Add blockchain_import utility

This imports to the blockchain database from an exported blockchain
file.

It can be used to bootstrap a new database or to add blocks to an
existing one.

Supports:
  - both the in-memory and LMDB implementations
  - optional: batching, verification, testnet

See help for usage.

Based on work by tomerkon.
See https://github.com/tomerkon
  src/cryptonote_core/bootfileloader.{h,cpp}

1 files changed, 687 insertions, 0 deletions

diff --git a/src/blockchain_converter/blockchain_import.cpp b/src/blockchain_converter/blockchain_import.cpp
new file mode 100644
index 000000000..ce2abf4ac
--- /dev/null
+++ b/src/blockchain_converter/blockchain_import.cpp
@@ -0,0 +1,687 @@
+// Copyright (c) 2014-2015, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <atomic>
+#include <cstdio>
+#include <algorithm>
+#include <fstream>
+
+#include <boost/filesystem.hpp>
+#include <boost/iostreams/stream.hpp>
+#include <boost/archive/binary_iarchive.hpp>
+#include "cryptonote_core/cryptonote_basic.h"
+#include "cryptonote_core/cryptonote_format_utils.h"
+#include "cryptonote_core/cryptonote_boost_serialization.h"
+#include "serialization/json_utils.h" // dump_json()
+#include "include_base_utils.h"
+#include "common/command_line.h"
+#include "version.h"
+
+
+#include "import.h"
+#include "fake_core.h"
+
+// CONFIG
+static bool opt_batch   = true;
+static bool opt_verify  = true; // use add_new_block, which does verification before calling add_block
+static bool opt_resume  = true;
+static bool opt_testnet = true;
+
+// number of blocks per batch transaction
+// adjustable through command-line argument according to available RAM
+static uint64_t db_batch_size = 20000;
+
+
+namespace po = boost::program_options;
+
+using namespace cryptonote;
+using namespace epee;
+
+int count_blocks(std::string& import_file_path)
+{
+  boost::filesystem::path raw_file_path(import_file_path);
+  boost::system::error_code ec;
+  if (!boost::filesystem::exists(raw_file_path, ec))
+  {
+    LOG_PRINT_L0("import file not found: " << raw_file_path);
+    throw std::runtime_error("Aborting");
+  }
+  std::ifstream import_file;
+  import_file.open(import_file_path, std::ios_base::binary | std::ifstream::in);
+
+  uint64_t h = 0;
+  if (import_file.fail())
+  {
+    LOG_PRINT_L0("import_file.open() fail");
+    throw std::runtime_error("Aborting");
+  }
+  LOG_PRINT_L0("Scanning blockchain from import file...");
+  char buffer1[STR_LENGTH_OF_INT + 1];
+  block b;
+  transaction tx;
+  bool quit = false;
+  uint64_t bytes_read = 0;
+  int progress_interval = 10;
+
+  while (! quit)
+  {
+    int chunk_size;
+    import_file.read(buffer1, STR_LENGTH_OF_INT);
+    if (!import_file) {
+      std::cout << "\r                   \r";
+      LOG_PRINT_L1("End of import file reached");
+      quit = true;
+      break;
+    }
+    h += NUM_BLOCKS_PER_CHUNK;
+    if (h % progress_interval == 0)
+    {
+      std::cout << "\r                   \r" << "block height: " << h <<
+        std::flush;
+    }
+    bytes_read += STR_LENGTH_OF_INT;
+    buffer1[STR_LENGTH_OF_INT] = '\0';
+    chunk_size = atoi(buffer1);
+    if (chunk_size > BUFFER_SIZE)
+    {
+      std::cout << "\r                   \r";
+      LOG_PRINT_L0("WARNING: chunk_size " << chunk_size << " > BUFFER_SIZE " << BUFFER_SIZE
+          << "  height: " << h);
+      throw std::runtime_error("Aborting: chunk size exceeds buffer size");
+    }
+    if (chunk_size > 100000)
+    {
+      std::cout << "\r                   \r";
+      LOG_PRINT_L0("WARNING: chunk_size " << chunk_size << " > 100000" << "  height: "
