c: allow set savepoint to writebatch

Summary:
Allow set SavePoint to WriteBatch in C ABI.
Closes https://github.com/facebook/rocksdb/pull/1698

Differential Revision: D4378556

Pulled By: yiwu-arbug

fbshipit-source-id: afca746

db/c.cc

@@ -1336,6 +1336,15 @@ const char* rocksdb_writebatch_data(rocksdb_writebatch_t* b, size_t* size) {
   return b->rep.Data().c_str();
 }
 
+void rocksdb_writebatch_set_save_point(rocksdb_writebatch_t* b) {
+  b->rep.SetSavePoint();
+}
+
+void rocksdb_writebatch_rollback_to_save_point(rocksdb_writebatch_t* b,
+                                               char** errptr) {
+  SaveError(errptr, b->rep.RollbackToSavePoint());
+}
+
 rocksdb_block_based_table_options_t*
 rocksdb_block_based_options_create() {
   return new rocksdb_block_based_table_options_t;

db/c_test.c

@@ -573,6 +573,23 @@ int main(int argc, char** argv) {
     rocksdb_writebatch_destroy(wb);
   }
 
+  StartPhase("writebatch_savepoint");
+  {
+    rocksdb_writebatch_t* wb = rocksdb_writebatch_create();
+    rocksdb_writebatch_set_save_point(wb);
+    const char* k_list[2] = {"z", "ap"};
+    const size_t k_sizes[2] = {1, 2};
+    const char* v_list[3] = {"x", "y", "z"};
+    const size_t v_sizes[3] = {1, 1, 1};
+    rocksdb_writebatch_putv(wb, 2, k_list, k_sizes, 3, v_list, v_sizes);
+    rocksdb_writebatch_rollback_to_save_point(wb, &err);
+    CheckNoError(err);
+    rocksdb_write(db, woptions, wb, &err);
+    CheckNoError(err);
+    CheckGet(db, roptions, "zap", NULL);
+    rocksdb_writebatch_destroy(wb);
+  }
+
   StartPhase("writebatch_rep");
   {
     rocksdb_writebatch_t* wb1 = rocksdb_writebatch_create();

include/rocksdb/c.h

@@ -448,6 +448,10 @@ extern ROCKSDB_LIBRARY_API void rocksdb_writebatch_iterate(
     void (*deleted)(void*, const char* k, size_t klen));
 extern ROCKSDB_LIBRARY_API const char* rocksdb_writebatch_data(
     rocksdb_writebatch_t*, size_t* size);
+extern ROCKSDB_LIBRARY_API void rocksdb_writebatch_set_save_point(
+    rocksdb_writebatch_t*);
+extern ROCKSDB_LIBRARY_API void rocksdb_writebatch_rollback_to_save_point(
+    rocksdb_writebatch_t*, char** errptr);
 
 /* Block based table options */