DBWithTTL::Open() param ttls: vector<int32_t> to const vector<int32_t>& (#7196)

Summary:
fix DBWithTTL::Open() param ttls: vector<int32_t> to const vector<int32_t>

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7196

Reviewed By: akankshamahajan15

Differential Revision: D23277772

Pulled By: ajkr

fbshipit-source-id: bf69834b5c2062c7e166dab21fbfd40416c7872d

include/rocksdb/utilities/db_ttl.h

@@ -57,7 +57,7 @@ class DBWithTTL : public StackableDB {
   static Status Open(const DBOptions& db_options, const std::string& dbname,
                      const std::vector<ColumnFamilyDescriptor>& column_families,
                      std::vector<ColumnFamilyHandle*>* handles,
-                     DBWithTTL** dbptr, std::vector<int32_t> ttls,
+                     DBWithTTL** dbptr, const std::vector<int32_t>& ttls,
                      bool read_only = false);
 
   virtual void SetTtl(int32_t ttl) = 0;

utilities/ttl/db_ttl_impl.cc

@@ -91,8 +91,7 @@ Status DBWithTTL::Open(
     const DBOptions& db_options, const std::string& dbname,
     const std::vector<ColumnFamilyDescriptor>& column_families,
     std::vector<ColumnFamilyHandle*>* handles, DBWithTTL** dbptr,
-    std::vector<int32_t> ttls, bool read_only) {
-
+    const std::vector<int32_t>& ttls, bool read_only) {
   if (ttls.size() != column_families.size()) {
     return Status::InvalidArgument(
         "ttls size has to be the same as number of column families");