Merge pull request #256

7d8acd1 explicitly disable AES on ARM (Riccardo Spagni)
4222b37 add arm6 target and flags (Riccardo Spagni)
5675325 new makefile targets for static builds (Riccardo Spagni)
9519526 Only compile BerkeleyDB as an option in non-static (Thomas Winget)
7b14d4a Steps toward multiple dbs available -- working (Thomas Winget)
dbdcf11 blockchain_converter: Add support for resume from last block (warptangent)
4880803 blockchain_import: lengthen string for line clear (warptangent)
7476d2e blockchain_export: show progress during export (warptangent)
4bedd68 Update Blockchain::get_db() to return reference instead of pointer (warptangent)
0386e99 Add README for blockchain converter, importer, and exporter utilities (warptangent)
ead7fad BerkeleyDB implementation of BlockchainDB seems to be working! (Thomas Winget)
ffadb65 blockchain_export: Add compile-time support for BlockchainDB (warptangent)
f6cbfb6 Add blockchain_export utility (warptangent)
275cbd4 Add support for database open with flags (warptangent)
cb862cb Add mdb_flags variable to LMDB database open (warptangent)
260cc56 Add blockchain_import utility (warptangent)
ca75b47 Blockchain: add get_db() accessor, needed for blockchain_import (warptangent)
a3dd9d1 blockchain_converter: Add support for batch transactions (warptangent)
acb5d29 Update and relocate comment that applies class wide (warptangent)
bd9da6d Merges #33 (Thomas Winget)
6e9e8ab Move db_drivers/ to external/ (Thomas Winget)
56a1bf5 fixed BUILD_64 option (Riccardo Spagni)
c97a685 fixed arch_width option (Riccardo Spagni)
3a3c07c fixed msys2 / mingw folders based on architecture, added license to unbound CMakeList as that is not part of standard Unbound (Riccardo Spagni)
3b3da86 moved 32-bit/64-bit detection into main CMakeLists (Riccardo Spagni)
a0cbf73 removed findlmdb.cmake, no longer required (Riccardo Spagni)
0e8bbdb 32-bit LMDB, removed check for in-system LMDB as it is consensus-critical (Riccardo Spagni)
11e8157 Revert "Moved db_drivers/ into external/ for consistency" (Thomas Winget)
daf2a8f Revert "Build fixed, goofed up some CMake" (Thomas Winget)
e146027 BlockchainBDB passes unit tests (Thomas Winget)
43477b7 BerkeleyDB Blockchain building, not working yet (Thomas Winget)
cade0da CMake wiring, minor cleanup, minor test addition (Thomas Winget)
1bc8939 BerkeleyDB BlockchainDB impl copy/paste/modify (Thomas Winget)
5112dc3 Try to not pollute cryptonote namespace (Thomas Winget)
edef0bb Initial commit of BDB BlockchainDB implementation (Thomas Winget)
eee3ee7 BlockchainDB implementations have names now (Thomas Winget)
5d2a2b7 Fixed includes in BlockchainDB unit tests (Thomas Winget)
8b82f3c Build fixed, goofed up some CMake (Thomas Winget)
b213356 Moved db_drivers/ into external/ for consistency (Thomas Winget)
5eab480 Moved BlockchainDB into its own src/ subfolder (Thomas Winget)
0ad0784 Changed log level of debug message -- too spammy (Thomas Winget)
6485dac BlockchainLMDB: Add profiling to tx_exists() (warptangent)
83fb6d8 BlockchainLMDB: Add batch transaction support to tx_exists() (warptangent)
8529c0e BlockchainDB, BlockchainLMDB: Add profiling for DB commits (warptangent)
7a66b8b BlockchainDB: Add virtual function declarations for batch transactions (warptangent)
b7a2d84 BlockchainLMDB: Add check for open database to two functions (warptangent)
58ecc58 BlockchainLMDB: Add support for batch transactions (warptangent)
8909d7d Improve block and tx processing efficiency by less repeat hashing (warptangent)
3676ac5 Add profiling to block and tx processing (warptangent)
ce71abd Move LMDB storage to subfolder (warptangent)
42f8fe5 Fix formatting (warptangent)
aa82f78 Fix log statement (warptangent)
26873db Remove unused variable (warptangent)
4b90fd3 Add log statement (warptangent)
2531aa3 Add and extend log statements (warptangent)
59305d3 Blockchain: match original function declaration from blockchain_storage (warptangent)
cd972bd Update year and formatting in license (warptangent)
b88ab64 Fix Blockchain::get_tail_id() to set parameter to last block number instead of height (warptangent)
963bc09 Revert "Bounds error, should fix #27" (warptangent)
6f1c4b4 Bounds error, should fix #27 (Thomas Winget)
84fe5fb Add compile-time support for both db implementations: in-memory and LMDB (warptangent)
8bd1983 Blockchain: reflect log updates from blockchain_storage (warptangent)
7f9b070 Blockchain: reflect log and assert updates from blockchain_storage (warptangent)
70342ec Blockchain: reflect log level of blockchain_storage (warptangent)
c8d27fb Blockchain: reflect assert behavior of blockchain_storage for get_tx_outputs_gindexs() (warptangent)
d00ee78 Update recently added log statement to fix possible null dereference (warptangent)
acd4c36 Should fix std::min issues related to size_t (Thomas Winget)
3488359 Add in-source lmdb to build process (Thomas Winget)
4e45fae Initial import of lmdb source (Thomas Winget)
800d9b9 Remove code previously made unused and marked unused (warptangent)
0840c2f Fix height assertion in Blockchain::handle_alternative_block() (warptangent)
63051be Fix comparison between main and alternate chain's cumulative difficulty. (warptangent)
909ea81 Remove a have_block() check so alternate block can be processed (warptangent)
4d0a94b Complete implementation of transaction removal (warptangent)
1701c26 Use block index when obtaining block's difficulty for log statement (warptangent)
4eba21f Fix transfers to support mixins (warptangent)
d045dfa Fix transfers (without mixins) (warptangent)
429a740 throw inline functions need to keep exception type (Thomas Winget)
14555ee Fixes segfault in Blockchain::handle_alternative_block (Thomas Winget)
5086ca1 add BlockchainDB tests to new cmake (Thomas Winget)
c5c100c Obtain tx hash and tx output index from amount and output offset (warptangent)
ad8200a db_lmdb: fix global index calculation off by 1 (moneromooo-monero)
57b80c5 db_lmdb: remove redundant checks (moneromooo-monero)
1362846 blockchain_converter: add --testnet for converting testnet blockchain (moneromooo-monero)
c50cd95 Fixes a bug with getting output metadata from BlockchainDB (Thomas Winget)
c3fa07b update comments to reflect changed code (Thomas Winget)
59d2b0e db_lmdb: do not give the group database write permissions (moneromooo-monero)
4c2a452 db_lmdb: catch attempt to remove block from an empty blockchain (moneromooo-monero)
3a3459d db_lmdb: factor all the log+throw code paths (moneromooo-monero)
3fcb8da db_lmdb: factor the MDB_val setup code (moneromooo-monero)
609cf7f blockchain_converter: a bit more user friendly output (moneromooo-monero)
2b9f737 blockchain_converter: only call data path function once (moneromooo-monero)
1860658 blockchain: do not append "testnet" to the data directory (moneromooo-monero)
1c578ad db_lmdb: remove block timestamp too when removing a block (moneromooo-monero)
