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txgraph: make GroupClusters use partition numbers directly (optimization)

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Pieter Wuille 2025-04-01 16:33:14 -04:00
parent c72c8d5d45
commit 2835216ec0
1 changed files with 49 additions and 58 deletions
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107
src/txgraph.cpp
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@ -1103,38 +1103,37 @@ void TxGraphImpl::GroupClusters(int level) noexcept
// with inefficient and/or oversized Clusters which just end up being split again anyway.
SplitAll(level);
/** Annotated clusters: an entry for each Cluster, together with the representative for the
* partition it is in if known, or with nullptr if not yet known. */
std::vector<std::pair<Cluster*, Cluster*>> an_clusters;
/** Annotated clusters: an entry for each Cluster, together with the sequence number for the
* representative for the partition it is in (initially its own, later that of the
* to-be-merged group). */
std::vector<std::pair<Cluster*, uint64_t>> an_clusters;
/** Annotated dependencies: an entry for each m_deps_to_add entry (excluding ones that apply
* to removed transactions), together with the representative root of the partition of
* Clusters it applies to. */
std::vector<std::pair<std::pair<GraphIndex, GraphIndex>, Cluster*>> an_deps;
* to removed transactions), together with the sequence number of the representative root of
* Clusters it applies to (initially that of the child Cluster, later that of the
* to-be-merged group). */
std::vector<std::pair<std::pair<GraphIndex, GraphIndex>, uint64_t>> an_deps;
// Construct a an_clusters entry for every parent and child in the to-be-applied dependencies.
// Construct a an_clusters entry for every parent and child in the to-be-applied dependencies,
// and an an_deps entry for each dependency to be applied.
an_deps.reserve(clusterset.m_deps_to_add.size());
for (const auto& [par, chl] : clusterset.m_deps_to_add) {
auto par_cluster = FindCluster(par, level);
auto chl_cluster = FindCluster(chl, level);
// Skip dependencies for which the parent or child transaction is removed.
if (par_cluster == nullptr || chl_cluster == nullptr) continue;
an_clusters.emplace_back(par_cluster, nullptr);
an_clusters.emplace_back(par_cluster, par_cluster->m_sequence);
// Do not include a duplicate when parent and child are identical, as it'll be removed
// below anyway.
if (chl_cluster != par_cluster) an_clusters.emplace_back(chl_cluster, nullptr);
if (chl_cluster != par_cluster) an_clusters.emplace_back(chl_cluster, chl_cluster->m_sequence);
// Add entry to an_deps, using the child sequence number.
an_deps.emplace_back(std::pair{par, chl}, chl_cluster->m_sequence);
}
// Sort and deduplicate an_clusters, so we end up with a sorted list of all involved Clusters
// to which dependencies apply.
std::sort(an_clusters.begin(), an_clusters.end(), [](auto& a, auto& b) noexcept { return CompareClusters(a.first, b.first) < 0; });
std::sort(an_clusters.begin(), an_clusters.end(), [](auto& a, auto& b) noexcept { return a.second < b.second; });
an_clusters.erase(std::unique(an_clusters.begin(), an_clusters.end()), an_clusters.end());
// Sort the dependencies by child Cluster::m_sequence.
std::sort(clusterset.m_deps_to_add.begin(), clusterset.m_deps_to_add.end(), [&](auto& a, auto& b) noexcept {
auto [_a_par, a_chl] = a;
auto [_b_par, b_chl] = b;
auto a_chl_cluster = FindCluster(a_chl, level);
auto b_chl_cluster = FindCluster(b_chl, level);
return CompareClusters(a_chl_cluster, b_chl_cluster) < 0;
});
// Sort an_deps by applying the same order to the involved child cluster.
std::sort(an_deps.begin(), an_deps.end(), [&](auto& a, auto& b) noexcept { return a.second < b.second; });
// Run the union-find algorithm to to find partitions of the input Clusters which need to be
// grouped together. See https://en.wikipedia.org/wiki/Disjoint-set_data_structure.
@ -1142,8 +1141,8 @@ void TxGraphImpl::GroupClusters(int level) noexcept
/** Each PartitionData entry contains information about a single input Cluster. */
struct PartitionData
{
/** The cluster this holds information for. */
Cluster* cluster;
/** The sequence number of the cluster this holds information for. */
uint64_t sequence;
/** All PartitionData entries belonging to the same partition are organized in a tree.
