fcmp++: trim tree when removing a block

- trim_tree now re-adds trimmed outputs back to the locked outputs
table. remove_output then deletes from the locked output table.
- Since outputs added to the tree in a specific block may have
originated from distinct younger blocks (thanks to distinct unlock
times), we need to store the 8 byte output_id in the leaves table
as well, so that in the event of a reorg, upon removing outputs
from the tree we can add them back to the locked outputs table
in the correct order.

src/blockchain_db/blockchain_db.h

@@ -1785,7 +1785,7 @@ public:
   // TODO: description and make private
   virtual void grow_tree(std::vector<fcmp_pp::curve_trees::OutputContext> &&new_outputs) = 0;
 
-  virtual void trim_tree(const uint64_t trim_n_leaf_tuples) = 0;
+  virtual void trim_tree(const uint64_t trim_n_leaf_tuples, const uint64_t trim_block_id) = 0;
 
   // TODO: description
   virtual bool audit_tree(const uint64_t expected_n_leaf_tuples) const = 0;

src/blockchain_db/lmdb/db_lmdb.cpp

@@ -200,7 +200,7 @@ namespace
  * spent_keys       input hash   -
  *
  * locked_outputs   block ID     [{output ID, output pubkey, commitment}...]
- * leaves           leaf_idx     {output pubkey, commitment}
+ * leaves           leaf_idx     {output ID, output pubkey, commitment}
  * layers           layer_idx    [{child_chunk_idx, child_chunk_hash}...]
  *
  * txpool_meta      txn hash     txn metadata
@@ -828,8 +828,7 @@ void BlockchainLMDB::add_block(const block& blk, size_t block_weight, uint64_t l
 
   // Grow the tree with outputs that unlock at this block height
   auto unlocked_outputs = this->get_outs_at_unlock_block_id(m_height);
-  if (!unlocked_outputs.empty())
-    this->grow_tree(std::move(unlocked_outputs));
+  this->grow_tree(std::move(unlocked_outputs));
 
   // Now that we've used the unlocked leaves to grow the tree, we can delete them from the locked outputs table
   this->del_locked_outs_at_block_id(m_height);
@@ -935,6 +934,15 @@ void BlockchainLMDB::remove_block()
 
   if ((result = mdb_cursor_del(m_cur_block_info, 0)))
       throw1(DB_ERROR(lmdb_error("Failed to add removal of block info to db transaction: ", result).c_str()));
+
+  // Get n_leaf_tuples from the new tip so we can trim the curve trees tree to the new tip
+  const uint64_t new_n_leaf_tuples = get_top_block_n_leaf_tuples();
+  const uint64_t old_n_leaf_tuples = bi->bi_n_leaf_tuples;
+
+  if (new_n_leaf_tuples > old_n_leaf_tuples)
+      throw1(DB_ERROR("Unexpected: more leaf tuples are in prev block, tree is expected to only grow"));
+
+  this->trim_tree(old_n_leaf_tuples - new_n_leaf_tuples, bi->bi_height/*trim_block_id*/);
 }
 
 uint64_t BlockchainLMDB::add_transaction_data(const crypto::hash& blk_hash, const std::pair<transaction, blobdata_ref>& txp, const crypto::hash& tx_hash, const crypto::hash& tx_prunable_hash)
@@ -1244,6 +1252,32 @@ void BlockchainLMDB::remove_output(const uint64_t amount, const uint64_t& out_in
   {
     throw1(DB_ERROR(lmdb_error("Error adding removal of output tx to db transaction", result).c_str()));
   }
+
+  // Remove output from locked outputs table. We expect the output to be in the
+  // locked outputs table because remove_output is called when removing the
+  // top block from the chain, and all outputs from the top block are expected
+  // to be locked until they are at least 10 blocks old.
+  CURSOR(locked_outputs);
+
+  const uint64_t unlock_block = cryptonote::get_unlock_block_index(ok->data.unlock_time, ok->data.height);
+
+  MDB_val_set(k_block_id, unlock_block);
+  MDB_val_set(v_output, ok->output_id);
+
+  result = mdb_cursor_get(m_cur_locked_outputs, &k_block_id, &v_output, MDB_GET_BOTH);
+  if (result == MDB_NOTFOUND)
+  {
+    throw0(DB_ERROR("Unexpected: output not found in m_cur_locked_outputs"));
+  }
+  else if (result)
+  {
+    throw1(DB_ERROR(lmdb_error("Error adding removal of locked output to db transaction", result).c_str()));
+  }
+
+  result = mdb_cursor_del(m_cur_locked_outputs, 0);
+  if (result)
+    throw0(DB_ERROR(lmdb_error(std::string("Error deleting locked output index ").append(boost::lexical_cast<std::string>(out_index).append(": ")).c_str(), result).c_str()));
+
   result = mdb_cursor_del(m_cur_output_txs, 0);
   if (result)
     throw0(DB_ERROR(lmdb_error(std::string("Error deleting output index ").append(boost::lexical_cast<std::string>(out_index).append(": ")).c_str(), result).c_str()));
@@ -1475,7 +1509,7 @@ void BlockchainLMDB::grow_layer(const std::unique_ptr<C> &curve,
   }
 }
 
