protocol: pass blockchain cumulative difficulty when syncing

Not used yet.

src/cryptonote_core/blockchain.cpp

@@ -2038,6 +2038,7 @@ bool Blockchain::find_blockchain_supplement(const std::list<crypto::hash>& qbloc
   {
     resp.m_block_ids.push_back(m_db->get_block_hash_from_height(i));
   }
+  resp.cumulative_difficulty = m_db->get_block_cumulative_difficulty(m_db->height() - 1);
   m_db->block_txn_stop();
   return true;
 }

src/cryptonote_core/blockchain.h

@@ -826,6 +826,16 @@ namespace cryptonote
      */
     bool for_all_outputs(std::function<bool(uint64_t amount, const crypto::hash &tx_hash, size_t tx_idx)>) const;
 
+    /**
+     * @brief get a reference to the BlockchainDB in use by Blockchain
+     *
+     * @return a reference to the BlockchainDB instance
+     */
+    const BlockchainDB& get_db() const
+    {
+      return *m_db;
+    }
+
     /**
      * @brief get a reference to the BlockchainDB in use by Blockchain
      *

src/cryptonote_core/cryptonote_core.cpp

@@ -1103,6 +1103,11 @@ namespace cryptonote
     return m_blockchain_storage.get_tail_id();
   }
   //-----------------------------------------------------------------------------------------------
+  difficulty_type core::get_block_cumulative_difficulty(uint64_t height) const
+  {
+    return m_blockchain_storage.get_db().get_block_cumulative_difficulty(height);
+  }
+  //-----------------------------------------------------------------------------------------------
   size_t core::get_pool_transactions_count() const
   {
     return m_mempool.get_transactions_count();

src/cryptonote_core/cryptonote_core.h

@@ -520,6 +520,13 @@ namespace cryptonote
       */
      crypto::hash get_tail_id() const;
 
+     /**
+      * @copydoc Blockchain::get_block_cumulative_difficulty
+      *
+      * @note see Blockchain::get_block_cumulative_difficulty
+      */
+     difficulty_type get_block_cumulative_difficulty(uint64_t height) const;
+
      /**
       * @copydoc Blockchain::get_random_outs_for_amounts
       *

src/cryptonote_protocol/cryptonote_protocol_defs.h

@@ -197,11 +197,13 @@ namespace cryptonote
   struct CORE_SYNC_DATA
   {
     uint64_t current_height;
+    uint64_t cumulative_difficulty;
     crypto::hash  top_id;
     uint8_t top_version;
 
     BEGIN_KV_SERIALIZE_MAP()
       KV_SERIALIZE(current_height)
+      KV_SERIALIZE(cumulative_difficulty)
       KV_SERIALIZE_VAL_POD_AS_BLOB(top_id)
       KV_SERIALIZE_OPT(top_version, (uint8_t)0)
     END_KV_SERIALIZE_MAP()
@@ -229,11 +231,13 @@ namespace cryptonote
     {
       uint64_t start_height;
       uint64_t total_height;
+      uint64_t cumulative_difficulty;
       std::list<crypto::hash> m_block_ids;
 
       BEGIN_KV_SERIALIZE_MAP()
         KV_SERIALIZE(start_height)
         KV_SERIALIZE(total_height)
+        KV_SERIALIZE(cumulative_difficulty)
         KV_SERIALIZE_CONTAINER_POD_AS_BLOB(m_block_ids)
       END_KV_SERIALIZE_MAP()
     };

src/cryptonote_protocol/cryptonote_protocol_handler.inl

@@ -309,6 +309,7 @@ namespace cryptonote
   {
     m_core.get_blockchain_top(hshd.current_height, hshd.top_id);
     hshd.top_version = m_core.get_hard_fork_version(hshd.current_height);
+    hshd.cumulative_difficulty = m_core.get_block_cumulative_difficulty(hshd.current_height);
     hshd.current_height +=1;
     return true;
   }

tests/core_proxy/core_proxy.h

@@ -98,5 +98,6 @@ namespace tests
     bool get_block_by_hash(const crypto::hash &h, cryptonote::block &blk, bool *orphan = NULL) const { return false; }
     uint8_t get_ideal_hard_fork_version(uint64_t height) const { return 0; }
     uint8_t get_hard_fork_version(uint64_t height) const { return 0; }
+    cryptonote::difficulty_type get_block_cumulative_difficulty(uint64_t height) const { return 0; }
   };
 }

tests/unit_tests/ban.cpp

@@ -75,6 +75,7 @@ public:
   bool get_block_by_hash(const crypto::hash &h, cryptonote::block &blk, bool *orphan = NULL) const { return false; }
   uint8_t get_ideal_hard_fork_version(uint64_t height) const { return 0; }
   uint8_t get_hard_fork_version(uint64_t height) const { return 0; }
+  cryptonote::difficulty_type get_block_cumulative_difficulty(uint64_t height) const { return 0; }
 };
 
 typedef nodetool::node_server<cryptonote::t_cryptonote_protocol_handler<test_core>> Server;