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