Pruning

The blockchain prunes seven eighths of prunable tx data.
This saves about two thirds of the blockchain size, while
keeping the node useful as a sync source for an eighth
of the blockchain.

No other data is currently pruned.

There are three ways to prune a blockchain:

- run monerod with --prune-blockchain
- run "prune_blockchain" in the monerod console
- run the monero-blockchain-prune utility

The first two will prune in place. Due to how LMDB works, this
will not reduce the blockchain size on disk. Instead, it will
mark parts of the file as free, so that future data will use
that free space, causing the file to not grow until free space
grows scarce.

The third way will create a second database, a pruned copy of
the original one. Since this is a new file, this one will be
smaller than the original one.

Once the database is pruned, it will stay pruned as it syncs.
That is, there is no need to use --prune-blockchain again, etc.

1 files changed, 663 insertions, 0 deletions

diff --git a/src/blockchain_utilities/blockchain_prune.cpp b/src/blockchain_utilities/blockchain_prune.cpp
new file mode 100644
index 000000000..8e13f2c04
--- /dev/null
+++ b/src/blockchain_utilities/blockchain_prune.cpp
@@ -0,0 +1,663 @@
+// Copyright (c) 2018, 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 <array>
+#include <lmdb.h>
+#include <boost/algorithm/string.hpp>
+#include "common/command_line.h"
+#include "common/pruning.h"
+#include "cryptonote_core/cryptonote_core.h"
+#include "cryptonote_core/blockchain.h"
+#include "blockchain_db/blockchain_db.h"
+#include "blockchain_db/lmdb/db_lmdb.h"
+#include "blockchain_db/db_types.h"
+#include "version.h"
+
+#undef MONERO_DEFAULT_LOG_CATEGORY
+#define MONERO_DEFAULT_LOG_CATEGORY "bcutil"
+
+#define MDB_val_set(var, val)   MDB_val var = {sizeof(val), (void *)&val}
+
+namespace po = boost::program_options;
+using namespace epee;
+using namespace cryptonote;
+
+static std::string db_path;
+
+// default to fast:1
+static uint64_t records_per_sync = 128;
+static const size_t slack = 512 * 1024 * 1024;
+
+static std::error_code replace_file(const boost::filesystem::path& replacement_name, const boost::filesystem::path& replaced_name)
+{
+  std::error_code ec = tools::replace_file(replacement_name.string(), replaced_name.string());
+  if (ec)
+    MERROR("Error renaming " << replacement_name << " to " << replaced_name << ": " << ec.message());
+  return ec;
+}
+
+static void open(MDB_env *&env, const boost::filesystem::path &path, uint64_t db_flags, bool readonly)
+{
+  int dbr;
+  int flags = 0;
+
+  if (db_flags & DBF_FAST)
+    flags |= MDB_NOSYNC;
+  if (db_flags & DBF_FASTEST)
+    flags |= MDB_NOSYNC | MDB_WRITEMAP | MDB_MAPASYNC;
+  if (readonly)
+    flags |= MDB_RDONLY;
+
+  dbr = mdb_env_create(&env);
+  if (dbr) throw std::runtime_error("Failed to create LDMB environment: " + std::string(mdb_strerror(dbr)));
+  dbr = mdb_env_set_maxdbs(env, 32);
+  if (dbr) throw std::runtime_error("Failed to set max env dbs: " + std::string(mdb_strerror(dbr)));
+  dbr = mdb_env_open(env, path.string().c_str(), flags, 0664);
+  if (dbr) throw std::runtime_error("Failed to open database file '"
+      + path.string() + "': " + std::string(mdb_strerror(dbr)));
+}
+
+static void close(MDB_env *env)
+{
+  mdb_env_close(env);
+}
+
+static void add_size(MDB_env *env, uint64_t bytes)
+{
+  try
+  {
+    boost::filesystem::path path(db_path);
+    boost::filesystem::space_info si = boost::filesystem::space(path);
+    if(si.available < bytes)
+    {
+      MERROR("!! WARNING: Insufficient free space to extend database !!: " <<
+          (si.available >> 20L) << " MB available, " << (bytes >> 20L) << " MB needed");
+      return;
+    }
+  }
+  catch(...)
+  {
+    // print something but proceed.
