add allow os buffer conf

src/ffi.rs

@@ -147,6 +147,7 @@ extern "C" {
     pub fn rocksdb_options_set_bytes_per_sync(options: DBOptions, bytes: u64);
     pub fn rocksdb_options_set_disable_data_sync(options: DBOptions,
                                                  v: c_int);
+    pub fn rocksdb_options_set_allow_os_buffer(options: DBOptions, is_allow: bool);
     pub fn rocksdb_options_optimize_for_point_lookup(options: DBOptions,
                                                      block_cache_size_mb: u64);
     pub fn rocksdb_options_set_table_cache_numshardbits(options: DBOptions,

src/rocksdb_options.rs

@@ -195,6 +195,13 @@ impl Options {
         }
     }
 
+    pub fn allow_os_buffer(&mut self, is_allow: bool) {
+        unsafe {
+            rocksdb_ffi::rocksdb_options_set_allow_os_buffer(self.inner,
+                                                             is_allow);
+        }
+    }
+
     pub fn set_table_cache_num_shard_bits(&mut self, nbits: c_int) {
         unsafe {
             rocksdb_ffi::rocksdb_options_set_table_cache_numshardbits(self.inner,