bench: fix stateful benchmark setup and inputs#130
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`WalletBalanceMine` duplicated `WalletBalanceClean` exactly. Remove the duplicate registration so the balance benchmark list stays distinct.
`MempoolCheckEphemeralSpends` wrote every prevout to `tx2.vin[0]` instead of `tx2.vin[i]`. That left only one child input pointing at the parent transaction, while the remaining inputs kept default prevouts. Write each prevout to `vin[i]` instead. Add an assertion that the last child input spends the last parent output.
`setup()` in nanobench runs once per epoch, not once per timed call. If an epoch executes the benchmark body multiple times, `setup()` can silently leave later iterations with different preconditions. Fail fast when `setup()` is combined with anything other than `epochIterations(1)`.
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`CHACHA20` and `FSCHACHA20POLY1305` kept one cipher object alive across timed calls. That advanced the stream state across samples, and `FSChaCha20Poly1305` could cross a rekey boundary. Rebuild the cipher in `setup()` for each timed call so each sample starts from the same state.
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Problem
The
CHACHA20andFSCHACHA20POLY1305benchmarks reused a single cipher object across timed calls.That advanced the stream state across samples, so later samples no longer measured work from the same starting point.
A few other benchmarks could benefit from the same iteration-stability treatment, but that is outside the scope of this PR.
While investigating this, it also became clear that
MempoolCheckEphemeralSpendsonly populatedvin[0]in its loop, and thatWalletBalanceMineduplicatedWalletBalanceClean.The same review also showed that nanobench
setup()can be misused as though it runs once per timed call.Fix
Rebuild the
ChaChaciphers insetup()and pair that setup withepochIterations(1)so each timed call starts from the same state.Add a nanobench assertion that
setup()is only used withepochIterations(1).Also fix the ephemeral spend benchmark inputs and remove the duplicate wallet balance benchmark.
Context
Found while reviewing bitcoin#35018, which led to a few additional benchmark fixes.