* Each element points to its parent, or to itself if it is the root. The root is then
* a representative for the entire tree, and can be found by walking upwards from any
@ -1157,11 +1156,11 @@ void TxGraphImpl::GroupClusters(int level) noexcept
std::vector<PartitionData> partition_data;
/** Given a Cluster, find its corresponding PartitionData. */
auto locate_fn = [&](Cluster* arg) noexcept -> PartitionData* {
auto it = std::lower_bound(partition_data.begin(), partition_data.end(), arg,
[](auto& a, Cluster* ptr) noexcept { return CompareClusters(a.cluster, ptr) < 0; });
auto locate_fn = [&](uint64_t sequence) noexcept -> PartitionData* {
auto it = std::lower_bound(partition_data.begin(), partition_data.end(), sequence,
[](auto& a, uint64_t seq) noexcept { return a.sequence < seq; });
Assume(it != partition_data.end());
Assume(it->cluster == arg);
Assume(it->sequence == sequence);
return &*it;
};
@ -1196,67 +1195,59 @@ void TxGraphImpl::GroupClusters(int level) noexcept
// Start by initializing every Cluster as its own singleton partition.
partition_data.resize(an_clusters.size());
for (size_t i = 0; i < an_clusters.size(); ++i) {
partition_data[i].cluster = an_clusters[i].first;
partition_data[i].sequence = an_clusters[i].first->m_sequence;
partition_data[i].parent = &partition_data[i];
partition_data[i].rank = 0;
}
// Run through all parent/child pairs in m_deps_to_add, and union the
// the partitions their Clusters are in.
// Run through all parent/child pairs in an_deps, and union the partitions their Clusters
// are in.
Cluster* last_chl_cluster{nullptr};
PartitionData* last_partition{nullptr};
for (const auto& [par, chl] : clusterset.m_deps_to_add) {
for (const auto& [dep, _] : an_deps) {
auto [par, chl] = dep;
auto par_cluster = FindCluster(par, level);
auto chl_cluster = FindCluster(chl, level);
Assume(chl_cluster != nullptr && par_cluster != nullptr);
// Nothing to do if parent and child are in the same Cluster.
if (par_cluster == chl_cluster) continue;
// Nothing to do if either parent or child transaction is removed already.
if (par_cluster == nullptr || chl_cluster == nullptr) continue;
Assume(par != chl);
if (chl_cluster == last_chl_cluster) {
// If the child Clusters is the same as the previous iteration, union with the
// tree they were in, avoiding the need for another lookup. Note that m_deps_to_add
// tree they were in, avoiding the need for another lookup. Note that an_deps
// is sorted by child Cluster, so batches with the same child are expected.
last_partition = union_fn(locate_fn(par_cluster), last_partition);
last_partition = union_fn(locate_fn(par_cluster->m_sequence), last_partition);
} else {
last_chl_cluster = chl_cluster;
last_partition = union_fn(locate_fn(par_cluster), locate_fn(chl_cluster));
last_partition = union_fn(locate_fn(par_cluster->m_sequence), locate_fn(chl_cluster->m_sequence));
}
}
// Populate the an_clusters and an_deps data structures with the list of input Clusters,
// and the input dependencies, annotated with the representative of the Cluster partition
// it applies to.
an_deps.reserve(clusterset.m_deps_to_add.size());
auto deps_it = clusterset.m_deps_to_add.begin();
// Update the sequence numbers in an_clusters and an_deps to be those of the partition
// representative.
auto deps_it = an_deps.begin();
for (size_t i = 0; i < partition_data.size(); ++i) {
auto& data = partition_data[i];
// Find the representative of the partition Cluster i is in, and store it with the
// Cluster.
auto rep = find_root_fn(&data)->cluster;
Assume(an_clusters[i].second == nullptr);
an_clusters[i].second = rep;
// Find the sequence of the representative of the partition Cluster i is in, and store
// it with the Cluster.
auto rep_seq = find_root_fn(&data)->sequence;
an_clusters[i].second = rep_seq;
// Find all dependencies whose child Cluster is Cluster i, and annotate them with rep.
while (deps_it != clusterset.m_deps_to_add.end()) {
auto [par, chl] = *deps_it;
while (deps_it != an_deps.end()) {
auto [par, chl] = deps_it->first;
auto chl_cluster = FindCluster(chl, level);
if (CompareClusters(chl_cluster, data.cluster) > 0) break;
// Skip dependencies that apply to earlier Clusters (those necessary are for
// deleted transactions, as otherwise we'd have processed them already).
if (chl_cluster == data.cluster) {
auto par_cluster = FindCluster(par, level);
// Also filter out dependencies applying to a removed parent.
if (par_cluster != nullptr) an_deps.emplace_back(*deps_it, rep);
}
Assume(chl_cluster != nullptr);
if (chl_cluster->m_sequence > data.sequence) break;
deps_it->second = rep_seq;
++deps_it;
}
}
}
// Sort both an_clusters and an_deps by representative of the partition they are in, grouping
// all those applying to the same partition together.
std::sort(an_deps.begin(), an_deps.end(), [](auto& a, auto& b) noexcept { return CompareClusters(a.second, b.second) < 0; });
std::sort(an_clusters.begin(), an_clusters.end(), [](auto& a, auto& b) noexcept { return CompareClusters(a.second, b.second) < 0; });
// Sort both an_clusters and an_deps by sequence number of the representative of the
// partition they are in, grouping all those applying to the same partition together.
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, and the dependencies
// back to m_deps_to_add.