c93a186 db_lmdb: do not cast const away (moneromooo-monero)
198368b blockchain: fix wallet syncing from scratch (moneromooo-monero)
1d23db2 db_lmdb: do not keep a dangling pointer to stack objects (moneromooo-monero)
29b5876 db_lmdb: make cursor internal members private (moneromooo-monero)
a3157d7 blockchain_storage: refactor genesis block creation (moneromooo-monero)
8e41b1e blockchain_storage: add consts where appropriate (moneromooo-monero)
98bdadc blockchain_converter: delete blockchain on succesful exit (moneromooo-monero)
256162f checkpoints: add consts where appropriate (moneromooo-monero)
b7270ab blockchain: add consts where appropriate (moneromooo-monero)
23f3cb4 blockchain_db: add consts where appropriate (moneromooo-monero)
10fd6ca blockchain_db: factor some exception code (moneromooo-monero)
11129b9 blockchain_converter: use the actual blockchain location (moneromooo-monero)
0886183 build: add liblmdb to the cmake autodetection system (moneromooo-monero)
215e63b extraneous semicolon in Blockchain::complete_timestamps_vector (Thomas Winget)
8e1b7e2 raised maximum mapsize for lmdb to ~16GB (Thomas Winget)
6c8b8ac more blockchain height-related fixes, syncing other nodes code this time (Thomas Winget)
9455e0c ~ didn't work, need hard path.  debug print. (Thomas Winget)
4af0918 very, VERY primitive blockchain converter (Thomas Winget)
26a7db3 add new checkpointing behavior to Blockchain class (Thomas Winget)
767aac2 Remove unused dependency (Thomas Winget)
006e106 Store output pubkeys separately, bug fixes (Thomas Winget)
ab7951d Minor bugfixes, redundancy removal (Thomas Winget)
71b18d7 moar bug fixes, removed debug prints (Thomas Winget)
0915913 BlockchainLMDB seems to be working*! (Thomas Winget)
1a546e3 some bug fixes, but still needs work (Thomas Winget)
006afe2 Minor bug fixes and debug prints (Thomas Winget)
90f402e minor fixes to Blockchain.cpp (Thomas Winget)
74a1a89 Integrate BlockchainDB into cryptonote_core (Thomas Winget)
d8c570b All LMDB BlockchainDB implemented, not tested (Thomas Winget)
e47e343 LMDB blockchain: remove outputs and spent keys (Thomas Winget)
a0af217 Adding block data to LMDB BlockchainDB coded (Thomas Winget)
db00ce0 Parts of LMDB impl of BlockchainDB done and working (Thomas Winget)
1240cf8 BlockchainDB unit tests, lmdb linker flag (Thomas Winget)
b98b964 Initial commit of lmdb BlockchainDB impl (Thomas Winget)
bc44bc1 Initial commit of BlockchainDB tests, other misc (Thomas Winget)
90d6f8b Adding libglim as an external library (Thomas Winget)
07733f9 update new blockchain to build with new changes (Thomas Winget)
1ffbeb2 stupid past me, fixing typos and shit... (Thomas Winget)
67515b8 missing typedef (Thomas Winget)
aba548c import of BlockchainDB files (Thomas Winget)

1 files changed, 1814 insertions, 0 deletions

diff --git a/src/blockchain_db/lmdb/db_lmdb.cpp b/src/blockchain_db/lmdb/db_lmdb.cpp
new file mode 100644
index 000000000..8e09dfab2
--- /dev/null
+++ b/src/blockchain_db/lmdb/db_lmdb.cpp
@@ -0,0 +1,1814 @@
+// Copyright (c) 2014, 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 "db_lmdb.h"
+
+#include <boost/filesystem.hpp>
+#include <memory>  // std::unique_ptr
+#include <cstring>  // memcpy
+
+#include "cryptonote_core/cryptonote_format_utils.h"
+#include "crypto/crypto.h"
+#include "profile_tools.h"
+
+using epee::string_tools::pod_to_hex;
+
+namespace
+{
+
+template <typename T>
+inline void throw0(const T &e)
+{
+  LOG_PRINT_L0(e.what());
+  throw e;
+}
+
+template <typename T>
+inline void throw1(const T &e)
+{
+  LOG_PRINT_L1(e.what());
+  throw e;
+}
+
+//  cursor needs to be closed when it goes out of scope,
+//  this helps if the function using it throws
+struct lmdb_cur
+{
+  lmdb_cur(MDB_txn* txn, MDB_dbi dbi)
+  {
+    if (mdb_cursor_open(txn, dbi, &m_cur))
+      throw0(cryptonote::DB_ERROR("Error opening db cursor"));
+    done = false;
+  }
+
+  ~lmdb_cur() { close(); }
+
+  operator MDB_cursor*() { return m_cur; }
+  operator MDB_cursor**() { return &m_cur; }
+
+  void close()
+  {
+    if (!done)
+    {
+      mdb_cursor_close(m_cur);
+      done = true;
+    }
+  }
+
+private:
+  MDB_cursor* m_cur;
+  bool done;
+};
+
+template<typename T>
+struct MDB_val_copy: public MDB_val
+{
+  MDB_val_copy(const T &t): t_copy(t)
+  {
+    mv_size = sizeof (T);
+    mv_data = &t_copy;
+  }
+private:
+  T t_copy;
+};
+
+template<>
+struct MDB_val_copy<cryptonote::blobdata>: public MDB_val
+{
+  MDB_val_copy(const cryptonote::blobdata &bd): data(new char[bd.size()])
+  {
+    memcpy(data.get(), bd.data(), bd.size());
+    mv_size = bd.size();
+    mv_data = data.get();
+  }
+private:
+  std::unique_ptr<char[]> data;
+};
+
+auto compare_uint64 = [](const MDB_val *a, const MDB_val *b) {
+  const uint64_t va = *(const uint64_t*)a->mv_data;
+  const uint64_t vb = *(const uint64_t*)b->mv_data;
+  if (va < vb) return -1;
+  else if (va == vb) return 0;
+  else return 1;
+};
+
+const char* const LMDB_BLOCKS = "blocks";
+const char* const LMDB_BLOCK_TIMESTAMPS = "block_timestamps";
+const char* const LMDB_BLOCK_HEIGHTS = "block_heights";
+const char* const LMDB_BLOCK_HASHES = "block_hashes";
+const char* const LMDB_BLOCK_SIZES = "block_sizes";
+const char* const LMDB_BLOCK_DIFFS = "block_diffs";
+const char* const LMDB_BLOCK_COINS = "block_coins";
+
+const char* const LMDB_TXS = "txs";
+const char* const LMDB_TX_UNLOCKS = "tx_unlocks";
+const char* const LMDB_TX_HEIGHTS = "tx_heights";
+const char* const LMDB_TX_OUTPUTS = "tx_outputs";
+
+const char* const LMDB_OUTPUT_TXS = "output_txs";
+const char* const LMDB_OUTPUT_INDICES = "output_indices";
+const char* const LMDB_OUTPUT_AMOUNTS = "output_amounts";
+const char* const LMDB_OUTPUT_KEYS = "output_keys";
+const char* const LMDB_OUTPUTS = "outputs";
+const char* const LMDB_OUTPUT_GINDICES = "output_gindices";
+const char* const LMDB_SPENT_KEYS = "spent_keys";
+
+inline void lmdb_db_open(MDB_txn* txn, const char* name, int flags, MDB_dbi& dbi, const std::string& error_string)
+{
+  if (mdb_dbi_open(txn, name, flags, &dbi))
+    throw0(cryptonote::DB_OPEN_FAILURE(error_string.c_str()));
+}
+
+}  // anonymous namespace
+
+namespace cryptonote
+{
+
+// If m_batch_active is set, a batch transaction exists beyond this class, such
+// as a batch import with verification enabled, or possibly (later) a batch
+// network sync.
+//
+// For some of the lookup methods, such as get_block_timestamp(), tx_exists(),
+// and get_tx(), when m_batch_active is set, the lookup uses the batch
+// transaction. This isn't only because the transaction is available, but it's
+// necessary so that lookups include the database updates only present in the
+// current batch write.
+//
+// A regular network sync without batch writes is expected to open a new read
+// transaction, as those lookups are part of the validation done prior to the
+// write for block and tx data, so no write transaction is open at the time.