-void BlockchainLMDB::trim_tree(const uint64_t trim_n_leaf_tuples)
+void BlockchainLMDB::trim_tree(const uint64_t trim_n_leaf_tuples, const uint64_t trim_block_id)
 {
   LOG_PRINT_L3("BlockchainLMDB::" << __func__);
   if (trim_n_leaf_tuples == 0)
@@ -1485,6 +1519,7 @@ void BlockchainLMDB::trim_tree(const uint64_t trim_n_leaf_tuples)
   mdb_txn_cursors *m_cursors = &m_wcursors;
 
   CURSOR(leaves)
+  CURSOR(locked_outputs)
   CURSOR(layers)
 
   const uint64_t old_n_leaf_tuples = this->get_num_leaf_tuples();
@@ -1511,11 +1546,12 @@ void BlockchainLMDB::trim_tree(const uint64_t trim_n_leaf_tuples)
 
   // Trim the leaves
   // TODO: trim_leaves
+  MDB_val_set(k_block_id, trim_block_id);
   for (uint64_t i = 0; i < trim_n_leaf_tuples; ++i)
   {
-    uint64_t last_leaf_tuple_idx = (old_n_leaf_tuples - 1 - i);
+    uint64_t leaf_tuple_idx = (old_n_leaf_tuples - trim_n_leaf_tuples + i);
 
-    MDB_val_copy<uint64_t> k(last_leaf_tuple_idx);
+    MDB_val_copy<uint64_t> k(leaf_tuple_idx);
     MDB_val v;
     int result = mdb_cursor_get(m_cur_leaves, &k, &v, MDB_SET);
     if (result == MDB_NOTFOUND)
@@ -1523,11 +1559,20 @@ void BlockchainLMDB::trim_tree(const uint64_t trim_n_leaf_tuples)
     if (result != MDB_SUCCESS)
       throw0(DB_ERROR(lmdb_error("Failed to get leaf: ", result).c_str()));
 
+    // Re-add the output to the locked output table in order. The output should
+    // be in the outputs tables.
+    const auto o = *(fcmp_pp::curve_trees::OutputContext *)v.mv_data;
+    MDB_val_set(v_output, o);
+    result = mdb_cursor_put(m_cur_locked_outputs, &k_block_id, &v_output, MDB_APPENDDUP);
+    if (result != MDB_SUCCESS)
+      throw0(DB_ERROR(lmdb_error("Failed to re-add locked output: ", result).c_str()));
+
+    // Delete the leaf
     result = mdb_cursor_del(m_cur_leaves, 0);
     if (result != MDB_SUCCESS)
       throw0(DB_ERROR(lmdb_error("Error removing leaf: ", result).c_str()));
 
-    MDEBUG("Successfully removed leaf at last_leaf_tuple_idx: " << last_leaf_tuple_idx);
+    MDEBUG("Successfully removed leaf at leaf_tuple_idx: " << leaf_tuple_idx);
   }
 
   // Trim the layers
@@ -1599,6 +1644,7 @@ void BlockchainLMDB::trim_layer(const std::unique_ptr<C> &curve,
 
   CURSOR(layers)
 
+  MDEBUG("Trimming layer " << layer_idx);
   MDB_val_copy<uint64_t> k(layer_idx);
 
   // Get the number of existing elements in the layer
@@ -1685,6 +1731,32 @@ uint64_t BlockchainLMDB::get_num_leaf_tuples() const
   return n_leaf_tuples;
 }
 
