future

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-module(future_manual).

-export([create/0]).

%% Creates a future that only resolves when it recieves a message

%% 

%% The future will resolve with the value of the message

%% 

%% To send a message use the returned functions

%%

%% Returns [resolve, reject, fail, future]

%% 

%% > Please note that lifecycle management of this future is managed by YOU!

%% > You MUST release it when you are done with it else have a memory leak! (This comes from how the erlang gc works)

%% > If you want to immediately release the future on completion then use `auto_release`!

create() ->
    Ref = make_ref(),
    FuturePid = 'futureFfi':start(fun(RequiredRef) when is_reference(RequiredRef) ->
        receive
            {ok, RequiredRef, Result} ->
                {ok, Result};
            {error, RequiredRef, Result} ->
                {error, Result};
            {failed, RequiredRef, Result} when is_binary(Result) ->
                {failed, Result};
            {failed, RequiredRef, _} ->
                {failed, <<"Manual future recieved invalid message. Must fail with a binary reason."/utf8>>}
        end
    end, Ref),
    case catch gen_server:call(FuturePid, get_child) of
        {'EXIT', _} ->
            throw(<<"Manual future failed to start"/utf8>>);
        nil ->
            throw(<<"Manual future resolved too early"/utf8>>);
        ChildPid when is_pid(ChildPid) ->
            {fun (Value) ->
                ChildPid ! {ok, Ref, Value},
                ok
            end, fun (Value) ->
                ChildPid ! {error, Ref, Value},
                ok
            end, fun (Reason) when is_binary(Reason) ->
                ChildPid ! {failed, Ref, Reason},
                ok
            end, FuturePid};
        _ ->
            throw(<<"Manual future has invalid child pid response"/utf8>>)
    end.