+
+void BlockchainLMDB::add_block( const block& blk
+              , const size_t& block_size
+              , const difficulty_type& cumulative_difficulty
+              , const uint64_t& coins_generated
+              , const crypto::hash& blk_hash
+              )
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  MDB_val_copy<crypto::hash> val_h(blk_hash);
+  MDB_val unused;
+  if (mdb_get(*m_write_txn, m_block_heights, &val_h, &unused) == 0)
+    throw1(BLOCK_EXISTS("Attempting to add block that's already in the db"));
+
+  if (m_height > 0)
+  {
+    MDB_val_copy<crypto::hash> parent_key(blk.prev_id);
+    MDB_val parent_h;
+    if (mdb_get(*m_write_txn, m_block_heights, &parent_key, &parent_h))
+    {
+      LOG_PRINT_L3("m_height: " << m_height);
+      LOG_PRINT_L3("parent_key: " << blk.prev_id);
+      throw0(DB_ERROR("Failed to get top block hash to check for new block's parent"));
+    }
+    uint64_t parent_height = *(const uint64_t *)parent_h.mv_data;
+    if (parent_height != m_height - 1)
+      throw0(BLOCK_PARENT_DNE("Top block is not new block's parent"));
+  }
+
+  MDB_val_copy<uint64_t> key(m_height);
+
+  MDB_val_copy<blobdata> blob(block_to_blob(blk));
+  auto res = mdb_put(*m_write_txn, m_blocks, &key, &blob, 0);
+  if (res)
+    throw0(DB_ERROR(std::string("Failed to add block blob to db transaction: ").append(mdb_strerror(res)).c_str()));
+
+  MDB_val_copy<size_t> sz(block_size);
+  if (mdb_put(*m_write_txn, m_block_sizes, &key, &sz, 0))
+    throw0(DB_ERROR("Failed to add block size to db transaction"));
+
+  MDB_val_copy<uint64_t> ts(blk.timestamp);
+  if (mdb_put(*m_write_txn, m_block_timestamps, &key, &ts, 0))
+    throw0(DB_ERROR("Failed to add block timestamp to db transaction"));
+
+  MDB_val_copy<difficulty_type> diff(cumulative_difficulty);
+  if (mdb_put(*m_write_txn, m_block_diffs, &key, &diff, 0))
+    throw0(DB_ERROR("Failed to add block cumulative difficulty to db transaction"));
+
+  MDB_val_copy<uint64_t> coinsgen(coins_generated);
+  if (mdb_put(*m_write_txn, m_block_coins, &key, &coinsgen, 0))
+    throw0(DB_ERROR("Failed to add block total generated coins to db transaction"));
+
+  if (mdb_put(*m_write_txn, m_block_heights, &val_h, &key, 0))
+    throw0(DB_ERROR("Failed to add block height by hash to db transaction"));
+
+  if (mdb_put(*m_write_txn, m_block_hashes, &key, &val_h, 0))
+    throw0(DB_ERROR("Failed to add block hash to db transaction"));
+
+}
+
+void BlockchainLMDB::remove_block()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  if (m_height == 0)
+    throw0(BLOCK_DNE ("Attempting to remove block from an empty blockchain"));
+
+  MDB_val_copy<uint64_t> k(m_height - 1);
+  MDB_val h;
+  if (mdb_get(*m_write_txn, m_block_hashes, &k, &h))
+      throw1(BLOCK_DNE("Attempting to remove block that's not in the db"));
+
+  if (mdb_del(*m_write_txn, m_blocks, &k, NULL))
+      throw1(DB_ERROR("Failed to add removal of block to db transaction"));
+
+  if (mdb_del(*m_write_txn, m_block_sizes, &k, NULL))
+      throw1(DB_ERROR("Failed to add removal of block size to db transaction"));
+
+  if (mdb_del(*m_write_txn, m_block_diffs, &k, NULL))
+      throw1(DB_ERROR("Failed to add removal of block cumulative difficulty to db transaction"));
+
+  if (mdb_del(*m_write_txn, m_block_coins, &k, NULL))
+      throw1(DB_ERROR("Failed to add removal of block total generated coins to db transaction"));
+
+  if (mdb_del(*m_write_txn, m_block_timestamps, &k, NULL))
+      throw1(DB_ERROR("Failed to add removal of block timestamp to db transaction"));
+
+  if (mdb_del(*m_write_txn, m_block_heights, &h, NULL))
+      throw1(DB_ERROR("Failed to add removal of block height by hash to db transaction"));
+
+  if (mdb_del(*m_write_txn, m_block_hashes, &k, NULL))
+      throw1(DB_ERROR("Failed to add removal of block hash to db transaction"));
+}
+
+void BlockchainLMDB::add_transaction_data(const crypto::hash& blk_hash, const transaction& tx, const crypto::hash& tx_hash)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  MDB_val_copy<crypto::hash> val_h(tx_hash);
+  MDB_val unused;
+  if (mdb_get(*m_write_txn, m_txs, &val_h, &unused) == 0)
+      throw1(TX_EXISTS("Attempting to add transaction that's already in the db"));
+
+  MDB_val_copy<blobdata> blob(tx_to_blob(tx));
+  if (mdb_put(*m_write_txn, m_txs, &val_h, &blob, 0))
+    throw0(DB_ERROR("Failed to add tx blob to db transaction"));
+
+  MDB_val_copy<uint64_t> height(m_height);
+  if (mdb_put(*m_write_txn, m_tx_heights, &val_h, &height, 0))
+    throw0(DB_ERROR("Failed to add tx block height to db transaction"));
+
+  MDB_val_copy<uint64_t> unlock_time(tx.unlock_time);
+  if (mdb_put(*m_write_txn, m_tx_unlocks, &val_h, &unlock_time, 0))
+    throw0(DB_ERROR("Failed to add tx unlock time to db transaction"));
+}
+
+void BlockchainLMDB::remove_transaction_data(const crypto::hash& tx_hash, const transaction& tx)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  MDB_val_copy<crypto::hash> val_h(tx_hash);
+  MDB_val unused;
+  if (mdb_get(*m_write_txn, m_txs, &val_h, &unused))
+      throw1(TX_DNE("Attempting to remove transaction that isn't in the db"));
+
+  if (mdb_del(*m_write_txn, m_txs, &val_h, NULL))
+      throw1(DB_ERROR("Failed to add removal of tx to db transaction"));
+  if (mdb_del(*m_write_txn, m_tx_unlocks, &val_h, NULL))
+      throw1(DB_ERROR("Failed to add removal of tx unlock time to db transaction"));
+  if (mdb_del(*m_write_txn, m_tx_heights, &val_h, NULL))
+      throw1(DB_ERROR("Failed to add removal of tx block height to db transaction"));
+
+  remove_tx_outputs(tx_hash, tx);
+
+  if (mdb_del(*m_write_txn, m_tx_outputs, &val_h, NULL))
+      throw1(DB_ERROR("Failed to add removal of tx outputs to db transaction"));
+
+}
+
+void BlockchainLMDB::add_output(const crypto::hash& tx_hash, const tx_out& tx_output, const uint64_t& local_index)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  MDB_val_copy<uint64_t> k(m_num_outputs);
+  MDB_val_copy<crypto::hash> v(tx_hash);
+
+  if (mdb_put(*m_write_txn, m_output_txs, &k, &v, 0))
+    throw0(DB_ERROR("Failed to add output tx hash to db transaction"));
+  if (mdb_put(*m_write_txn, m_tx_outputs, &v, &k, 0))
+    throw0(DB_ERROR("Failed to add tx output index to db transaction"));
+
+  MDB_val_copy<uint64_t> val_local_index(local_index);
+  if (mdb_put(*m_write_txn, m_output_indices, &k, &val_local_index, 0))
+    throw0(DB_ERROR("Failed to add tx output index to db transaction"));
+
+  MDB_val_copy<uint64_t> val_amount(tx_output.amount);
+  if (auto result = mdb_put(*m_write_txn, m_output_amounts, &val_amount, &k, 0))
+    throw0(DB_ERROR(std::string("Failed to add output amount to db transaction").append(mdb_strerror(result)).c_str()));
+
+  if (tx_output.target.type() == typeid(txout_to_key))
+  {
+    MDB_val_copy<crypto::public_key> val_pubkey(boost::get<txout_to_key>(tx_output.target).key);
+    if (mdb_put(*m_write_txn, m_output_keys, &k, &val_pubkey, 0))
+      throw0(DB_ERROR("Failed to add output pubkey to db transaction"));
+  }
+
+
+/****** Uncomment if ever outputs actually need to be stored in this manner
+ *
+  blobdata b = output_to_blob(tx_output);
+
+  v.mv_size = b.size();
+  v.mv_data = &b;
+  if (mdb_put(*m_write_txn, m_outputs, &k, &v, 0))
+    throw0(DB_ERROR("Failed to add output to db transaction"));
+  if (mdb_put(*m_write_txn, m_output_gindices, &v, &k, 0))
+    throw0(DB_ERROR("Failed to add output global index to db transaction"));
+************************************************************************/
+
+  m_num_outputs++;
+}
+
+void BlockchainLMDB::remove_tx_outputs(const crypto::hash& tx_hash, const transaction& tx)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+
+  lmdb_cur cur(*m_write_txn, m_tx_outputs);
+