+          << h);
+    }
+    else if (chunk_size <= 0) {
+      std::cout << "\r                   \r";
+      LOG_PRINT_L0("ERROR: chunk_size " << chunk_size << " <= 0" << "  height: " << h);
+      throw std::runtime_error("Aborting");
+    }
+    // skip to next expected block size value
+    import_file.seekg(chunk_size, std::ios_base::cur);
+    if (! import_file) {
+      std::cout << "\r                   \r";
+      LOG_PRINT_L0("ERROR: unexpected end of import file: bytes read before error: "
+          << import_file.gcount() << " of chunk_size " << chunk_size);
+      throw std::runtime_error("Aborting");
+    }
+    bytes_read += chunk_size;
+    std::cout << "\r                   \r";
+    LOG_PRINT_L3("Total bytes scanned: " << bytes_read);
+  }
+
+  import_file.close();
+
+  std::cout << ENDL;
+  std::cout << "Done scanning import file" << ENDL;
+  std::cout << "Total bytes scanned: " << bytes_read << ENDL;
+  std::cout << "Height: " << h << ENDL;
+
+  return h;
+}
+
+template <typename FakeCore>
+int import_from_file(FakeCore& simple_core, std::string& import_file_path)
+{
+#if !defined(BLOCKCHAIN_DB)
+  static_assert(std::is_same<fake_core_memory, FakeCore>::value || std::is_same<fake_core_lmdb, FakeCore>::value,
+      "FakeCore constraint error");
+#endif
+#if !defined(BLOCKCHAIN_DB) || (BLOCKCHAIN_DB == DB_LMDB)
+  if (std::is_same<fake_core_lmdb, FakeCore>::value)
+  {
+    // 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();
+  }
+#endif
+  boost::filesystem::path raw_file_path(import_file_path);
+  boost::system::error_code ec;
+  if (!boost::filesystem::exists(raw_file_path, ec))
+  {
+    LOG_PRINT_L0("import file not found: " << raw_file_path);
+    return false;
+  }
+
+  uint64_t source_height = count_blocks(import_file_path);
+  LOG_PRINT_L0("import file blockchain height: " << source_height);
+
+  std::ifstream import_file;
+  import_file.open(import_file_path, std::ios_base::binary | std::ifstream::in);
+
+  uint64_t h = 0;
+  if (import_file.fail())
+  {
+    LOG_PRINT_L0("import_file.open() fail");
+    return false;
+  }
+  char buffer1[STR_LENGTH_OF_INT + 1];
+  char buffer_block[BUFFER_SIZE];
+  block b;
+  transaction tx;
+  int quit = 0;
+  uint64_t bytes_read = 0;
+
+  uint64_t start_height = 1;
+  if (opt_resume)
+    start_height = simple_core.m_storage.get_current_blockchain_height();
+
+  // Note that a new blockchain will start with a height of 1 (block number 0)
+  // due to genesis block being added at initialization.
+
+  // CONFIG
+  // TODO: can expand on this, e.g. with --block-number option
+  uint64_t stop_height = source_height;
+
+  // These are what we'll try to use, and they don't have to be a determination
+  // from source and destination blockchains, but those are the current
+  // defaults.
+  LOG_PRINT_L0("start height: " << start_height << "  stop height: " <<
+      stop_height);
+
+  bool use_batch = false;
+  if (opt_batch)
+  {
+    if (simple_core.support_batch)
+      use_batch = true;
+    else
+      LOG_PRINT_L0("WARNING: batch transactions enabled but unsupported or unnecessary for this database engine - ignoring");
+  }
+
+  if (use_batch)
+    simple_core.batch_start();
+
+  LOG_PRINT_L0("Reading blockchain from import file...");
+  std::cout << ENDL;
+
+  // Within the loop, we skip to start_height before we start adding.
+  // TODO: Not a bottleneck, but we can use what's done in count_blocks() and
+  // only do the chunk size reads, skipping the chunk content reads until we're
+  // at start_height.
