Added atomic module

1 files changed, 57 insertions, 0 deletions

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.