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txgraph: Avoid per-group vectors for clusters & dependencies (optimization)

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Instead construct a single vector with the list of all clusters in all groups,
and then store per-group offset/range in that list.

For dependencies, reuse m_deps_to_add, and store offset/range into that.
This commit is contained in:
Pieter Wuille 2025-01-25 23:23:28 -05:00
parent ee57e93099
commit c80aecc24d
1 changed files with 45 additions and 18 deletions
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63
src/txgraph.cpp
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@ -164,11 +164,23 @@ private:
/** Information about one group of Clusters to be merged. */
struct GroupEntry
{
/** Which clusters are to be merged. */
std::vector<Cluster*> m_clusters;
/** Which dependencies are to be applied to those merged clusters, as (parent, child)
* pairs. */
std::vector<std::pair<GraphIndex, GraphIndex>> m_deps;
/** Where the clusters to be merged start in m_group_clusters. */
uint32_t m_cluster_offset;
/** How many clusters to merge. */
uint32_t m_cluster_count;
/** Where the dependencies for this cluster group in m_deps_to_add start. */
uint32_t m_deps_offset;
/** How many dependencies to add. */
uint32_t m_deps_count;
};
/** Information about all groups of Clusters to be merged. */
struct GroupData
{
/** The groups of Clusters to be merged. */
std::vector<GroupEntry> m_groups;
/** Which clusters are to be merged. GroupEntry::m_cluster_offset indexes into this. */
std::vector<Cluster*> m_group_clusters;
};
/** The vectors of clusters, one vector per quality level. ClusterSetIndex indexes into each. */
@ -179,7 +191,7 @@ private:
* into this. */
std::vector<std::pair<GraphIndex, GraphIndex>> m_deps_to_add;
/** Information about the merges to be performed, if known. */
std::optional<std::vector<GroupEntry>> m_group_data = std::vector<GroupEntry>{};
std::optional<GroupData> m_group_data = GroupData{};
/** Total number of transactions in this graph (sum of all transaction counts in all Clusters).
* */
GraphIndex m_txcount{0};
@ -796,24 +808,34 @@ void TxGraphImpl::GroupClusters() noexcept
std::sort(an_deps.begin(), an_deps.end(), [](auto& a, auto& b) noexcept { return a.second < b.second; });
std::sort(an_clusters.begin(), an_clusters.end(), [](auto& a, auto& b) noexcept { return a.second < b.second; });
// Translate the resulting cluster groups to the m_group_data structure.
m_group_data = std::vector<GroupEntry>{};
// Translate the resulting cluster groups to the m_group_data structure, and the dependencies
// back to m_deps_to_add.
m_group_data = GroupData{};
m_group_data->m_group_clusters.reserve(an_clusters.size());
m_deps_to_add.clear();
m_deps_to_add.reserve(an_deps.size());
auto an_deps_it = an_deps.begin();
auto an_clusters_it = an_clusters.begin();
while (an_clusters_it != an_clusters.end()) {
// Process all clusters/dependencies belonging to the partition with representative rep.
auto rep = an_clusters_it->second;
// Create and initialize a new GroupData entry for the partition.
auto& new_entry = m_group_data->emplace_back();
// Add all its clusters to it (copying those from an_clusters to m_clusters).
auto& new_entry = m_group_data->m_groups.emplace_back();
new_entry.m_cluster_offset = m_group_data->m_group_clusters.size();
new_entry.m_cluster_count = 0;
new_entry.m_deps_offset = m_deps_to_add.size();
new_entry.m_deps_count = 0;
// Add all its clusters to it (copying those from an_clusters to m_group_clusters).
while (an_clusters_it != an_clusters.end() && an_clusters_it->second == rep) {
new_entry.m_clusters.push_back(an_clusters_it->first);
m_group_data->m_group_clusters.push_back(an_clusters_it->first);
++an_clusters_it;
++new_entry.m_cluster_count;
}
// Add all its dependencies to it (copying those back from an_deps to m_deps).
// Add all its dependencies to it (copying those back from an_deps to m_deps_to_add).
while (an_deps_it != an_deps.end() && an_deps_it->second == rep) {
new_entry.m_deps.push_back(an_deps_it->first);
m_deps_to_add.push_back(an_deps_it->first);
++an_deps_it;
++new_entry.m_deps_count;
}
}
Assume(an_deps_it == an_deps.end());
@ -857,14 +879,19 @@ void TxGraphImpl::ApplyDependencies() noexcept
if (m_deps_to_add.empty()) return;
// For each group of to-be-merged Clusters.
for (auto& group_data : *m_group_data) {
for (const auto& group_data : m_group_data->m_groups) {
// Invoke Merge() to merge them into a single Cluster.
Merge(group_data.m_clusters);
auto cluster_span = std::span{m_group_data->m_group_clusters}
.subspan(group_data.m_cluster_offset, group_data.m_cluster_count);
Merge(cluster_span);
// Actually apply all to-be-added dependencies (all parents and children from this grouping
// belong to the same Cluster at this point because of the merging above).
const auto& loc = m_entries[group_data.m_deps[0].second].m_locator;
auto deps_span = std::span{m_deps_to_add}
.subspan(group_data.m_deps_offset, group_data.m_deps_count);
Assume(!deps_span.empty());
const auto& loc = m_entries[deps_span[0].second].m_locator;
Assume(loc.IsPresent());
loc.cluster->ApplyDependencies(*this, group_data.m_deps);
loc.cluster->ApplyDependencies(*this, deps_span);
}
// Wipe the list of to-be-added dependencies now that they are applied.
@ -872,7 +899,7 @@ void TxGraphImpl::ApplyDependencies() noexcept
Compact();
// Also no further Cluster mergings are needed (note that we clear, but don't set to
// std::nullopt, as that would imply the groupings are unknown).
m_group_data = std::vector<GroupEntry>{};
m_group_data = GroupData{};
}
void Cluster::Relinearize(TxGraphImpl& graph, uint64_t max_iters) noexcept