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fcmp++: Enable trimming to empty tree
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@j-berman
j-berman committed Sep 5, 2024
1 parent 5ac03e7 commit f8e9307
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Showing 2 changed files with 68 additions and 31 deletions.
87 changes: 58 additions & 29 deletions src/blockchain_db/lmdb/db_lmdb.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -921,6 +921,8 @@ void BlockchainLMDB::remove_block()

// must use h now; deleting from m_block_info will invalidate it
mdb_block_info *bi = (mdb_block_info *)h.mv_data;
const uint64_t block_id = bi->bi_height;
const uint64_t old_n_leaf_tuples = bi->bi_n_leaf_tuples;
blk_height bh = {bi->bi_hash, 0};
h.mv_data = (void *)&bh;
h.mv_size = sizeof(bh);
Expand All @@ -937,12 +939,10 @@ void BlockchainLMDB::remove_block()

// 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*/);
const uint64_t trim_n_leaf_tuples = old_n_leaf_tuples - new_n_leaf_tuples;
this->trim_tree(trim_n_leaf_tuples, block_id/*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)
Expand Down Expand Up @@ -1523,7 +1523,7 @@ void BlockchainLMDB::trim_tree(const uint64_t trim_n_leaf_tuples, const uint64_t
CURSOR(layers)

const uint64_t old_n_leaf_tuples = this->get_num_leaf_tuples();
CHECK_AND_ASSERT_THROW_MES(old_n_leaf_tuples > trim_n_leaf_tuples, "cannot trim more leaves than exist");
CHECK_AND_ASSERT_THROW_MES(old_n_leaf_tuples >= trim_n_leaf_tuples, "cannot trim more leaves than exist");

CHECK_AND_ASSERT_THROW_MES(m_curve_trees != nullptr, "curve trees must be set");
const auto trim_instructions = m_curve_trees->get_trim_instructions(old_n_leaf_tuples, trim_n_leaf_tuples);
Expand All @@ -1542,8 +1542,6 @@ void BlockchainLMDB::trim_tree(const uint64_t trim_n_leaf_tuples, const uint64_t
CHECK_AND_ASSERT_THROW_MES((tree_reduction.new_total_leaf_tuples + trim_n_leaf_tuples) == old_n_leaf_tuples,
"unexpected new total leaves");

MDEBUG("Trimming " << trim_n_leaf_tuples << " leaf tuples");

// Trim the leaves
// TODO: trim_leaves
MDB_val_set(k_block_id, trim_block_id);
Expand Down Expand Up @@ -1579,12 +1577,13 @@ void BlockchainLMDB::trim_tree(const uint64_t trim_n_leaf_tuples, const uint64_t
// TODO: trim_layers
const auto &c2_layer_reductions = tree_reduction.c2_layer_reductions;
const auto &c1_layer_reductions = tree_reduction.c1_layer_reductions;
CHECK_AND_ASSERT_THROW_MES(!c2_layer_reductions.empty(), "empty c2 layer reductions");

const std::size_t n_layers = c2_layer_reductions.size() + c1_layer_reductions.size();

bool use_c2 = true;
uint64_t c2_idx = 0;
uint64_t c1_idx = 0;
for (uint64_t i = 0; i < (c2_layer_reductions.size() + c1_layer_reductions.size()); ++i)
for (uint64_t i = 0; i < n_layers; ++i)
{
if (use_c2)
{
Expand All @@ -1606,29 +1605,51 @@ void BlockchainLMDB::trim_tree(const uint64_t trim_n_leaf_tuples, const uint64_t

// Trim any remaining layers in layers after the root
// TODO: trim_leftovers_after_root
const uint64_t expected_root_idx = c2_layer_reductions.size() + c1_layer_reductions.size() - 1;
while (1)
if (n_layers > 0)
{
MDB_val k, v;
int result = mdb_cursor_get(m_cur_layers, &k, &v, MDB_LAST);
if (result != MDB_SUCCESS)
throw0(DB_ERROR(lmdb_error("Failed to get last elem: ", result).c_str()));
const uint64_t expected_root_idx = n_layers - 1;
while (1)
{
MDB_val k, v;
int result = mdb_cursor_get(m_cur_layers, &k, &v, MDB_LAST);
if (result != MDB_SUCCESS)
throw0(DB_ERROR(lmdb_error("Failed to get last elem: ", result).c_str()));

const uint64_t last_layer_idx = *(uint64_t *)k.mv_data;
const uint64_t last_layer_idx = *(uint64_t *)k.mv_data;

