new multibatch write (#452)

Signed-off-by: Little-Wallace <bupt2013211450@gmail.com>

renew branch of multibatch-write. Optimize for large write batch block other thread.

librocksdb_sys/crocksdb/c.cc

@@ -985,12 +985,11 @@ void crocksdb_write_multi_batch(
     crocksdb_writebatch_t** batches,
     size_t batch_size,
     char** errptr) {
-  thread_local std::vector<WriteBatch*> ws;
-  ws.clear();
+  std::vector<WriteBatch*> ws;
   for (size_t i = 0; i < batch_size; i ++) {
     ws.push_back(&batches[i]->rep);
   }
-  SaveError(errptr, db->rep->MultiThreadWrite(options->rep, ws));
+  SaveError(errptr, db->rep->MultiBatchWrite(options->rep, std::move(ws)));
 }
 
 char* crocksdb_get(

src/rocksdb.rs

@@ -774,11 +774,7 @@ impl DB {
         writeopts: &WriteOptions,
     ) -> Result<(), String> {
         unsafe {
-            let b: Vec<*mut DBWriteBatch> = batches
-                .iter()
-                .filter(|w| w.count() > 0)
-                .map(|w| w.inner)
-                .collect();
+            let b: Vec<*mut DBWriteBatch> = batches.iter().map(|w| w.inner).collect();
             if !b.is_empty() {
                 ffi_try!(crocksdb_write_multi_batch(
                     self.inner,