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txgraph: (optimization) special-case singletons in chunk index

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This commit is contained in:
Pieter Wuille 2024-11-27 15:29:40 -05:00
parent cef85dd49a
commit 2dbcf92287
1 changed files with 35 additions and 12 deletions
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47
src/txgraph.cpp
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@ -220,7 +220,7 @@ private:
{
/** The Entry which is the last transaction of the chunk. */
mutable GraphIndex m_graph_index;
/** How many transactions the chunk contains. */
/** How many transactions the chunk contains (-1 = singleton tail of cluster). */
LinearizationIndex m_chunk_count;
ChunkData(GraphIndex graph_index, LinearizationIndex chunk_count) noexcept :
@ -575,6 +575,12 @@ void Cluster::Updated(TxGraphImpl& graph) noexcept
chunk.transactions.Reset(idx);
if (chunk.transactions.None()) {
// Last transaction in the chunk.
if (chunk_count == 1 && chunk_idx + 1 == chunking.NumChunksLeft()) {
// If this is the final chunk of the cluster, and it contains just a single
// transaction (which will always be true for the very common singleton
// clusters), store the special value -1 as chunk count.
chunk_count = LinearizationIndex(-1);
}
graph.CreateChunkData(graph_idx, chunk_count);
break;
}
@ -2039,13 +2045,22 @@ void BlockBuilderImpl::Next() noexcept
// If we previously skipped a chunk from this cluster we cannot include more from it.
if (m_excluded_clusters.contains(cluster)) continue;
// Populate m_current_chunk.
m_chunkdata.resize(chunk_data.m_chunk_count);
auto start_pos = chunk_end_entry.m_main_lin_index + 1 - chunk_data.m_chunk_count;
bool is_end = cluster->GetClusterRefs(*m_graph, m_chunkdata, start_pos);
if (is_end) {
if (chunk_data.m_chunk_count == LinearizationIndex(-1)) {
// Special case in case just a single transaction remains, avoiding the need to
// dispatch to and dereference Cluster.
m_chunkdata.resize(1);
Assume(chunk_end_entry.m_ref != nullptr);
m_chunkdata[0] = chunk_end_entry.m_ref;
m_remaining_cluster = std::nullopt;
} else {
m_remaining_cluster = cluster;
m_chunkdata.resize(chunk_data.m_chunk_count);
auto start_pos = chunk_end_entry.m_main_lin_index + 1 - chunk_data.m_chunk_count;
bool is_end = cluster->GetClusterRefs(*m_graph, m_chunkdata, start_pos);
if (is_end) {
m_remaining_cluster = std::nullopt;
} else {
m_remaining_cluster = cluster;
}
}
m_current_chunk.emplace(m_chunkdata, chunk_end_entry.m_main_chunk_feerate);
return;
@ -2107,13 +2122,21 @@ void EvictorImpl::Next() noexcept
const auto& chunk_end_entry = m_graph->m_entries[chunk_data.m_graph_index];
Cluster* cluster = chunk_end_entry.m_locator[0].cluster;
// Populate m_current_chunk.
m_chunkdata.resize(chunk_data.m_chunk_count);
auto start_pos = chunk_end_entry.m_main_lin_index + 1 - chunk_data.m_chunk_count;
cluster->GetClusterRefs(*m_graph, m_chunkdata, start_pos);
if (chunk_data.m_chunk_count == LinearizationIndex(-1) || chunk_data.m_chunk_count == 1) {
// Special case for single-transaction chunks, avoiding the need to dispatch to and
// dereference Cluster.
m_chunkdata.resize(1);
Assume(chunk_end_entry.m_ref != nullptr);
m_chunkdata[0] = chunk_end_entry.m_ref;
} else {
m_chunkdata.resize(chunk_data.m_chunk_count);
auto start_pos = chunk_end_entry.m_main_lin_index + 1 - chunk_data.m_chunk_count;
cluster->GetClusterRefs(*m_graph, m_chunkdata, start_pos);
// GetClusterRefs emits in topological order; Evictor interface expects children before
// parents, so reverse.
std::reverse(m_chunkdata.begin(), m_chunkdata.end());
}
m_current_chunk.emplace(m_chunkdata, chunk_end_entry.m_main_chunk_feerate);
// GetClusterRefs emits in topological order; Evictor interface expects children before
// parents, so reverse.
std::reverse(m_chunkdata.begin(), m_chunkdata.end());
return;
}
// We reached the end of m_chunkindex.