txn_btree: add some rsearch test case

txn_btree.cc

@@ -17,6 +17,10 @@
 
 #include "scopedperf.hh"
 
+#if defined(NDB_MASSTREE)
+#define HAVE_REVERSE_RANGE_SCANS
+#endif
+
 using namespace std;
 using namespace util;
 uint64_t initial_timestamp;
@@ -463,9 +467,26 @@ test_long_keys()
       ALWAYS_ASSERT_COND_IN_TXN(t, c.ctr == N);
     }
 
+#ifdef HAVE_REVERSE_RANGE_SCANS
+    {
+      TxnType<Traits> t(txn_flags, arena);
+      const string lowkey_s = make_long_key(4, 5, 3, 0);
+      const string highkey_s = make_long_key(4, 5, 3, N);
+      const varkey lowkey(lowkey_s);
+      counting_scan_callback<TxnType> c(1);
+      btr.rsearch_range_call(t, varkey(highkey_s), &lowkey, c);
+      AssertSuccessfulCommit(t);
+      if (c.ctr != (N-1))
+        cerr << "c.ctr: " << c.ctr << ", N: " << N << endl;
+      ALWAYS_ASSERT_COND_IN_TXN(t, c.ctr == (N-1));
+    }
+#endif
+
     txn_epoch_sync<TxnType>::sync();
     txn_epoch_sync<TxnType>::finish();
   }
+
+  cerr << "test_long_keys passed" << endl;
 }
 
 template <template <typename> class TxnType, typename Traits>

txn_btree.h

@@ -352,6 +352,21 @@ class txn_btree : public base_txn_btree<Transaction, txn_btree_> {
         upper ? &u : nullptr, callback, max_bytes_read);
   }
 
+  template <typename Traits>
+  inline void
+  rsearch_range_call(Transaction<Traits> &t,
+                     const varkey &upper,
+                     const varkey *lower,
+                     search_range_callback &callback,
+                     size_type max_bytes_read = string_type::npos)
+  {
+    key_type l;
+    if (lower)
+      l = to_string_type(*lower);
+    rsearch_range_call(t, to_string_type(upper),
+        lower ? &l : nullptr, callback, max_bytes_read);
+  }
+
   template <typename Traits, typename T>
   inline void
   search_range(Transaction<Traits> &t,