+  while (! quit)
+  {
+    int chunk_size;
+    import_file.read(buffer1, STR_LENGTH_OF_INT);
+    if (! import_file) {
+      std::cout << "\r                   \r";
+      LOG_PRINT_L0("End of import file reached");
+      quit = 1;
+      break;
+    }
+    bytes_read += STR_LENGTH_OF_INT;
+    buffer1[STR_LENGTH_OF_INT] = '\0';
+    chunk_size = atoi(buffer1);
+    if (chunk_size > BUFFER_SIZE)
+    {
+      LOG_PRINT_L0("WARNING: chunk_size " << chunk_size << " > BUFFER_SIZE " << BUFFER_SIZE);
+      throw std::runtime_error("Aborting: chunk size exceeds buffer size");
+    }
+    if (chunk_size > 100000)
+    {
+      LOG_PRINT_L0("WARNING: chunk_size " << chunk_size << " > 100000");
+    }
+    else if (chunk_size < 0) {
+      LOG_PRINT_L0("ERROR: chunk_size " << chunk_size << " < 0");
+      return 2;
+    }
+    import_file.read(buffer_block, chunk_size);
+    if (! import_file) {
+      LOG_PRINT_L0("ERROR: unexpected end of import file: bytes read before error: "
+          << import_file.gcount() << " of chunk_size " << chunk_size);
+      return 2;
+    }
+    bytes_read += chunk_size;
+    LOG_PRINT_L3("Total bytes read: " << bytes_read);
+
+    if (h + NUM_BLOCKS_PER_CHUNK < start_height + 1)
+    {
+      h += NUM_BLOCKS_PER_CHUNK;
+      continue;
+    }
+    if (h > stop_height)
+    {
+      LOG_PRINT_L0("Specified height reached - stopping.  height: " << h << "  block: " << h-1);
+      quit = 1;
+      break;
+    }
+
+    try
+    {
+      boost::iostreams::basic_array_source<char> device(buffer_block, chunk_size);
+      boost::iostreams::stream<boost::iostreams::basic_array_source<char>> s(device);
+      boost::archive::binary_iarchive a(s);
+
+      int display_interval = 1000;
+      int progress_interval = 10;
+      for (int chunk_ind = 0; chunk_ind < NUM_BLOCKS_PER_CHUNK; chunk_ind++)
+      {
+        h++;
+        if (h % display_interval == 0)
+        {
+          std::cout << "\r                   \r";
+          LOG_PRINT_L0("loading block height " << h);
+        }
+        else
+        {
+          LOG_PRINT_L3("loading block height " << h);
+        }
+        try {
+          a >> b;
+        }
+        catch (const std::exception& e)
+        {
+          std::cout << "\r                   \r";
+          LOG_PRINT_RED_L0("exception while de-archiving block, height=" << h);
+          quit = 1;
+          break;
+        }
+        LOG_PRINT_L2("block prev_id: " << b.prev_id << ENDL);
+
+        if (h % progress_interval == 0)
+        {
+          std::cout << "\r                   \r" << "block " << h-1
+            << std::flush;
+        }
+
+        std::vector<transaction> txs;
+
+        int num_txs;
+        try
+        {
+          a >> num_txs;
+        }
+        catch (const std::exception& e)
+        {
+          std::cout << "\r                   \r";
+          LOG_PRINT_RED_L0("exception while de-archiving tx-num, height=" << h);
+          quit = 1;
+          break;
+        }
+        for(int tx_num = 1; tx_num <= num_txs; tx_num++)
+        {
+          try {
+                a >> tx;
+          }
+          catch (const std::exception& e)
+          {
+            LOG_PRINT_RED_L0("exception while de-archiving tx, height=" << h <<", tx_num=" << tx_num);
+            quit = 1;
+            break;
+          }
+          // if (tx_num == 1) {
+          //   std::cout << "coinbase transaction" << ENDL;
+          // }
+          // crypto::hash hsh = null_hash;
+          // size_t blob_size = 0;
+          // NOTE: all tx hashes except for coinbase tx are available in the block data
+          // get_transaction_hash(tx, hsh, blob_size);
+          // LOG_PRINT_L0("tx " << tx_num << "  " << hsh << " : " << ENDL);
+          // LOG_PRINT_L0(obj_to_json_str(tx) << ENDL);
+
+          // add blocks with verification.
+          // for Blockchain and blockchain_storage add_new_block().
+          if (opt_verify)
+          {
+            if (tx_num == 1) {
+              continue; // coinbase transaction. no need to insert to tx_pool.
