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Fix machi_flu_filename_mgr to avoid double-write errors during network partitions

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This commit is contained in:
Scott Lystig Fritchie 2016-02-10 18:17:15 +09:00
parent 546901ef49
commit ecfad4726b
1 changed files with 10 additions and 35 deletions
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45
src/machi_flu_filename_mgr.erl
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@ -100,7 +100,7 @@ find_or_make_filename_from_prefix(FluName, EpochId,
{coc, _CoC_Ns, _CoC_Loc}=CoC_NL)
when is_atom(FluName) ->
N = make_filename_mgr_name(FluName),
gen_server:call(N, {find_filename, EpochId, CoC_NL, Prefix}, ?TIMEOUT);
gen_server:call(N, {find_filename, FluName, EpochId, CoC_NL, Prefix}, ?TIMEOUT);
find_or_make_filename_from_prefix(_FluName, _EpochId, Other, Other2) ->
lager:error("~p is not a valid prefix/CoC ~p", [Other, Other2]),
error(badarg).
@ -142,14 +142,14 @@ handle_cast(Req, State) ->
%% the FLU has already validated that the caller's epoch id and the FLU's epoch id
%% are the same. So we *assume* that remains the case here - that is to say, we
%% are not wedged.
handle_call({find_filename, EpochId, CoC_NL, Prefix}, _From, S = #state{ datadir = DataDir,
handle_call({find_filename, FluName, EpochId, CoC_NL, Prefix}, _From, S = #state{ datadir = DataDir,
epoch = EpochId,
tid = Tid }) ->
%% Our state and the caller's epoch ids are the same. Business as usual.
File = handle_find_file(Tid, CoC_NL, Prefix, DataDir),
File = handle_find_file(FluName, Tid, CoC_NL, Prefix, DataDir),
{reply, {file, File}, S};
handle_call({find_filename, EpochId, CoC_NL, Prefix}, _From, S = #state{ datadir = DataDir, tid = Tid }) ->
handle_call({find_filename, _FluName, EpochId, CoC_NL, Prefix}, _From, S = #state{ datadir = DataDir, tid = Tid }) ->
%% If the epoch id in our state and the caller's epoch id were the same, it would've
%% matched the above clause. Since we're here, we know that they are different.
%% If epoch ids between our state and the caller's are different, we must increment the
@ -191,12 +191,6 @@ generate_uuid_v4_str() ->
io_lib:format("~8.16.0b-~4.16.0b-4~3.16.0b-~4.16.0b-~12.16.0b",
[A, B, C band 16#0fff, D band 16#3fff bor 16#8000, E]).
find_file(DataDir, {coc,CoC_Namespace,CoC_Locator}=_CoC_NL, Prefix, N) ->
{_Filename, Path} = machi_util:make_data_filename(DataDir,
CoC_Namespace,CoC_Locator,
Prefix, "*", N),
filelib:wildcard(Path).
list_files(DataDir, Prefix) ->
{F_bin, Path} = machi_util:make_data_filename(DataDir, "*^" ++ Prefix ++ "^*"),
filelib:wildcard(binary_to_list(F_bin), filename:dirname(Path)).
@ -204,26 +198,12 @@ list_files(DataDir, Prefix) ->
make_filename_mgr_name(FluName) when is_atom(FluName) ->
list_to_atom(atom_to_list(FluName) ++ "_filename_mgr").
handle_find_file(Tid, {coc,CoC_Namespace,CoC_Locator}=CoC_NL, Prefix, DataDir) ->
handle_find_file(_FluName, Tid, {coc,CoC_Namespace,CoC_Locator}, Prefix, DataDir) ->
case ets:lookup(Tid, {CoC_Namespace, CoC_Locator, Prefix}) of
[] ->
N = machi_util:read_max_filenum(DataDir, CoC_Namespace, CoC_Locator, Prefix),
{File, Cleanup} = case find_file(DataDir, CoC_NL, Prefix, N) of
[] ->
{find_or_make_filename(Tid, DataDir, CoC_Namespace, CoC_Locator, Prefix, N), false};
[H] -> {H, true};
[Fn | _ ] = L ->
lager:debug(
"Searching for a matching file to prefix ~p and sequence number ~p gave multiples: ~p",
[Prefix, N, L]),
{Fn, true}
end,
maybe_cleanup(Tid, {CoC_Namespace, CoC_Locator, Prefix, N}, Cleanup),
filename:basename(File).
find_or_make_filename(Tid, DataDir, CoC_Namespace, CoC_Locator, Prefix, N) ->
case ets:lookup(Tid, {CoC_Namespace, CoC_Locator, Prefix, N}) of
[] ->
F = generate_filename(DataDir, CoC_Namespace, CoC_Locator, Prefix, N),
true = ets:insert_new(Tid, {{CoC_Namespace, CoC_Locator, Prefix, N}, F}),
true = ets:insert(Tid, {{CoC_Namespace, CoC_Locator, Prefix}, F}),
F;
[{_Key, File}] ->
File
@ -237,17 +217,12 @@ generate_filename(DataDir, CoC_Namespace, CoC_Locator, Prefix, N) ->
N),
binary_to_list(F).
maybe_cleanup(_Tid, _Key, false) ->
ok;
maybe_cleanup(Tid, Key, true) ->
true = ets:delete(Tid, Key).
increment_and_cache_filename(Tid, DataDir, {coc,CoC_Namespace,CoC_Locator}, Prefix) ->
ok = machi_util:increment_max_filenum(DataDir, CoC_Namespace, CoC_Locator, Prefix),
N = machi_util:read_max_filenum(DataDir, CoC_Namespace, CoC_Locator, Prefix),
F = generate_filename(DataDir, CoC_Namespace, CoC_Locator, Prefix, N),
true = ets:insert_new(Tid, {{CoC_Namespace, CoC_Locator, Prefix, N}, F}),
filename:basename(F).
true = ets:insert(Tid, {{CoC_Namespace, CoC_Locator, Prefix}, F}),
F.