+    MWARNING("Unable to query free disk space.");
+  }
+
+  MDB_envinfo mei;
+  mdb_env_info(env, &mei);
+  MDB_stat mst;
+  mdb_env_stat(env, &mst);
+
+  uint64_t new_mapsize = (uint64_t)mei.me_mapsize + bytes;
+  new_mapsize += (new_mapsize % mst.ms_psize);
+
+  int result = mdb_env_set_mapsize(env, new_mapsize);
+  if (result)
+    throw std::runtime_error("Failed to set new mapsize to " + std::to_string(new_mapsize) + ": " + std::string(mdb_strerror(result)));
+
+  MGINFO("LMDB Mapsize increased." << "  Old: " << mei.me_mapsize / (1024 * 1024) << "MiB" << ", New: " << new_mapsize / (1024 * 1024) << "MiB");
+}
+
+static void check_resize(MDB_env *env, size_t bytes)
+{
+  MDB_envinfo mei;
+  MDB_stat mst;
+
+  mdb_env_info(env, &mei);
+  mdb_env_stat(env, &mst);
+
+  uint64_t size_used = mst.ms_psize * mei.me_last_pgno;
+  if (size_used + bytes + slack >= mei.me_mapsize)
+    add_size(env, size_used + bytes + 2 * slack - mei.me_mapsize);
+}
+
+static bool resize_point(size_t nrecords, MDB_env *env, MDB_txn **txn, size_t &bytes)
+{
+  if (nrecords % records_per_sync && bytes <= slack / 2)
+    return false;
+  int dbr = mdb_txn_commit(*txn);
+  if (dbr) throw std::runtime_error("Failed to commit txn: " + std::string(mdb_strerror(dbr)));
+  check_resize(env, bytes);
+  dbr = mdb_txn_begin(env, NULL, 0, txn);
+  if (dbr) throw std::runtime_error("Failed to create LMDB transaction: " + std::string(mdb_strerror(dbr)));
+  bytes = 0;
+  return true;
+}
+
+static void copy_table(MDB_env *env0, MDB_env *env1, const char *table, unsigned int flags, unsigned int putflags, int (*cmp)(const MDB_val*, const MDB_val*)=0)
+{
+  MDB_dbi dbi0, dbi1;
+  MDB_txn *txn0, *txn1;
+  MDB_cursor *cur0, *cur1;
+  bool tx_active0 = false, tx_active1 = false;
+  int dbr;
+
+  MINFO("Copying " << table);
+
+  epee::misc_utils::auto_scope_leave_caller txn_dtor = epee::misc_utils::create_scope_leave_handler([&](){
+    if (tx_active1) mdb_txn_abort(txn1);
+    if (tx_active0) mdb_txn_abort(txn0);
+  });
+
+  dbr = mdb_txn_begin(env0, NULL, MDB_RDONLY, &txn0);
+  if (dbr) throw std::runtime_error("Failed to create LMDB transaction: " + std::string(mdb_strerror(dbr)));
+  tx_active0 = true;
+  dbr = mdb_txn_begin(env1, NULL, 0, &txn1);
+  if (dbr) throw std::runtime_error("Failed to create LMDB transaction: " + std::string(mdb_strerror(dbr)));
+  tx_active1 = true;
+
+  dbr = mdb_dbi_open(txn0, table, flags, &dbi0);
+  if (dbr) throw std::runtime_error("Failed to open LMDB dbi: " + std::string(mdb_strerror(dbr)));
+  if (cmp)
+    ((flags & MDB_DUPSORT) ? mdb_set_dupsort : mdb_set_compare)(txn0, dbi0, cmp);
+
+  dbr = mdb_dbi_open(txn1, table, flags, &dbi1);
+  if (dbr) throw std::runtime_error("Failed to open LMDB dbi: " + std::string(mdb_strerror(dbr)));
+  if (cmp)
+    ((flags & MDB_DUPSORT) ? mdb_set_dupsort : mdb_set_compare)(txn1, dbi1, cmp);
+
+  dbr = mdb_txn_commit(txn1);
+  if (dbr) throw std::runtime_error("Failed to commit txn: " + std::string(mdb_strerror(dbr)));
+  tx_active1 = false;
+  MDB_stat stats;
+  dbr = mdb_env_stat(env0, &stats);
+  if (dbr) throw std::runtime_error("Failed to stat " + std::string(table) + " LMDB table: " + std::string(mdb_strerror(dbr)));
