add interface to support write multi batch

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

librocksdb_sys/crocksdb/c.cc

@@ -960,6 +960,19 @@ void crocksdb_write(
   SaveError(errptr, db->rep->Write(options->rep, &batch->rep));
 }
 
+void crocksdb_write_multi_batch(
+    crocksdb_t* db,
+    const crocksdb_writeoptions_t* options,
+    crocksdb_writebatch_t** batches,
+    size_t batch_size,
+    char** errptr) {
+    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));
+}
+
 char* crocksdb_get(
     crocksdb_t* db,
     const crocksdb_readoptions_t* options,

librocksdb_sys/crocksdb/crocksdb/c.h

@@ -341,6 +341,9 @@ extern C_ROCKSDB_LIBRARY_API void crocksdb_merge_cf(
 extern C_ROCKSDB_LIBRARY_API void crocksdb_write(
     crocksdb_t* db, const crocksdb_writeoptions_t* options,
     crocksdb_writebatch_t* batch, char** errptr);
+extern C_ROCKSDB_LIBRARY_API void crocksdb_write_multi_batch(
+    crocksdb_t* db, const crocksdb_writeoptions_t* options,
+    crocksdb_writebatch_t** batches, size_t batch_size, char** errptr);
 
 /* Returns NULL if not found.  A malloc()ed array otherwise.
    Stores the length of the array in *vallen. */

librocksdb_sys/src/lib.rs

@@ -912,6 +912,14 @@ extern "C" {
         batch: *mut DBWriteBatch,
         err: *mut *mut c_char,
     );
+    pub fn crocksdb_write_multi_batch(
+        db: *mut DBInstance,
+        writeopts: *const DBWriteOptions,
+        batch: *const *mut DBWriteBatch,
+        batchlen: size_t,
+        err: *mut *mut c_char,
+    );
+
     pub fn crocksdb_writebatch_create() -> *mut DBWriteBatch;
     pub fn crocksdb_writebatch_create_with_capacity(cap: size_t) -> *mut DBWriteBatch;
     pub fn crocksdb_writebatch_create_from(rep: *const u8, size: size_t) -> *mut DBWriteBatch;

src/rocksdb.rs

@@ -738,6 +738,18 @@ impl DB {
         &self.path
     }
 
+    pub fn multi_thread_write(&self, batches: &Vec<WriteBatch>, writeopts: &WriteOptions) -> Result<(), String> {
+        unsafe {
+            if batches.len() == 1 {
+                ffi_try!(crocksdb_write(self.inner, writeopts.inner, batches[0].inner));
+            } else {
+                let b : Vec<*mut DBWriteBatch> = batches.iter().map(|w| w.inner).collect();
+                ffi_try!(crocksdb_write_multi_batch(self.inner, writeopts.inner, b.as_ptr(), b.len()));
+            }
+        }
+        Ok(())
+    }
+
     pub fn write_opt(&self, batch: &WriteBatch, writeopts: &WriteOptions) -> Result<(), String> {
         unsafe {
             ffi_try!(crocksdb_write(self.inner, writeopts.inner, batch.inner));