From 08a4b1ab4faa22630aee32acf34a62f006ef0726 Mon Sep 17 00:00:00 2001
From: Magnus Ahltorp <map@kth.se>
Date: Wed, 28 Jan 2015 22:41:15 +0100
Subject: Delay fsync for index writes

---
 src/db.erl    |  2 +-
 src/index.erl | 18 +++++++++++++++---
 2 files changed, 16 insertions(+), 4 deletions(-)

(limited to 'src')

diff --git a/src/db.erl b/src/db.erl
index 0541678..0361aaf 100644
--- a/src/db.erl
+++ b/src/db.erl
@@ -181,7 +181,7 @@ handle_call(stop, _From, State) ->
 handle_call({add_index_nosync, {LeafHash, Index}}, _From, State) ->
     ok = perm:ensurefile_nosync(indexforhash_root_path(),
                                 LeafHash, integer_to_binary(Index)),
-    ok = index:add(index_path(), Index, LeafHash),
+    ok = index:add_nosync(index_path(), Index, LeafHash),
     {reply, ok, State}.
 
 indexforhash_sync(LeafHash, Index) ->
diff --git a/src/index.erl b/src/index.erl
index 96195e3..c0e344a 100644
--- a/src/index.erl
+++ b/src/index.erl
@@ -12,13 +12,20 @@
 %% TODO: Checksums
 
 -module(index).
--export([get/2, getrange/3, add/3, addlast/2, indexsize/1]).
+-export([get/2, getrange/3, add/3, add_nosync/3, addlast/2, indexsize/1]).
 
 -define(ENTRYSIZE, 32).
 -define(ENTRYSIZEINFILE, (?ENTRYSIZE*2+1)).
 
 -spec add(string(), integer() | last, binary()) -> ok.
-add(Basepath, Index, Entry) when is_binary(Entry), size(Entry) == ?ENTRYSIZE ->
+add(Basepath, Index, Entry) ->
+    add(Basepath, Index, Entry, sync).
+
+-spec add_nosync(string(), integer() | last, binary()) -> ok.
+add_nosync(Basepath, Index, Entry) ->
+    add(Basepath, Index, Entry, nosync).
+
+add(Basepath, Index, Entry, Syncflag) when is_binary(Entry), size(Entry) == ?ENTRYSIZE ->
     case file:open(Basepath, [read, write, binary]) of
         {ok, File} ->
             {ok, Position} = file:position(File, eof),
@@ -55,7 +62,12 @@ add(Basepath, Index, Entry) when is_binary(Entry), size(Entry) == ?ENTRYSIZE ->
                     end
             end,
             ok = file:close(File),
-            util:fsync([Basepath, filename:dirname(Basepath)]);
+            case Syncflag of
+                sync ->
+                    util:fsync([Basepath, filename:dirname(Basepath)]);
+                nosync ->
+                    ok
+            end;
         {error, Error} ->
             util:exit_with_error(Error, writefile,
                                  "Error opening file for writing")
-- 
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