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Fix race listing readable files #198

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Merged
merged 2 commits into from
Sep 17, 2014
Merged

Fix race listing readable files #198

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d3e7e3c
Add failing list data files race test
engelsanchez Sep 16, 2014
694480f
Fix race listing readable files
engelsanchez Sep 16, 2014
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63 changes: 50 additions & 13 deletions src/bitcask.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -1335,19 +1335,9 @@ get_filestate(FileId, Dirname, ReadFiles, Mode) ->


list_data_files(Dirname, WritingFile, MergingFile) ->
%% Get list of {tstamp, filename} for all files in the directory then
%% reverse sort that list and extract the fully-qualified filename.
Files1 = bitcask_fileops:data_file_tstamps(Dirname),
Files2 = bitcask_fileops:data_file_tstamps(Dirname),
% TODO: Remove crazy
if Files1 == Files2 ->
%% No race, Files1 is a stable list.
[F || {_Tstamp, F} <- lists:sort(Files1),
F /= WritingFile,
F /= MergingFile];
true ->
list_data_files(Dirname, WritingFile, MergingFile)
end.
[F || {_Tstamp, F} <- lists:sort(Files1),
F /= WritingFile, F /= MergingFile].

merge_files(#mstate { input_files = [] } = State) ->
State;
Expand Down Expand Up @@ -1668,7 +1658,16 @@ readable_and_setuid_files(Dirname) ->
%% Filter out files with setuid bit set: they've been marked for
%% deletion by an earlier *successful* merge.
Fs = [F || F <- list_data_files(Dirname, WritingFile, MergingFile)],
lists:partition(fun(F) -> not has_pending_delete_bit(F) end, Fs).

WritingFile2 = bitcask_lockops:read_activefile(write, Dirname),
MergingFile2 = bitcask_lockops:read_activefile(merge, Dirname),
case {WritingFile2, MergingFile2} of
{WritingFile, MergingFile} ->
lists:partition(fun(F) -> not has_pending_delete_bit(F) end, Fs);
_ ->
% Changed while fetching file list, retry
readable_and_setuid_files(Dirname)
end.

%% Internal put - have validated that the file is opened for write
%% and looked up the state at this point
Expand Down Expand Up @@ -2043,6 +2042,44 @@ list_data_files_test2() ->
%% Now use the list_data_files to scan the dir
ExpFiles = list_data_files("/tmp/bc.test.list", undefined, undefined).

% Test that readable_files will not return the currently active
% write or merge file by mistake if they change in between fetching them
% and listing the files in the directory.
list_data_files_race_test() ->
Dir = "/tmp/bc.test.list.race",
Fname = fun(N) ->
filename:join(Dir, integer_to_list(N) ++ ".bitcask.data")
end,
WriteFile = fun(N) ->
ok = file:write_file(Fname(N), <<>>)
end,
WriteFiles = fun(S,E) ->
[WriteFile(N) || N <- lists:seq(S, E)]
end,
os:cmd("rm -rf " ++ Dir ++ "; mkdir -p " ++ Dir),
WriteFiles(1,5),
% Faking 4 as merge file, 5 as write file,
% then switching to 6 as merge, 7 as write
KindN = fun(merge) -> 4; (write) -> 5 end,
meck:new(bitcask_lockops, [passthrough]),
meck:expect(bitcask_lockops, read_activefile,
fun(Kind, _) ->
case get({fake_activefile, Kind}) of
undefined ->
N = KindN(Kind),
% Next time return file + 2
WriteFile(N+2),
put({fake_activefile, Kind}, Fname(N+2)),
Fname(N);
File ->
File
end
end),
ReadFiles = lists:usort(bitcask:readable_files(Dir)),
meck:unload(),
?assertEqual([Fname(N)||N<-lists:seq(1,5)],
ReadFiles).

fold_test_() ->
{timeout, 60, fun fold_test2/0}.

Expand Down