+            }
+            // crypto::hash hsh = null_hash;
+            // size_t blob_size = 0;
+            // get_transaction_hash(tx, hsh, blob_size);
+            tx_verification_context tvc = AUTO_VAL_INIT(tvc);
+            bool r = true;
+            r = simple_core.m_pool.add_tx(tx, tvc, true);
+            if (!r)
+            {
+              LOG_PRINT_RED_L0("failed to add transaction to transaction pool, height=" << h <<", tx_num=" << tx_num);
+              quit = 1;
+              break;
+            }
+          }
+          else
+          {
+            // for add_block() method, without (much) processing.
+            // don't add coinbase transaction to txs.
+            //
+            // because add_block() calls
+            // add_transaction(blk_hash, blk.miner_tx) first, and
+            // then a for loop for the transactions in txs.
+            if (tx_num > 1)
+            {
+              txs.push_back(tx);
+            }
+          }
+        }
+
+        if (opt_verify)
+        {
+          block_verification_context bvc = boost::value_initialized<block_verification_context>();
+          simple_core.m_storage.add_new_block(b, bvc);
+
+          if (bvc.m_verifivation_failed)
+          {
+            LOG_PRINT_L0("Failed to add block to blockchain, verification failed, height = " << h);
+            LOG_PRINT_L0("skipping rest of import file");
+            // ok to commit previously batched data because it failed only in
+            // verification of potential new block with nothing added to batch
+            // yet
+            quit = 1;
+            break;
+          }
+          if (! bvc.m_added_to_main_chain)
+          {
+            LOG_PRINT_L0("Failed to add block to blockchain, height = " << h);
+            LOG_PRINT_L0("skipping rest of import file");
+            // make sure we don't commit partial block data
+            quit = 2;
+            break;
+          }
+        }
+        else
+        {
+          size_t block_size;
+          difficulty_type cumulative_difficulty;
+          uint64_t coins_generated;
+
+          a >> block_size;
+          a >> cumulative_difficulty;
+          a >> coins_generated;
+
+          std::cout << "\r                   \r";
+          LOG_PRINT_L2("block_size: " << block_size);
+          LOG_PRINT_L2("cumulative_difficulty: " << cumulative_difficulty);
+          LOG_PRINT_L2("coins_generated: " << coins_generated);
+
+          try
+          {
+            simple_core.add_block(b, block_size, cumulative_difficulty, coins_generated, txs);
+          }
+          catch (const std::exception& e)
+          {
+            std::cout << "\r                   \r";
+            LOG_PRINT_RED_L0("Error adding block to blockchain: " << e.what());
+            quit = 2; // make sure we don't commit partial block data
+            break;
+          }
+        }
+
+        if (use_batch)
+        {
+          if (h % db_batch_size == 0)
+          {
+            std::cout << "\r                   \r";
+            std::cout << ENDL << "[- batch commit at height " << h << " -]" << ENDL;
+            simple_core.batch_stop();
+            simple_core.batch_start();
+            std::cout << ENDL;
+#if !defined(BLOCKCHAIN_DB) || (BLOCKCHAIN_DB == DB_LMDB)
+            simple_core.m_storage.get_db()->show_stats();
+#endif
+          }
+        }
+      }
+    }
+    catch (const std::exception& e)
+    {
+      std::cout << "\r                   \r";
+      LOG_PRINT_RED_L0("exception while reading from import file, height=" << h);
+      return 2;
+    }
+  } // while
+
+  import_file.close();
+
+  if (use_batch)
+  {
+    if (quit > 1)
+    {
+      // There was an error, so don't commit pending data.
+      // Destructor will abort write txn.
