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txgraph: Add GetMainStagingDiagrams function (feature)

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This allows determining whether the changes in a staging diagram unambiguously improve
the graph, through CompareChunks().
This commit is contained in:
Pieter Wuille 2024-11-28 10:40:42 -05:00
parent e5a00b2497
commit e1cb50a957
3 changed files with 175 additions and 0 deletions
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134
src/test/fuzz/txgraph.cpp
View file

@ -11,6 +11,7 @@
#include <util/feefrac.h>
#include <algorithm>
#include <iterator>
#include <map>
#include <memory>
#include <set>
@ -52,6 +53,9 @@ struct SimTxGraph
std::optional<bool> oversized;
/** The configured maximum number of transactions per cluster. */
DepGraphIndex max_cluster_count;
/** Which transactions have been modified in the graph since creation, either directly or by
* being in a cluster which includes modifications. Only relevant for the staging graph. */
SetType modified;
/** Construct a new SimTxGraph with the specified maximum cluster count. */
explicit SimTxGraph(DepGraphIndex max_cluster) : max_cluster_count(max_cluster) {}
@ -80,9 +84,24 @@ struct SimTxGraph
return *oversized;
}
void MakeModified(DepGraphIndex index)
{
modified |= graph.GetConnectedComponent(graph.Positions(), index);
}
/** Determine the number of (non-removed) transactions in the graph. */
DepGraphIndex GetTransactionCount() const { return graph.TxCount(); }
/** Get the sum of all fees/sizes in the graph. */
FeePerWeight SumAll() const
{
FeePerWeight ret;
for (auto i : graph.Positions()) {
ret += graph.FeeRate(i);
}
return ret;
}
/** Get the position where ref occurs in this simulated graph, or -1 if it does not. */
Pos Find(const TxGraph::Ref* ref) const
{
@ -104,6 +123,7 @@ struct SimTxGraph
{
assert(graph.TxCount() < MAX_TRANSACTIONS);
auto simpos = graph.AddTransaction(feerate);
MakeModified(simpos);
assert(graph.Positions()[simpos]);
simmap[simpos] = std::make_shared<TxGraph::Ref>();
auto ptr = simmap[simpos].get();
@ -119,6 +139,7 @@ struct SimTxGraph
auto chl_pos = Find(child);
if (chl_pos == MISSING) return;
graph.AddDependencies(SetType::Singleton(par_pos), chl_pos);
MakeModified(par_pos);
// This may invalidate our cached oversized value.
if (oversized.has_value() && !*oversized) oversized = std::nullopt;
}
@ -128,6 +149,7 @@ struct SimTxGraph
{
auto pos = Find(ref);
if (pos == MISSING) return;
// No need to invoke MakeModified, because this equally affects main and staging.
graph.FeeRate(pos).fee = fee;
}
@ -136,6 +158,7 @@ struct SimTxGraph
{
auto pos = Find(ref);
if (pos == MISSING) return;
MakeModified(pos);
graph.RemoveTransactions(SetType::Singleton(pos));
simrevmap.erase(simmap[pos].get());
// Retain the TxGraph::Ref corresponding to this position, so the Ref destruction isn't
@ -160,6 +183,7 @@ struct SimTxGraph
auto remove = std::partition(removed.begin(), removed.end(), [&](auto& arg) { return arg.get() != ref; });
removed.erase(remove, removed.end());
} else {
MakeModified(pos);
graph.RemoveTransactions(SetType::Singleton(pos));
simrevmap.erase(simmap[pos].get());
simmap[pos].reset();
@ -282,6 +306,39 @@ FUZZ_TARGET(txgraph)
return &empty_ref;
};
/** Function to construct the correct fee-size diagram a real graph has based on its graph
* order (as reported by GetCluster(), so it works for both main and staging). */
auto get_diagram_fn = [&](bool main_only) -> std::vector<FeeFrac> {
int level = main_only ? 0 : sims.size() - 1;
auto& sim = sims[level];
// For every transaction in the graph, request its cluster, and throw them into a set.
std::set<std::vector<TxGraph::Ref*>> clusters;
for (auto i : sim.graph.Positions()) {
auto ref = sim.GetRef(i);
clusters.insert(real->GetCluster(*ref, main_only));
}
// Compute the chunkings of each (deduplicated) cluster.
size_t num_tx{0};
std::vector<FeeFrac> chunk_feerates;
for (const auto& cluster : clusters) {
num_tx += cluster.size();
std::vector<SimTxGraph::Pos> linearization;
linearization.reserve(cluster.size());
for (auto refptr : cluster) linearization.push_back(sim.Find(refptr));
for (const FeeFrac& chunk_feerate : ChunkLinearization(sim.graph, linearization)) {
chunk_feerates.push_back(chunk_feerate);
}
}
// Verify the number of transactions after deduplicating clusters. This implicitly verifies
// that GetCluster on each element of a cluster reports the cluster transactions in the same
// order.
assert(num_tx == sim.GetTransactionCount());
// Sort by feerate only, since violating topological constraints within same-feerate
// chunks won't affect diagram comparisons.
std::sort(chunk_feerates.begin(), chunk_feerates.end(), std::greater{});
return chunk_feerates;
};
LIMITED_WHILE(provider.remaining_bytes() > 0, 200) {
// Read a one-byte command.
int command = provider.ConsumeIntegral<uint8_t>();
@ -444,6 +501,7 @@ FUZZ_TARGET(txgraph)
// Just do some quick checks that the reported value is in range. A full