+  check_resize(env1, (stats.ms_branch_pages + stats.ms_overflow_pages + stats.ms_leaf_pages) * stats.ms_psize);
+  dbr = mdb_txn_begin(env1, NULL, 0, &txn1);
+  if (dbr) throw std::runtime_error("Failed to create LMDB transaction: " + std::string(mdb_strerror(dbr)));
+  tx_active1 = true;
+
+  dbr = mdb_drop(txn1, dbi1, 0);
+  if (dbr) throw std::runtime_error("Failed to empty " + std::string(table) + " LMDB table: " + std::string(mdb_strerror(dbr)));
+
+  dbr = mdb_cursor_open(txn0, dbi0, &cur0);
+  if (dbr) throw std::runtime_error("Failed to create LMDB cursor: " + std::string(mdb_strerror(dbr)));
+  dbr = mdb_cursor_open(txn1, dbi1, &cur1);
+  if (dbr) throw std::runtime_error("Failed to create LMDB cursor: " + std::string(mdb_strerror(dbr)));
+
+  MDB_val k;
+  MDB_val v;
+  MDB_cursor_op op = MDB_FIRST;
+  size_t nrecords = 0, bytes = 0;
+  while (1)
+  {
+    int ret = mdb_cursor_get(cur0, &k, &v, op);
+    op = MDB_NEXT;
+    if (ret == MDB_NOTFOUND)
+      break;
+    if (ret)
+      throw std::runtime_error("Failed to enumerate " + std::string(table) + " records: " + std::string(mdb_strerror(ret)));
+
+    bytes += k.mv_size + v.mv_size;
+    if (resize_point(++nrecords, env1, &txn1, bytes))
+    {
+      dbr = mdb_cursor_open(txn1, dbi1, &cur1);
+      if (dbr) throw std::runtime_error("Failed to create LMDB cursor: " + std::string(mdb_strerror(dbr)));
+    }
+
+    ret = mdb_cursor_put(cur1, &k, &v, putflags);
+    if (ret)
+      throw std::runtime_error("Failed to write " + std::string(table) + " record: " + std::string(mdb_strerror(ret)));
+  }
+
+  mdb_cursor_close(cur1);
+  mdb_cursor_close(cur0);
+  mdb_txn_commit(txn1);
+  tx_active1 = false;
+  mdb_txn_commit(txn0);
+  tx_active0 = false;
+  mdb_dbi_close(env1, dbi1);
+  mdb_dbi_close(env0, dbi0);
+}
+
+static bool is_v1_tx(MDB_cursor *c_txs_pruned, MDB_val *tx_id)
+{
+  MDB_val v;
+  int ret = mdb_cursor_get(c_txs_pruned, tx_id, &v, MDB_SET);
+  if (ret)
+    throw std::runtime_error("Failed to find transaction pruned data: " + std::string(mdb_strerror(ret)));
+  if (v.mv_size == 0)
+    throw std::runtime_error("Invalid transaction pruned data");
+  return cryptonote::is_v1_tx(cryptonote::blobdata_ref{(const char*)v.mv_data, v.mv_size});
+}
+
+static void prune(MDB_env *env0, MDB_env *env1)
+{
+  MDB_dbi dbi0_blocks, dbi0_txs_pruned, dbi0_txs_prunable, dbi0_tx_indices, dbi1_txs_prunable, dbi1_txs_prunable_tip, dbi1_properties;
+  MDB_txn *txn0, *txn1;
+  MDB_cursor *cur0_txs_pruned, *cur0_txs_prunable, *cur0_tx_indices, *cur1_txs_prunable, *cur1_txs_prunable_tip;
+  bool tx_active0 = false, tx_active1 = false;
+  int dbr;
+
+  MGINFO("Creating pruned txs_prunable");
+
+  epee::misc_utils::auto_scope_leave_caller txn_dtor = epee::misc_utils::create_scope_leave_handler([&](){
+    if (tx_active1) mdb_txn_abort(txn1);
+    if (tx_active0) mdb_txn_abort(txn0);
+  });
+
+  dbr = mdb_txn_begin(env0, NULL, MDB_RDONLY, &txn0);
+  if (dbr) throw std::runtime_error("Failed to create LMDB transaction: " + std::string(mdb_strerror(dbr)));
+  tx_active0 = true;
+  dbr = mdb_txn_begin(env1, NULL, 0, &txn1);
+  if (dbr) throw std::runtime_error("Failed to create LMDB transaction: " + std::string(mdb_strerror(dbr)));
+  tx_active1 = true;