+uint64_t BlockchainLMDB::get_top_block_n_leaf_tuples() const
+{
+  LOG_PRINT_L3("BlockchainLMDB::" << __func__);
+  check_open();
+
+  TXN_PREFIX_RDONLY();
+  RCURSOR(block_info);
+
+  // if no blocks, return 0
+  uint64_t m_height = height();
+  if (m_height == 0)
+  {
+    return 0;
+  }
+
+  MDB_val_copy<uint64_t> k(m_height - 1);
+  MDB_val h = k;
+  int result = 0;
+  if ((result = mdb_cursor_get(m_cur_block_info, (MDB_val *)&zerokval, &h, MDB_GET_BOTH)))
+    throw1(BLOCK_DNE(lmdb_error("Failed to get top block: ", result).c_str()));
+
+  const uint64_t n_leaf_tuples = ((mdb_block_info *)h.mv_data)->bi_n_leaf_tuples;
+  TXN_POSTFIX_RDONLY();
+  return n_leaf_tuples;
+}
+
 std::array<uint8_t, 32UL> BlockchainLMDB::get_tree_root() const
 {
   LOG_PRINT_L3("BlockchainLMDB::" << __func__);
@@ -1811,10 +1883,10 @@ fcmp_pp::curve_trees::CurveTreesV1::LastChunkChildrenToTrim BlockchainLMDB::get_
         if (result != MDB_SUCCESS)
           throw0(DB_ERROR(lmdb_error("Failed to get leaf: ", result).c_str()));
 
-        const auto output_pair = *(fcmp_pp::curve_trees::OutputPair *)v.mv_data;
+        const auto o = *(fcmp_pp::curve_trees::OutputContext *)v.mv_data;
 
         // TODO: parallelize calls to this function
-        auto leaf = m_curve_trees->leaf_tuple(output_pair);
+        auto leaf = m_curve_trees->leaf_tuple(o.output_pair);
 
         leaves_to_trim.emplace_back(std::move(leaf.O_x));
         leaves_to_trim.emplace_back(std::move(leaf.I_x));
@@ -1987,8 +2059,8 @@ bool BlockchainLMDB::audit_tree(const uint64_t expected_n_leaf_tuples) const
       if (result != MDB_SUCCESS)
         throw0(DB_ERROR(lmdb_error("Failed to add leaf: ", result).c_str()));
 
-      const auto output_pair = *(fcmp_pp::curve_trees::OutputPair *)v.mv_data;
-      auto leaf = m_curve_trees->leaf_tuple(output_pair);
+      const auto o = *(fcmp_pp::curve_trees::OutputContext *)v.mv_data;
+      auto leaf = m_curve_trees->leaf_tuple(o.output_pair);
 
       leaf_tuples_chunk.emplace_back(std::move(leaf));
 

src/blockchain_db/lmdb/db_lmdb.h

@@ -370,7 +370,7 @@ public:
   // make private
   virtual void grow_tree(std::vector<fcmp_pp::curve_trees::OutputContext> &&new_outputs);
 
-  virtual void trim_tree(const uint64_t trim_n_leaf_tuples);
+  virtual void trim_tree(const uint64_t trim_n_leaf_tuples, const uint64_t trim_block_id);
 
   virtual bool audit_tree(const uint64_t expected_n_leaf_tuples) const;
 
@@ -431,6 +431,8 @@ private:
 
   virtual uint64_t get_num_leaf_tuples() const;
 
+  uint64_t get_top_block_n_leaf_tuples() const;
+
   virtual std::array<uint8_t, 32UL> get_tree_root() const;
 
   fcmp_pp::curve_trees::CurveTreesV1::LastHashes get_tree_last_hashes() const;

src/blockchain_db/testdb.h

@@ -117,7 +117,7 @@ public:
   virtual void add_spent_key(const crypto::key_image& k_image) override {}
   virtual void remove_spent_key(const crypto::key_image& k_image) override {}
   virtual void grow_tree(std::vector<fcmp_pp::curve_trees::OutputContext> &&new_outputs) override {};
-  virtual void trim_tree(const uint64_t trim_n_leaf_tuples) override {};
+  virtual void trim_tree(const uint64_t trim_n_leaf_tuples, const uint64_t trim_block_id) override {};
   virtual bool audit_tree(const uint64_t expected_n_leaf_tuples) const override { return false; };
   virtual std::array<uint8_t, 32UL> get_tree_root() const override { return {}; };
   virtual uint64_t get_num_leaf_tuples() const override { return 0; };

src/fcmp_pp/curve_trees.cpp

@@ -740,7 +740,7 @@ typename CurveTrees<C1, C2>::TreeExtension CurveTrees<C1, C2>::get_tree_extensio
         flattened_leaves.emplace_back(std::move(leaf.C_x));
 