+    }
+    else
+    {
+      simple_core.batch_stop();
+    }
+#if !defined(BLOCKCHAIN_DB) || (BLOCKCHAIN_DB == DB_LMDB)
+    simple_core.m_storage.get_db()->show_stats();
+#endif
+    if (h > 0)
+      LOG_PRINT_L0("Finished at height: " << h << "  block: " << h-1);
+  }
+  std::cout << ENDL;
+  return 0;
+}
+
+int main(int argc, char* argv[])
+{
+  std::string import_filename = BLOCKCHAIN_RAW;
+#if defined(BLOCKCHAIN_DB) && (BLOCKCHAIN_DB == DB_MEMORY)
+  std::string default_db_engine = "memory";
+#else
+  std::string default_db_engine = "lmdb";
+#endif
+
+  uint32_t log_level = LOG_LEVEL_0;
+  std::string dirname;
+  std::string db_engine;
+
+  boost::filesystem::path default_data_path {tools::get_default_data_dir()};
+  boost::filesystem::path default_testnet_data_path {default_data_path / "testnet"};
+
+  po::options_description desc_cmd_only("Command line options");
+  po::options_description desc_cmd_sett("Command line options and settings options");
+  const command_line::arg_descriptor<uint32_t> arg_log_level   =  {"log-level",  "", log_level};
+  const command_line::arg_descriptor<uint64_t> arg_batch_size  =  {"batch-size", "", db_batch_size};
+  const command_line::arg_descriptor<bool>     arg_testnet_on  = {
+    "testnet"
+      , "Run on testnet."
+      , false
+  };
+  const command_line::arg_descriptor<bool>     arg_count_blocks = {
+    "count-blocks"
+      , "Count blocks in import file and exit"
+      , false
+  };
+  const command_line::arg_descriptor<std::string> arg_database = {
+    "database", "available: memory, lmdb"
+      , default_db_engine
+  };
+  const command_line::arg_descriptor<bool> arg_verify =  {"verify",
+    "Verify blocks and transactions during import", true};
+  const command_line::arg_descriptor<bool> arg_batch  =  {"batch",
+    "Batch transactions for faster import", true};
+  const command_line::arg_descriptor<bool> arg_resume =  {"resume",
+    "Resume from current height if output database already exists", true};
+
+  command_line::add_arg(desc_cmd_sett, command_line::arg_data_dir, default_data_path.string());
+  command_line::add_arg(desc_cmd_sett, command_line::arg_testnet_data_dir, default_testnet_data_path.string());
+  command_line::add_arg(desc_cmd_sett, arg_log_level);
+  command_line::add_arg(desc_cmd_sett, arg_batch_size);
+  command_line::add_arg(desc_cmd_sett, arg_testnet_on);
+  command_line::add_arg(desc_cmd_sett, arg_database);
+
+  command_line::add_arg(desc_cmd_only, arg_count_blocks);
+  command_line::add_arg(desc_cmd_only, command_line::arg_help);
+
+  // call add_options() directly for these arguments since
+  // command_line helpers support only boolean switch, not boolean argument
+  desc_cmd_sett.add_options()
+    (arg_verify.name, make_semantic(arg_verify), arg_verify.description)
+    (arg_batch.name,  make_semantic(arg_batch),  arg_batch.description)
+    (arg_resume.name, make_semantic(arg_resume), arg_resume.description)
+    ;
+
+  po::options_description desc_options("Allowed options");
+  desc_options.add(desc_cmd_only).add(desc_cmd_sett);
+
+  po::variables_map vm;
+  bool r = command_line::handle_error_helper(desc_options, [&]()
+  {
+    po::store(po::parse_command_line(argc, argv, desc_options), vm);
+    po::notify(vm);
+    return true;
+  });
+  if (! r)
+    return 1;
+
+  log_level     = command_line::get_arg(vm, arg_log_level);
+  opt_verify    = command_line::get_arg(vm, arg_verify);
+  opt_batch     = command_line::get_arg(vm, arg_batch);
+  opt_resume    = command_line::get_arg(vm, arg_resume);
+  db_batch_size = command_line::get_arg(vm, arg_batch_size);
+
+  if (command_line::get_arg(vm, command_line::arg_help))
+  {
+    std::cout << CRYPTONOTE_NAME << " v" << MONERO_VERSION_FULL << ENDL << ENDL;
+    std::cout << desc_options << std::endl;