+
+  dbr = mdb_dbi_open(txn0, "txs_pruned", MDB_INTEGERKEY, &dbi0_txs_pruned);
+  if (dbr) throw std::runtime_error("Failed to open LMDB dbi: " + std::string(mdb_strerror(dbr)));
+  mdb_set_compare(txn0, dbi0_txs_pruned, BlockchainLMDB::compare_uint64);
+  dbr = mdb_cursor_open(txn0, dbi0_txs_pruned, &cur0_txs_pruned);
+  if (dbr) throw std::runtime_error("Failed to create LMDB cursor: " + std::string(mdb_strerror(dbr)));
+
+  dbr = mdb_dbi_open(txn0, "txs_prunable", MDB_INTEGERKEY, &dbi0_txs_prunable);
+  if (dbr) throw std::runtime_error("Failed to open LMDB dbi: " + std::string(mdb_strerror(dbr)));
+  mdb_set_compare(txn0, dbi0_txs_prunable, BlockchainLMDB::compare_uint64);
+  dbr = mdb_cursor_open(txn0, dbi0_txs_prunable, &cur0_txs_prunable);
+  if (dbr) throw std::runtime_error("Failed to create LMDB cursor: " + std::string(mdb_strerror(dbr)));
+
+  dbr = mdb_dbi_open(txn0, "tx_indices", MDB_INTEGERKEY | MDB_DUPSORT | MDB_DUPFIXED, &dbi0_tx_indices);
+  if (dbr) throw std::runtime_error("Failed to open LMDB dbi: " + std::string(mdb_strerror(dbr)));
+  mdb_set_dupsort(txn0, dbi0_tx_indices, BlockchainLMDB::compare_hash32);
+  dbr = mdb_cursor_open(txn0, dbi0_tx_indices, &cur0_tx_indices);
+  if (dbr) throw std::runtime_error("Failed to create LMDB cursor: " + std::string(mdb_strerror(dbr)));
+
+  dbr = mdb_dbi_open(txn1, "txs_prunable", MDB_INTEGERKEY, &dbi1_txs_prunable);
+  if (dbr) throw std::runtime_error("Failed to open LMDB dbi: " + std::string(mdb_strerror(dbr)));
+  mdb_set_compare(txn1, dbi1_txs_prunable, BlockchainLMDB::compare_uint64);
+  dbr = mdb_cursor_open(txn1, dbi1_txs_prunable, &cur1_txs_prunable);
+  if (dbr) throw std::runtime_error("Failed to create LMDB cursor: " + std::string(mdb_strerror(dbr)));
+
+  dbr = mdb_dbi_open(txn1, "txs_prunable_tip", MDB_INTEGERKEY | MDB_DUPSORT | MDB_DUPFIXED, &dbi1_txs_prunable_tip);
+  if (dbr) throw std::runtime_error("Failed to open LMDB dbi: " + std::string(mdb_strerror(dbr)));
+  mdb_set_dupsort(txn1, dbi1_txs_prunable_tip, BlockchainLMDB::compare_uint64);
+  dbr = mdb_cursor_open(txn1, dbi1_txs_prunable_tip, &cur1_txs_prunable_tip);
+  if (dbr) throw std::runtime_error("Failed to create LMDB cursor: " + std::string(mdb_strerror(dbr)));
+
+  dbr = mdb_drop(txn1, dbi1_txs_prunable, 0);
+  if (dbr) throw std::runtime_error("Failed to empty LMDB table: " + std::string(mdb_strerror(dbr)));
+  dbr = mdb_drop(txn1, dbi1_txs_prunable_tip, 0);
+  if (dbr) throw std::runtime_error("Failed to empty LMDB table: " + std::string(mdb_strerror(dbr)));
+
+  dbr = mdb_dbi_open(txn1, "properties", 0, &dbi1_properties);
+  if (dbr) throw std::runtime_error("Failed to open LMDB dbi: " + std::string(mdb_strerror(dbr)));
+
+  MDB_val k, v;
+  uint32_t pruning_seed = tools::make_pruning_seed(tools::get_random_stripe(), CRYPTONOTE_PRUNING_LOG_STRIPES);
+  static char pruning_seed_key[] = "pruning_seed";
+  k.mv_data = pruning_seed_key;
+  k.mv_size = strlen("pruning_seed") + 1;
+  v.mv_data = (void*)&pruning_seed;
+  v.mv_size = sizeof(pruning_seed);
+  dbr = mdb_put(txn1, dbi1_properties, &k, &v, 0);
+  if (dbr) throw std::runtime_error("Failed to save pruning seed: " + std::string(mdb_strerror(dbr)));
+
+  MDB_stat stats;