+  MDB_val_copy<crypto::hash> k(tx_hash);
+  MDB_val v;
+
+  auto result = mdb_cursor_get(cur, &k, &v, MDB_SET);
+  if (result == MDB_NOTFOUND)
+  {
+    LOG_ERROR("Attempting to remove a tx's outputs, but none found.  Continuing, but...be wary, because that's weird.");
+  }
+  else if (result)
+  {
+    throw0(DB_ERROR("DB error attempting to get an output"));
+  }
+  else
+  {
+    size_t num_elems = 0;
+    mdb_cursor_count(cur, &num_elems);
+
+    mdb_cursor_get(cur, &k, &v, MDB_FIRST_DUP);
+
+    for (uint64_t i = 0; i < num_elems; ++i)
+    {
+      const tx_out tx_output = tx.vout[i];
+      remove_output(*(const uint64_t*)v.mv_data, tx_output.amount);
+      if (i < num_elems - 1)
+      {
+        mdb_cursor_get(cur, &k, &v, MDB_NEXT_DUP);
+      }
+    }
+  }
+
+  cur.close();
+}
+
+// TODO: probably remove this function
+void BlockchainLMDB::remove_output(const tx_out& tx_output)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__ << " (unused version - does nothing)");
+  return;
+}
+
+void BlockchainLMDB::remove_output(const uint64_t& out_index, const uint64_t amount)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  MDB_val_copy<uint64_t> k(out_index);
+
+/****** Uncomment if ever outputs actually need to be stored in this manner
+  blobdata b;
+  t_serializable_object_to_blob(tx_output, b);
+  k.mv_size = b.size();
+  k.mv_data = &b;
+
+  if (mdb_get(*m_write_txn, m_output_gindices, &k, &v))
+      throw1(OUTPUT_DNE("Attempting to remove output that does not exist"));
+
+  uint64_t gindex = *(uint64_t*)v.mv_data;
+
+  auto result = mdb_del(*m_write_txn, m_output_gindices, &k, NULL);
+  if (result != 0 && result != MDB_NOTFOUND)
+      throw1(DB_ERROR("Error adding removal of output global index to db transaction"));
+
+  result = mdb_del(*m_write_txn, m_outputs, &v, NULL);
+  if (result != 0 && result != MDB_NOTFOUND)
+      throw1(DB_ERROR("Error adding removal of output to db transaction"));
+*********************************************************************/
+
+  auto result = mdb_del(*m_write_txn, m_output_indices, &k, NULL);
+  if (result == MDB_NOTFOUND)
+  {
+    LOG_PRINT_L0("Unexpected: global output index not found in m_output_indices");
+  }
+  else if (result)
+  {
+    throw1(DB_ERROR("Error adding removal of output tx index to db transaction"));
+  }
+
+  result = mdb_del(*m_write_txn, m_output_txs, &k, NULL);
+  // if (result != 0 && result != MDB_NOTFOUND)
+  //    throw1(DB_ERROR("Error adding removal of output tx hash to db transaction"));
+  if (result == MDB_NOTFOUND)
+  {
+    LOG_PRINT_L0("Unexpected: global output index not found in m_output_txs");
+  }
+  else if (result)
+  {
+    throw1(DB_ERROR("Error adding removal of output tx hash to db transaction"));
+  }
+
+  result = mdb_del(*m_write_txn, m_output_keys, &k, NULL);
+  if (result == MDB_NOTFOUND)
+  {
+      LOG_PRINT_L0("Unexpected: global output index not found in m_output_keys");
+  }
+  else if (result)
+    throw1(DB_ERROR("Error adding removal of output pubkey to db transaction"));
+
+  remove_amount_output_index(amount, out_index);
+
+  m_num_outputs--;
+}
+
+void BlockchainLMDB::remove_amount_output_index(const uint64_t amount, const uint64_t global_output_index)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  lmdb_cur cur(*m_write_txn, m_output_amounts);
+
+  MDB_val_copy<uint64_t> k(amount);
+  MDB_val v;
+
+  auto result = mdb_cursor_get(cur, &k, &v, MDB_SET);
+  if (result == MDB_NOTFOUND)
+    throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));
+  else if (result)
+    throw0(DB_ERROR("DB error attempting to get an output"));
+
+  size_t num_elems = 0;
+  mdb_cursor_count(cur, &num_elems);
+
+  mdb_cursor_get(cur, &k, &v, MDB_FIRST_DUP);
+
+  uint64_t amount_output_index = 0;
+  uint64_t goi = 0;
+  bool found_index = false;
+  for (uint64_t i = 0; i < num_elems; ++i)
+  {
+    mdb_cursor_get(cur, &k, &v, MDB_GET_CURRENT);
+    goi = *(const uint64_t *)v.mv_data;
+    if (goi == global_output_index)
+    {
+      amount_output_index = i;
+      found_index = true;
+      break;
+    }
+    mdb_cursor_get(cur, &k, &v, MDB_NEXT_DUP);
+  }
+  if (found_index)
+  {
+    // found the amount output index
+    // now delete it
+    result = mdb_cursor_del(cur, 0);
+    if (result)
+      throw0(DB_ERROR(std::string("Error deleting amount output index ").append(boost::lexical_cast<std::string>(amount_output_index)).c_str()));
+  }
+  else
+  {
+    // not found
+    cur.close();
+    throw1(OUTPUT_DNE("Failed to find amount output index"));
+  }
+  cur.close();
+}
+
+void BlockchainLMDB::add_spent_key(const crypto::key_image& k_image)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  MDB_val_copy<crypto::key_image> val_key(k_image);
+  MDB_val unused;
+  if (mdb_get(*m_write_txn, m_spent_keys, &val_key, &unused) == 0)
+      throw1(KEY_IMAGE_EXISTS("Attempting to add spent key image that's already in the db"));
+
+  char anything = '\0';
+  unused.mv_size = sizeof(char);
+  unused.mv_data = &anything;
+  if (auto result = mdb_put(*m_write_txn, m_spent_keys, &val_key, &unused, 0))
+    throw1(DB_ERROR(std::string("Error adding spent key image to db transaction: ").append(mdb_strerror(result)).c_str()));
+}
+
+void BlockchainLMDB::remove_spent_key(const crypto::key_image& k_image)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  MDB_val_copy<crypto::key_image> k(k_image);
+  auto result = mdb_del(*m_write_txn, m_spent_keys, &k, NULL);
+  if (result != 0 && result != MDB_NOTFOUND)
+      throw1(DB_ERROR("Error adding removal of key image to db transaction"));
+}
+
+blobdata BlockchainLMDB::output_to_blob(const tx_out& output)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  blobdata b;
+  if (!t_serializable_object_to_blob(output, b))
+    throw1(DB_ERROR("Error serializing output to blob"));
+  return b;
+}
+
+tx_out BlockchainLMDB::output_from_blob(const blobdata& blob) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  std::stringstream ss;
+  ss << blob;
+  binary_archive<false> ba(ss);
+  tx_out o;
+
+  if (!(::serialization::serialize(ba, o)))
+    throw1(DB_ERROR("Error deserializing tx output blob"));
+
+  return o;
+}
+
+uint64_t BlockchainLMDB::get_output_global_index(const uint64_t& amount, const uint64_t& index) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  lmdb_cur cur(txn, m_output_amounts);
+
+  MDB_val_copy<uint64_t> k(amount);
+  MDB_val v;
+
+  auto result = mdb_cursor_get(cur, &k, &v, MDB_SET);
+  if (result == MDB_NOTFOUND)
+    throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));
+  else if (result)
+    throw0(DB_ERROR("DB error attempting to get an output"));
+
+  size_t num_elems = 0;
+  mdb_cursor_count(cur, &num_elems);
+  if (num_elems <= index)
+    throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but output not found"));
+
+  mdb_cursor_get(cur, &k, &v, MDB_FIRST_DUP);
+
+  for (uint64_t i = 0; i < index; ++i)
+  {
+    mdb_cursor_get(cur, &k, &v, MDB_NEXT_DUP);
+  }
+
+  mdb_cursor_get(cur, &k, &v, MDB_GET_CURRENT);
+
+  uint64_t glob_index = *(const uint64_t*)v.mv_data;
+
+  cur.close();
+
+  txn.commit();
+
+  return glob_index;
+}
+
+void BlockchainLMDB::check_open() const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  if (!m_open)
+    throw0(DB_ERROR("DB operation attempted on a not-open DB instance"));
+}
+
+BlockchainLMDB::~BlockchainLMDB()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+
+  // batch transaction shouldn't be active at this point. If it is, consider it aborted.
+  if (m_batch_active)
+    batch_abort();
+}
+
+BlockchainLMDB::BlockchainLMDB(bool batch_transactions)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  // initialize folder to something "safe" just in case
+  // someone accidentally misuses this class...
