From 6fdc0f0ae77d6aaefd175277fa8355089f41806a Mon Sep 17 00:00:00 2001
From: Magnus Ahltorp <map@kth.se>
Date: Wed, 28 Jan 2015 17:29:58 +0100
Subject: Perform frontend index writes in two phases

---
 src/perm.erl | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

(limited to 'src/perm.erl')

diff --git a/src/perm.erl b/src/perm.erl
index 9f02b55..614656a 100644
--- a/src/perm.erl
+++ b/src/perm.erl
@@ -2,7 +2,7 @@
 %%% See LICENSE for licensing information.
 
 -module(perm).
--export([ensurefile/3, readfile/2]).
+-export([ensurefile/3, ensurefile_nosync/3, readfile/2]).
 
 -spec readfile_and_verify(string(), binary()) -> ok | differ | {error, atom()}.
 readfile_and_verify(Name, Content) ->
@@ -49,13 +49,21 @@ path_for_key(Rootdir, Key) ->
 
 -spec ensurefile(string(), binary(), binary()) -> ok | differ.
 ensurefile(Rootdir, Key, Content) ->
+    ensurefile(Rootdir, Key, Content, sync).
+
+-spec ensurefile_nosync(string(), binary(), binary()) -> ok | differ.
+ensurefile_nosync(Rootdir, Key, Content) ->
+    ensurefile(Rootdir, Key, Content, nosync).
+
+ensurefile(Rootdir, Key, Content, Syncflag) ->
     lager:debug("dir ~p key ~p", [Rootdir, Key]),
     {Dirs, Path} = path_for_key(Rootdir, Key),
     case readfile_and_verify(Path, Content) of
 	ok ->
             lager:debug("key ~p existed, fsync", [Key]),
-	    util:fsync([Path, Rootdir | Dirs]),
-            lager:debug("key ~p fsynced", [Key]);
+	    ok = util:fsync([Path, Rootdir | Dirs]),
+            lager:debug("key ~p fsynced", [Key]),
+            ok;
         differ ->
             lager:debug("key ~p existed, was different", [Key]),
             differ;
@@ -67,9 +75,15 @@ ensurefile(Rootdir, Key, Content) ->
             NurseryName = Rootdir ++ "nursery/" ++
                 util:tempfilename(hex:bin_to_hexstr(Key)),
             util:write_tempfile_and_rename(Path, NurseryName, Content),
-            lager:debug("key ~p added, fsync", [Key]),
-            util:fsync([Path, Rootdir | Dirs]),
-            lager:debug("key ~p fsynced", [Key]);
+            case Syncflag of
+                sync ->
+                    lager:debug("key ~p added, fsync", [Key]),
+                    ok = util:fsync([Path, Rootdir | Dirs]),
+                    lager:debug("key ~p fsynced", [Key]),
+                    ok;
+                nosync ->
+                    ok
+            end;
 	{error, Error} ->
             util:exit_with_error(Error, readfile, "Error reading file")
     end.
-- 
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