+  dbr = mdb_dbi_open(txn0, "blocks", 0, &dbi0_blocks);
+  if (dbr) throw std::runtime_error("Failed to open LMDB dbi: " + std::string(mdb_strerror(dbr)));
+  dbr = mdb_stat(txn0, dbi0_blocks, &stats);
+  if (dbr) throw std::runtime_error("Failed to query size of blocks: " + std::string(mdb_strerror(dbr)));
+  mdb_dbi_close(env0, dbi0_blocks);
+  const uint64_t blockchain_height = stats.ms_entries;
+  size_t nrecords = 0, bytes = 0;
+
+  MDB_cursor_op op = MDB_FIRST;
+  while (1)
+  {
+    int ret = mdb_cursor_get(cur0_tx_indices, &k, &v, op);
+    op = MDB_NEXT;
+    if (ret == MDB_NOTFOUND)
+      break;
+    if (ret) throw std::runtime_error("Failed to enumerate records: " + std::string(mdb_strerror(ret)));
+
+    const txindex *ti = (const txindex*)v.mv_data;
+    const uint64_t block_height = ti->data.block_id;
+    MDB_val_set(kk, ti->data.tx_id);
+    if (block_height + CRYPTONOTE_PRUNING_TIP_BLOCKS >= blockchain_height)
+    {
+      MDEBUG(block_height << "/" << blockchain_height << " is in tip");
+      MDB_val_set(vv, block_height);
+      dbr = mdb_cursor_put(cur1_txs_prunable_tip, &kk, &vv, 0);
+      if (dbr) throw std::runtime_error("Failed to write prunable tx tip data: " + std::string(mdb_strerror(dbr)));
+      bytes += kk.mv_size + vv.mv_size;
+    }
+    if (tools::has_unpruned_block(block_height, blockchain_height, pruning_seed) || is_v1_tx(cur0_txs_pruned, &kk))
+    {
+      MDB_val vv;
+      dbr = mdb_cursor_get(cur0_txs_prunable, &kk, &vv, MDB_SET);
+      if (dbr) throw std::runtime_error("Failed to read prunable tx data: " + std::string(mdb_strerror(dbr)));
+      bytes += kk.mv_size + vv.mv_size;
+      if (resize_point(++nrecords, env1, &txn1, bytes))
+      {
+        dbr = mdb_cursor_open(txn1, dbi1_txs_prunable, &cur1_txs_prunable);
+        if (dbr) throw std::runtime_error("Failed to create LMDB cursor: " + std::string(mdb_strerror(dbr)));
+        dbr = mdb_cursor_open(txn1, dbi1_txs_prunable_tip, &cur1_txs_prunable_tip);
+        if (dbr) throw std::runtime_error("Failed to create LMDB cursor: " + std::string(mdb_strerror(dbr)));
+      }
+      dbr = mdb_cursor_put(cur1_txs_prunable, &kk, &vv, 0);
+      if (dbr) throw std::runtime_error("Failed to write prunable tx data: " + std::string(mdb_strerror(dbr)));
+    }
+    else
+    {
+      MDEBUG("" << block_height << "/" << blockchain_height << " should be pruned, dropping");
+    }
+  }
+
+  mdb_cursor_close(cur1_txs_prunable_tip);
+  mdb_cursor_close(cur1_txs_prunable);
+  mdb_cursor_close(cur0_txs_prunable);
+  mdb_cursor_close(cur0_txs_pruned);
+  mdb_cursor_close(cur0_tx_indices);
+  mdb_txn_commit(txn1);
+  tx_active1 = false;
+  mdb_txn_commit(txn0);
+  tx_active0 = false;
+  mdb_dbi_close(env1, dbi1_properties);
+  mdb_dbi_close(env1, dbi1_txs_prunable_tip);
+  mdb_dbi_close(env1, dbi1_txs_prunable);
+  mdb_dbi_close(env0, dbi0_txs_prunable);
+  mdb_dbi_close(env0, dbi0_txs_pruned);
+  mdb_dbi_close(env0, dbi0_tx_indices);
+}
+
+static bool parse_db_sync_mode(std::string db_sync_mode, uint64_t &db_flags)
+{
+  std::vector<std::string> options;
+  boost::trim(db_sync_mode);
+  boost::split(options, db_sync_mode, boost::is_any_of(" :"));
+
+  for(const auto &option : options)