+  m_folder = "thishsouldnotexistbecauseitisgibberish";
+  m_open = false;
+
+  m_batch_transactions = batch_transactions;
+  m_write_txn = nullptr;
+  m_batch_active = false;
+  m_height = 0;
+}
+
+void BlockchainLMDB::open(const std::string& filename, const int mdb_flags)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+
+  if (m_open)
+    throw0(DB_OPEN_FAILURE("Attempted to open db, but it's already open"));
+
+  boost::filesystem::path direc(filename);
+  if (boost::filesystem::exists(direc))
+  {
+    if (!boost::filesystem::is_directory(direc))
+      throw0(DB_OPEN_FAILURE("LMDB needs a directory path, but a file was passed"));
+  }
+  else
+  {
+    if (!boost::filesystem::create_directory(direc))
+      throw0(DB_OPEN_FAILURE(std::string("Failed to create directory ").append(filename).c_str()));
+  }
+
+  // check for existing LMDB files in base directory
+  boost::filesystem::path old_files = direc.parent_path();
+  if (boost::filesystem::exists(old_files / "data.mdb") ||
+      boost::filesystem::exists(old_files / "lock.mdb"))
+  {
+    LOG_PRINT_L0("Found existing LMDB files in " << old_files.c_str());
+    LOG_PRINT_L0("Move data.mdb and/or lock.mdb to " << filename << ", or delete them, and then restart");
+    throw DB_ERROR("Database could not be opened");
+  }
+
+  m_folder = filename;
+
+  // set up lmdb environment
+  if (mdb_env_create(&m_env))
+    throw0(DB_ERROR("Failed to create lmdb environment"));
+  if (mdb_env_set_maxdbs(m_env, 20))
+    throw0(DB_ERROR("Failed to set max number of dbs"));
+
+  size_t mapsize = 1LL << 34;
+  if (auto result = mdb_env_set_mapsize(m_env, mapsize))
+    throw0(DB_ERROR(std::string("Failed to set max memory map size: ").append(mdb_strerror(result)).c_str()));
+  if (auto result = mdb_env_open(m_env, filename.c_str(), mdb_flags, 0644))
+    throw0(DB_ERROR(std::string("Failed to open lmdb environment: ").append(mdb_strerror(result)).c_str()));
+
+  // get a read/write MDB_txn
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, 0, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  // open necessary databases, and set properties as needed
+  // uses macros to avoid having to change things too many places
+  lmdb_db_open(txn, LMDB_BLOCKS, MDB_INTEGERKEY | MDB_CREATE, m_blocks, "Failed to open db handle for m_blocks");
+
+  lmdb_db_open(txn, LMDB_BLOCK_TIMESTAMPS, MDB_INTEGERKEY | MDB_CREATE, m_block_timestamps, "Failed to open db handle for m_block_timestamps");
+  lmdb_db_open(txn, LMDB_BLOCK_HEIGHTS, MDB_CREATE, m_block_heights, "Failed to open db handle for m_block_heights");
+  lmdb_db_open(txn, LMDB_BLOCK_HASHES, MDB_INTEGERKEY | MDB_CREATE, m_block_hashes, "Failed to open db handle for m_block_hashes");
+  lmdb_db_open(txn, LMDB_BLOCK_SIZES, MDB_INTEGERKEY | MDB_CREATE, m_block_sizes, "Failed to open db handle for m_block_sizes");
+  lmdb_db_open(txn, LMDB_BLOCK_DIFFS, MDB_INTEGERKEY | MDB_CREATE, m_block_diffs, "Failed to open db handle for m_block_diffs");
+  lmdb_db_open(txn, LMDB_BLOCK_COINS, MDB_INTEGERKEY | MDB_CREATE, m_block_coins, "Failed to open db handle for m_block_coins");
+
+  lmdb_db_open(txn, LMDB_TXS, MDB_CREATE, m_txs, "Failed to open db handle for m_txs");
+  lmdb_db_open(txn, LMDB_TX_UNLOCKS, MDB_CREATE, m_tx_unlocks, "Failed to open db handle for m_tx_unlocks");
+  lmdb_db_open(txn, LMDB_TX_HEIGHTS, MDB_CREATE, m_tx_heights, "Failed to open db handle for m_tx_heights");
+  lmdb_db_open(txn, LMDB_TX_OUTPUTS, MDB_DUPSORT | MDB_CREATE, m_tx_outputs, "Failed to open db handle for m_tx_outputs");
+
+  lmdb_db_open(txn, LMDB_OUTPUT_TXS, MDB_INTEGERKEY | MDB_CREATE, m_output_txs, "Failed to open db handle for m_output_txs");
+  lmdb_db_open(txn, LMDB_OUTPUT_INDICES, MDB_INTEGERKEY | MDB_CREATE, m_output_indices, "Failed to open db handle for m_output_indices");
+  lmdb_db_open(txn, LMDB_OUTPUT_AMOUNTS, MDB_INTEGERKEY | MDB_DUPSORT | MDB_CREATE, m_output_amounts, "Failed to open db handle for m_output_amounts");
+  lmdb_db_open(txn, LMDB_OUTPUT_KEYS, MDB_INTEGERKEY | MDB_CREATE, m_output_keys, "Failed to open db handle for m_output_keys");
+
+/*************** not used, but kept for posterity
+  lmdb_db_open(txn, LMDB_OUTPUTS, MDB_INTEGERKEY | MDB_CREATE, m_outputs, "Failed to open db handle for m_outputs");
+  lmdb_db_open(txn, LMDB_OUTPUT_GINDICES, MDB_CREATE, m_output_gindices, "Failed to open db handle for m_output_gindices");
+*************************************************/
+
+  lmdb_db_open(txn, LMDB_SPENT_KEYS, MDB_CREATE, m_spent_keys, "Failed to open db handle for m_spent_keys");
+
+  mdb_set_dupsort(txn, m_output_amounts, compare_uint64);
+  mdb_set_dupsort(txn, m_tx_outputs, compare_uint64);
+
+  // get and keep current height
+  MDB_stat db_stats;
+  if (mdb_stat(txn, m_blocks, &db_stats))
+    throw0(DB_ERROR("Failed to query m_blocks"));
+  LOG_PRINT_L2("Setting m_height to: " << db_stats.ms_entries);
+  m_height = db_stats.ms_entries;
+
+  // get and keep current number of outputs
+  if (mdb_stat(txn, m_output_indices, &db_stats))
+    throw0(DB_ERROR("Failed to query m_output_indices"));
+  m_num_outputs = db_stats.ms_entries;
+
+  // commit the transaction
+  txn.commit();
+
+  m_open = true;
+  // from here, init should be finished
+}
+
+void BlockchainLMDB::close()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  if (m_batch_active)
+  {
+    LOG_PRINT_L3("close() first calling batch_abort() due to active batch transaction");
+    batch_abort();
+  }
+  this->sync();
+
+  // FIXME: not yet thread safe!!!  Use with care.
+  mdb_env_close(m_env);
+}
+
+void BlockchainLMDB::sync()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  // Does nothing unless LMDB environment was opened with MDB_NOSYNC or in part
+  // MDB_NOMETASYNC. Force flush to be synchronous.
+  if (auto result = mdb_env_sync(m_env, true))
+  {
+    throw0(DB_ERROR(std::string("Failed to sync database").append(mdb_strerror(result)).c_str()));
+  }
+}
+
+void BlockchainLMDB::reset()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  // TODO: this
+}
+
+std::vector<std::string> BlockchainLMDB::get_filenames() const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  std::vector<std::string> filenames;
+
+  boost::filesystem::path datafile(m_folder);
+  datafile /= "data.mdb";
+  boost::filesystem::path lockfile(m_folder);
+  lockfile /= "lock.mdb";
+
+  filenames.push_back(datafile.string());
+  filenames.push_back(lockfile.string());
+
+  return filenames;
+}
+
+std::string BlockchainLMDB::get_db_name() const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+
+  return std::string("lmdb");
+}
+
+// TODO: this?
+bool BlockchainLMDB::lock()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+  return false;
+}
+
+// TODO: this?
