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bench: add fluent API for untimed setup steps in `nanobench`
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95/100 · Strong
What the developer wrote
Authored by Lőrinc
bench: add fluent API for untimed setup steps in `nanobench`
Some benchmarks need per-epoch state reset so every measured run does the same work.
Add `Bench::setup(...).run(...)` for untimed per-epoch setup.
The existing `run()` now delegates to `runImpl()` with an empty setup lambda, keeping the old API unchanged.
This vendors the upstream change from `martinus/nanobench`.
The upstream PR also adds tests that verify setup is excluded from timing and runs once before each epoch's iterations.
Those tests are not copied here because wiring them into `src/bench/nanobench.h` outside the benchmarking setup would be awkward.
The `Default is 1ms, so we are mostly relying ...` comment update matches current upstream `nanobench` master.
-------
Running a few benchmarks (which will be migrated in the next commit to use the new setup method) several times to showcase the spread:
./build/bin/bench_bitcoin -filter='^(BnBExhaustion|AddrManAddThenGood|DeserializeBlockTest|DeserializeAndCheckBlockTest|CheckBlockTest|LoadExternalBlockFile|FindByte|WalletCreatePlain|WalletCreateEncrypted|WalletLoadingDescriptors)$'
| ns/op | op/s | err% | total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
| 26,400,542.00 | 37.88 | 0.4% | 0.29 | `AddrManAddThenGood`
| 189,075.00 | 5,288.91 | 0.4% | 0.01 | `BnBExhaustion`
| ns/block | block/s | err% | total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
| 1,237,000.00 | 808.41 | 2.4% | 0.01 | `DeserializeAndCheckBlockTest`
| 893,333.00 | 1,119.40 | 0.6% | 0.01 | `DeserializeBlockTest`
| ns/op | op/s | err% | total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
| 31.62 | 31,622,370.70 | 0.2% | 0.01 | `FindByte`
| 5,506,875.00 | 181.59 | 1.4% | 0.06 | `LoadExternalBlockFile`
| 593,480,333.00 | 1.68 | 0.4% | 6.53 | `WalletCreateEncrypted`
| 174,305,167.00 | 5.74 | 0.7% | 1.93 | `WalletCreatePlain`
| 160,833,875.00 | 6.22 | 0.2% | 0.80 | `WalletLoadingDescriptors`
| ns/op | op/s | err% | total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
| 26,005,125.00 | 38.45 | 1.3% | 0.29 | `AddrManAddThenGood`
| 181,909.67 | 5,497.23 | 0.1% | 0.01 | `BnBExhaustion`
| ns/block | block/s | err% | total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
| 1,223,000.00 | 817.66 | 2.8% | 0.01 | `DeserializeAndCheckBlockTest`
| 892,917.00 | 1,119.92 | 0.7% | 0.01 | `DeserializeBlockTest`
| ns/op | op/s | err% | total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
| 31.58 | 31,660,608.70 | 0.5% | 0.01 | `FindByte`
| 5,612,750.00 | 178.17 | 1.1% | 0.06 | `LoadExternalBlockFile`
| 594,012,250.00 | 1.68 | 0.2% | 6.53 | `WalletCreateEncrypted`
| 174,668,334.00 | 5.73 | 0.8% | 1.92 | `WalletCreatePlain`
| 158,494,375.00 | 6.31 | 0.3% | 0.79 | `WalletLoadingDescriptors`
✓ Specific, descriptive subject✓ Names a concrete action or component✓ Provides detailed explanatory context✓ Explains rationale or failure mode✓ Mentions testing or verification
What changed, and why it matters
This commit is a clean, non-functional change to Bitcoin Core's internal benchmarking header. It adds a new fluent API (bench.setup(...).run(...)) so benchmark authors can run an untimed setup step before each timed epoch. The old run(...) API is preserved by delegating to a new internal runImpl(...) with an empty setup lambda. There is no change to consensus, networking, wallet logic, or any runtime node behavior.