+    MDEBUG("option: " << option);
+
+  // default to fast:async:1
+  uint64_t DEFAULT_FLAGS = DBF_FAST;
+
+  db_flags = 0;
+
+  if(options.size() == 0)
+  {
+    // default to fast:async:1
+    db_flags = DEFAULT_FLAGS;
+  }
+
+  bool safemode = false;
+  if(options.size() >= 1)
+  {
+    if(options[0] == "safe")
+    {
+      safemode = true;
+      db_flags = DBF_SAFE;
+    }
+    else if(options[0] == "fast")
+    {
+      db_flags = DBF_FAST;
+    }
+    else if(options[0] == "fastest")
+    {
+      db_flags = DBF_FASTEST;
+      records_per_sync = 1000; // default to fastest:async:1000
+    }
+    else
+      return false;
+  }
+
+  if(options.size() >= 2 && !safemode)
+  {
+    char *endptr;
+    uint64_t bps = strtoull(options[1].c_str(), &endptr, 0);
+    if (*endptr != '\0')
+      return false;
+    records_per_sync = bps;
+  }
+
+  return true;
+}
+
+int main(int argc, char* argv[])
+{
+  TRY_ENTRY();
+
+  epee::string_tools::set_module_name_and_folder(argv[0]);
+
+  std::string default_db_type = "lmdb";
+
+  std::string available_dbs = cryptonote::blockchain_db_types(", ");
+  available_dbs = "available: " + available_dbs;
+
+  uint32_t log_level = 0;
+
+  tools::on_startup();
+
+  boost::filesystem::path output_file_path;
+
+  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<std::string> arg_log_level  = {"log-level",  "0-4 or categories", ""};
+  const command_line::arg_descriptor<std::string> arg_database = {
+    "database", available_dbs.c_str(), default_db_type
+  };
+  const command_line::arg_descriptor<std::string> arg_db_sync_mode = {
+    "db-sync-mode"
+  , "Specify sync option, using format [safe|fast|fastest]:[nrecords_per_sync]."
+  , "fast:1000"
+  };
+  const command_line::arg_descriptor<bool> arg_copy_pruned_database  = {"copy-pruned-database",  "Copy database anyway if already pruned"};
+
+  command_line::add_arg(desc_cmd_sett, cryptonote::arg_data_dir);
+  command_line::add_arg(desc_cmd_sett, cryptonote::arg_testnet_on);
+  command_line::add_arg(desc_cmd_sett, cryptonote::arg_stagenet_on);
+  command_line::add_arg(desc_cmd_sett, arg_log_level);
+  command_line::add_arg(desc_cmd_sett, arg_database);
+  command_line::add_arg(desc_cmd_sett, arg_db_sync_mode);
+  command_line::add_arg(desc_cmd_sett, arg_copy_pruned_database);
+  command_line::add_arg(desc_cmd_only, command_line::arg_help);
+
+  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, [&]()
+  {
+    auto parser = po::command_line_parser(argc, argv).options(desc_options);
+    po::store(parser.run(), vm);
+    po::notify(vm);
+    return true;
+  });
+  if (! r)
+    return 1;
+
+  if (command_line::get_arg(vm, command_line::arg_help))
+  {
+    std::cout << "Monero '" << MONERO_RELEASE_NAME << "' (v" << MONERO_VERSION_FULL << ")" << ENDL << ENDL;
+    std::cout << desc_options << std::endl;
+    return 1;
+  }
+
+  mlog_configure(mlog_get_default_log_path("monero-blockchain-prune.log"), true);
+  if (!command_line::is_arg_defaulted(vm, arg_log_level))
+    mlog_set_log(command_line::get_arg(vm, arg_log_level).c_str());
+  else
+    mlog_set_log(std::string(std::to_string(log_level) + ",bcutil:INFO").c_str());
+
+  MINFO("Starting...");
+