+void BlockchainLMDB::unlock()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+}
+
+bool BlockchainLMDB::block_exists(const crypto::hash& h) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  MDB_val_copy<crypto::hash> key(h);
+  MDB_val result;
+  auto get_result = mdb_get(txn, m_block_heights, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+  {
+    txn.commit();
+    LOG_PRINT_L3("Block with hash " << epee::string_tools::pod_to_hex(h) << " not found in db");
+    return false;
+  }
+  else if (get_result)
+    throw0(DB_ERROR("DB error attempting to fetch block index from hash"));
+
+  txn.commit();
+  return true;
+}
+
+block BlockchainLMDB::get_block(const crypto::hash& h) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  return get_block_from_height(get_block_height(h));
+}
+
+uint64_t BlockchainLMDB::get_block_height(const crypto::hash& h) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  MDB_val_copy<crypto::hash> key(h);
+  MDB_val result;
+  auto get_result = mdb_get(txn, m_block_heights, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+    throw1(BLOCK_DNE("Attempted to retrieve non-existent block height"));
+  else if (get_result)
+    throw0(DB_ERROR("Error attempting to retrieve a block height from the db"));
+
+  txn.commit();
+  return *(const uint64_t*)result.mv_data;
+}
+
+block_header BlockchainLMDB::get_block_header(const crypto::hash& h) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  // block_header object is automatically cast from block object
+  return get_block(h);
+}
+
+block BlockchainLMDB::get_block_from_height(const uint64_t& height) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  MDB_val_copy<uint64_t> key(height);
+  MDB_val result;
+  auto get_result = mdb_get(txn, m_blocks, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+  {
+    throw0(DB_ERROR(std::string("Attempt to get block from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- block not in db").c_str()));
+  }
+  else if (get_result)
+    throw0(DB_ERROR("Error attempting to retrieve a block from the db"));
+
+  txn.commit();
+
+  blobdata bd;
+  bd.assign(reinterpret_cast<char*>(result.mv_data), result.mv_size);
+
+  block b;
+  if (!parse_and_validate_block_from_blob(bd, b))
+    throw0(DB_ERROR("Failed to parse block from blob retrieved from the db"));
+
+  return b;
+}
+
+uint64_t BlockchainLMDB::get_block_timestamp(const uint64_t& height) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  mdb_txn_safe* txn_ptr = &txn;
+  if (m_batch_active)
+    txn_ptr = m_write_txn;
+  else
+  {
+    if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+  }
+  MDB_val_copy<uint64_t> key(height);
+  MDB_val result;
+  auto get_result = mdb_get(*txn_ptr, m_block_timestamps, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+  {
+    throw0(DB_ERROR(std::string("Attempt to get timestamp from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- timestamp not in db").c_str()));
+  }
+  else if (get_result)
+    throw0(DB_ERROR("Error attempting to retrieve a timestamp from the db"));
+
+  if (! m_batch_active)
+    txn.commit();
+  return *(const uint64_t*)result.mv_data;
+}
+
+uint64_t BlockchainLMDB::get_top_block_timestamp() const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  // if no blocks, return 0
+  if (m_height == 0)
+  {
+    return 0;
+  }
+
+  return get_block_timestamp(m_height - 1);
+}
+
+size_t BlockchainLMDB::get_block_size(const uint64_t& height) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  mdb_txn_safe* txn_ptr = &txn;
+  if (m_batch_active)
+    txn_ptr = m_write_txn;
+  else
+  {
+    if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+  }
+
+  MDB_val_copy<uint64_t> key(height);
+  MDB_val result;
+  auto get_result = mdb_get(*txn_ptr, m_block_sizes, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+  {
+    throw0(DB_ERROR(std::string("Attempt to get block size from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- block size not in db").c_str()));
+  }
+  else if (get_result)
+    throw0(DB_ERROR("Error attempting to retrieve a block size from the db"));
+
+  if (! m_batch_active)
+    txn.commit();
+  return *(const size_t*)result.mv_data;
+}
+
+difficulty_type BlockchainLMDB::get_block_cumulative_difficulty(const uint64_t& height) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__ << "  height: " << height);
+  check_open();
+
+  mdb_txn_safe txn;
+  mdb_txn_safe* txn_ptr = &txn;
+  if (m_batch_active)
+    txn_ptr = m_write_txn;
+  else
+  {
+    if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+  }
+  MDB_val_copy<uint64_t> key(height);
+  MDB_val result;
+  auto get_result = mdb_get(*txn_ptr, m_block_diffs, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+  {
+    throw0(DB_ERROR(std::string("Attempt to get cumulative difficulty from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- difficulty not in db").c_str()));
+  }
+  else if (get_result)
+    throw0(DB_ERROR("Error attempting to retrieve a cumulative difficulty from the db"));
+
+  if (! m_batch_active)
+    txn.commit();
+  return *(difficulty_type*)result.mv_data;
+}
+
+difficulty_type BlockchainLMDB::get_block_difficulty(const uint64_t& height) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  difficulty_type diff1 = 0;
+  difficulty_type diff2 = 0;
+
+  diff1 = get_block_cumulative_difficulty(height);
+  if (height != 0)
+  {
+    diff2 = get_block_cumulative_difficulty(height - 1);
+  }
+
+  return diff1 - diff2;
+}
+
+uint64_t BlockchainLMDB::get_block_already_generated_coins(const uint64_t& height) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  mdb_txn_safe* txn_ptr = &txn;
+  if (m_batch_active)
+    txn_ptr = m_write_txn;
+  else
+  {
+    if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+  }
+
+  MDB_val_copy<uint64_t> key(height);
+  MDB_val result;
+  auto get_result = mdb_get(*txn_ptr, m_block_coins, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+  {
+    throw0(DB_ERROR(std::string("Attempt to get generated coins from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- block size not in db").c_str()));
+  }
+  else if (get_result)
+    throw0(DB_ERROR("Error attempting to retrieve a total generated coins from the db"));
+
+  if (! m_batch_active)
+    txn.commit();
+  return *(const uint64_t*)result.mv_data;
+}
+
+crypto::hash BlockchainLMDB::get_block_hash_from_height(const uint64_t& height) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  mdb_txn_safe* txn_ptr = &txn;
+  if (m_batch_active)
+    txn_ptr = m_write_txn;
+  else
+  {
+    if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+  }
+
+  MDB_val_copy<uint64_t> key(height);
+  MDB_val result;
+  auto get_result = mdb_get(*txn_ptr, m_block_hashes, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+  {
+    throw0(BLOCK_DNE(std::string("Attempt to get hash from height ").append(boost::lexical_cast<std::string>(height)).append(" failed -- hash not in db").c_str()));
+  }
+  else if (get_result)
+    throw0(DB_ERROR(std::string("Error attempting to retrieve a block hash from the db: ").
+          append(mdb_strerror(get_result)).c_str()));
+
+  if (! m_batch_active)
+    txn.commit();
+  return *(crypto::hash*)result.mv_data;
+}
+
+std::vector<block> BlockchainLMDB::get_blocks_range(const uint64_t& h1, const uint64_t& h2) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+  std::vector<block> v;
+
+  for (uint64_t height = h1; height <= h2; ++height)
+  {
+    v.push_back(get_block_from_height(height));
+  }
+
+  return v;
+}
+
+std::vector<crypto::hash> BlockchainLMDB::get_hashes_range(const uint64_t& h1, const uint64_t& h2) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+  std::vector<crypto::hash> v;
+
+  for (uint64_t height = h1; height <= h2; ++height)
+  {
+    v.push_back(get_block_hash_from_height(height));
+  }
+
+  return v;
+}
+
+crypto::hash BlockchainLMDB::top_block_hash() const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+  if (m_height != 0)
+  {
+    return get_block_hash_from_height(m_height - 1);
+  }
+
+  return null_hash;
+}
+
+block BlockchainLMDB::get_top_block() const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  if (m_height != 0)
+  {
+    return get_block_from_height(m_height - 1);
+  }
+
+  block b;
+  return b;
+}
+
+uint64_t BlockchainLMDB::height() const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  return m_height;
+}
+
+bool BlockchainLMDB::tx_exists(const crypto::hash& h) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  mdb_txn_safe* txn_ptr = &txn;
