diff options
| -rw-r--r-- | src/atomic.erl | 24 | ||||
| -rw-r--r-- | src/hex.erl | 1 | ||||
| -rw-r--r-- | src/perm.erl | 73 | ||||
| -rw-r--r-- | src/util.erl | 57 |
4 files changed, 97 insertions, 58 deletions
diff --git a/src/atomic.erl b/src/atomic.erl new file mode 100644 index 0000000..5bf5670 --- /dev/null +++ b/src/atomic.erl @@ -0,0 +1,24 @@ +%% +%% Copyright (c) 2014 Kungliga Tekniska Högskolan +%% (KTH Royal Institute of Technology, Stockholm, Sweden). +%% + +-module(atomic). +-export([replacefile/2, readfile/1]). + +-spec replacefile(string(), binary()) -> ok. +replacefile(Path, Content) -> + TempName = util:tempfilename(Path), + util:write_tempfile_and_rename(Path, TempName, Content), + util:fsync([Path, filename:dirname(Path)]). + +-spec readfile(string()) -> binary(). +readfile(Path) -> + case file:read_file(Path) of + {ok, Contents} -> + Contents; + {error, enoent} -> + noentry; + {error, Error} -> + util:exit_with_error(readfile, Error, "Error reading file") + end. diff --git a/src/hex.erl b/src/hex.erl index e3c8441..1eb1e6a 100644 --- a/src/hex.erl +++ b/src/hex.erl @@ -4,6 +4,7 @@ -module(hex). -export([bin_to_hexstr/1,hexstr_to_bin/1]). +-spec bin_to_hexstr(binary()) -> string(). bin_to_hexstr(Bin) -> lists:flatten([io_lib:format("~2.16.0B", [X]) || X <- binary_to_list(Bin)]). diff --git a/src/perm.erl b/src/perm.erl index 5cd2889..ccb23bc 100644 --- a/src/perm.erl +++ b/src/perm.erl @@ -6,16 +6,7 @@ -module(perm). -export([ensurefile/3, readfile/2]). -fsync([]) -> - ok; -fsync([Name | Rest]) -> - case fsyncport:fsync(Name) of - ok -> - fsync(Rest); - {error, Error} -> - {error, Error} - end. - +-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 -> @@ -26,21 +17,7 @@ readfile_and_verify(Name, Content) -> {error, Error} end. -writefile(Name, NurseryName, Content) -> - case file:open(NurseryName, [write, exclusive]) of - {ok, File} -> - %io:format("Write file: ~p~n", [Name]), - ok = file:write(File, Content), - file:close(File), - Result = file:rename(NurseryName, Name), - Result; - {error, eexist} -> - %% Should not happen, file name should be unique - {error, eexist}; - {error, Error} -> - {error, Error} - end. - +-spec make_dir(string()) -> ok | {error, atom()}. make_dir(Name) -> case file:make_dir(Name) of ok -> @@ -51,6 +28,7 @@ make_dir(Name) -> {error, Error} end. +-spec make_dirs([string()]) -> ok | {error, atom()}. make_dirs([]) -> ok; make_dirs([Name | Rest]) -> @@ -61,6 +39,7 @@ make_dirs([Name | Rest]) -> {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, @@ -70,49 +49,27 @@ path_for_key(Rootdir, Key) -> Fullpath = Thirdlevel ++ "/" ++ Name, {[Firstlevel, Secondlevel, Thirdlevel], Fullpath}. -tempfilename(Base) -> - {MegaSecs, Secs, MicroSecs} = now(), - Filename = io_lib:format("~s-~s-~p.