Recommended action
No security action required. This is a benign benchmarking infrastructure change.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The patch vendors an upstream nanobench change into src/bench/nanobench.h. It introduces detail::SetupRunner, a Bench::setup() template method returning a SetupRunner, and a private Bench::runImpl() that accepts a setup lambda and an operation lambda. The existing Bench::run(Op&&) now forwards to runImpl with a no-op setup lambda. A comment about the default minEpochTime is also corrected from ‘zero’ to ‘1ms’. The code is only used in the benchmark executable and does not affect bitcoind or bitcoin-qt.
Changed components
src/bench/nanobench.hInspect captured patch +55 / −1
diff --git a/src/bench/nanobench.h b/src/bench/nanobench.h
index 127240d3..1f798b84 100644
--- a/src/bench/nanobench.h
+++ b/src/bench/nanobench.h
@@ -137,6 +137,11 @@ class Result;
class Rng;
class BigO;
+namespace detail {
+template <typename SetupOp>
+class SetupRunner;
+} // namespace detail
+
/**
* @brief Renders output from a mustache-like template and benchmark results.
*
@@ -819,7 +824,7 @@ public:
/**
* @brief Minimum time each epoch should take.
*
- * Default is zero, so we are fully relying on clockResolutionMultiple(). In most cases this is exactly what you want. If you see
+ * Default is 1ms, so we are mostly relying on clockResolutionMultiple(). In most cases this is exactly what you want. If you see
* that the evaluation is unreliable with a high `err%`, you can increase either minEpochTime() or minEpochIterations().
*
* @see maxEpochTime, minEpochIterations
@@ -1007,7 +1012,21 @@ public:
Bench& config(Config const& benchmarkConfig);
ANKERL_NANOBENCH(NODISCARD) Config const& config() const noexcept;
+ /**
+ * @brief Configure an untimed setup step per epoch (fluent API).
+ *
+ * Example: `bench.setup(...).run(...);`
+ */
+ template <typename SetupOp>
+ detail::SetupRunner<SetupOp> setup(SetupOp setupOp);
+
private:
+ template <typename SetupOp, typename Op>
+ Bench& runImpl(SetupOp& setupOp, Op&& op);
+
+ template <typename SetupOp>
+ friend class detail::SetupRunner;
+
Config mConfig{};
std::vector<Result> mResults{};
};
@@ -1207,14 +1226,44 @@ constexpr uint64_t Rng::rotl(uint64_t x, unsigned k) noexcept {
return (x << k) | (x >> (64U - k));
}
+namespace detail {
+
+template <typename SetupOp>
+class SetupRunner {
+public:
+ explicit SetupRunner(SetupOp setupOp, Bench& bench)
+ : mSetupOp(std::move(setupOp))
+ , mBench(bench) {}
+
+ template <typename Op>
+ ANKERL_NANOBENCH_NO_SANITIZE("integer")
+ Bench& run(Op&& op) {
+ return mBench.runImpl(mSetupOp, std::forward<Op>(op));
+ }
+
+private:
+ SetupOp mSetupOp;
+ Bench& mBench;
+};
+} // namespace detail
+
template <typename Op>
ANKERL_NANOBENCH_NO_SANITIZE("integer")
Bench& Bench::run(Op&& op) {
+ auto setupOp = [] {};
+ return runImpl(setupOp, std::forward<Op>(op));
+}
+
+template <typename SetupOp, typename Op>
+ANKERL_NANOBENCH_NO_SANITIZE("integer")
+Bench& Bench::runImpl(SetupOp& setupOp, Op&& op) {
// It is important that this method is kept short so the compiler can do better optimizations/ inlining of op()
detail::IterationLogic iterationLogic(*this);
auto& pc = detail::performanceCounters();
while (auto n = iterationLogic.numIters()) {
+ setupOp();
+
pc.beginMeasure();
Clock::time_point const before = Clock::now();
while (n-- > 0) {
@@ -1229,6 +1278,11 @@ Bench& Bench::run(Op&& op) {
return *this;
}
+template <typename SetupOp>
+detail::SetupRunner<SetupOp> Bench::setup(SetupOp setupOp) {
+ return detail::SetupRunner<SetupOp>(std::move(setupOp), *this);
+}
+
// Performs all evaluations.
template <typename Op>
Bench& Bench::run(char const* benchmarkName, Op&& op) {
Risk score
Our methodology →Why this scored 15/100
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