+  if (m_batch_active)
+    txn_ptr = m_write_txn;
+  else
+  {
+    if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+  }
+
+  MDB_val_copy<crypto::hash> key(h);
+  MDB_val result;
+
+  TIME_MEASURE_START(time1);
+  auto get_result = mdb_get(*txn_ptr, m_txs, &key, &result);
+  TIME_MEASURE_FINISH(time1);
+  time_tx_exists += time1;
+  if (get_result == MDB_NOTFOUND)
+  {
+    if (! m_batch_active)
+      txn.commit();
+    LOG_PRINT_L1("transaction with hash " << epee::string_tools::pod_to_hex(h) << " not found in db");
+    return false;
+  }
+  else if (get_result)
+    throw0(DB_ERROR("DB error attempting to fetch transaction from hash"));
+
+  return true;
+}
+
+uint64_t BlockchainLMDB::get_tx_unlock_time(const crypto::hash& h) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  MDB_val_copy<crypto::hash> key(h);
+  MDB_val result;
+  auto get_result = mdb_get(txn, m_tx_unlocks, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+    throw1(TX_DNE(std::string("tx unlock time with hash ").append(epee::string_tools::pod_to_hex(h)).append(" not found in db").c_str()));
+  else if (get_result)
+    throw0(DB_ERROR("DB error attempting to fetch tx unlock time from hash"));
+
+  return *(const uint64_t*)result.mv_data;
+}
+
+transaction BlockchainLMDB::get_tx(const crypto::hash& h) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  mdb_txn_safe* txn_ptr = &txn;
+  if (m_batch_active)
+    txn_ptr = m_write_txn;
+  else
+  {
+    if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+  }
+
+  MDB_val_copy<crypto::hash> key(h);
+  MDB_val result;
+  auto get_result = mdb_get(*txn_ptr, m_txs, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+    throw1(TX_DNE(std::string("tx with hash ").append(epee::string_tools::pod_to_hex(h)).append(" not found in db").c_str()));
+  else if (get_result)
+    throw0(DB_ERROR("DB error attempting to fetch tx from hash"));
+
+  blobdata bd;
+  bd.assign(reinterpret_cast<char*>(result.mv_data), result.mv_size);
+
+  transaction tx;
+  if (!parse_and_validate_tx_from_blob(bd, tx))
+    throw0(DB_ERROR("Failed to parse tx from blob retrieved from the db"));
+  if (! m_batch_active)
+    txn.commit();
+
+  return tx;
+}
+
+uint64_t BlockchainLMDB::get_tx_count() const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  MDB_stat db_stats;
+  if (mdb_stat(txn, m_txs, &db_stats))
+    throw0(DB_ERROR("Failed to query m_txs"));
+
+  txn.commit();
+
+  return db_stats.ms_entries;
+}
+
+std::vector<transaction> BlockchainLMDB::get_tx_list(const std::vector<crypto::hash>& hlist) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+  std::vector<transaction> v;
+
+  for (auto& h : hlist)
+  {
+    v.push_back(get_tx(h));
+  }
+
+  return v;
+}
+
+uint64_t BlockchainLMDB::get_tx_block_height(const crypto::hash& h) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  mdb_txn_safe* txn_ptr = &txn;
+  if (m_batch_active)
+    txn_ptr = m_write_txn;
+  else
+  {
+    if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+  }
+
+  MDB_val_copy<crypto::hash> key(h);
+  MDB_val result;
+  auto get_result = mdb_get(*txn_ptr, m_tx_heights, &key, &result);
+  if (get_result == MDB_NOTFOUND)
+  {
+    throw1(TX_DNE(std::string("tx height with hash ").append(epee::string_tools::pod_to_hex(h)).append(" not found in db").c_str()));
+  }
+  else if (get_result)
+    throw0(DB_ERROR("DB error attempting to fetch tx height from hash"));
+
+  if (! m_batch_active)
+    txn.commit();
+
+  return *(const uint64_t*)result.mv_data;
+}
+
+//FIXME: make sure the random method used here is appropriate
+uint64_t BlockchainLMDB::get_random_output(const uint64_t& amount) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  uint64_t num_outputs = get_num_outputs(amount);
+  if (num_outputs == 0)
+    throw1(OUTPUT_DNE("Attempting to get a random output for an amount, but none exist"));
+
+  return crypto::rand<uint64_t>() % num_outputs;
+}
+
+uint64_t BlockchainLMDB::get_num_outputs(const uint64_t& amount) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  lmdb_cur cur(txn, m_output_amounts);
+
+  MDB_val_copy<uint64_t> k(amount);
+  MDB_val v;
+  auto result = mdb_cursor_get(cur, &k, &v, MDB_SET);
+  if (result == MDB_NOTFOUND)
+  {
+    return 0;
+  }
+  else if (result)
+    throw0(DB_ERROR("DB error attempting to get number of outputs of an amount"));
+
+  size_t num_elems = 0;
+  mdb_cursor_count(cur, &num_elems);
+
+  txn.commit();
+
+  return num_elems;
+}
+
+crypto::public_key BlockchainLMDB::get_output_key(const uint64_t& amount, const uint64_t& index) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  uint64_t glob_index = get_output_global_index(amount, index);
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  MDB_val_copy<uint64_t> k(glob_index);
+  MDB_val v;
+  auto get_result = mdb_get(txn, m_output_keys, &k, &v);
+  if (get_result == MDB_NOTFOUND)
+    throw0(DB_ERROR("Attempting to get output pubkey by global index, but key does not exist"));
+  else if (get_result)
+    throw0(DB_ERROR("Error attempting to retrieve an output pubkey from the db"));
+
+  return *(crypto::public_key*)v.mv_data;
+}
+
+tx_out BlockchainLMDB::get_output(const crypto::hash& h, const uint64_t& index) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  lmdb_cur cur(txn, m_tx_outputs);
+
+  MDB_val_copy<crypto::hash> k(h);
+  MDB_val v;
+  auto result = mdb_cursor_get(cur, &k, &v, MDB_SET);
+  if (result == MDB_NOTFOUND)
+    throw1(OUTPUT_DNE("Attempting to get an output by tx hash and tx index, but output not found"));
+  else if (result)
+    throw0(DB_ERROR("DB error attempting to get an output"));
+
+  size_t num_elems = 0;
+  mdb_cursor_count(cur, &num_elems);
+  if (num_elems <= index)
+    throw1(OUTPUT_DNE("Attempting to get an output by tx hash and tx index, but output not found"));
+
+  mdb_cursor_get(cur, &k, &v, MDB_FIRST_DUP);
+
+  for (uint64_t i = 0; i < index; ++i)
+  {
+    mdb_cursor_get(cur, &k, &v, MDB_NEXT_DUP);
+  }
+
+  mdb_cursor_get(cur, &k, &v, MDB_GET_CURRENT);
+
+  blobdata b;
+  b = *(blobdata*)v.mv_data;
+
+  cur.close();
+  txn.commit();
+
+  return output_from_blob(b);
+}
+
+// As this is not used, its return is now a blank output.
+// This will save on space in the db.
+tx_out BlockchainLMDB::get_output(const uint64_t& index) const
+{
+  return tx_out();
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  MDB_val_copy<uint64_t> k(index);
+  MDB_val v;
+  auto get_result = mdb_get(txn, m_outputs, &k, &v);
+  if (get_result == MDB_NOTFOUND)
+  {
+    throw OUTPUT_DNE("Attempting to get output by global index, but output does not exist");
+  }
+  else if (get_result)
+    throw0(DB_ERROR("Error attempting to retrieve an output from the db"));
+
+  blobdata b = *(blobdata*)v.mv_data;
+
+  return output_from_blob(b);
+}
+
+tx_out_index BlockchainLMDB::get_output_tx_and_index_from_global(const uint64_t& index) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  mdb_txn_safe* txn_ptr = &txn;
+  if (m_batch_active)
+    txn_ptr = m_write_txn;
+  else
+  {
+    if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+  }
+  MDB_val_copy<uint64_t> k(index);
+  MDB_val v;
+
+  auto get_result = mdb_get(*txn_ptr, m_output_txs, &k, &v);
+  if (get_result == MDB_NOTFOUND)
+    throw1(OUTPUT_DNE("output with given index not in db"));
+  else if (get_result)
+    throw0(DB_ERROR("DB error attempting to fetch output tx hash"));
+
+  crypto::hash tx_hash = *(crypto::hash*)v.mv_data;
+
+  get_result = mdb_get(*txn_ptr, m_output_indices, &k, &v);
+  if (get_result == MDB_NOTFOUND)
+    throw1(OUTPUT_DNE("output with given index not in db"));
+  else if (get_result)
+    throw0(DB_ERROR("DB error attempting to fetch output tx index"));
+  if (! m_batch_active)
+    txn.commit();
+
+  return tx_out_index(tx_hash, *(const uint64_t *)v.mv_data);
+}
+
+tx_out_index BlockchainLMDB::get_output_tx_and_index(const uint64_t& amount, const uint64_t& index) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  mdb_txn_safe* txn_ptr = &txn;
+  if (m_batch_active)
+    txn_ptr = m_write_txn;
+  else
+  {
+    if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+  }
+  lmdb_cur cur(*txn_ptr, m_output_amounts);
+
+  MDB_val_copy<uint64_t> k(amount);
+  MDB_val v;
+
+  auto result = mdb_cursor_get(cur, &k, &v, MDB_SET);
+  if (result == MDB_NOTFOUND)
+    throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));
+  else if (result)
+    throw0(DB_ERROR("DB error attempting to get an output"));
+
+  size_t num_elems = 0;
+  mdb_cursor_count(cur, &num_elems);
+  if (num_elems <= index)