if (last_layer_idx > expected_root_idx)
{
// Delete all elements in layers after the root
result = mdb_cursor_del(m_cur_layers, MDB_NODUPDATA);
}
else if (last_layer_idx < expected_root_idx)
{
throw0(DB_ERROR("Encountered unexpected last elem in tree before the root"));
if (last_layer_idx > expected_root_idx)
{
// Delete all elements in layers after the root
result = mdb_cursor_del(m_cur_layers, MDB_NODUPDATA);
if (result != MDB_SUCCESS)
throw0(DB_ERROR(lmdb_error("Error removing elems after root: ", result).c_str()));
}
else if (last_layer_idx < expected_root_idx)
{
throw0(DB_ERROR("Encountered unexpected last elem in tree before the root"));
}
else // last_layer_idx == expected_root_idx
{
// We've trimmed all layers past the root, we're done
break;
}
}
else // last_layer_idx == expected_root_idx
}
else // n_layers == 0
{
// We're removing everything
while (1)
{
// We've trimmed all layers past the root, we're done
break;
MDB_val k, v;
int result = mdb_cursor_get(m_cur_layers, &k, &v, MDB_LAST);
if (result == MDB_NOTFOUND)
break;
if (result != MDB_SUCCESS)
throw0(DB_ERROR(lmdb_error("Failed to get last elem: ", result).c_str()));

result = mdb_cursor_del(m_cur_layers, MDB_NODUPDATA);
if (result != MDB_SUCCESS)
throw0(DB_ERROR(lmdb_error("Error removing elems after root: ", result).c_str()));
}
}
}
Expand Down Expand Up @@ -1842,14 +1863,18 @@ fcmp_pp::curve_trees::CurveTreesV1::LastChunkChildrenToTrim BlockchainLMDB::get_
const std::vector<fcmp_pp::curve_trees::TrimLayerInstructions> &trim_instructions) const
{
LOG_PRINT_L3("BlockchainLMDB::" << __func__);

fcmp_pp::curve_trees::CurveTreesV1::LastChunkChildrenToTrim last_chunk_children_to_trim;
if (trim_instructions.empty())
return last_chunk_children_to_trim;

check_open();

CHECK_AND_ASSERT_THROW_MES(m_curve_trees != nullptr, "curve trees must be set");

TXN_PREFIX_RDONLY();
RCURSOR(layers)

fcmp_pp::curve_trees::CurveTreesV1::LastChunkChildrenToTrim last_chunk_children_to_trim;
auto &c1_last_children_out = last_chunk_children_to_trim.c1_children;
auto &c2_last_children_out = last_chunk_children_to_trim.c2_children;

Expand Down Expand Up @@ -1965,12 +1990,16 @@ fcmp_pp::curve_trees::CurveTreesV1::LastHashes BlockchainLMDB::get_last_hashes_t
const std::vector<fcmp_pp::curve_trees::TrimLayerInstructions> &trim_instructions) const
{
LOG_PRINT_L3("BlockchainLMDB::" << __func__);

fcmp_pp::curve_trees::CurveTreesV1::LastHashes last_hashes_out;
if (trim_instructions.empty())
return last_hashes_out;

check_open();

TXN_PREFIX_RDONLY();
RCURSOR(layers)

fcmp_pp::curve_trees::CurveTreesV1::LastHashes last_hashes_out;

// Traverse the tree layer-by-layer starting at the layer closest to leaf layer
uint64_t layer_idx = 0;
Expand Down
12 changes: 10 additions & 2 deletions src/fcmp_pp/curve_trees.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -812,11 +812,14 @@ std::vector<TrimLayerInstructions> CurveTrees<C1, C2>::get_trim_instructions(
const uint64_t old_n_leaf_tuples,
const uint64_t trim_n_leaf_tuples) const
{
CHECK_AND_ASSERT_THROW_MES(old_n_leaf_tuples > trim_n_leaf_tuples, "cannot trim more leaves than exist");
CHECK_AND_ASSERT_THROW_MES(old_n_leaf_tuples >= trim_n_leaf_tuples, "cannot trim more leaves than exist");
CHECK_AND_ASSERT_THROW_MES(trim_n_leaf_tuples > 0, "must be trimming some leaves");

std::vector<TrimLayerInstructions> trim_instructions;

if (old_n_leaf_tuples == trim_n_leaf_tuples)
return trim_instructions;

// Get trim instructions for the leaf layer
{
const uint64_t old_total_leaves = old_n_leaf_tuples * LEAF_TUPLE_SIZE;
Expand Down Expand Up @@ -865,7 +868,12 @@ typename CurveTrees<C1, C2>::TreeReduction CurveTrees<C1, C2>::get_tree_reductio
{
TreeReduction tree_reduction_out;

CHECK_AND_ASSERT_THROW_MES(!trim_instructions.empty(), "missing trim instructions");
if (trim_instructions.empty())
{
tree_reduction_out.new_total_leaf_tuples = 0;
return tree_reduction_out;
}

CHECK_AND_ASSERT_THROW_MES((trim_instructions[0].new_total_children % LEAF_TUPLE_SIZE) == 0,
"unexpected new total leaves");
const uint64_t new_total_leaf_tuples = trim_instructions[0].new_total_children / LEAF_TUPLE_SIZE;
Expand Down

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