+  bool opt_testnet = command_line::get_arg(vm, cryptonote::arg_testnet_on);
+  bool opt_stagenet = command_line::get_arg(vm, cryptonote::arg_stagenet_on);
+  network_type net_type = opt_testnet ? TESTNET : opt_stagenet ? STAGENET : MAINNET;
+  bool opt_copy_pruned_database = command_line::get_arg(vm, arg_copy_pruned_database);
+  std::string data_dir = command_line::get_arg(vm, cryptonote::arg_data_dir);
+  while (boost::ends_with(data_dir, "/") || boost::ends_with(data_dir, "\\"))
+    data_dir.pop_back();
+
+  std::string db_type = command_line::get_arg(vm, arg_database);
+  if (!cryptonote::blockchain_valid_db_type(db_type))
+  {
+    MERROR("Invalid database type: " << db_type);
+    return 1;
+  }
+  if (db_type != "lmdb")
+  {
+    MERROR("Unsupported database type: " << db_type << ". Only lmdb is supported");
+    return 1;
+  }
+
+  std::string db_sync_mode = command_line::get_arg(vm, arg_db_sync_mode);
+  uint64_t db_flags = 0;
+  if (!parse_db_sync_mode(db_sync_mode, db_flags))
+  {
+    MERROR("Invalid db sync mode: " << db_sync_mode);
+    return 1;
+  }
+
+  // If we wanted to use the memory pool, we would set up a fake_core.
+
+  // Use Blockchain instead of lower-level BlockchainDB for two reasons:
+  // 1. Blockchain has the init() method for easy setup
+  // 2. exporter needs to use get_current_blockchain_height(), get_block_id_by_height(), get_block_by_hash()
+  //
+  // cannot match blockchain_storage setup above with just one line,
+  // e.g.
+  //   Blockchain* core_storage = new Blockchain(NULL);
+  // because unlike blockchain_storage constructor, which takes a pointer to
+  // tx_memory_pool, Blockchain's constructor takes tx_memory_pool object.
+  MINFO("Initializing source blockchain (BlockchainDB)");
+  std::array<std::unique_ptr<Blockchain>, 2> core_storage;
+  Blockchain *blockchain = NULL;
+  tx_memory_pool m_mempool(*blockchain);
+  boost::filesystem::path paths[2];
+  bool already_pruned = false;
+  for (size_t n = 0; n < core_storage.size(); ++n)
+  {
+    core_storage[n].reset(new Blockchain(m_mempool));
+
+    BlockchainDB* db = new_db(db_type);
+    if (db == NULL)
+    {
+      MERROR("Attempted to use non-existent database type: " << db_type);
+      throw std::runtime_error("Attempting to use non-existent database type");
+    }
+    MDEBUG("database: " << db_type);
+
+    if (n == 1)
+    {
+      paths[1] = boost::filesystem::path(data_dir) / (db->get_db_name() + "-pruned");
+      if (boost::filesystem::exists(paths[1]))
+      {
+        if (!boost::filesystem::is_directory(paths[1]))
+        {
+          MERROR("LMDB needs a directory path, but a file was passed: " << paths[1].string());
+          return 1;
+        }
+      }
+      else
+      {
+        if (!boost::filesystem::create_directories(paths[1]))
+        {
+          MERROR("Failed to create directory: " << paths[1].string());
+          return 1;
+        }
+      }
+      db_path = paths[1].string();
+    }
+    else
+    {
+      paths[0] = boost::filesystem::path(data_dir) / db->get_db_name();
+    }
+
+    MINFO("Loading blockchain from folder " << paths[n] << " ...");
+
+    try
+    {
+      db->open(paths[n].string(), n == 0 ? DBF_RDONLY : 0);
+    }
+    catch (const std::exception& e)
