From c3096afd61c9a88ae76dc5e8d7c38a31c5e8691a Mon Sep 17 00:00:00 2001
From: Dhruba Borthakur <dhruba@dev3936.snc6.facebook.com>
Date: Fri, 3 Aug 2012 15:20:58 -0700
Subject: [PATCH] Introduce a new option disableDataSync for opening the
 database. If this is set to true, then the data written to newly created data
 files are not sycned to disk, instead depend on the OS to flush dirty data to
 stable storage. This option is good for bulk

Test Plan:
manual tests

Task ID: #

Blame Rev:

Differential Revision: https://reviews.facebook.net/D4515
---
 db/db_impl.cc             | 2 +-
 include/leveldb/options.h | 8 ++++++++
 util/options.cc           | 3 ++-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/db/db_impl.cc b/db/db_impl.cc
index c2e853c88..72e85f936 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -810,7 +810,7 @@ Status DBImpl::FinishCompactionOutputFile(CompactionState* compact,
   compact->builder = NULL;
 
   // Finish and check for file errors
-  if (s.ok()) {
+  if (s.ok() && !options_.disableDataSync) {
     s = compact->outfile->Sync();
   }
   if (s.ok()) {
diff --git a/include/leveldb/options.h b/include/leveldb/options.h
index 41c356ffb..d0b5a4cf9 100644
--- a/include/leveldb/options.h
+++ b/include/leveldb/options.h
@@ -190,6 +190,14 @@ struct Options {
   // If non-null, then we should collect metrics about database operations
   Statistics* statistics;
 
+  // If true, then the contents of data files are not synced
+  // to stable storage. Their contents remain in the OS buffers till the
+  // OS decides to flush them. This option is good for bulk-loading
+  // of data. Once the bulk-loading is complete, please issue a
+  // sync to the OS to flush all dirty buffesrs to stable storage.
+  // Default: false
+  bool disableDataSync;
+
   // Create an Options object with default values for all fields.
   Options();
 };
diff --git a/util/options.cc b/util/options.cc
index 0ad742ce2..50ed00f9c 100644
--- a/util/options.cc
+++ b/util/options.cc
@@ -34,7 +34,8 @@ Options::Options()
       expanded_compaction_factor(25),
       max_grandparent_overlap_factor(10),
       filter_policy(NULL),
-      statistics(NULL) {
+      statistics(NULL),
+      disableDataSync(false) {
 }
 
 }  // namespace leveldb