// recomputation of expected chunk feerates is done at the end.
assert(feerate.size >= main_sim.graph.FeeRate(simpos).size);
assert(feerate.size <= main_sim.SumAll().size);
}
break;
} else if (!sel_sim.IsOversized() && command-- == 0) {
@ -517,6 +575,7 @@ FUZZ_TARGET(txgraph)
} else if (sims.size() < 2 && command-- == 0) {
// StartStaging.
sims.emplace_back(sims.back());
sims.back().modified = SimTxGraph::SetType{};
real->StartStaging();
break;
} else if (sims.size() > 1 && command-- == 0) {
@ -586,6 +645,25 @@ FUZZ_TARGET(txgraph)
// DoWork.
real->DoWork();
break;
} else if (sims.size() == 2 && !sims[0].IsOversized() && !sims[1].IsOversized() && command-- == 0) {
// GetMainStagingDiagrams()
auto [main_diagram, staged_diagram] = real->GetMainStagingDiagrams();
auto sum_main = std::accumulate(main_diagram.begin(), main_diagram.end(), FeeFrac{});
auto sum_staged = std::accumulate(staged_diagram.begin(), staged_diagram.end(), FeeFrac{});
auto diagram_gain = sum_staged - sum_main;
auto real_gain = sims[1].SumAll() - sims[0].SumAll();
// Just check that the total fee gained/lost and size gained/lost according to the
// diagram matches the difference in these values in the simulated graph. A more
// complete check of the GetMainStagingDiagrams result is performed at the end.
assert(diagram_gain == real_gain);
// Check that the feerates in each diagram are monotonically decreasing.
for (size_t i = 1; i < main_diagram.size(); ++i) {
assert(FeeRateCompare(main_diagram[i], main_diagram[i - 1]) <= 0);
}
for (size_t i = 1; i < staged_diagram.size(); ++i) {
assert(FeeRateCompare(staged_diagram[i], staged_diagram[i - 1]) <= 0);
}
break;
}
}
}
@ -639,6 +717,62 @@ FUZZ_TARGET(txgraph)
assert(FeeRateCompare(after_feerate, pos_feerate) <= 0);
}
}
// Check that the implied ordering gives rise to a combined diagram that matches the
// diagram constructed from the individual cluster linearization chunkings.
auto main_real_diagram = get_diagram_fn(/*main_only=*/true);
auto main_implied_diagram = ChunkLinearization(sims[0].graph, vec1);
assert(CompareChunks(main_real_diagram, main_implied_diagram) == 0);
if (sims.size() >= 2 && !sims[1].IsOversized()) {
// When the staging graph is not oversized as well, call GetMainStagingDiagrams, and
// fully verify the result.
auto [main_cmp_diagram, stage_cmp_diagram] = real->GetMainStagingDiagrams();
// Check that the feerates in each diagram are monotonically decreasing.
for (size_t i = 1; i < main_cmp_diagram.size(); ++i) {
assert(FeeRateCompare(main_cmp_diagram[i], main_cmp_diagram[i - 1]) <= 0);
}
for (size_t i = 1; i < stage_cmp_diagram.size(); ++i) {
assert(FeeRateCompare(stage_cmp_diagram[i], stage_cmp_diagram[i - 1]) <= 0);
}
// Treat the diagrams as sets of chunk feerates, and sort them in the same way so that
// std::set_difference can be used on them below. The exact ordering does not matter
// here, but it has to be consistent with the one used in main_diagram and
// stage_diagram).
std::sort(main_cmp_diagram.begin(), main_cmp_diagram.end(), std::greater{});
std::sort(stage_cmp_diagram.begin(), stage_cmp_diagram.end(), std::greater{});
// Find the chunks that appear in main_diagram but are missing from main_cmp_diagram.
// This is allowed, because GetMainStagingDiagrams omits clusters in main unaffected
// by staging.
std::vector<FeeFrac> missing_main_cmp;
std::set_difference(main_real_diagram.begin(), main_real_diagram.end(),
main_cmp_diagram.begin(), main_cmp_diagram.end(),
std::inserter(missing_main_cmp, missing_main_cmp.end()),
std::greater{});
assert(main_cmp_diagram.size() + missing_main_cmp.size() == main_real_diagram.size());
// Do the same for chunks in stage_diagram missing from stage_cmp_diagram.
auto stage_real_diagram = get_diagram_fn(false);
std::vector<FeeFrac> missing_stage_cmp;
std::set_difference(stage_real_diagram.begin(), stage_real_diagram.end(),
stage_cmp_diagram.begin(), stage_cmp_diagram.end(),
std::inserter(missing_stage_cmp, missing_stage_cmp.end()),
std::greater{});
assert(stage_cmp_diagram.size() + missing_stage_cmp.size() == stage_real_diagram.size());
// The missing chunks must be equal across main & staging (otherwise they couldn't have
// been omitted).
assert(missing_main_cmp == missing_stage_cmp);
// The missing part must include at least all transactions in staging which have not been
// modified, or been in a cluster together with modified transactions, since they were
// copied from main. Note that due to the reordering of removals w.r.t. dependency
// additions, it is possible that the real implementation found more unaffected things.
FeeFrac missing_real;
for (const auto& feerate : missing_main_cmp) missing_real += feerate;
FeeFrac missing_expected = sims[1].graph.FeeRate(sims[1].graph.Positions() - sims[1].modified);
// Note that missing_real.fee < missing_expected.fee is possible to due the presence of
// negative-fee transactions.
assert(missing_real.size >= missing_expected.size);
}
}
assert(real->HaveStaging() == (sims.size() > 1));

