Update Blockchain::get_db() to return reference instead of pointer

Where this method is used, a BlockchainDB object is always expected, so
a pointer is unnecessary and less safe.

src/blockchain_converter/blockchain_export.cpp

@@ -148,7 +148,7 @@ void BlockchainExport::write_block(block& block)
 #if SOURCE_DB == DB_MEMORY
   const transaction* cb_tx_full = m_blockchain_storage->get_tx(coinbase_tx_hash);
 #else
-  transaction cb_tx_full = m_blockchain_storage->get_db()->get_tx(coinbase_tx_hash);
+  transaction cb_tx_full = m_blockchain_storage->get_db().get_tx(coinbase_tx_hash);
 #endif
 
 #if SOURCE_DB == DB_MEMORY
@@ -167,7 +167,7 @@ void BlockchainExport::write_block(block& block)
 #if SOURCE_DB == DB_MEMORY
     const transaction* tx = m_blockchain_storage->get_tx(tx_id);
 #else
-    transaction tx = m_blockchain_storage->get_db()->get_tx(tx_id);
+    transaction tx = m_blockchain_storage->get_db().get_tx(tx_id);
 #endif
 
 #if SOURCE_DB == DB_MEMORY
@@ -205,18 +205,18 @@ void BlockchainExport::write_block(block& block)
 #if SOURCE_DB == DB_MEMORY
     size_t block_size = m_blockchain_storage->get_block_size(block_height);
 #else
-    size_t block_size = m_blockchain_storage->get_db()->get_block_size(block_height);
+    size_t block_size = m_blockchain_storage->get_db().get_block_size(block_height);
 #endif
 #if SOURCE_DB == DB_MEMORY
     difficulty_type cumulative_difficulty = m_blockchain_storage->get_block_cumulative_difficulty(block_height);
 #else
-    difficulty_type cumulative_difficulty = m_blockchain_storage->get_db()->get_block_cumulative_difficulty(block_height);
+    difficulty_type cumulative_difficulty = m_blockchain_storage->get_db().get_block_cumulative_difficulty(block_height);
 #endif
 #if SOURCE_DB == DB_MEMORY
     uint64_t coins_generated = m_blockchain_storage->get_block_coins_generated(block_height);
 #else
     // TODO TEST to verify that this is the equivalent. make sure no off-by-one error with block height vs block number
-    uint64_t coins_generated = m_blockchain_storage->get_db()->get_block_already_generated_coins(block_height);
+    uint64_t coins_generated = m_blockchain_storage->get_db().get_block_already_generated_coins(block_height);
 #endif
 
     *m_raw_archive << block_size;

src/blockchain_converter/blockchain_import.cpp

@@ -214,7 +214,7 @@ int import_from_file(FakeCore& simple_core, std::string& import_file_path)
     // Reset stats, in case we're using newly created db, accumulating stats
     // from addition of genesis block.
     // This aligns internal db counts with importer counts.
-    simple_core.m_storage.get_db()->reset_stats();
+    simple_core.m_storage.get_db().reset_stats();
   }
 #endif
   boost::filesystem::path raw_file_path(import_file_path);
@@ -497,7 +497,7 @@ int import_from_file(FakeCore& simple_core, std::string& import_file_path)
             simple_core.batch_start();
             std::cout << ENDL;
 #if !defined(BLOCKCHAIN_DB) || (BLOCKCHAIN_DB == DB_LMDB)
-            simple_core.m_storage.get_db()->show_stats();
+            simple_core.m_storage.get_db().show_stats();
 #endif
           }
         }
@@ -525,7 +525,7 @@ int import_from_file(FakeCore& simple_core, std::string& import_file_path)
       simple_core.batch_stop();
     }
 #if !defined(BLOCKCHAIN_DB) || (BLOCKCHAIN_DB == DB_LMDB)
-    simple_core.m_storage.get_db()->show_stats();
+    simple_core.m_storage.get_db().show_stats();
 #endif
     if (h > 0)
       LOG_PRINT_L0("Finished at height: " << h << "  block: " << h-1);

src/blockchain_converter/fake_core.h

@@ -55,7 +55,7 @@ struct fake_core_lmdb
     m_pool.init(path.string());
     m_storage.init(path.string(), use_testnet, mdb_flags);
     if (do_batch)
-      m_storage.get_db()->set_batch_transactions(do_batch);
+      m_storage.get_db().set_batch_transactions(do_batch);
     support_batch = true;
     support_add_block = true;
   }
@@ -71,17 +71,17 @@ struct fake_core_lmdb
                             , const std::vector<transaction>& txs
                             )
   {
-    return m_storage.get_db()->add_block(blk, block_size, cumulative_difficulty, coins_generated, txs);
+    return m_storage.get_db().add_block(blk, block_size, cumulative_difficulty, coins_generated, txs);
   }
 
   void batch_start()
   {
-    m_storage.get_db()->batch_start();
+    m_storage.get_db().batch_start();
   }
 
   void batch_stop()
   {
-    m_storage.get_db()->batch_stop();
+    m_storage.get_db().batch_stop();
   }
 
 };

src/cryptonote_core/blockchain.h

@@ -145,9 +145,9 @@ namespace cryptonote
     void set_enforce_dns_checkpoints(bool enforce);
     bool update_checkpoints(const std::string& file_path, bool check_dns);
 
-    BlockchainDB* get_db()
+    BlockchainDB& get_db()
     {
-      return m_db;
+      return *m_db;
     }
 
   private: