add support for db.sync_wal()

librocksdb_sys/crocksdb/c.cc

@@ -1050,6 +1050,12 @@ void crocksdb_flush_cf(
   SaveError(errptr, db->rep->Flush(options->rep, column_family->rep));
 }
 
+void crocksdb_sync_wal(
+    crocksdb_t* db,
+    char** errptr) {
+  SaveError(errptr, db->rep->SyncWAL());
+}
+
 void crocksdb_disable_file_deletions(
     crocksdb_t* db,
     char** errptr) {

librocksdb_sys/crocksdb/rocksdb/c.h

@@ -360,6 +360,9 @@ extern C_ROCKSDB_LIBRARY_API void crocksdb_flush_cf(
     crocksdb_t* db, crocksdb_column_family_handle_t* column_family,
     const crocksdb_flushoptions_t* options, char** errptr);
 
+extern C_ROCKSDB_LIBRARY_API void crocksdb_sync_wal(
+    crocksdb_t* db, char** errptr);
+
 extern C_ROCKSDB_LIBRARY_API void crocksdb_disable_file_deletions(crocksdb_t* db,
                                                                char** errptr);
 

librocksdb_sys/src/lib.rs

@@ -581,6 +581,8 @@ extern "C" {
                              cf: *mut DBCFHandle,
                              options: *const DBFlushOptions,
                              err: *mut *mut c_char);
+    pub fn crocksdb_sync_wal(db: *mut DBInstance,
+                             err: *mut *mut c_char);
 
     pub fn crocksdb_approximate_sizes(db: *mut DBInstance,
                                       num_ranges: c_int,

src/rocksdb.rs

@@ -744,6 +744,17 @@ impl DB {
         }
     }
 
+    /// Sync the wal. Note that Write() followed by SyncWAL() is not exactly the
+    /// same as Write() with sync=true: in the latter case the changes won't be
+    /// visible until the sync is done.
+    /// Currently only works if allow_mmap_writes = false in Options.
+    pub fn sync_wal(&self) -> Result<(), String> {
+        unsafe {
+            ffi_try!(crocksdb_sync_wal(self.inner));
+            Ok(())
+        }
+    }
+
     /// Return the approximate file system space used by keys in each ranges.
     ///
     /// Note that the returned sizes measure file system space usage, so

tests/test_rocksdb_options.rs

@@ -135,6 +135,17 @@ fn test_set_wal_opt() {
     drop(db);
 }
 
+#[test]
+fn test_sync_wal() {
+    let path = TempDir::new("_rust_rocksdb_test_sync_wal").expect("");
+    let mut opts = Options::new();
+    opts.create_if_missing(true);
+    let db = DB::open(opts, path.path().to_str().unwrap()).unwrap();
+    db.put(b"key", b"value");
+    db.sync_wal();
+    drop(db);
+}
+
 #[test]
 fn test_create_info_log() {
     let path = TempDir::new("_rust_rocksdb_test_create_info_log_opt").expect("");