Outputs where all amounts are known spent can now be pruned

Only for pre rct for obvious reasons.

Note: DO NOT use a known spent list which includes outputs
which are not known spent. If the list includes any output
that's just strongly thought to be spent, but not provably
so, you risk finding yourself unable to sync past the point
where that output is spent.

I estimate only 200 MB saved on current mainnet though,
unless the new blackballing rule unearths a good amount of
large-amount-set extra spent outs.

src/blockchain_db/blockchain_db.h

@@ -1405,6 +1405,13 @@ public:
    */
   virtual cryptonote::blobdata get_txpool_tx_blob(const crypto::hash& txid) const = 0;
 
+  /**
+   * @brief prune output data for the given amount
+   *
+   * @param amount the amount for which to prune data
+   */
+  virtual void prune_outputs(uint64_t amount) = 0;
+
   /**
    * @brief runs a function over all txpool transactions
    *

src/blockchain_db/lmdb/db_lmdb.cpp

@@ -1077,6 +1077,60 @@ void BlockchainLMDB::remove_output(const uint64_t amount, const uint64_t& out_in
     throw0(DB_ERROR(lmdb_error(std::string("Error deleting amount for output index ").append(boost::lexical_cast<std::string>(out_index).append(": ")).c_str(), result).c_str()));
 }
 
+void BlockchainLMDB::prune_outputs(uint64_t amount)
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+  mdb_txn_cursors *m_cursors = &m_wcursors;
+  CURSOR(output_amounts);
+  CURSOR(output_txs);
+
+  MINFO("Pruning outputs for amount " << amount);
+
+  MDB_val v;
+  MDB_val_set(k, amount);
+  int result = mdb_cursor_get(m_cur_output_amounts, &k, &v, MDB_SET);
+  if (result == MDB_NOTFOUND)
+    return;
+  if (result)
+    throw0(DB_ERROR(lmdb_error("Error looking up outputs: ", result).c_str()));
+
+  // gather output ids
+  mdb_size_t num_elems;
+  mdb_cursor_count(m_cur_output_amounts, &num_elems);
+  MINFO(num_elems << " outputs found");
+  std::vector<uint64_t> output_ids;
+  output_ids.reserve(num_elems);
+  while (1)
+  {
+    const pre_rct_outkey *okp = (const pre_rct_outkey *)v.mv_data;
+    output_ids.push_back(okp->output_id);
+    MDEBUG("output id " << okp->output_id);
+    result = mdb_cursor_get(m_cur_output_amounts, &k, &v, MDB_NEXT_DUP);
+    if (result == MDB_NOTFOUND)
+      break;
+    if (result)
+      throw0(DB_ERROR(lmdb_error("Error counting outputs: ", result).c_str()));
+  }
+  if (output_ids.size() != num_elems)
+    throw0(DB_ERROR("Unexpected number of outputs"));
+
+  result = mdb_cursor_del(m_cur_output_amounts, MDB_NODUPDATA);
+  if (result)
+    throw0(DB_ERROR(lmdb_error("Error deleting outputs: ", result).c_str()));
+
+  for (uint64_t output_id: output_ids)
+  {
+    MDB_val_set(v, output_id);
+    result = mdb_cursor_get(m_cur_output_txs, (MDB_val *)&zerokval, &v, MDB_GET_BOTH);
+    if (result)
+      throw0(DB_ERROR(lmdb_error("Error looking up output: ", result).c_str()));
+    result = mdb_cursor_del(m_cur_output_txs, 0);
+    if (result)
+      throw0(DB_ERROR(lmdb_error("Error deleting output: ", result).c_str()));
+  }
+}
+
 void BlockchainLMDB::add_spent_key(const crypto::key_image& k_image)
 {
   LOG_PRINT_L3("BlockchainLMDB::" << __func__);
@@ -2231,11 +2285,19 @@ uint64_t BlockchainLMDB::num_outputs() const
   TXN_PREFIX_RDONLY();
   int result;
 
-  // get current height
-  MDB_stat db_stats;
-  if ((result = mdb_stat(m_txn, m_output_txs, &db_stats)))
+  RCURSOR(output_txs)
+
+  uint64_t num = 0;
+  MDB_val k, v;
+  result = mdb_cursor_get(m_cur_output_txs, &k, &v, MDB_LAST);
+  if (result == MDB_NOTFOUND)
+    num = 0;
+  else if (result == 0)
+    num = 1 + ((const outtx*)v.mv_data)->output_id;
+  else
     throw0(DB_ERROR(lmdb_error("Failed to query m_output_txs: ", result).c_str()));
-  return db_stats.ms_entries;
+
+  return num;
 }
 
 bool BlockchainLMDB::tx_exists(const crypto::hash& h) const

src/blockchain_db/lmdb/db_lmdb.h

@@ -345,6 +345,8 @@ private:
 
   void remove_output(const uint64_t amount, const uint64_t& out_index);
 