         // We can derive {O.x,I.x,C.x} from output pairs, so we store just the output pair in the db to save 32 bytes
-        tree_extension.leaves.tuples.emplace_back(std::move(o.output_pair));
+        tree_extension.leaves.tuples.emplace_back(std::move(o));
     }
 
     if (flattened_leaves.empty())

src/fcmp_pp/curve_trees.h

@@ -197,9 +197,9 @@ public:
     struct Leaves final
     {
         // Starting leaf tuple index in the leaf layer
-        uint64_t                start_leaf_tuple_idx{0};
+        uint64_t                   start_leaf_tuple_idx{0};
         // Contiguous leaves in a tree that start at the start_idx
-        std::vector<OutputPair> tuples;
+        std::vector<OutputContext> tuples;
     };
 
     // A struct useful to extend an existing tree

src/fcmp_pp/fcmp_pp_rust/fcmp++.h

@@ -139,4 +139,4 @@ CResult hash_trim_selene(SelenePoint existing_hash,
                                              SeleneScalar child_to_grow_back);
 
 } // extern "C"
-}//namespace fcmp_pp
+}//namespace fcmp_pp_rust

tests/unit_tests/curve_trees.cpp

@@ -169,9 +169,9 @@ void CurveTreesGlobalTree::extend_tree(const CurveTreesV1::TreeExtension &tree_e
         "unexpected leaf start idx");
 
     m_tree.leaves.reserve(m_tree.leaves.size() + tree_extension.leaves.tuples.size());
-    for (const auto &output_pair : tree_extension.leaves.tuples)
+    for (const auto &o : tree_extension.leaves.tuples)
     {
-        auto leaf = m_curve_trees.leaf_tuple(output_pair);
+        auto leaf = m_curve_trees.leaf_tuple(o.output_pair);
 
         m_tree.leaves.emplace_back(CurveTreesV1::LeafTuple{
             .O_x = std::move(leaf.O_x),
@@ -641,14 +641,14 @@ void CurveTreesGlobalTree::log_tree_extension(const CurveTreesV1::TreeExtension
     MDEBUG("Leaf start idx: " << tree_extension.leaves.start_leaf_tuple_idx);
     for (std::size_t i = 0; i < tree_extension.leaves.tuples.size(); ++i)
     {
-        const auto &output_pair = tree_extension.leaves.tuples[i];
+        const auto &output_pair = tree_extension.leaves.tuples[i].output_pair;
         const auto leaf = m_curve_trees.leaf_tuple(output_pair);
 
         const auto O_x = m_curve_trees.m_c2->to_string(leaf.O_x);
         const auto I_x = m_curve_trees.m_c2->to_string(leaf.I_x);
         const auto C_x = m_curve_trees.m_c2->to_string(leaf.C_x);
 
-        MDEBUG("Leaf tuple idx " << (tree_extension.leaves.start_leaf_tuple_idx)
+        MDEBUG("Leaf tuple idx " << (tree_extension.leaves.start_leaf_tuple_idx + (i * CurveTreesV1::LEAF_TUPLE_SIZE))
             << " : { O_x: " << O_x << " , I_x: " << I_x << " , C_x: " << C_x << " }");
     }
 
@@ -926,7 +926,8 @@ static bool trim_tree_db(const std::size_t init_leaves,
         MDEBUG("Successfully added initial " << init_leaves << " leaves to db, trimming by "
             << trim_leaves << " leaves");
 
-        test_db.m_db->trim_tree(trim_leaves);
+        // Can use 0 from trim_block_id since it's unused in tests
+        test_db.m_db->trim_tree(trim_leaves, 0);
         CHECK_AND_ASSERT_MES(test_db.m_db->audit_tree(init_leaves - trim_leaves), false,
             "failed to trim tree in db");