36
src/txgraph.cpp
View file

@ -140,6 +140,8 @@ public:
void ApplyDependencies(TxGraphImpl& graph, std::span<std::pair<GraphIndex, GraphIndex>> to_apply) noexcept;
/** Improve the linearization of this Cluster. */
void Relinearize(TxGraphImpl& graph, uint64_t max_iters) noexcept;
/** For every chunk in the cluster, append its FeeFrac to ret. */
void AppendChunkFeerates(std::vector<FeeFrac>& ret) const noexcept;
// Functions that implement the Cluster-specific side of public TxGraph functions.
@ -478,6 +480,7 @@ public:
bool IsOversized(bool main_only = false) noexcept final;
std::strong_ordering CompareMainOrder(const Ref& a, const Ref& b) noexcept final;
GraphIndex CountDistinctClusters(std::span<const Ref* const> refs, bool main_only = false) noexcept final;
std::pair<std::vector<FeeFrac>, std::vector<FeeFrac>> GetMainStagingDiagrams() noexcept final;
void SanityCheck() const final;
};
@ -692,6 +695,13 @@ void Cluster::MoveToMain(TxGraphImpl& graph) noexcept
Updated(graph);
}
void Cluster::AppendChunkFeerates(std::vector<FeeFrac>& ret) const noexcept
{
auto chunk_feerates = ChunkLinearization(m_depgraph, m_linearization);
ret.reserve(ret.size() + chunk_feerates.size());
ret.insert(ret.end(), chunk_feerates.begin(), chunk_feerates.end());
}
bool Cluster::Split(TxGraphImpl& graph) noexcept
{
// This function can only be called when the Cluster needs splitting.
@ -1916,6 +1926,32 @@ TxGraph::GraphIndex TxGraphImpl::CountDistinctClusters(std::span<const Ref* cons
return ret;
}
std::pair<std::vector<FeeFrac>, std::vector<FeeFrac>> TxGraphImpl::GetMainStagingDiagrams() noexcept
{
Assume(m_staging_clusterset.has_value());
MakeAllAcceptable(0);
Assume(m_main_clusterset.m_deps_to_add.empty()); // can only fail if main is oversized
MakeAllAcceptable(1);
Assume(m_staging_clusterset->m_deps_to_add.empty()); // can only fail if staging is oversized
// For all Clusters in main which conflict with Clusters in staging (i.e., all that are removed
// by, or replaced in, staging), gather their chunk feerates.
auto main_clusters = GetConflicts();
std::vector<FeeFrac> main_feerates, staging_feerates;
for (Cluster* cluster : main_clusters) {
cluster->AppendChunkFeerates(main_feerates);
}
// Do the same for the Clusters in staging themselves.
for (int quality = 0; quality < int(QualityLevel::NONE); ++quality) {
for (const auto& cluster : m_staging_clusterset->m_clusters[quality]) {
cluster->AppendChunkFeerates(staging_feerates);
}
}
// Sort both by decreasing feerate to obtain diagrams, and return them.
std::sort(main_feerates.begin(), main_feerates.end(), [](auto& a, auto& b) { return a > b; });
std::sort(staging_feerates.begin(), staging_feerates.end(), [](auto& a, auto& b) { return a > b; });
return std::make_pair(std::move(main_feerates), std::move(staging_feerates));
}
void Cluster::SanityCheck(const TxGraphImpl& graph, int level) const
{
// There must be an m_mapping for each m_depgraph position (including holes).

5
src/txgraph.h
View file

@ -162,6 +162,11 @@ public:
* main clusters are counted. Refs that do not exist in the queried graph are ignored. Refs
* can not be null. The queried graph must not be oversized. */
virtual GraphIndex CountDistinctClusters(std::span<const Ref* const>, bool main_only = false) noexcept = 0;
/** For both main and staging (which must both exist and not be oversized), return the combined
* respective feerate diagrams, including chunks from all clusters, but excluding clusters
* that appear identically in both. Use FeeFrac rather than FeePerWeight so CompareChunks is
* usable without type-conversion. */
virtual std::pair<std::vector<FeeFrac>, std::vector<FeeFrac>> GetMainStagingDiagrams() noexcept = 0;
/** Perform an internal consistency check on this object. */
virtual void SanityCheck() const = 0;