+    return 1;
+  }
+
+  if (! opt_batch && ! vm["batch-size"].defaulted())
+  {
+    std::cerr << "Error: batch-size set, but batch option not enabled" << ENDL;
+    exit(1);
+  }
+  if (! db_batch_size)
+  {
+    std::cerr << "Error: batch-size must be > 0" << ENDL;
+    exit(1);
+  }
+
+  std::vector<std::string> db_engines {"memory", "lmdb"};
+
+  opt_testnet = command_line::get_arg(vm, arg_testnet_on);
+  auto data_dir_arg = opt_testnet ? command_line::arg_testnet_data_dir : command_line::arg_data_dir;
+  dirname = command_line::get_arg(vm, data_dir_arg);
+  db_engine = command_line::get_arg(vm, arg_database);
+
+  log_space::get_set_log_detalisation_level(true, log_level);
+  log_space::log_singletone::add_logger(LOGGER_CONSOLE, NULL, NULL);
+  LOG_PRINT_L0("Starting...");
+  LOG_PRINT_L0("Setting log level = " << log_level);
+
+  boost::filesystem::path file_path {dirname};
+  std::string import_file_path;
+
+  import_file_path = (file_path / "export" / import_filename).string();
+
+  if (command_line::has_arg(vm, arg_count_blocks))
+  {
+    count_blocks(import_file_path);
+    exit(0);
+  }
+
+  if (std::find(db_engines.begin(), db_engines.end(), db_engine) == db_engines.end())
+  {
+    std::cerr << "Invalid database engine: " << db_engine << std::endl;
+    exit(1);
+  }
+
+  LOG_PRINT_L0("database: " << db_engine);
+  LOG_PRINT_L0("verify:  " << std::boolalpha << opt_verify << std::noboolalpha);
+  if (opt_batch)
+  {
+    LOG_PRINT_L0("batch:   " << std::boolalpha << opt_batch << std::noboolalpha
+        << "  batch size: " << db_batch_size);
+  }
+  else
+  {
+    LOG_PRINT_L0("batch:   " << std::boolalpha << opt_batch << std::noboolalpha);
+  }
+  LOG_PRINT_L0("resume:  " << std::boolalpha << opt_resume  << std::noboolalpha);
+  LOG_PRINT_L0("testnet: " << std::boolalpha << opt_testnet << std::noboolalpha);
+
+  std::cout << "import file path: " << import_file_path << ENDL;
+  std::cout << "database path:    " << file_path.string() << ENDL;
+
+  try
+  {
+
+  // fake_core needed for verification to work when enabled.
+  //
+  // NOTE: don't need fake_core method of doing things when we're going to call
+  // BlockchainDB add_block() directly and have available the 3 block
+  // properties to do so. Both ways work, but fake core isn't necessary in that
+  // circumstance.
+
+  // for multi_db_runtime:
+#if !defined(BLOCKCHAIN_DB)
+  if (db_engine == "lmdb")
+  {
+    fake_core_lmdb simple_core(dirname, opt_testnet, opt_batch);
+    import_from_file(simple_core, import_file_path);
+  }
+  else if (db_engine == "memory")
+  {
+    fake_core_memory simple_core(dirname, opt_testnet);
+    import_from_file(simple_core, import_file_path);
+  }
+  else
+  {
+    std::cerr << "database engine unrecognized" << ENDL;
+    exit(1);
+  }
+
+  // for multi_db_compile:
+#else
+  if (db_engine != default_db_engine)
+  {
+    std::cerr << "Invalid database engine for compiled version: " << db_engine << std::endl;
+    exit(1);
+  }
+#if BLOCKCHAIN_DB == DB_LMDB
+  fake_core_lmdb simple_core(dirname, opt_testnet, opt_batch);
+#else
+  fake_core_memory simple_core(dirname, opt_testnet);
+#endif
+
+  import_from_file(simple_core, import_file_path);
+#endif
+
+  }
+  catch (const DB_ERROR& e)
+  {
+    std::cout << std::string("Error loading blockchain db: ") + e.what() + " -- shutting down now" << ENDL;
+    exit(1);
+  }
+
+  // destructors called at exit:
+  //
+  // ensure db closed
+  //   - transactions properly checked and handled
+  //   - disk sync if needed
+  //
+  // fake_core object's destructor is called when it goes out of scope. For an
+  // LMDB fake_core, it calls Blockchain::deinit() on its object, which in turn
+  // calls delete on its BlockchainDB derived class' object, which closes its
+  // files.
+}