+    {
+      MERROR("Error opening database: " << e.what());
+      return 1;
+    }
+    r = core_storage[n]->init(db, net_type);
+
+    std::string source_dest = n == 0 ? "source" : "pruned";
+    CHECK_AND_ASSERT_MES(r, 1, "Failed to initialize " << source_dest << " blockchain storage");
+    MINFO(source_dest << " blockchain storage initialized OK");
+    if (n == 0 && core_storage[0]->get_blockchain_pruning_seed())
+    {
+      if (!opt_copy_pruned_database)
+      {
+        MERROR("Blockchain is already pruned, use --" << arg_copy_pruned_database.name << " to copy it anyway");
+        return 1;
+      }
+      already_pruned = true;
+    }
+  }
+  core_storage[0]->deinit();
+  core_storage[0].reset(NULL);
+  core_storage[1]->deinit();
+  core_storage[1].reset(NULL);
+
+  MINFO("Pruning...");
+  MDB_env *env0 = NULL, *env1 = NULL;
+  open(env0, paths[0], db_flags, true);
+  open(env1, paths[1], db_flags, false);
+  copy_table(env0, env1, "blocks", MDB_INTEGERKEY, MDB_APPEND);
+  copy_table(env0, env1, "block_info", MDB_INTEGERKEY | MDB_DUPSORT| MDB_DUPFIXED, MDB_APPENDDUP, BlockchainLMDB::compare_uint64);
+  copy_table(env0, env1, "block_heights", MDB_INTEGERKEY | MDB_DUPSORT| MDB_DUPFIXED, 0, BlockchainLMDB::compare_hash32);
+  //copy_table(env0, env1, "txs", MDB_INTEGERKEY);
+  copy_table(env0, env1, "txs_pruned", MDB_INTEGERKEY, MDB_APPEND);
+  copy_table(env0, env1, "txs_prunable_hash", MDB_INTEGERKEY | MDB_DUPSORT | MDB_DUPFIXED, MDB_APPEND);
+  // not copied: prunable, prunable_tip
+  copy_table(env0, env1, "tx_indices", MDB_INTEGERKEY | MDB_DUPSORT | MDB_DUPFIXED, 0, BlockchainLMDB::compare_hash32);
+  copy_table(env0, env1, "tx_outputs", MDB_INTEGERKEY, MDB_APPEND);
+  copy_table(env0, env1, "output_txs", MDB_INTEGERKEY | MDB_DUPSORT | MDB_DUPFIXED, MDB_APPENDDUP, BlockchainLMDB::compare_uint64);
+  copy_table(env0, env1, "output_amounts", MDB_INTEGERKEY | MDB_DUPSORT | MDB_DUPFIXED, MDB_APPENDDUP, BlockchainLMDB::compare_uint64);
+  copy_table(env0, env1, "spent_keys", MDB_INTEGERKEY | MDB_DUPSORT | MDB_DUPFIXED, MDB_NODUPDATA, BlockchainLMDB::compare_hash32);
+  copy_table(env0, env1, "txpool_meta", 0, MDB_NODUPDATA, BlockchainLMDB::compare_hash32);
+  copy_table(env0, env1, "txpool_blob", 0, MDB_NODUPDATA, BlockchainLMDB::compare_hash32);
+  copy_table(env0, env1, "hf_versions", MDB_INTEGERKEY, MDB_APPEND);
+  copy_table(env0, env1, "properties", 0, 0, BlockchainLMDB::compare_string);
+  if (already_pruned)
+  {
+    copy_table(env0, env1, "txs_prunable", MDB_INTEGERKEY, MDB_APPEND, BlockchainLMDB::compare_uint64);
+    copy_table(env0, env1, "txs_prunable_tip", MDB_INTEGERKEY | MDB_DUPSORT | MDB_DUPFIXED, MDB_NODUPDATA, BlockchainLMDB::compare_uint64);
+  }
+  else
+  {
+    prune(env0, env1);
+  }
+  close(env1);
+  close(env0);
+
+  MINFO("Swapping databases, pre-pruning blockchain will be left in " << paths[0].string() + "-old and can be removed if desired");
+  if (replace_file(paths[0].string(), paths[0].string() + "-old") || replace_file(paths[1].string(), paths[0].string()))
+  {
+    MERROR("Blockchain pruned OK, but renaming failed");
+    return 1;
+  }
+
+  MINFO("Blockchain pruned OK");
+  return 0;
+
+  CATCH_ENTRY("Pruning error", 1);
+}