cryptogera/bitcoin
1
0
Fork 0
mirror of https://github.com/bitcoin/bitcoin.git synced 2026-01-31 10:41:08 +00:00
Code Issues Packages Projects Releases Wiki Activity

optimization: introduce PresaltedSipHasher for repeated hashing

Browse Source 
Replaces the `SipHashUint256Extra` function with the `PresaltedSipHasher` class that caches the constant-salted state (v[0-3] after XORing with keys).
This avoids redundant XOR operations when hashing multiple values with the same keys, benefiting use cases like `SaltedOutpointHasher`.

This essentially 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

Co-authored-by: sipa <pieter@wuille.net>
This commit is contained in:
Lőrinc 2025-02-01 19:21:34 +01:00
parent 20330548cf
commit ec11b9fede
No known key found for this signature in database
GPG Key ID: 669FFF0FFA477A76
6 changed files with 31 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
src/crypto/siphash.cpp
View File

@ -137,17 +137,12 @@ 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 PresaltedSipHasher::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 followup 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;

16
src/crypto/siphash.h
View File

@ -48,6 +48,20 @@ 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 PresaltedSipHasher
{
uint64_t v[4];
public:
explicit PresaltedSipHasher(uint64_t k0, 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)PresaltedSipHasher(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 PresaltedSipHasher.
FastRandomContext ctx;
for (int i = 0; i < 16; ++i) {
uint64_t k0 = ctx.rand64();
@ -146,7 +146,7 @@ BOOST_AUTO_TEST_CASE(siphash)
uint8_t nb[4];
WriteLE32(nb, n);
sip288.Write(nb);
BOOST_CHECK_EQUAL(SipHashUint256Extra(k0, k1, x, n), sip288.Finalize()); // TODO modified in follow-up commit
BOOST_CHECK_EQUAL(PresaltedSipHasher(k0, k1)(x, n), sip288.Finalize());
}
}

9
src/util/hasher.cpp
View File

@ -19,14 +19,15 @@ SaltedWtxidHasher::SaltedWtxidHasher() :
k0{FastRandomContext().rand64()},
k1{FastRandomContext().rand64()} {}
SaltedOutpointHasher::SaltedOutpointHasher(bool deterministic) :
k0{deterministic ? 0x8e819f2607a18de6 : FastRandomContext().rand64()},
k1{deterministic ? 0xf4020d2e3983b0eb : FastRandomContext().rand64()}
SaltedOutpointHasher::SaltedOutpointHasher(bool deterministic) : m_hasher{
deterministic ? 0x8e819f2607a18de6 : FastRandomContext().rand64(),
deterministic ? 0xf4020d2e3983b0eb : FastRandomContext().rand64()}
{}
SaltedSipHasher::SaltedSipHasher() :
m_k0{FastRandomContext().rand64()},
m_k1{FastRandomContext().rand64()} {}
m_k1{FastRandomContext().rand64()}
{}
size_t SaltedSipHasher::operator()(const std::span<const unsigned char>& script) const
{

9
src/util/hasher.h
View File

@ -60,9 +60,7 @@ public:
class SaltedOutpointHasher
{
private:
/** Salt */
const uint64_t k0, k1;
const PresaltedSipHasher m_hasher;
public:
SaltedOutpointHasher(bool deterministic = false);
@ -76,8 +74,9 @@ 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.ToUint256(), id.n);
size_t operator()(const COutPoint& id) const noexcept
{
return m_hasher(id.hash.ToUint256(), id.n);
}
};