~p", [Base, os:getpid(), - MegaSecs * 1000000 + Secs, MicroSecs]), - Filename. - -exit_with_error(Error, Message) -> - io:format("~s: ~w~n", [Message, Error]), - exit({perm, fileerror, Message, Error}). - -check_error(ReturnValue, ErrorMessage) -> - case ReturnValue of - ok -> - ok; - {error, Error} -> - exit_with_error(Error, ErrorMessage) - end. - +-spec ensurefile(string(), binary(), binary()) -> ok | differ. ensurefile(Rootdir, Key, Content) -> {Dirs, Path} = path_for_key(Rootdir, Key), case readfile_and_verify(Path, Content) of ok -> - check_error(fsync([Path, Rootdir | Dirs]), "Error in fsync"); + util:fsync([Path, Rootdir | Dirs]); differ -> differ; {error, enoent} -> - check_error(make_dirs([Rootdir, Rootdir ++ "nursery/"] ++ Dirs), - "Error creating directory"), + util:check_error(make_dirs([Rootdir, Rootdir ++ "nursery/"] + ++ Dirs), + makedir, "Error creating directory"), NurseryName = Rootdir ++ "nursery/" ++ - tempfilename(hex:bin_to_hexstr(Key)), - _Result = writefile(Path, NurseryName, Content), - check_error(fsync([Path, Rootdir | Dirs]), "Error in fsync"); + util:tempfilename(hex:bin_to_hexstr(Key)), + util:write_tempfile_and_rename(Path, NurseryName, Content), + util:fsync([Path, Rootdir | Dirs]); {error, Error} -> - exit_with_error(Error, "Error reading file") + util:exit_with_error(Error, readfile, "Error reading file") end. +-spec readfile(string(), binary()) -> binary(). readfile(Rootdir, Key) -> {_Dirs, Path} = path_for_key(Rootdir, Key), - case file:read_file(Path) of - {ok, Contents} -> - Contents; - {error, enoent} -> - noentry; - {error, Error} -> - exit_with_error(Error, "Error reading file") - end. + atomic:readfile(Path). diff --git a/src/util.erl b/src/util.erl new file mode 100644 index 0000000..48ebbb0 --- /dev/null +++ b/src/util.erl @@ -0,0 +1,57 @@ +%% +%% Copyright (c) 2014 Kungliga Tekniska Högskolan +%% (KTH Royal Institute of Technology, Stockholm, Sweden). +%% + +-module(util). +-export([tempfilename/1, fsync/1, exit_with_error/3, + check_error/3, write_tempfile_and_rename/3]). + +-spec tempfilename(string()) -> string(). +tempfilename(Base) -> + {MegaSecs, Secs, MicroSecs} = now(), + Filename = io_lib:format("~s-~s-~p.~p", [Base, os:getpid(), + MegaSecs * 1000000 + Secs, MicroSecs]), + Filename. + +-spec fsync([string()]) -> ok. +fsync([]) -> + ok; +fsync([Name | Rest]) -> + case fsyncport:fsync(Name) of + ok -> + fsync(Rest); + {error, Error} -> + exit_with_error(fsync, Error, "Error in fsync") + end. + +-spec exit_with_error(atom(), atom(), string()) -> no_return(). +exit_with_error(Operation, Error, ErrorMessage) -> + io:format("~s(~w): ~w~n", [ErrorMessage, Operation, Error]), + exit({fileerror, Operation, Error, ErrorMessage}). + +-spec check_error(any(), atom(), string()) -> ok. +check_error(ReturnValue, Operation, ErrorMessage) -> + case ReturnValue of + ok -> + ok; + {error, Error} -> + exit_with_error(Operation, Error, ErrorMessage) + end. + +-spec write_tempfile_and_rename(string(), string(), binary()) -> ok. +write_tempfile_and_rename(Name, NurseryName, Content) -> + case file:open(NurseryName, [write, exclusive]) of + {ok, File} -> + ok = file:write(File, Content), + file:close(File), + check_error(file:rename(NurseryName, Name), rename, + "Error when renaming tempfile to final file"); + {error, eexist} -> + %% Should not happen, file name should be unique + exit_with_error(writefile, eexist, + "File existed when creating tempfile"); + {error, Error} -> + exit_with_error(writefile, Error, + "Error when creating tempfile") + end. |