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%%% Copyright (c) 2014-2015, NORDUnet A/S.
%%% See LICENSE for licensing information.
-module(fsdb).
-behaviour(gen_server).
-export([start_link/2, stop/1, init_module/0]).
-export([getvalue/2, addvalue/3, commit/1, commit/2]).
%% gen_server callbacks.
-export([init/1, handle_call/3, terminate/2, handle_cast/2, handle_info/2,
code_change/3]).
-record(state, {name, dirtylistname}).
-define(DIRECTORY_TABLE, perm_directory).
init_module() ->
case ets:info(?DIRECTORY_TABLE) of
undefined -> ok;
_ -> ets:delete(?DIRECTORY_TABLE)
end,
ets:new(?DIRECTORY_TABLE, [set, public, named_table]).
start_link(Name, Filename) ->
gen_server:start_link({local, Name}, ?MODULE,
[Name, Filename], []).
stop(Name) ->
gen_server:call(Name, stop).
addfsyncfiles(Name, Files) ->
gen_server:call(Name, {addfsyncfiles, Files}).
init([Name, Filename]) ->
Dirtylistname = list_to_atom(atom_to_list(Name) ++ "_dirty"),
true = ets:insert(?DIRECTORY_TABLE, {Name, Filename ++ "/"}),
ets:new(Dirtylistname, [set, public, named_table]),
{ok, #state{name = Name, dirtylistname = Dirtylistname}}.
handle_cast(_Request, State) ->
{noreply, State}.
handle_info(_Info, State) ->
{noreply, State}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
terminate(_Reason, _State) ->
io:format("~p terminating~n", [?MODULE]),
ok.
handle_call({addfsyncfiles, Files}, _From, State) ->
Insert = lists:map(fun (File) -> {File} end, Files),
ets:insert(State#state.dirtylistname, Insert),
{reply, ok, State};
handle_call({commit, Timeout}, _From, State) ->
lager:debug("doing commit for ~p", [State#state.name]),
Files = lists:map(fun ([File]) -> File end, ets:match(State#state.dirtylistname, {'$1'})),
util:fsync(Files, Timeout),
ets:delete_all_objects(State#state.dirtylistname),
{reply, ok, State};
handle_call(stop, _From, State) ->
{stop, normal, stopped, State}.
getvalue(Name, Key) ->
[{_, Filename}] = ets:lookup(?DIRECTORY_TABLE, Name),
readfile(Filename, Key).
addvalue(Name, Key, Value) ->
[{_, Filename}] = ets:lookup(?DIRECTORY_TABLE, Name),
{Result, FsyncFiles} = ensurefile(Filename, Key, Value),
addfsyncfiles(Name, FsyncFiles),
Result.
commit(Name) ->
commit(Name, 5000).
commit(Name, Timeout) ->
gen_server:call(Name, {commit, Timeout}, Timeout).
-spec readfile_and_verify(string(), binary()) -> ok | differ | {error, atom()}.
readfile_and_verify(Name, Content) ->
case file:read_file(Name) of
{ok, ContentsRead} when Content == ContentsRead ->
ok;
{ok, _ContentsRead} ->
differ;
{error, Error} ->
{error, Error}
end.
-spec make_dir(string()) -> ok | {error, atom()}.
make_dir(Name) ->
case file:make_dir(Name) of
ok ->
ok;
{error, eexist} ->
ok;
{error, Error} ->
{error, Error}
end.
-spec make_dirs([string()]) -> ok | {error, atom()}.
make_dirs([]) ->
ok;
make_dirs([Name | Rest]) ->
case make_dir(Name) of
ok ->
make_dirs(Rest);
{error, Error} ->
{error, Error}
end.
-spec path_for_key(string(), binary()) -> {[string()], string()}.
path_for_key(Rootdir, Key) ->
Name = hex:bin_to_hexstr(Key),
[C1, C2, C3, C4, C5, C6 | _] = Name,
Firstlevel = Rootdir ++ [C1, C2],
Secondlevel = Firstlevel ++ "/" ++ [C3, C4],
Thirdlevel = Secondlevel ++ "/" ++ [C5, C6],
Fullpath = Thirdlevel ++ "/" ++ Name,
{[Firstlevel, Secondlevel, Thirdlevel], Fullpath}.
ensurefile(Rootdir, Key, Content) ->
lager:debug("dir ~p key ~s", [Rootdir, mochihex:to_hex(Key)]),
{Dirs, Path} = path_for_key(Rootdir, Key),
Result =
case readfile_and_verify(Path, Content) of
ok ->
lager:debug("key ~s existed, fsync", [mochihex:to_hex(Key)]),
ok = util:fsync([Path, Rootdir | Dirs]),
lager:debug("key ~s fsynced", [mochihex:to_hex(Key)]),
ok;
differ ->
lager:debug("key ~s existed, was different",
[mochihex:to_hex(Key)]),
differ;
{error, enoent} ->
lager:debug("key ~s didn't exist, add", [mochihex:to_hex(Key)]),
util:check_error(make_dirs([Rootdir, Rootdir ++ "nursery/"]
++ Dirs),
makedir, "Error creating directory"),
NurseryName = Rootdir ++ "nursery/" ++
util:tempfilename(hex:bin_to_hexstr(Key)),
util:write_tempfile_and_rename(Path, NurseryName, Content),
ok;
{error, Error} ->
util:exit_with_error(Error, readfile, "Error reading file")
end,
{Result, [Path, Rootdir | Dirs]}.
-spec readfile(string(), binary()) -> binary() | noentry.
readfile(Rootdir, Key) ->
{_Dirs, Path} = path_for_key(Rootdir, Key),
atomic:readfile(Path).
|
