-module(albedo_settings_lock).
-export([with_lock/3]).

%% One daemon owns each home. This lock serializes its settings mutations,
%% including credential updates. It is not a lock shared with CLI processes.
%% Nested operations in the same process retain the outer lock until it exits.
with_lock(Home, Run, Busy) ->
    Directory = unicode:characters_to_binary(filename:absname(Home)),
    Key = {?MODULE, Directory},
    case get(Key) of
        held -> Run();
        _ ->
            Locked = fun() ->
                put(Key, held),
                try Run() after erase(Key) end
            end,
            case global:trans({Key, self()}, Locked, [node()], 8) of
                aborted -> Busy();
                Result -> Result
            end
    end.