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optimization: refactor: Introduce Uint256ExtraSipHasher to cache SipHash constant state

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Previously, only k0 and k1 were stored, causing the constant xor operations to be recomputed in every call to `SipHashUint256Extra`.
This commit adds a dedicated `Uint256ExtraSipHasher` class that caches the initial state (v0-v3) and to perform the `SipHash` computation on a `uint256` (with an extra parameter), hiding the constant computation details from higher-level code and improving efficiency.
This basically brings the precalculations in the `CSipHasher` constructor to the `uint256` specialized SipHash implementation.

> cmake -B build -DBUILD_BENCH=ON -DCMAKE_BUILD_TYPE=Release && cmake --build build -j$(nproc) && build/src/bench/bench_bitcoin -filter='SaltedOutpointHasherBench' -min-time=10000

> C++ compiler .......................... AppleClang 16.0.0.16000026

|               ns/op |                op/s |    err% |     total | benchmark
|--------------------:|--------------------:|--------:|----------:|:----------
|               57.27 |       17,462,299.19 |    0.1% |     11.02 | `SaltedOutpointHasherBench_create_set`
|               11.24 |       88,997,888.48 |    0.3% |     11.04 | `SaltedOutpointHasherBench_hash`
|               13.91 |       71,902,014.20 |    0.2% |     11.01 | `SaltedOutpointHasherBench_match`
|               13.29 |       75,230,390.31 |    0.1% |     11.00 | `SaltedOutpointHasherBench_mismatch`

compared to master:
create_set - 17,462,299.19/17,065,922.04 - 2.3% faster
hash       - 88,997,888.48/83,576,684.83 - 6.4% faster
match      - 71,902,014.20/68,985,850.12 - 4.2% faster
mismatch   - 75,230,390.31/71,942,033.47 - 4.5% faster

> C++ compiler .......................... GNU 13.3.0

|               ns/op |                op/s |    err% |          ins/op |          cyc/op |    IPC |         bra/op |   miss% |     total | benchmark
|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:----------
|              135.38 |        7,386,349.49 |    0.0% |        1,078.19 |          486.16 |  2.218 |         119.56 |    1.1% |     11.00 | `SaltedOutpointHasherBench_create_set`
|               23.67 |       42,254,558.08 |    0.0% |          247.01 |           85.01 |  2.906 |           4.00 |    0.0% |     11.00 | `SaltedOutpointHasherBench_hash`
|               58.95 |       16,962,220.14 |    0.1% |          446.55 |          211.74 |  2.109 |          20.86 |    1.4% |     11.01 | `SaltedOutpointHasherBench_match`
|               76.98 |       12,991,047.69 |    0.1% |          548.93 |          276.50 |  1.985 |          20.25 |    2.3% |     10.72 | `SaltedOutpointHasherBench_mismatch`

compared to master:
create_set -  7,386,349.49/7,312,133.16  - 1% faster
hash       - 42,254,558.08/41,978,882.62 - 0.6% faster
match      - 16,962,220.14/16,549,695.42 - 2.4% faster
mismatch   - 12,991,047.69/12,713,595.35 - 2% faster
This commit is contained in:
Lőrinc 2025-02-01 19:21:34 +01:00
parent 39e33d4928
commit a06a674b43
6 changed files with 27 additions and 21 deletions
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13
src/crypto/siphash.cpp
View file

@ -132,17 +132,12 @@ uint64_t SipHashUint256(uint64_t k0, uint64_t k1, const uint256& val)
return v0 ^ v1 ^ v2 ^ v3;
}
uint64_t SipHashUint256Extra(uint64_t k0, uint64_t k1, const uint256& val, uint32_t extra)
/* Specialized implementation for efficiency */
uint64_t Uint256ExtraSipHasher::operator()(const uint256& val, uint32_t extra) const noexcept
{
/* Specialized implementation for efficiency */
uint64_t v0 = v[0], v1 = v[1], v2 = v[2], v3 = v[3];
uint64_t d = val.GetUint64(0);
// TODO moved in next commit
uint64_t v0 = CSipHasher::C0 ^ k0;
uint64_t v1 = CSipHasher::C1 ^ k1;
uint64_t v2 = CSipHasher::C2 ^ k0;
uint64_t v3 = CSipHasher::C3 ^ k1 ^ d;
v3 ^= d;
SIPROUND;
SIPROUND;
v0 ^= d;