+    throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but output not found"));
+
+  mdb_cursor_get(cur, &k, &v, MDB_FIRST_DUP);
+
+  for (uint64_t i = 0; i < index; ++i)
+  {
+    mdb_cursor_get(cur, &k, &v, MDB_NEXT_DUP);
+  }
+
+  mdb_cursor_get(cur, &k, &v, MDB_GET_CURRENT);
+
+  uint64_t glob_index = *(const uint64_t*)v.mv_data;
+
+  cur.close();
+
+  if (! m_batch_active)
+    txn.commit();
+
+  return get_output_tx_and_index_from_global(glob_index);
+}
+
+std::vector<uint64_t> BlockchainLMDB::get_tx_output_indices(const crypto::hash& h) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+  std::vector<uint64_t> index_vec;
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  lmdb_cur cur(txn, m_tx_outputs);
+
+  MDB_val_copy<crypto::hash> k(h);
+  MDB_val v;
+  auto result = mdb_cursor_get(cur, &k, &v, MDB_SET);
+  if (result == MDB_NOTFOUND)
+    throw1(OUTPUT_DNE("Attempting to get an output by tx hash and tx index, but output not found"));
+  else if (result)
+    throw0(DB_ERROR("DB error attempting to get an output"));
+
+  size_t num_elems = 0;
+  mdb_cursor_count(cur, &num_elems);
+
+  mdb_cursor_get(cur, &k, &v, MDB_FIRST_DUP);
+
+  for (uint64_t i = 0; i < num_elems; ++i)
+  {
+    mdb_cursor_get(cur, &k, &v, MDB_GET_CURRENT);
+    index_vec.push_back(*(const uint64_t *)v.mv_data);
+    mdb_cursor_get(cur, &k, &v, MDB_NEXT_DUP);
+  }
+
+  cur.close();
+  txn.commit();
+
+  return index_vec;
+}
+
+std::vector<uint64_t> BlockchainLMDB::get_tx_amount_output_indices(const crypto::hash& h) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+  std::vector<uint64_t> index_vec;
+  std::vector<uint64_t> index_vec2;
+
+  // get the transaction's global output indices first
+  index_vec = get_tx_output_indices(h);
+  // these are next used to obtain the amount output indices
+
+  transaction tx = get_tx(h);
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  uint64_t i = 0;
+  uint64_t global_index;
+  BOOST_FOREACH(const auto& vout, tx.vout)
+  {
+    uint64_t amount =  vout.amount;
+
+    global_index = index_vec[i];
+
+    lmdb_cur cur(txn, m_output_amounts);
+
+    MDB_val_copy<uint64_t> k(amount);
+    MDB_val v;
+
+    auto result = mdb_cursor_get(cur, &k, &v, MDB_SET);
+    if (result == MDB_NOTFOUND)
+      throw1(OUTPUT_DNE("Attempting to get an output index by amount and amount index, but amount not found"));
+    else if (result)
+      throw0(DB_ERROR("DB error attempting to get an output"));
+
+    size_t num_elems = 0;
+    mdb_cursor_count(cur, &num_elems);
+
+    mdb_cursor_get(cur, &k, &v, MDB_FIRST_DUP);
+
+    uint64_t amount_output_index = 0;
+    uint64_t output_index = 0;
+    bool found_index = false;
+    for (uint64_t j = 0; j < num_elems; ++j)
+    {
+      mdb_cursor_get(cur, &k, &v, MDB_GET_CURRENT);
+      output_index = *(const uint64_t *)v.mv_data;
+      if (output_index == global_index)
+      {
+        amount_output_index = j;
+        found_index = true;
+        break;
+      }
+      mdb_cursor_get(cur, &k, &v, MDB_NEXT_DUP);
+    }
+    if (found_index)
+    {
+      index_vec2.push_back(amount_output_index);
+    }
+    else
+    {
+      // not found
+      cur.close();
+      txn.commit();
+      throw1(OUTPUT_DNE("specified output not found in db"));
+    }
+
+    cur.close();
+    ++i;
+  }
+
+  txn.commit();
+
+  return index_vec2;
+}
+
+
+
+bool BlockchainLMDB::has_key_image(const crypto::key_image& img) const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (mdb_txn_begin(m_env, NULL, MDB_RDONLY, txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+
+  MDB_val_copy<crypto::key_image> val_key(img);
+  MDB_val unused;
+  if (mdb_get(txn, m_spent_keys, &val_key, &unused) == 0)
+  {
+    txn.commit();
+    return true;
+  }
+
+  txn.commit();
+  return false;
+}
+
+void BlockchainLMDB::batch_start()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  if (! m_batch_transactions)
+    throw0(DB_ERROR("batch transactions not enabled"));
+  if (m_batch_active)
+    throw0(DB_ERROR("batch transaction already in progress"));
+  if (m_write_txn)
+    throw0(DB_ERROR("batch transaction attempted, but m_write_txn already in use"));
+  check_open();
+  // NOTE: need to make sure it's destroyed properly when done
+  if (mdb_txn_begin(m_env, NULL, 0, m_write_batch_txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+  // indicates this transaction is for batch transactions, but not whether it's
+  // active
+  m_write_batch_txn.m_batch_txn = true;
+  m_write_txn = &m_write_batch_txn;
+  m_batch_active = true;
+  LOG_PRINT_L3("batch transaction: begin");
+}
+
+void BlockchainLMDB::batch_commit()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  if (! m_batch_transactions)
+    throw0(DB_ERROR("batch transactions not enabled"));
+  if (! m_batch_active)
+    throw0(DB_ERROR("batch transaction not in progress"));
+  check_open();
+  LOG_PRINT_L3("batch transaction: committing...");
+  TIME_MEASURE_START(time1);
+  m_write_txn->commit();
+  TIME_MEASURE_FINISH(time1);
+  time_commit1 += time1;
+  LOG_PRINT_L3("batch transaction: committed");
+
+  if (mdb_txn_begin(m_env, NULL, 0, m_write_batch_txn))
+    throw0(DB_ERROR("Failed to create a transaction for the db"));
+  if (! m_write_batch_txn.m_batch_txn)
+    throw0(DB_ERROR("m_write_batch_txn not marked as a batch transaction"));
+  m_write_txn = &m_write_batch_txn;
+}
+
+void BlockchainLMDB::batch_stop()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  if (! m_batch_transactions)
+    throw0(DB_ERROR("batch transactions not enabled"));
+  if (! m_batch_active)
+    throw0(DB_ERROR("batch transaction not in progress"));
+  check_open();
+  LOG_PRINT_L3("batch transaction: committing...");
+  TIME_MEASURE_START(time1);
+  m_write_txn->commit();
+  TIME_MEASURE_FINISH(time1);
+  time_commit1 += time1;
+  // for destruction of batch transaction
+  m_write_txn = nullptr;
+  m_batch_active = false;
+  LOG_PRINT_L3("batch transaction: end");
+}
+
+void BlockchainLMDB::batch_abort()
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  if (! m_batch_transactions)
+    throw0(DB_ERROR("batch transactions not enabled"));
+  if (! m_batch_active)
+    throw0(DB_ERROR("batch transaction not in progress"));
+  check_open();
+  // for destruction of batch transaction
+  m_write_txn = nullptr;
+  // explicitly call in case mdb_env_close() (BlockchainLMDB::close()) called before BlockchainLMDB destructor called.
+  m_write_batch_txn.abort();
+  m_batch_active = false;
+  LOG_PRINT_L3("batch transaction: aborted");
+}
+
+void BlockchainLMDB::set_batch_transactions(bool batch_transactions)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  m_batch_transactions = batch_transactions;
+  LOG_PRINT_L3("batch transactions " << (m_batch_transactions ? "enabled" : "disabled"));
+}
+
+uint64_t BlockchainLMDB::add_block( const block& blk
+                                  , const size_t& block_size
+                                  , const difficulty_type& cumulative_difficulty
+                                  , const uint64_t& coins_generated
+                                  , const std::vector<transaction>& txs
+                                  )
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (! m_batch_active)
+  {
+    if (mdb_txn_begin(m_env, NULL, 0, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+    m_write_txn = &txn;
+  }
+
+  uint64_t num_outputs = m_num_outputs;
+  try
+  {
+    BlockchainDB::add_block(blk, block_size, cumulative_difficulty, coins_generated, txs);
+    if (! m_batch_active)
+    {
+      m_write_txn = NULL;
+
+      TIME_MEASURE_START(time1);
+      txn.commit();
+      TIME_MEASURE_FINISH(time1);
+      time_commit1 += time1;
+    }
+  }
+  catch (...)
+  {
+    m_num_outputs = num_outputs;
+    if (! m_batch_active)
+      m_write_txn = NULL;
+    throw;
+  }
+
+  return ++m_height;
+}
+
+void BlockchainLMDB::pop_block(block& blk, std::vector<transaction>& txs)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  mdb_txn_safe txn;
+  if (! m_batch_active)
+  {
+    if (mdb_txn_begin(m_env, NULL, 0, txn))
+      throw0(DB_ERROR("Failed to create a transaction for the db"));
+    m_write_txn = &txn;
+  }
+
+  uint64_t num_outputs = m_num_outputs;
+  try
+  {
+    BlockchainDB::pop_block(blk, txs);
+    if (! m_batch_active)
+    {
+      m_write_txn = NULL;
+
+      txn.commit();
+    }
+  }
+  catch (...)
+  {
+    m_num_outputs = num_outputs;
+    m_write_txn = NULL;
+    throw;
+  }
+
+  --m_height;
+}
+
+}  // namespace cryptonote