-module(machi_plist). %%% @doc persistent list of binaries that support mutual exclusion -export([open/2, close/1, find/2, add/2]). -ifdef(TEST). -export([all/1]). -endif. -record(machi_plist, {filename :: file:filename_all(), fd :: file:io_device(), list = [] :: list(string)}). -type plist() :: #machi_plist{}. -export_type([plist/0]). -spec open(file:filename_all(), proplists:proplist()) -> {ok, plist()} | {error, file:posix()}. open(Filename, _Opt) -> List = case file:read_file(Filename) of {ok, <<>>} -> []; {ok, Bin} -> binary_to_term(Bin); {error, enoent} -> [] end, case file:open(Filename, [read, write, raw, binary, sync]) of {ok, Fd} -> {ok, #machi_plist{filename=Filename, fd=Fd, list=List}}; Error -> Error end. -spec close(plist()) -> ok. close(#machi_plist{fd=Fd}) -> _ = file:close(Fd). -spec find(plist(), string()) -> boolean(). find(#machi_plist{list=List}, Name) -> lists:member(Name, List). -spec add(plist(), string()) -> {ok, plist()} | {error, file:posix()}. add(Plist = #machi_plist{list=List0, fd=Fd}, Name) -> case find(Plist, Name) of true -> {ok, Plist}; false -> List = lists:append(List0, [Name]), case file:pwrite(Fd, 0, term_to_binary(List)) of ok -> {ok, Plist#machi_plist{list=List}}; Error -> Error end end. -ifdef(TEST). -spec all(plist()) -> [file:filename()]. all(#machi_plist{list=List}) -> List. -endif.