/2, undefined, Specs).
    +
    +minimal_interval({_App, #couch_epi_spec{options = Options}}, Min) ->
    +    case lists:keyfind(interval, 1, Options) of
    +        {interval, Interval} -> min(Interval, Min);
    +        false -> Min
         end.
     
    -safe_set(Hash, #state{} = State) ->
    -    #state{
    -        handle = Handle,
    -        subscriber = Subscriber,
    -        module = Module,
    -        key = Key} = State,
    -    try
    -        Data = get_from_module(Module),
    -        OldData = couch_epi_data_gen:current_data(Handle, Subscriber),
    -        ok = couch_epi_data_gen:set(Handle, Subscriber, Data),
    -        couch_epi_server:notify(Subscriber, Key, {data, OldData}, {data, Data}),
    -        {ok, State#state{hash = Hash}}
    -    catch Class:Reason ->
    -        {{Class, Reason}, State}
    +locate_sources(Specs) ->
    +    lists:map(fun({ProviderApp, #couch_epi_spec{value = Src}}) ->
    +        {ok, Locator} = locate(ProviderApp, Src),
    +        {ProviderApp, Locator}
    +    end, Specs).
    +
    +locate(App, {priv_file, FileName}) ->
    +    case priv_path(App, FileName) of
    +        {ok, FilePath} ->
    +            ok = ensure_exists(FilePath),
    +            {ok, {file, FilePath}};
    +        Else ->
    +            Else
    +    end;
    +locate(_App, {file, FilePath}) ->
    +    ok = ensure_exists(FilePath),
    +    {ok, {file, FilePath}};
    +locate(_App, Locator) ->
    +    {ok, Locator}.
    +
    +priv_path(AppName, FileName) ->
    +    case code:priv_dir(AppName) of
    +        {error, _Error} = Error ->
    +            Error;
    +        Dir ->
    +            {ok, filename:join(Dir, FileName)}
         end.
     
    -get_from_module(Module) ->
    -    Module:data().
    +ensure_exists(FilePath) ->
    +    case filelib:is_regular(FilePath) of
    +        true ->
    +            ok;
    +        false ->
    +            {error, {notfound, FilePath}}
    --- End diff --
    
    given that every call to it does `ok = ensure_exists(`, why not call filelib:is_regular directly?


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