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clusterlin tests: separate testing of Search- and SimpleCandidateFinder

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This separates the existing fuzz test into:

* clusterlin_search_finder: establishes SearchCandidateFinder's correctness using the
                            simpler SimpleCandidateFinder.
* clusterlin_simple_finder: establishes SimpleCandidateFinder's correctness using the
                            (even) simpler ExhaustiveCandidateFinder.

rather than trying to do both at once.
This commit is contained in:
Pieter Wuille
2024-08-07 13:40:47 -04:00
parent 77a432ee70
commit a38c38951e
1 changed files with 90 additions and 24 deletions
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114
src/test/fuzz/cluster_linearize.cpp
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@@ -92,9 +92,8 @@ public:
/** A very simple finder class for optimal candidate sets, which tries every subset.
*
* It is even simpler than SimpleCandidateFinder, and is primarily included here to test the
* correctness of SimpleCandidateFinder, which is then used to test the correctness of
* SearchCandidateFinder.
* It is even simpler than SimpleCandidateFinder, and exists just to help test the correctness of
* SimpleCandidateFinder, which is then used to test the correctness of SearchCandidateFinder.
*/
template<typename SetType>
class ExhaustiveCandidateFinder
@@ -640,11 +639,94 @@ FUZZ_TARGET(clusterlin_ancestor_finder)
static constexpr auto MAX_SIMPLE_ITERATIONS = 300000;
FUZZ_TARGET(clusterlin_simple_finder)
{
// Verify that SimpleCandidateFinder works as expected by sanity checking the results
// and comparing them (if claimed to be optimal) against the sets found by
// ExhaustiveCandidateFinder and AncestorCandidateFinder.
//
// Note that SimpleCandidateFinder is only used in tests; the purpose of this fuzz test is to
// establish confidence in SimpleCandidateFinder, so that it can be used to test
// SearchCandidateFinder below.
// Retrieve a depgraph from the fuzz input.
SpanReader reader(buffer);
DepGraph<TestBitSet> depgraph;
try {
reader >> Using<DepGraphFormatter>(depgraph);
} catch (const std::ios_base::failure&) {}
// Instantiate the SimpleCandidateFinder to be tested, and the ExhaustiveCandidateFinder and
// AncestorCandidateFinder it is being tested against.
SimpleCandidateFinder smp_finder(depgraph);
ExhaustiveCandidateFinder exh_finder(depgraph);
AncestorCandidateFinder anc_finder(depgraph);
auto todo = depgraph.Positions();
while (todo.Any()) {
assert(!smp_finder.AllDone());
assert(!exh_finder.AllDone());
assert(!anc_finder.AllDone());
assert(anc_finder.NumRemaining() == todo.Count());
// Call SimpleCandidateFinder.
auto [found, iterations_done] = smp_finder.FindCandidateSet(MAX_SIMPLE_ITERATIONS);
bool optimal = (iterations_done != MAX_SIMPLE_ITERATIONS);
// Sanity check the result.
assert(iterations_done <= MAX_SIMPLE_ITERATIONS);
assert(found.transactions.Any());
assert(found.transactions.IsSubsetOf(todo));
assert(depgraph.FeeRate(found.transactions) == found.feerate);
// Check that it is topologically valid.
for (auto i : found.transactions) {
assert(found.transactions.IsSupersetOf(depgraph.Ancestors(i) & todo));
}
// At most 2^(N-1) iterations can be required: the number of non-empty connected subsets a
// graph with N transactions can have. If MAX_SIMPLE_ITERATIONS exceeds this number, the
// result is necessarily optimal.
assert(iterations_done <= (uint64_t{1} << (todo.Count() - 1)));
if (MAX_SIMPLE_ITERATIONS > (uint64_t{1} << (todo.Count() - 1))) assert(optimal);
// Perform quality checks only if SimpleCandidateFinder claims an optimal result.
if (optimal) {
// Optimal sets are always connected.
assert(depgraph.IsConnected(found.transactions));
// Compare with AncestorCandidateFinder.