+  virtual void prune_outputs(uint64_t amount);
+
   virtual void add_spent_key(const crypto::key_image& k_image);
 
   virtual void remove_spent_key(const crypto::key_image& k_image);

src/blockchain_utilities/CMakeLists.txt

@@ -81,6 +81,17 @@ monero_private_headers(blockchain_usage
 
 
 
+set(blockchain_prune_known_spent_data_sources
+  blockchain_prune_known_spent_data.cpp
+  )
+
+set(blockchain_prune_known_spent_data_private_headers)
+
+monero_private_headers(blockchain_prune_known_spent_data
+	  ${blockchain_prune_known_spent_data_private_headers})
+
+
+
 set(blockchain_ancestry_sources
   blockchain_ancestry.cpp
   )
@@ -265,3 +276,25 @@ set_property(TARGET blockchain_stats
 	PROPERTY
 	OUTPUT_NAME "monero-blockchain-stats")
 install(TARGETS blockchain_stats DESTINATION bin)
+
+monero_add_executable(blockchain_prune_known_spent_data
+  ${blockchain_prune_known_spent_data_sources}
+  ${blockchain_prune_known_spent_data_private_headers})
+
+target_link_libraries(blockchain_prune_known_spent_data
+  PRIVATE
+    cryptonote_core
+    blockchain_db
+    p2p
+    version
+    epee
+    ${Boost_FILESYSTEM_LIBRARY}
+    ${Boost_SYSTEM_LIBRARY}
+    ${Boost_THREAD_LIBRARY}
+    ${CMAKE_THREAD_LIBS_INIT}
+    ${EXTRA_LIBRARIES})
+
+set_property(TARGET blockchain_prune_known_spent_data
+	PROPERTY
+	OUTPUT_NAME "monero-blockchain-prune-known-spent-data")
+install(TARGETS blockchain_prune_known_spent_data DESTINATION bin)