15
src/crypto/siphash.h
View file

@ -48,6 +48,19 @@ public:
* .Finalize()
*/
uint64_t SipHashUint256(uint64_t k0, uint64_t k1, const uint256& val);
uint64_t SipHashUint256Extra(uint64_t k0, uint64_t k1, const uint256& val, uint32_t extra);
class Uint256ExtraSipHasher {
uint64_t v[4];
public:
Uint256ExtraSipHasher(const uint64_t k0, const uint64_t k1) noexcept {
v[0] = CSipHasher::C0 ^ k0;
v[1] = CSipHasher::C1 ^ k1;
v[2] = CSipHasher::C2 ^ k0;
v[3] = CSipHasher::C3 ^ k1;
}
uint64_t operator()(const uint256& val, uint32_t extra) const noexcept;
};
#endif // BITCOIN_CRYPTO_SIPHASH_H

2
src/test/fuzz/integer.cpp
View file

@ -119,7 +119,7 @@ FUZZ_TARGET(integer, .init = initialize_integer)
(void)MillisToTimeval(i64);
(void)SighashToStr(uch);
(void)SipHashUint256(u64, u64, u256);
(void)SipHashUint256Extra(u64, u64, u256, u32);
(void)Uint256ExtraSipHasher(u64, u64)(u256, u32);
(void)ToLower(ch);
(void)ToUpper(ch);
{

4
src/test/hash_tests.cpp
View file

@ -130,7 +130,7 @@ BOOST_AUTO_TEST_CASE(siphash)
ss << TX_WITH_WITNESS(tx);
BOOST_CHECK_EQUAL(SipHashUint256(1, 2, ss.GetHash()), 0x79751e980c2a0a35ULL);
// Check consistency between CSipHasher and SipHashUint256[Extra].
// Check consistency between CSipHasher and SipHashUint256 and Uint256ExtraSipHasher.
FastRandomContext ctx;
for (int i = 0; i < 16; ++i) {
uint64_t k0 = ctx.rand64();
@ -144,7 +144,7 @@ BOOST_AUTO_TEST_CASE(siphash)
CSipHasher sip288 = sip256;
sip288.Write(nb);
BOOST_CHECK_EQUAL(SipHashUint256(k0, k1, x), sip256.Finalize());
BOOST_CHECK_EQUAL(SipHashUint256Extra(k0, k1, x, n), sip288.Finalize()); // TODO modified in follow-up commit
BOOST_CHECK_EQUAL(Uint256ExtraSipHasher(k0, k1)(x, n), sip288.Finalize());
}
}

6
src/util/hasher.cpp
View file

@ -11,9 +11,9 @@ SaltedTxidHasher::SaltedTxidHasher() :
k0{FastRandomContext().rand64()},
k1{FastRandomContext().rand64()} {}
SaltedOutpointHasher::SaltedOutpointHasher(bool deterministic) :
k0{deterministic ? 0x8e819f2607a18de6 : FastRandomContext().rand64()},
k1{deterministic ? 0xf4020d2e3983b0eb : FastRandomContext().rand64()}
SaltedOutpointHasher::SaltedOutpointHasher(bool deterministic) : hasher{
deterministic ? 0x8e819f2607a18de6 : FastRandomContext().rand64(),
deterministic ? 0xf4020d2e3983b0eb : FastRandomContext().rand64()}
{}
SaltedSipHasher::SaltedSipHasher() :

8
src/util/hasher.h
View file

@ -30,12 +30,10 @@ public:
class SaltedOutpointHasher
{
private:
/** Salt */
const uint64_t k0, k1;
const Uint256ExtraSipHasher hasher;
public:
SaltedOutpointHasher(bool deterministic = false);
explicit SaltedOutpointHasher(bool deterministic = false);
/**
* Having the hash noexcept allows libstdc++'s unordered_map to recalculate
@ -47,7 +45,7 @@ public:
* @see https://gcc.gnu.org/onlinedocs/gcc-13.2.0/libstdc++/manual/manual/unordered_associative.html
*/
size_t operator()(const COutPoint& id) const noexcept {
return SipHashUint256Extra(k0, k1, id.hash, id.n);
return hasher(id.hash, id.n);
}
};