auto anc = anc_finder.FindCandidateSet();
assert(anc.feerate <= found.feerate);
if (todo.Count() <= 12) {
// Compare with ExhaustiveCandidateFinder. This quickly gets computationally
// expensive for large clusters (O(2^n)), so only do it for sufficiently small ones.
auto exhaustive = exh_finder.FindCandidateSet();
assert(exhaustive.feerate == found.feerate);
}
}
// Find a topologically valid subset of transactions to remove from the graph.
auto del_set = ReadTopologicalSet(depgraph, todo, reader);
// If we did not find anything, use found itself, because we should remove something.
if (del_set.None()) del_set = found.transactions;
todo -= del_set;
smp_finder.MarkDone(del_set);
exh_finder.MarkDone(del_set);
anc_finder.MarkDone(del_set);
}
assert(smp_finder.AllDone());
assert(exh_finder.AllDone());
assert(anc_finder.AllDone());
assert(anc_finder.NumRemaining() == 0);
}
FUZZ_TARGET(clusterlin_search_finder)
{
// Verify that SearchCandidateFinder works as expected by sanity checking the results
// and comparing with the results from SimpleCandidateFinder, ExhaustiveCandidateFinder, and
// AncestorCandidateFinder.
// and comparing with the results from SimpleCandidateFinder and AncestorCandidateFinder,
// if the result is claimed to be optimal.
// Retrieve an RNG seed, a depgraph, and whether to make it connected, from the fuzz input.
SpanReader reader(buffer);
@@ -658,17 +740,15 @@ FUZZ_TARGET(clusterlin_search_finder)
// the graph to be connected.
if (make_connected) MakeConnected(depgraph);
// Instantiate ALL the candidate finders.
// Instantiate the candidate finders.
SearchCandidateFinder src_finder(depgraph, rng_seed);
SimpleCandidateFinder smp_finder(depgraph);
ExhaustiveCandidateFinder exh_finder(depgraph);
AncestorCandidateFinder anc_finder(depgraph);
auto todo = depgraph.Positions();
while (todo.Any()) {
assert(!src_finder.AllDone());
assert(!smp_finder.AllDone());
assert(!exh_finder.AllDone());
assert(!anc_finder.AllDone());
assert(anc_finder.NumRemaining() == todo.Count());
@@ -684,6 +764,7 @@ FUZZ_TARGET(clusterlin_search_finder)
// Call the search finder's FindCandidateSet for what remains of the graph.
auto [found, iterations_done] = src_finder.FindCandidateSet(max_iterations, init_best);
bool optimal = iterations_done < max_iterations;
// Sanity check the result.
assert(iterations_done <= max_iterations);
@@ -709,7 +790,7 @@ FUZZ_TARGET(clusterlin_search_finder)
}
// Perform quality checks only if SearchCandidateFinder claims an optimal result.
if (iterations_done < max_iterations) {
if (optimal) {
// Optimal sets are always connected.
assert(depgraph.IsConnected(found.transactions));
@@ -723,19 +804,6 @@ FUZZ_TARGET(clusterlin_search_finder)
// Compare with AncestorCandidateFinder;
auto anc = anc_finder.FindCandidateSet();
assert(found.feerate >= anc.feerate);
// Compare with ExhaustiveCandidateFinder. This quickly gets computationally expensive
// for large clusters (O(2^n)), so only do it for sufficiently small ones.
if (todo.Count() <= 12) {
auto exhaustive = exh_finder.FindCandidateSet();
assert(exhaustive.feerate == found.feerate);
// Also compare ExhaustiveCandidateFinder with SimpleCandidateFinder (this is
// primarily a test for SimpleCandidateFinder's correctness).
assert(exhaustive.feerate >= simple.feerate);
if (simple_iters < MAX_SIMPLE_ITERATIONS) {
assert(exhaustive.feerate == simple.feerate);
}
}
}
// Find a topologically valid subset of transactions to remove from the graph.
@@ -745,13 +813,11 @@ FUZZ_TARGET(clusterlin_search_finder)
todo -= del_set;
src_finder.MarkDone(del_set);
smp_finder.MarkDone(del_set);
exh_finder.MarkDone(del_set);
anc_finder.MarkDone(del_set);
}
assert(src_finder.AllDone());
assert(smp_finder.AllDone());
assert(exh_finder.AllDone());
assert(anc_finder.AllDone());
assert(anc_finder.NumRemaining() == 0);
}