src/blockchain_utilities/blockchain_prune_known_spent_data.cpp

@@ -0,0 +1,268 @@
+// Copyright (c) 2014-2018, 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 <boost/algorithm/string.hpp>
+#include "common/command_line.h"
+#include "serialization/crypto.h"
+#include "cryptonote_core/tx_pool.h"
+#include "cryptonote_core/cryptonote_core.h"
+#include "cryptonote_core/blockchain.h"
+#include "blockchain_db/blockchain_db.h"
+#include "blockchain_db/db_types.h"
+#include "version.h"
+
+#undef MONERO_DEFAULT_LOG_CATEGORY
+#define MONERO_DEFAULT_LOG_CATEGORY "bcutil"
+
+namespace po = boost::program_options;
+using namespace epee;
+using namespace cryptonote;
+
+static std::map<uint64_t, uint64_t> load_outputs(const std::string &filename)
+{
+  std::map<uint64_t, uint64_t> outputs;
+  uint64_t amount = std::numeric_limits<uint64_t>::max();
+  FILE *f;
+
+  f = fopen(filename.c_str(), "r");
+  if (!f)
+  {
+    MERROR("Failed to load outputs from " << filename << ": " << strerror(errno));
+    return {};
+  }
+  while (1)
+  {
+    char s[256];
+    if (!fgets(s, sizeof(s), f))
+      break;
+    if (feof(f))
+      break;
+    const size_t len = strlen(s);
+    if (len > 0 && s[len - 1] == '\n')
+      s[len - 1] = 0;
+    if (!s[0])
+      continue;
+    std::pair<uint64_t, uint64_t> output;
+    uint64_t offset, num_offsets;
+    if (sscanf(s, "@%" PRIu64, &amount) == 1)
+    {
+      continue;
+    }
+    if (amount == std::numeric_limits<uint64_t>::max())
+    {
+      MERROR("Bad format in " << filename);
+      continue;
+    }
+    if (sscanf(s, "%" PRIu64 "*%" PRIu64, &offset, &num_offsets) == 2 && num_offsets < std::numeric_limits<uint64_t>::max() - offset)
+    {
+      outputs[amount] += num_offsets;
+    }
+    else if (sscanf(s, "%" PRIu64, &offset) == 1)
+    {
+      outputs[amount] += 1;
+    }
+    else
+    {
+      MERROR("Bad format in " << filename);
+      continue;
+    }
+  }
+  fclose(f);
+  return outputs;
+}
+
+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();
+
+  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<bool> arg_verbose  = {"verbose", "Verbose output", false};
+  const command_line::arg_descriptor<bool> arg_dry_run  = {"dry-run", "Do not actually prune", false};
+  const command_line::arg_descriptor<std::string> arg_input = {"input", "Path to the known spent outputs file"};
+
+  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_verbose);
+  command_line::add_arg(desc_cmd_sett, arg_dry_run);
+  command_line::add_arg(desc_cmd_sett, arg_input);
+  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-known-spent-data.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());
+
+  LOG_PRINT_L0("Starting...");
+
+  std::string opt_data_dir = command_line::get_arg(vm, cryptonote::arg_data_dir);
+  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_verbose = command_line::get_arg(vm, arg_verbose);
+  bool opt_dry_run = command_line::get_arg(vm, arg_dry_run);
+
+  std::string db_type = command_line::get_arg(vm, arg_database);
+  if (!cryptonote::blockchain_valid_db_type(db_type))
+  {
+    std::cerr << "Invalid database type: " << db_type << std::endl;
+    return 1;
+  }
+
+  const std::string input = command_line::get_arg(vm, arg_input);
+  if (input.empty())
+  {
+    LOG_PRINT_L0("No input given");
+    return 1;
+  }
+
+  LOG_PRINT_L0("Initializing source blockchain (BlockchainDB)");
+  std::unique_ptr<Blockchain> core_storage;
+  tx_memory_pool m_mempool(*core_storage);
+  core_storage.reset(new Blockchain(m_mempool));
+  BlockchainDB *db = new_db(db_type);
+  if (db == NULL)
+  {
+    LOG_ERROR("Attempted to use non-existent database type: " << db_type);
+    throw std::runtime_error("Attempting to use non-existent database type");
+  }
+  LOG_PRINT_L0("database: " << db_type);
+
+  const std::string filename = (boost::filesystem::path(opt_data_dir) / db->get_db_name()).string();
+  LOG_PRINT_L0("Loading blockchain from folder " << filename << " ...");
+
+  try
+  {
+    db->open(filename, 0);
+  }
+  catch (const std::exception& e)
+  {
+    LOG_PRINT_L0("Error opening database: " << e.what());
+    return 1;
+  }
+  r = core_storage->init(db, net_type);
+
+  CHECK_AND_ASSERT_MES(r, 1, "Failed to initialize source blockchain storage");
+  LOG_PRINT_L0("Source blockchain storage initialized OK");
+
+  LOG_PRINT_L0("Loading known spent data...");
+  const std::map<uint64_t, uint64_t> known_spent_outputs = load_outputs(input);
+
+  LOG_PRINT_L0("Pruning known spent data...");
+
+  bool stop_requested = false;
+  tools::signal_handler::install([&stop_requested](int type) {
+    stop_requested = true;
+  });
+
+  db->batch_start();
+
+  size_t num_total_outputs = 0, num_prunable_outputs = 0, num_known_spent_outputs = 0, num_eligible_outputs = 0, num_eligible_known_spent_outputs = 0;
+  for (auto i = known_spent_outputs.begin(); i != known_spent_outputs.end(); ++i)
+  {
+    uint64_t num_outputs = db->get_num_outputs(i->first);
+    num_total_outputs += num_outputs;
+    num_known_spent_outputs += i->second;
+    if (i->first == 0 || is_valid_decomposed_amount(i->first))
+    {
+      if (opt_verbose)
+        MINFO("Ignoring output value " << i->first << ", with " << num_outputs << " outputs");
+      continue;
+    }
+    num_eligible_outputs += num_outputs;
+    num_eligible_known_spent_outputs += i->second;
+    if (opt_verbose)
+      MINFO(i->first << ": " << i->second << "/" << num_outputs);
+    if (num_outputs > i->second)
+      continue;
+    if (num_outputs && num_outputs < i->second)
+    {
+      MERROR("More outputs are spent than known for amount " << i->first << ", not touching");
+      continue;
+    }
+    if (opt_verbose)
+      MINFO("Pruning data for " << num_outputs << " outputs");
+    if (!opt_dry_run)
+      db->prune_outputs(i->first);
+    num_prunable_outputs += i->second;
+  }
+
+  db->batch_stop();
+
+  MINFO("Total outputs: " << num_total_outputs);
+  MINFO("Known spent outputs: " << num_known_spent_outputs);
+  MINFO("Eligible outputs: " << num_eligible_outputs);
+  MINFO("Eligible known spent outputs: " << num_eligible_known_spent_outputs);
+  MINFO("Prunable outputs: " << num_prunable_outputs);
+
+  LOG_PRINT_L0("Blockchain known spent data pruned OK");
+  core_storage->deinit();
+  return 0;
+
+  CATCH_ENTRY("Error", 1);
+}

tests/unit_tests/testdb.h

@@ -142,5 +142,6 @@ public:
   virtual bool prune_blockchain(uint32_t pruning_seed = 0) { return true; }
   virtual bool update_pruning() { return true; }
   virtual bool check_pruning() { return true; }
+  virtual void prune_outputs(uint64_t amount) {}
 };